vendex and Muscle-Spasticity

Skeletal muscle has the remarkable ability to remodel and adapt, such as the increase in serial sarcomere number (SSN) or fascicle length (FL) observed after overstretching a muscle. This type of remodeling is termed longitudinal muscle fascicle growth, and its impact on biomechanical function has been of interest since the 1960s due to its clinical applications in muscle strain injury, muscle spasticity, and sarcopenia. Despite simplified hypotheses on how longitudinal muscle fascicle growth might influence mechanical function, existing literature presents conflicting results partly due to a breadth of methodologies. The purpose of this review is to outline what is currently known about the influence of longitudinal muscle fascicle growth on mechanical function and suggest future directions to address current knowledge gaps and methodological limitations. Various interventions indicate longitudinal muscle fascicle growth can increase the optimal muscle length for active force, but whether the whole force-length relationship widens has been less investigated. Future research should also explore the ability for longitudinal fascicle growth to broaden the torque-angle relationship's plateau region, and the relation to increased force during shortening. Without a concurrent increase in intramuscular collagen, longitudinal muscle fascicle growth also reduces passive tension at long muscle lengths; further research is required to understand whether this translates to increased joint range of motion. Finally, some evidence suggests longitudinal fascicle growth can increase maximum shortening velocity and peak isotonic power; however, there has yet to be direct assessment of these measures in a neurologically intact model of longitudinal muscle fascicle growth.

Topics: Biomechanical Phenomena; Humans; Muscle Spasticity; Muscle, Skeletal; Range of Motion, Articular; Sarcomeres; Torque

The investigations presented in this chapter lead to the conclusion that proprioceptive afferent inflow to the CNS induced by RPMS elicits various modulatory effects in sensorimotor and cognitive systems. Since the build-up of the conditioning effects is delayed and the effects itself are long-lasting, it has to be assumed that these effects are caused via neuromodulators. Therefore, the presented approach is promising to improve sensorimotor and cognitive disturbances after lesions in the CNS, e.g. after a stroke, by facilitation of reorganization.

Topics: Animals; Cognition; Electric Stimulation; Electromyography; Functional Laterality; Humans; Magnetics; Muscle Spasticity; Peripheral Nerves; Posture; Psychomotor Performance; Somatosensory Cortex; Time Factors; Torque

In clinical settings, the spastic catch is judged subjectively. This study assessed the psychometric properties of objective parameters that define and quantify the severity of the spastic catch in children with cerebral palsy (CP). A convenience sample of children with spastic CP (N=46; age range: 4-16 years) underwent objective spasticity assessments. High velocity, passive stretches were applied to the gastrocnemius (GAS) and medial hamstrings (MEH). Muscle activity was measured with surface electromyography (sEMG), joint angle characteristics using inertial sensors and reactive torque using a force sensor. To test reliability, a group of 12 children were retested after an average of 13 ± 9 days. The angle of spastic catch (AOC) was estimated by three biomechanical definitions: joint angle at (1) maximum angular deceleration; (2) maximum change in torque; and (3) minimum power. Each definition was checked for reliability and validity. Construct and clinical validity were evaluated by correlating each AOC definition to the averaged root mean square envelope of EMG (RMS-EMG) and the Modified Tardieu Scale (MTS). Severity categories were created based on selected parameters to establish face validity. All definitions showed moderate to high reliability. Significant correlations were found between AOC3 and the MTS of both muscles and the RMS-EMG of the MEH, though coefficients were only weak. AOC3 further distinguished between mild, moderate and severe catches. Objective parameters can define and quantify the severity of the spastic catch in children with CP. However, a comprehensive understanding requires the integration of both biomechanical and RMS-EMG data.

Topics: Adolescent; Biomechanical Phenomena; Cerebral Palsy; Child; Child, Preschool; Disability Evaluation; Electrodiagnosis; Electromyography; Female; Humans; Joints; Male; Movement; Muscle Spasticity; Muscle, Skeletal; Psychometrics; Reproducibility of Results; Torque

The objectives of this study were to probe the contribution of spinal neuron persistent sodium conductances to reflex hyperexcitability in human chronic spinal cord injury. The intrinsic excitability of spinal neurons provides a novel target for medical intervention. Studies in animal models have shown that persistent inward currents, such as persistent sodium currents, profoundly influence neuronal excitability, and recovery of persistent inward currents in spinal neurons of animals with spinal cord injury routinely coincides with the appearance of spastic reflexes. Pharmacologically, this neuronal excitability can be decreased by agents that reduce persistent inward currents, such as the selective persistent sodium current inhibitor riluzole. We were able to recruit seven subjects with chronic incomplete spinal cord injury who were not concurrently taking antispasticity medications into the study. Reflex responses (flexion withdrawal and H-reflexes) and volitional strength (isometric maximum voluntary contractions) were tested at the ankle before and after placebo-controlled, double-blinded oral administration of riluzole (50 mg). Riluzole significantly decreased the peak ankle dorsiflexion torque component of the flexion withdrawal reflex. Peak maximum voluntary torque in both dorsiflexion and plantarflexion directions was not significantly changed. Average dorsiflexion torque sustained during the 5-s isometric maximum voluntary contraction, however, increased significantly. There was no effect, however, on the monosynaptic plantar and dorsiflexor H-reflex responses. Overall, these results demonstrate a contribution of persistent sodium conductances to polysynaptic reflex excitability in human chronic spinal cord injury without a significant role in maximum strength production. These results suggest that intrinsic spinal cellular excitability could be a target for managing chronic spinal cord injury hyperreflexia impairments without causing a significant loss in volitional strength.

Topics: Adult; Analysis of Variance; Ankle; Double-Blind Method; Electric Stimulation; Electromyography; Female; Humans; Male; Middle Aged; Movement Disorders; Muscle Contraction; Muscle Spasticity; Muscle, Skeletal; Neuroprotective Agents; Reflex; Riluzole; Sensory Thresholds; Spinal Cord Injuries; Torque

Stiffness and shortening of the calf muscle due to neural or mechanical factors can profoundly affect motor function. The aim of this study was to investigate non-neurally mediated calf-muscle tightness in children with cerebral palsy (CP) before and after botulinum toxin type A (BoNT-A) injection.. Sixteen children with spastic CP (seven females, nine males; eight at Gross Motor Function Classification System level I, eight at level II; age range 4-10 y) and calf muscle spasticity were tested before and during the pharmaceutically active phase after injection of BoNT-A. Measures of passive muscle compliance and viscoelastic responses, hysteresis, and the gradient of the torque-angle curve were computed and compared before and after injection.. Although there was a slight, but significant increase in ankle range of motion after BoNT-A injection and a small, significant decrease in the torque required to achieve plantigrade and 5° of dorsiflexion, no significant difference in myotendinous stiffness or hysteresis were detected after BoNT-A injection.. Despite any effect on neurally mediated responses, the compliance of the calf muscle was not changed and the muscle continued to offer significant resistance to passive motion of the ankle. These findings suggest that additional treatment approaches are required to supplement the effects of BoNT-A injections when managing children with calf muscle spasticity.

Topics: Botulinum Toxins, Type A; Cerebral Palsy; Child; Child, Preschool; Electromyography; Female; Humans; Injections, Intramuscular; Joints; Male; Muscle Spasticity; Muscle, Skeletal; Neuromuscular Agents; Prospective Studies; Range of Motion, Articular; Statistics, Nonparametric; Torque

Conventional methods of rehabilitation in patients with chronic, severe motor impairments after stroke usually do not lessen paresis.. A novel therapeutic approach (assisted movement with enhanced sensation [AMES]) was employed in a medical device phase I clinical trial to reduce paresis and spasticity and, thereby, to improve motor function.. Twenty subjects more than 1 year poststroke with severe motor disability of the upper or lower extremity were studied. A robotic device cycled the ankle or the wrist and fingers at 5 degrees/s through +/-17.5 degrees in flexion and extension while the subject assisted this motion. Feedback of the subject's active torque was displayed on a monitor. Simultaneously, 2 vibrators applied a 60 pps stimulus to the tendons of the lengthening muscles, alternating from flexors to extensors as the joint rotation reversed from extension to flexion, respectively. Subjects treated themselves at home for 30 min/day for 6 months. Every other day prior to treatment, the therapy device performed automated tests of strength and joint positioning. Functional testing was performed prior to enrollment, immediately after completing the protocol, and 6 months later. Functional tests included gait and weight distribution (lower extremity subjects only) and the Stroke Impact Scale.. Most subjects improved on most tests, and gains were sustained for 6 months in most subjects. No safety problems arose.. The AMES strategy appears safe and possibly effective in patients with severe chronic impairments. The mechanism underlying these gains is likely to be multifactorial.

Topics: Adult; Aged; Arm; Biomechanical Phenomena; Exercise Therapy; Feedback; Female; Humans; Joints; Leg; Male; Middle Aged; Movement Disorders; Muscle Spasticity; Muscle, Skeletal; Paresis; Physical Therapy Modalities; Proprioception; Robotics; Stroke; Stroke Rehabilitation; Tendons; Torque; Treatment Outcome; Vibration

To evaluate the feasibility and effects of using motor imagery during therapeutic stretching in individuals with spasticity.. Randomized single-blind controlled pilot trial.. Chronic day care unit, neurological rehabilitation unit and in the community.. Eleven individuals with spasticity in the arm requiring stretching as part of their normal routine.. In addition to their normal stretching routine, subjects in the experimental group received motor imagery during their stretches (n = 6). The control group received progressive muscle relaxation during their stretches (n = 5). The dose varied between 8 and 56 sessions over eight weeks.. Resistance to passive movement, measured with a torque transducer, passive range of movement, measured with an electro-goniometer, Modified Ashworth Scale (MAS) and level of discomfort during the MAS were assessed at baseline and after eight weeks by an independent assessor. These measures were recorded before and after a stretch intervention on both assessments.. Participants, therapists and carers tolerated the techniques well. Compliance was variable and adherence was good. Mixed ANOVA showed no difference over time and no difference between the motor imagery and progressive muscle relaxation group on the primary and secondary outcome measures (P>0.05).. It is feasible to use motor imagery during therapeutic stretching. Statistical power was low due to the large variability in the population and the small sample size. Post-hoc sample size calculation suggests that future studies of this subject should include at least 54 participants per group. Further research is warranted.

Topics: Adult; Aged; Feasibility Studies; Female; Humans; Imagery, Psychotherapy; Male; Middle Aged; Muscle Spasticity; Muscle Stretching Exercises; Pain Measurement; Patient Compliance; Pilot Projects; Range of Motion, Articular; Relaxation Therapy; Single-Blind Method; Torque; Treatment Outcome; Young Adult

Past studies have suggested that acupuncture may reduce spasticity in stroke survivors. We do not know, however, whether acupuncture may enhance the effect of strength training on motor function. This study compared upper-limb motor functional improvement in chronic stroke survivors who received a combination of acupuncture and strength training with that of subjects who received strength training alone. A total of 10 chronic stroke patients with moderate or severe wrist muscle spasticity were recruited for this study. The study used a crossover design with a random order of either combined electroacupuncture and strength training or strength training alone. Each subject received one of the two types of treatment twice a week for the first 6 weeks and switched to the other for another 6 weeks. Quantitative measurements of wrist spasticity, active wrist extension range of motion, isometric wrist strength, and clinical evaluation with Fugl-Meyer (FM) upper-limb motor scores were conducted before and after either treatment. After the combined treatment, the quantitative spasticity level, active wrist extension range of motion (increased by a mean of 16.3 degrees), and FM upper-limb motor score (increased by a mean of 4.9 points) changed significantly (p < 0.01) but no significant changes were noted in isometric wrist strength. The strength training alone resulted in no significant changes to any measured variable. The results of the current study indicate that the combined acupuncture and strength training treatment reduced muscle spasticity and may have improved motor function for chronic stroke survivors with moderate or severe muscle spasticity.

Topics: Adult; Aged; Arm; Cross-Over Studies; Electroacupuncture; Female; Humans; Male; Middle Aged; Muscle Spasticity; Muscle Strength; Pilot Projects; Range of Motion, Articular; Recovery of Function; Stroke; Survivors; Torque; Treatment Outcome

To quantitatively assess the change in spasticity of the impaired wrist joint in chronic stroke patients after electro-acupuncture treatment.. Crossover design.. University medical center research laboratory.. Seven chronic stroke subjects (age, 63.14+/-7.01y).. Participants received two 6-week treatment regimens: combined electro-acupuncture and strengthening twice a week, and strengthening twice a week only. Muscle strength and spasticity of the wrist joint were quantified by using the Biodex multijoint System 3 Pro. Electro-acupuncture was given through a commercial electro-acupuncture device.. Velocity sensitivity of averaged speed-dependent reflex torque (VASRT); segmented averaged speed-dependent reflex torque (SASRT); Modified Ashworth Scale (MAS) scores; and integrated electromyographic activity of the affected wrist flexors during passive stretch of the affected wrist joint.. VASRT was reduced significantly in the combined treatment group (P=.02) after the 6-week period, but not in the strengthening-only group (P=.23); however, no significant immediate effect of electro-acupuncture was observed (P>.05). MAS scores also showed a significant reduction (P<.01). SASRT did not differ significantly across different positions of the joint or across velocity; however, significant differences were present between the 2 treatment groups (P<.05) for each position and at all the velocities except at 20 degrees /s. Integrated electromyographic activity showed a trend for reduction after the combined treatment.. A combination of electro-acupuncture and muscle strengthening exercise for 6 weeks significantly reduced spasticity. The effect of spasticity reduction was consistent across different joint positions and different velocities of passive stretch.

Topics: Aged; Cross-Over Studies; Electroacupuncture; Electromyography; Exercise Therapy; Female; Humans; Male; Middle Aged; Muscle Spasticity; Muscle Strength; Stroke; Survivors; Torque; Wrist Joint

This study investigated the effects of spasticity in the hamstrings and quadriceps muscles on gait parameters including temporal spatial measures, knee position, excursion and angular velocity in 25 children with spastic diplegic cerebral palsy (CP) as compared to 17 age-matched peers. While subjects were instructed to relax, an isokinetic device alternately flexed and extended the left knee at one of the three constant velocities 30 degrees/s, 60 degrees/s and 120 degrees/s, while surface electromyography (EMG) electrodes over the biceps femoris and the rectus femoris recorded muscle activity. Patients then participated in 3D gait analysis at a self-selected speed. Results showed that, those with CP who exhibited heightened stretch responses (spasticity) in both muscles, had significantly slower knee angular velocities during the swing phase of gait as compared to those with and without CP who did not exhibit stretch responses at the joint and the tested speeds. The measured amount (torque) of the resistance to passive flexion or extension was not related to gait parameters in subjects with CP; however, the rate of change in resistance torque per unit angle change (stiffness) at the fastest test speed of 120 degrees/s showed weak to moderate relationships with knee angular velocity and motion during gait. For the subset of seven patients with CP who subsequently underwent a selective dorsal rhizotomy, knee angular extension and flexion velocity increased post-operatively, suggesting some degree of causality between spasticity and movement speed.

Topics: Biomechanical Phenomena; Cerebral Palsy; Child; Electromyography; Gait Disorders, Neurologic; Humans; Knee Joint; Muscle Spasticity; Muscle, Skeletal; Postoperative Period; Range of Motion, Articular; Reflex, Stretch; Rhizotomy; Torque

To investigate the influence of rhythmic passive movements of the legs on the reduction of spasticity after spinal cord injury (SCI).. Swiss Paraplegic Centre Nottwil, Switzerland.. A total of 10 subjects with motor complete SCI were treated with a cycling device for half an hour. Before and after cycling their spasticity was tested with an isokinetic dynamometer. The subjects were tested one week later by exactly the same procedure with a half an hour break instead of the cycling. Subjects were asked about their spasticity before and after the cycling and break.. There was no significant difference in elicited peak torque either before and after the cycling, or before and after the break (MANOVA, P<0.05). Six out of 10 subjects estimated their spasticity as less after the cycling.. With the isokinetic dynamometer, it was not possible to show an effect of passive cycling on spasticity reduction. However, six out of 10 of the subjects estimated their spasticity to be less after cycling. This positive effect might be attributed to a reduced spasticity in the trunk and/or to the attention the subjects perceived during the intervention.

Topics: Adult; Biomechanical Phenomena; Female; Humans; Knee Joint; Male; Middle Aged; Multivariate Analysis; Muscle Spasticity; Muscle, Skeletal; Physical Therapy Modalities; Reaction Time; Spinal Cord Injuries; Torque; Treatment Outcome

Although numerous studies revealed that isokinetic dynamometers were valuable tools for assessing spastic hypertonia, no standard methodology using such devices is currently widespread in clinical setting. The aim of this study was to standardize a protocol to assess spastic hypertonia in the triceps surae.. The passive resistance during dorsiflexions imposed from 10 to 300 degrees /s with an isokinetic dynamometer was measured at the neutral position in 15 patients with spastic hypertonia and 12 healthy subjects. The normalized passive resistance was obtained by expressing raw passive resistance as a percent of the values measured at the lowest velocity (10 degrees /s). EMG signals from plantar and dorsiflexors were also recorded.. While no significant difference between spastic patients and control subjects was observed in raw passive resistance values, the difference was significant for each tested velocity when considering the normalized values. Furthermore, the Ashworth score was significantly correlated with the normalized passive resistance for each velocity whereas no correlation was observed with the raw passive resistance. For the patients, except at the highest velocity, the normalized passive resistance was not affected by the fact that reflex responses in the triceps surae were elicited or not.. The normalized passive resistance, expressed with respect to the initial one, i.e., measured at very low velocity, seems a very effective parameter to quantify the velocity-dependent increase in resistance to passive stretch in spastic plantarflexors. However, while the simplicity of the isokinetic tests and the reduced time of data treatment seems to support the clinical use of this methodology, further investigations are required to definitely standardize the protocol.

Topics: Adult; Aged; Aged, 80 and over; Ankle Joint; Diagnosis, Computer-Assisted; Female; Humans; Male; Middle Aged; Models, Biological; Movement; Muscle Contraction; Muscle Hypertonia; Muscle Spasticity; Muscle, Skeletal; Physical Exertion; Severity of Illness Index; Statistics as Topic; Torque

An intelligent stretching device was developed to treat the spastic/contractured ankle of neurologically impaired patients. The device stretched the ankle safely throughout the range of motion (ROM) to extreme dorsiflexion and plantarflexion until a specified peak resistance torque was reached with the stretching velocity controlled based on the resistance torque. The ankle was held at the extreme position for a period of time to let stress relaxation occur before it was rotated back to the other extreme position. Stretching was slow at the joint extreme positions, making it possible to reach a larger ROM safely and it was fast in the middle ROM so the majority of the treatment was spent in stretching the problematic extreme ROM. Furthermore, the device evaluated treatment outcome quantitatively in multiple aspects, including active and passive ROM, joint stiffness and viscous damping and reflex excitability. The stretching resulted in considerable changes in joint passive ROM, stiffness, viscous damping and reflex gain. The intelligent control and yet simple design of the device suggest that with appropriate simplification, the device can be made portable and low cost, making it available to patients and therapists for frequent use in clinics/home and allowing more effective treatment and long-term improvement.

Topics: Adult; Ankle Joint; Artificial Intelligence; Contracture; Elasticity; Equipment Design; Feasibility Studies; Humans; Male; Middle Aged; Motion Therapy, Continuous Passive; Muscle Spasticity; Range of Motion, Articular; Reflex, Stretch; Rotation; Sensitivity and Specificity; Stroke; Torque; Treatment Outcome; Viscosity

The effects of long-term functional electrical stimulation (FES)-assisted walking on ankle dynamic stiffness were examined in spinal cord-injured (SCI) subjects with incomplete motor function loss. A parallel-cascade system identification method was used to identify intrinsic and reflex contributions to dynamic ankle stiffness at different ankle positions while subjects remained relaxed. Intrinsic stiffness dynamics were well modeled by a linear second-order model relating intrinsic torque to joint position. Reflex stiffness dynamics were accurately described by a linear third-order model relating halfwave rectified velocity to reflex torque. We examined four SCI subjects before and after long-term FES-assisted walking (> 16 mo). Another SCI subject, who used FES for only five months was examined 12 mo latter to serve as a non-FES, SCI control. Reflex stiffness decreased in FES subjects by an average of 53% following FES-assisted walking, intrinsic stiffness also dropped by 45%. In contrast, both reflex and intrinsic stiffness increased in the non-FES, SCI control. These findings suggest that FES-assisted walking may have therapeutic effects, helping to reduce abnormal joint stiffness.

Topics: Adult; Ankle Joint; Cervical Vertebrae; Chronic Disease; Elasticity; Electric Stimulation Therapy; Female; Follow-Up Studies; Gait Disorders, Neurologic; Humans; Longitudinal Studies; Lumbar Vertebrae; Male; Middle Aged; Models, Biological; Muscle Spasticity; Muscle, Skeletal; Range of Motion, Articular; Reflex, Stretch; Sensitivity and Specificity; Spinal Cord Injuries; Stress, Mechanical; Thoracic Vertebrae; Torque; Treatment Outcome; Walking

To measure spasticity of the knee flexors and extensor muscles in two different hip positions.. Swiss Paraplegic Center Nottwil, Switzerland.. Twenty spinal cord injured (SCI) patients with complete lesions were tested with a torque-velocity dynamometer in the following positions: (1) supine with a hip angle of 0 degrees; (2) sitting with a hip angle of 90 degrees. The excursion of the knee was measured for both positions using a goniometer. Two flexion/extension movements of the knee were performed at a speed of 10 degrees per sec. A further four flexion/extension movements over the same trajectory were made at a speed of 120 degrees per sec. Eccentric peak torques were measured continuously during movement of both legs for both speeds.. At a speed of 120 degrees per second, there was a significant difference in stretch reflex of the hamstrings and quadriceps femoris muscles for the two positions (Wilcoxon's paired t-test, P<0.05). Excitability was higher for the quadriceps femoris muscles in supine than in sitting position. For the hamstrings, the effect was reversed. Significant differences between sitting and supine position were not found for the speed of 10 degrees per sec. Test-retest reliability was high for the movements of 120 degrees per sec but low for 10 degrees per sec.. Our findings indicate that for a reliable and comparable measurement of spasticity, an exact description of test position and procedure is essential.

Topics: Adult; Cervical Vertebrae; Hip; Humans; Isotonic Contraction; Knee; Middle Aged; Muscle Spasticity; Muscle, Skeletal; Paralysis; Posture; Reflex, Stretch; Reproducibility of Results; Spinal Cord Injuries; Thoracic Vertebrae; Torque

Hip adductor spasticity and strength in participants with cerebral palsy (CP) were quantified before and after selective dorsal rhizotomy (SDR) and intensive physical therapy. Twenty-four participants with cerebral palsy (CP group) and 35 non-disabled participants (ND controls) were tested with a dynamometer (OP group: mean age 8 years 5 months, 13 males, 11 females; ND group: mean age 8 years 6 months, 19 males, 16 females). According to the Gross Motor Function Classification System (GMFCS), of the 24 participants with CP, eight were at level I, six were at level II, and 10 participants were at level III. For the spasticity measure, the dynamometer quantified the resistive torque of the hip adductors during passive abduction at 4 speeds. The adductor strength test recorded a maximum concentric contraction. CP group spasticity was significantly reduced following SDR and adductor strength was significantly increased after surgery. Both pre- and postoperative values remained significantly less than the ND controls. Spasticity results agreed with previous studies indicating a reduction. Strength results conflicted with previous literature subjectively reporting a decrease following SDR. However, results agreed with previous objective investigations examining knee and ankle strength, suggesting strength did not decrease following SDR.

Topics: Adolescent; Ankle; Cerebral Palsy; Child; Child, Preschool; Female; Ganglia, Spinal; Hip; Humans; Knee; Male; Muscle Spasticity; Muscle Weakness; Physical Therapy Modalities; Prospective Studies; Range of Motion, Articular; Rhizotomy; Torque; Treatment Outcome

To quantify changes in spastic hypertonia during repeated passive isokinetic knee movements in stroke patients and to assess the role of muscle activity.. A between-groups design with repeated measures.. Rehabilitation center for stroke patients.. Ten stroke patients with hypertonia and 10 healthy subjects matched for age and gender.. With an isokinetic apparatus, movements were imposed on the knee in series of 10 repetitions at speeds of 60 degrees /s, 180 degrees /s, and 300 degrees /s.. Spastic hypertonia was assessed on the basis of torque measurement and electromyographic activity of the quadriceps, hamstrings, and gastrocnemius muscles.. Compared with the controls, stroke patients presented a significantly stronger torque reduction during the mid- and endphases of movements at all speeds tested (P<.05). The strongest torque decline occurred during knee flexion and during the first movements. The effect increased toward the end phase of movements and with increasing speeds. The effect of movement repetitions on torque measurements was unchanged after electromyographic activity was included in the statistical analysis, except during extension movements at 180 degrees /s and 300 degrees /s.. Passive movements of the knee induced a decrease of spastic hypertonia in stroke patients through a combination of reflexive and mechanical factors. The role of these mechanisms is velocity dependent and differs for flexion and extension movements.

Topics: Biomechanical Phenomena; Electromyography; Female; Humans; Knee; Male; Middle Aged; Motion Therapy, Continuous Passive; Muscle Spasticity; Range of Motion, Articular; Reference Values; Stroke; Stroke Rehabilitation; Torque; Treatment Outcome

The impact of muscle biomechanics on spasticity was assessed by comparison of the reflex responses of the elbow and metacarpophalangeal (MCP) flexor muscles in individuals with chronic spastic hemiplegia following stroke. Specifically, methods were developed to quantify reflex responses and to normalize these responses for comparison across different muscle groups. Stretch reflexes were elicited in the muscles of interest by constant velocity ramp-and-hold stretches at the corresponding joint. The muscles were initially passive, with the joint placed in a midrange position. Estimates of biomechanical parameters were used to convert measured reflex joint torque and joint angle into composite flexor muscle stress and stretch. We found that the stretch reflex response for the MCP muscle group had a 74% greater mean stiffness modulus than that for the elbow muscle group, and that the reflex threshold was initiated at an 80% shorter mean muscle stretch. However, we determined that initial normalized fiber length was significantly greater for the experiments involving the MCP muscles than for those involving the elbow muscles. Increasing the initial composite fiber length of the elbow flexors produced significant reduction of the reflex threshold (p<0.001), while decreasing the initial length of the MCP flexors significantly reduced their measured reflex stiffness (p<0.001). Thus, biomechanical parameters of muscle do appear to have an important effect on the stretch reflex in individuals with impairment following stroke, and this effect should be accounted for when attempting to quantify spasticity.

Topics: Aged; Analysis of Variance; Elasticity; Elbow; Hemiplegia; Humans; Metacarpophalangeal Joint; Middle Aged; Models, Biological; Muscle Spasticity; Muscle, Skeletal; Reflex, Stretch; Reproducibility of Results; Rotation; Sensitivity and Specificity; Stroke; Torque

Movement impairments about a single joint in stroke patients may be related to deficits in the central regulation of stretch reflex (SR) thresholds of agonist and antagonist muscles. One boundary of the SR threshold range for elbow flexor and extensor muscles was measured in hemiparetic subjects by analysing electromyographic activity during stretching of relaxed muscles at seven different velocities. For each velocity, dynamic SR thresholds were measured as angles at which electromyographic activity appeared. These data were used to determine the sensitivity of the threshold to velocity and the static SR thresholds for flexors and extensors. In contrast to relaxed muscles in healthy subjects, static flexor and extensor thresholds lay within the physiological range in 11/12 and 4/12 subjects, respectively. This implies that, in the range between the static SR threshold and one of the physiological joint limits, relaxation of the muscle was impossible. Subjects then made slow movements against different loads to determine their ranges of active movement. Maximal flexor and extensor torques were lower in hemiparetic subjects throughout the angular range. In some subjects, ranges were found in which no active torque could be produced in either extensor or both muscle groups. These ranges were related to the boundary values of SR thresholds found during passive muscle stretch. The range in which reciprocally organized agonist and antagonist muscle activity could be generated was limited in all but one subject. When attempting to produce torque from positions outside their measured range of movement, excessive muscle coactivation occurred, typically producing no or paradoxical motion in the opposite direction. Results suggest a relationship between spasticity measured at rest and the movement deficit in stroke by demonstrating a link between motor deficits and control deficits in the central regulation of individual SR thresholds.

Topics: Adult; Aged; Biomechanical Phenomena; Elbow Joint; Electromyography; Female; Humans; Male; Middle Aged; Movement; Movement Disorders; Muscle Contraction; Muscle Spasticity; Muscle, Skeletal; Paresis; Range of Motion, Articular; Reflex, Stretch; Reproducibility of Results; Sensory Thresholds; Stroke; Torque

To determine the value of isokinetic dynamometric measurement of passive resistance in quantifying spasticity.. Turkey.. Thirty-three spastic spinal cord-injured patients and 14 age-matched normal individuals were studied. Five consecutive flexion-extensions of the knee, abduction-adductions of the hip, and dorsal-plantar flexions of the ankle were performed at specific velocities (15, 30, 60, 90 and 120 degrees /s) using a computerized isokinetic dynamometer set at the continuous passive motion mode. We recorded maximum torque and the sum of torque amplitudes for five repetitions of each type of joint motion at all velocities.. Maximum torque values and the sum of torque amplitudes were both significantly higher in spastic patients than in controls, and there was a positive correlation between torque values and Ashworth scores. There was no significant linear increase in torque values associated with increasing velocity for any of the motions in either controls or patients.. Isokinetic dynamometric measurement of passive resistance appeared to be a valuable tool for assessing and quantifying spasticity, as well as other types of hypertonus.

Topics: Adult; Ankle; Female; Hip; Humans; Knee; Male; Manometry; Movement; Muscle Contraction; Muscle Spasticity; Muscle, Skeletal; Spinal Cord Injuries; Torque

Despite the belief that after cerebral infarction only limited functional gains are possible beyond the subacute period, we tested the hypothesis that a 12-week program of "task-oriented" treadmill exercise would increase muscle strength and decrease spastic reflexes in chronic hemiparetic patients.. Fourteen subjects, aged 66+/-3 (mean+/-SEM) years, with residual gait deviations due to remote stroke (>6 months), underwent repeated measures of reflexive and volitional (concentric and eccentric) torque with use of isokinetic dynamometry on the hamstring musculature bilaterally. Torque output was measured at 4 angular velocities (30(o), 60(o), 90(o), and 120(o)/s).. After 3 months of 3 times/wk low-intensity aerobic exercise, there were significant main effects (2 legs [P<0.01]x2 times [P<0. 01]x4 angular velocities [P<0.05]) for concentric torque production. Torque/time production in the concentric mode also improved significantly in the paretic (50%, P<0.01) and nonparetic hamstrings (31%, P<0.01). Eccentric torque/time production increased by 21% (P<0.01) and 22% (P<0.01) in the paretic and nonparetic hamstrings, respectively. Passive (reflexive) torque/time generation in the paretic hamstrings decreased by 11% (P<0.027). Reflexive torque/time was unchanged in the nonparetic hamstrings (P=0.45).. These findings provide evidence that progressive treadmill aerobic exercise training improves volitional torque and torque/time generation and reduces reflexive torque/time production in the hemiparetic limb. Strength changes associated with improved functional mobility in chronic hemiparetic stroke survivors after treadmill training will be reported in future articles.

Topics: Aged; Aged, 80 and over; Chronic Disease; Exercise Therapy; Female; Humans; Male; Middle Aged; Muscle Spasticity; Reflex, Abnormal; Stroke; Tendons; Torque; Volition

The goal of this study was to validate a series elastic actuator (SEA)-based robotic arm that can mimic three abnormal muscle behaviors, namely lead-pipe rigidity, cogwheel rigidity, and spasticity for medical education training purposes. Key characteristics of each muscle behavior were first modeled mathematically based on clinically-observed data across severity levels. A controller that incorporated feedback, feedforward, and disturbance observer schemes was implemented to deliver haptic target muscle resistive torques to the trainee during passive stretch assessments of the robotic arm. A series of benchtop tests across all behaviors and severity levels were conducted to validate the torque estimation accuracy of the custom SEA (RMSE: ~ 0.16 Nm) and the torque tracking performance of the controller (torque error percentage: < 2.8 %). A clinical validation study was performed with seven experienced clinicians to collect feedback on the task trainer's simulation realism via a Classification Test and a Disclosed Test. In the Classification Test, subjects were able to classify different muscle behaviors with a mean accuracy > 87 % and could further distinguish severity level within each behavior satisfactorily. In the Disclosed Test, subjects generally agreed with the simulation realism and provided suggestions on haptic behaviors for future iterations. Overall, subjects scored 4.9 out of 5 for the potential usefulness of this device as a medical education tool for students to learn spasticity and rigidity assessment.

Topics: Computer Simulation; Elbow; Elbow Joint; Humans; Muscle Spasticity; Torque; Upper Extremity

Botulinum neurotoxin (BoNT) is commonly used to manage focal spasticity in stroke survivors. This study aimed to a perform comprehensive assessment of the effects of BoNT injection. Twelve stroke subjects with spastic hemiplegia (age: 52.0 ± 10.1 year; 5 females) received 100 units of BoNT to the spastic biceps brachii muscles. Clinical, biomechanical, electrophysiological, and neuro-motor assessments were performed one week (wk) before (pre-injection), 3 weeks (wks) after, and 3 months (mons) after BoNT injection. BoNT injection significantly reduced spasticity, muscle strength, reflex torque, and compound muscle action potential (CMAP) amplitude of spastic elbow flexors (all

Topics: Action Potentials; Adult; Biomechanical Phenomena; Botulinum Toxins; Chronic Disease; Cross-Sectional Studies; Elbow; Female; Hemiplegia; Humans; Male; Middle Aged; Muscle Spasticity; Muscle, Skeletal; Neuromuscular Agents; Reflex; Stroke; Survivors; Torque

This paper is to develop a simplified estimation method of internal torque for clinical use, such as spasticity assessment. Compared with many parameters to be tuned, the proposed estimation method only has a single tuning parameter by simplifying the neuro-musculoskeletal model. Moreover, based on forward dynamics, the proposed method uses EMG signals as the input, and uses muscle activation dynamics and musculotendon dynamics to calculate internal torque. A biomechanical method based on dynamometer was applied to determine the tuning parameter and to validate the estimation result of the proposed model. Through a pilot study with healthy subjects and stroke patients, we found that the proposed estimation method would be helpful for spasticity assessment.

Topics: Case-Control Studies; Elbow; Electromyography; Humans; Muscle Spasticity; Muscle, Skeletal; Pilot Projects; Reflex, Abnormal; Stroke; Torque

Topics: Adult; Biomechanical Phenomena; Cerebral Palsy; Computer Simulation; Female; Foot; Gait; Hamstring Muscles; Humans; Knee Joint; Male; Models, Biological; Muscle Spasticity; Reflex, Stretch; Robotics; Torque

The modified Tardieu Scale (MTS) is a clinical tool for the measurement of muscle spasticity. The present study aimed to investigate the relationship between the MTS and the slope of the work-velocity curve as a biomechanical measure in assessing knee extensor muscle spasticity in patients with stroke.. Thirty patients with stroke (22 female, 8 male; mean age 55.4 ± 12.0 years) participated in this study. The knee extensor spasticity was assessed with the MTS. An isokinetic dynamometer was used to move the knee passively from full extension to 90° flexion at speeds of 60°/s, 120°/s, 180°/s, and 240°/s to collect torque-angle data. The slope of the work-velocity curve was calculated using linear regression [J/(°/s)].. The lack of significant relationship between the MTS and the slope of work-velocity curve may question the usefulness of the MTS as a valid measure of muscle spasticity after stroke.

Topics: Adult; Aged; Biomechanical Phenomena; Cross-Sectional Studies; Female; Humans; Knee; Male; Middle Aged; Muscle Spasticity; Muscle Strength Dynamometer; Outcome Assessment, Health Care; Range of Motion, Articular; Stroke; Torque

The conventional tools to measure spasticity exhibited insufficient test-retest or inter-rater reliability. Therefore, the spasticity measurement using an isokinetic device has been proposed to improve these reliabilities of the angle of catch (AoC) measurements; however, this proposal has not been investigated in a standardized manner. In this study, the comparison of the AoC measurement was performed using two modes (isokinetic and manual motion) to investigate whether the standardized isokinetic motion could increase the reliabilities. Motion consistency was calculated using a newly developed index. To analyze the effect of the motion standardization, AoC were estimated using EMG data for both modes, and to compare the measurement reliability, AoC for isokinetic mode was estimated using both EMG and torque data. Although the test-retest reliability for manual motion was excellent, the use of isokinetic motion improved it to the level of extremely excellent. Intraclass correlation coefficient (ICC) for the inter-rater reliability of manual motion was 0.788, which was near the lower limit of the excellent. Isokinetic motion improved it to the ICC of 0.890 and 0.931 based on the EMG and torque, respectively. These improvements in reliabilities reduced the measurement errors, sample size, and need for the same rater in clinical trials.

Topics: Adult; Aged; Elbow; Elbow Joint; Electromyography; Female; Humans; Male; Middle Aged; Muscle Spasticity; Muscle, Skeletal; Range of Motion, Articular; Reflex, Stretch; Reproducibility of Results; Stroke; Torque

This paper presents a method based on a human upper limb model that assesses the severity of spasticity in patients with stroke objectively. The kinematic model consists of four moving segments connected by four joints. The joint torques are computed using inverse dynamics with measurements from three inertial measurement units (IMUs) attached to the participant's upper limb. The muscle activations are estimated using the joint torques via a musculoskeletal model which consists of 22 muscles. The severity of spasticity is then quantified by measuring the tonic stretch reflex threshold (TSRT) of the participant. 15 patient participants participated in the experiments where they were assessed by two qualified therapists using modified Ashworth scale (MAS), and their motions and EMG signals were captured at the same time. Using the upper limb model, the TSRT of each patient was measured and ranked. The estimated muscle activation profiles have a high correlation (0.707) to the EMG signal profiles. The null hypothesis that the rankings of the severity using the model and the MAS assessment have no correlation has been tested, and was rejected convincingly ( ). These findings suggest that the model has the potential to complement the existing practices by providing an alternative evaluation method.

Topics: Adult; Aged; Algorithms; Biomechanical Phenomena; Electromyography; Female; Humans; Joints; Male; Middle Aged; Models, Anatomic; Muscle Spasticity; Muscle, Skeletal; Musculoskeletal System; Reflex, Stretch; Reproducibility of Results; Robotics; Stroke Rehabilitation; Torque; Upper Extremity

The pendulum test is a sensitive clinical assessment of spasticity where the lower leg is dropped from the horizontal position and features of limb motion are recorded. Three key kinematic features are associated with the degree of severity of spasticity in children with cerebral palsy: decreased initial limb excursion, reduced number of limb oscillations, and a non-vertical resting limb angle. While spasticity is attributed to increased velocity-dependent resistance to motion, prior models simulating increased sensorimotor feedback of muscle velocity fail to explain the key pendulum test kinematic outcomes in spastic individuals. Here we hypothesized that increased muscle tone, causing a transient increase in muscle force, i.e. short-range stiffness, could account for reduced first swing excursion and non-vertical resting limb angle. We further hypothesized that hyperreflexia modeled based on muscle fiber force, and not velocity, feedback would be necessary to reduce the number of oscillations because of its interaction with transiently increased muscle force due to short-range stiffness. We simulated the lower leg as a torque-driven single-link pendulum. Muscle tone was modeled as a constant baseline joint torque, short-range stiffness torque was dependent on the level of muscle tone, and delayed sensory feedback torque to simulate reflex activity was based on either muscle velocity or force. Muscle tone and transient short-range stiffness were necessary to simulate decreased initial swing excursion and non-vertical resting leg angle. Moreover, the reduction in the number of oscillations was best reproduced by simulating stretch reflex activity in terms of force, and not velocity, feedback. Varying only baseline muscle torque and reflex gain, we simulated a range of pendulum test kinematics observed across different levels of spasticity. Our model lends insight into physiological mechanisms of spasticity whose contributions can vary on an individual-specific basis, and potentially across different neurological disorders that manifest spasticity as a symptom.

Topics: Adolescent; Adult; Biomechanical Phenomena; Cerebral Palsy; Child; Electromyography; Feedback, Sensory; Humans; Middle Aged; Models, Biological; Muscle Spasticity; Muscle Tonus; Muscle, Skeletal; Physical Therapy Modalities; Reflex, Stretch; Severity of Illness Index; Torque; Young Adult

Spasticity of the elbow was generally assessed by repeated passive stretch movement, including the modified Ashworth Scale (MAS) from physiotherapist, and biomechanics analysis of the movement. The MAS-based method depends on the subjective evaluations and the performance of biomechanics analysis assessment is affected by the individual difference. Therefore, the normalization to reduce the individual difference for the assessment of spasticity is very important. In this study, the elbow spasticity was assessed with MAS by one skillful physiotherapist and biomechanics measurements during repetitive passive isokinetic movements at velocity of 60 degree$/$second. 20 post-stroke patients with elbow spasticity caused by hemorrhagic cerebral damage were divided into three groups according to the MAS grades (MAS $=1, 1+$, 2). The torque and position were recorded when the patients extension their elbows passively. The mean stiffness and the mean torque features of the passive isokinetic were calculated. Two normalization factors for biomechanics analysis assessment were investigated: body weight normalization factor and maximum isometrics volunteer contraction normalization factor. Spearman correlation analysis was used to investigate the relationship between the features and spasticity grades. The results showed that the correlation between MAS and two biomechanics features (mean stiffness, mean torque) were significant improved. For mean stiffness feature, the correlation coefficients were $-0.313, -0.563$ and -0.603 individually for non-normalization, body weight normalization and maximum isometrics volunteer contraction normalization. For mean torque feature, the correlation coefficients were $-0.260, -0.523$ and -0.691, respectively. These results suggest that the normalization methods would be helpful for the assessment of spasticity in biomechanics and will be a necessary way of spasticity estimation in clinical methods.

Topics: Body Weight; Brain Injuries; Elbow; Elbow Joint; Female; Humans; Male; Movement; Muscle Spasticity; Range of Motion, Articular; Stroke; Torque

Stroke affects multiple joints in the arm with stereotypical patterns of arm deformity involving the shoulder, elbow, wrist, and hand and with disrupted coordination of multiple joints in active movements. However, there is a lack of systematic methods to evaluate multi-joints and multi-degree of freedoms (DOF) neuro-mechanical changes, especially for complex systems with three or more joints/DOFs involved. This paper used a novel systematic method to characterize dynamics and control of the shoulder, elbow, and wrist of the human arm individually and simultaneously, including the couplings across the multiple joints during controlled movements. A novel method was developed to decompose the complex system into manageable single-joint level for more reliable characterizations. The method was used in clinical studies to characterize the multi-joint changes associated with spastic impaired arm of 11 patients post stroke and 12 healthy controls. It was found that stroke survivors showed not only increased stiffness at the individual joints locally but also significantly higher couplings across the joints. The relative increases in couplings are often higher than that of the local joint stiffness. The multi-joint characterization provided a tool to characterize impairment of individual patients, which would allow more focused impairment-specific treatment. In general, the decomposition method can be used for even more complex systems, making characterization of intractable system dynamics of three or more joints/DOFs manageable.

Topics: Computer Simulation; Elastic Modulus; Elbow Joint; Female; Humans; Male; Middle Aged; Models, Biological; Movement; Muscle Spasticity; Range of Motion, Articular; Shoulder Joint; Stroke; Torque; Wrist Joint

The purpose of this research is to propose a design of a clinically relevant upper-limb (hand, wrist, and elbow) exoskeleton that meets the clinical requirements. At first, the proposed robot was designed to have sufficient torque for passive exercise therapy and spasticity measurement of post-stroke patients with spasticity (grade 3 or lower in Modified Ashworth Scale). Because the therapy of patients with high level spasticity could be laborious for therapists by increased muscle tone, and the patients tend not to get enough rehabilitation treatment. Secondly, this robot was designed to have user friendly features like as modularity, so that users have easy approach to assemble and disassemble for practical use. Thirdly, this robot system was designed to guarantee the safety for robot-aided passive training of patients with spasticity. As a result, we were able to see the usability of the robot system, even though it was a pilot test. This shows the possibility of measuring and classifying the spasticity.

Topics: Adult; Aged; Exoskeleton Device; Female; Humans; Male; Middle Aged; Muscle Spasticity; Stroke; Stroke Rehabilitation; Torque; Upper Extremity; Young Adult

Following a stroke, intrinsic muscle properties such as stiffness may be altered, which is accompanied by increased spasticity and contractures. Previously, quantification of muscle stiffness has been based off of indirect measurements. Using shear wave ultrasound elastography, direct measurements of muscle material properties can be made.. Our aim was to evaluate material properties, specifically passive stiffness, using shear wave ultrasound elastography across a range of muscle lengths, in the medial gastrocnemius and the tibialis anterior in chronic stroke survivors.. Our main results show significant increases of 27.7% and 26.9% in shear wave velocity of stroke-impaired medial gastrocnemius compared to the unimpaired contralateral side at 90° ankle angle (P=0.033) and 15° plantarflexion (P=0.001), respectively. However, no significant difference was found in the tibialis anterior between the two sides. Relatively weak correlations were found between SW velocity in the medial gastrocnemius and joint stiffness for both the non-paretic (ρ=0.384, P=0.001), and paretic side (ρ=0.363, P=0.002). Additionally, muscle stiffness estimates of stroke-impaired tibialis anterior from joint torque and angle measurements were significantly greater by 23.1% (P=0.033) than the unimpaired contralateral side. However, no significant difference was found in the medial gastrocnemius.. These results indicate that there are non-uniform changes in passive stiffness of stroke-impaired muscle. Therefore, muscles need to be evaluated individually to assess alterations. Additionally, interpretation of joint-based calculations of muscle stiffness should be made cautiously. Having the ability to non-invasively assess muscle stiffness adaptations in vivo would aid in prognosis, evaluation, and treatment following a stroke.

Topics: Aged; Ankle; Ankle Joint; Elasticity Imaging Techniques; Female; Humans; Male; Middle Aged; Muscle Spasticity; Muscle, Skeletal; Musculoskeletal Physiological Phenomena; Stroke; Survivors; Torque; Ultrasonography

Spasticity poststroke leads to muscle weakness and soft tissue contracture, however, it is not clear how muscle properties change due this motor neural disorder. The purpose was to compare medial gastrocnemius muscle architecture and mechanical properties of the plantarflexor muscles between stroke survivors with spasticity and healthy subjects.. The study included 15 stroke survivors with ankle spasticity and 15 healthy subjects. An isokinetic dynamometer was used for the evaluation of maximal isometric plantarflexor torque and images of the medial gastrocnemius muscle were obtained using ultrasonography. Images were collected at rest and during a maximum voluntary contraction.. The affected limb showed reduced fascicle excursion (0.9 ± 0.7 cm), shorter fascicle length, and reduced muscle thickness (0.095 ± 0.010% of leg length and 1.18 ± 0.20 cm, at rest) compared to contralateral (1.6 ± 0.4 cm, 0.106 ± 0.015% of leg length and 1.29 ± 0.24 cm, respectively) and to healthy participants (1.8 ± 0.7 cm, 0.121 ± 0.019% of leg length and 1.43 ± 0.22 cm, respectively). The contralateral limb showed lower force (between 32 and 40%) and similar architecture parameters compared to healthy participants.. The affected limb had a different muscle architecture that appears to result in lower force production. The contralateral limb showed a decrease in force compared to healthy participants due to the other neural impairments than muscle morphology. Spasticity likely leds to adaptations of muscle architecture in the affected limb and in force reductions in both limbs of stroke survivors.

Topics: Aged; Ankle; Female; Hemiplegia; Humans; Male; Microscopy, Acoustic; Middle Aged; Muscle Spasticity; Muscle, Skeletal; Stroke; Survivors; Torque

The present study compared the Achilles tendon morphological characteristics, plantar flexor toque and passive ankle stiffness between hemiparetic spastic stroke survivors and healthy subjects.. The Achilles tendon length was measured at the affected and contralateral limbs of twelve hemiparetic stroke survivors with ankle spasticity and twelve healthy subjects. The ankle was held at three different angles (20° plantar flexion, 0° and maximum dorsiflexion) while an ultrasound system was used to capture images from the Achilles tendon. Active and passive plantar flexor torque production was measured using an isokinetic dynamometer.. There was no significant difference in tendon length and Achilles tendon complacency between stroke survivors [affected limb: 20.8 (1.59) cm at 0° and 0.11 (0.09) cm/N; contralateral limb: 20.8 (1.7) cm at 0° and 0.12 (0.08) cm/N] and healthy subjects [20 (2.78) cm at 0° and 0.15 (0.1) cm/N]. The contralateral limb was stronger than the affected limb, while healthy participants presented larger active torque in relation to stroke survivors. There was no significant difference in passive ankle stiffness between the affected [0.43 (0.08) N/°] and the contralateral limb [0.40 (0.11) N/°], but affected limb was significantly stiffer than the healthy subjects [0.32 (0.07) N/°].. The larger passive torque and ankle joint stiffness from stroke survivors with similar Achilles tendon length compared to healthy subjects seem to be unrelated to tendon extensibility.

Topics: Achilles Tendon; Ankle; Female; Humans; Male; Middle Aged; Muscle Spasticity; Paresis; Stroke; Survivors; Torque; Ultrasonography

Spasticity of the biceps brachii muscle was assessed using the modified Ashworth Scale (MAS), Myotonometry and repeated passive stretch techniques, respectively. Fourteen subjects with chronic hemiplegia participated in the study. Spasticity was quantified by muscle displacements and compliance from the Myotonometer measurements and resistive torques from the repeated passive stretch at velocities of 5 °/s and 100 °/s, respectively. Paired t-tests indicated a significant decrease of muscle displacement and compliance in the spastic muscles as compared to the contralateral side (muscle displacement: spastic: 4.84 ± 0.33 mm, contralateral: 6.02 ± 0.49 mm, p = 0.038; compliance: spastic: 1.79 ± 0.12 mm/N, contralateral: 2.21 ± 0.18 mm/kg, p = 0.048). In addition, passive stretch tests indicated a significant increase of total torque at the velocity of 100 °/s compared with that of 5 °/s (T

Topics: Aged; Biomechanical Phenomena; Biometry; Elasticity; Female; Hemiplegia; Humans; Male; Middle Aged; Muscle Spasticity; Muscle, Skeletal; Myography; Torque

Although abnormal cutaneous reflex (CR) activity has been identified during gait after incomplete spinal cord injury (SCI), this activity has not been directly compared in subjects with and without the spasticity syndrome.. Characterisation of CR activity during controlled rest and 'ramp and hold' phases of controlled plantarflexion in subjects with and without the SCI spasticity syndrome.. Transverse descriptive study with non-parametric group analysis.. SCI rehabilitation hospital.. Tibialis Anterior (TA) reflexes were evoked by innocuous cutaneous plantar sole stimulation during rest and ramp and hold phases of plantarflexion torque in non-injured subjects (n=10) and after SCI with (n=9) and without (n=10) hypertonia and/or involuntary spasm activity. Integrated TA reflex responses were analysed as total (50-300 ms) or short (50-200 ms) and long-latency (200-300 ms) activity.. Total and long-latency TA activity was inhibited in non-injured subjects and the SCI group without the spasticity syndrome during plantarflexion torque but not in the SCI spasticity group. Furthermore, loss of TA reflex inhibition during plantarflexion correlated with time after SCI (ρ=0.79, P=0.009). Moreover, TA reflex activity inversely correlated with maximum plantarflexion torque in the spasticity group (ρ=-0.75, P=0.02), despite similar non-reflex TA electromyographic activity during plantarflexion after SCI in subjects with (0.11, 0.08-0.13 mV) or without the spasticity syndrome (0.09, 0.07-0.12 mV).. This reflex testing procedure supports previously published evidence for abnormal CR activity after SCI and may characterise the progressive disinhibition of TA reflex activity during controlled plantarflexion in subjects diagnosed with the spasticity syndrome.

Topics: Adult; Electromyography; Female; Humans; Male; Middle Aged; Muscle Contraction; Muscle Spasticity; Muscle, Skeletal; Reaction Time; Reflex, Abnormal; Skin; Spinal Cord Injuries; Statistics, Nonparametric; Torque; Young Adult

Dynamometry has been used extensively to measure knee extensor strength in individuals with cerebral palsy (CP). However, increased coactivation can lead to underestimation of knee extensor strength and, therefore, reduce validity of strength measurements. It is yet unknown to what extent coactivation occurs during dynamometry testing and whether coactivation is influenced by severity of CP, load levels, and muscle fatigue.. The aims of this study were: (1) to investigate coactivation in adolescents with and without CP during dynamometer tests and (2) to assess the effect of Gross Motor Function Classification System (GMFCS) level, load level, and muscle fatigue on coactivation.. A cross-sectional observational design was used.. Sixteen adolescents with CP (GMFCS levels I and II: n=10/6; age range=13-19 years) and 15 adolescents without CP (n=15; age range=12-19 years) performed maximal isometric contractions (maximal voluntary torque [MVT]) and a series of submaximal dynamic contractions at low (±65% MVT), medium (±75% MVT), and high (±85% MVT) loads until fatigue. A coactivation index (CAI) was calculated for each contraction from surface electromyography recordings from the quadriceps and hamstring muscles.. Adolescents with CP classified in GMFCS level II showed significantly higher CAI values than adolescents classified in GMFCS level I and those without CP during maximal and submaximal contractions. No differences were observed among load levels. During the series of fatiguing submaximal contractions, CAI remained constant in both the CP group and the group with typical development (TD), except for adolescents with TD at the low-load condition, which showed a significant decrease.. Electromyography tracings were normalized to amplitudes during maximal isometric contractions, whereas previous studies suggested that these types of contractions could not be reliably determined in the CP population.. Coactivation was higher in adolescents with CP classified in GMFCS level II than in adolescents with TD and those with CP in GMFCS level I at different load levels. Within all groups, coactivation was independent of load level and fatigue. In individuals with CP, coactivation can lead to an underestimation of agonist muscle strength, which should be taken into account while interpreting the results of both maximal and submaximal dynamometer tests.

Topics: Adolescent; Cerebral Palsy; Cross-Sectional Studies; Disability Evaluation; Electromyography; Female; Humans; Isometric Contraction; Leg; Male; Muscle Fatigue; Muscle Spasticity; Muscle Strength Dynamometer; Torque

About half of all chronic stroke patients experience loss of arm function coinciding with increased stiffness, reduced range of motion and a flexed wrist due to a change in neural and/or structural tissue properties. Quantitative assessment of these changes is of clinical importance, yet not trivial. The goal of this study was to quantify the neural and structural properties contributing to wrist joint stiffness and to compare these properties between healthy subjects and stroke patients.. Stroke patients (n=32) and healthy volunteers (n=14) were measured using ramp-and-hold rotations applied to the wrist joint by a haptic manipulator. Neural (reflexive torque) and structural (connective tissue stiffness and slack lengths and (contractile) optimal muscle lengths) parameters were estimated using an electromyography driven antagonistic wrist model. Kruskal-Wallis analysis with multiple comparisons was used to compare results between healthy subjects, stroke patients with modified Ashworth score of zero and stroke patients with modified Ashworth score of one or more.. Stroke patients with modified Ashworth score of one or more differed from healthy controls (P<0.05) by increased tissue stiffness, increased reflexive torque, decreased optimal muscle length and decreased slack length of connective tissue of the flexor muscles.. Non-invasive quantitative analysis, including estimation of optimal muscle lengths, enables to identify neural and non-neural changes in chronic stroke patients. Monitoring these changes in time is important to understand the recovery process and to optimize treatment.

Topics: Adult; Aged; Case-Control Studies; Electromyography; Female; Humans; Male; Middle Aged; Models, Theoretical; Muscle Contraction; Muscle Spasticity; Muscle, Skeletal; Range of Motion, Articular; Reflex; Stroke; Torque; Wrist Joint

Spasticity is one of the main causes of contracture, muscle weakness and subsequent functional incapacity. The passive static stretching can be included as having the purpose of increasing musculoskeletal flexibility, however, it also can influence the muscle torque. The objective is to verify the immediate effect of passive static stretching in the muscle strength of healthy and those who present spastic hemiparesis. There were assessed 20 subjects, 10 spastic hemiparetic (EG) and 10 healthy individuals (CG), including both sexes, aged between 22 and 78 years. The torque of extensor muscles of the knee was analyzed using isokinetic dynamometer. Results have shown that EG has less muscle torque compared to CG ( p < 0.01). In addition, EG presented a decrease in significance of muscle torque after stretching ( p < 0.05), however, it has not shown significant alteration in muscle torque of CG after performing the program that was prescribed. Immediately after the passive stretch, a significant torque decrease can be seen in hypertonic muscle; it is believed that this reduction may be associated with the physiological overlap between actin and myosin filaments and so preventing the muscle to develop a maximum contraction.

Topics: Adult; Aged; Case-Control Studies; Female; Humans; Male; Middle Aged; Muscle Contraction; Muscle Hypertonia; Muscle Spasticity; Muscle Strength; Muscle Strength Dynamometer; Muscle, Skeletal; Paresis; Torque; Young Adult

Cross-sectional study.. To determine the effect of injury duration on plantar-flexor elastic properties in individuals with chronic spinal cord injury (SCI) and spasticity.. National Rehabilitation Center for Persons with Disabilities, Japan.. A total of 16 chronic SCI patients (age, 33±9.3 years; injury localization, C6-T12; injury duration, 11-371 months) participated. Spasticity of the ankle plantar-flexors was assessed using the Modified Ashworth Scale (MAS). The calf circumference and muscle thickness of the medial gastrocnemius (MG), lateral gastrocnemius and soleus were assessed using tape measure and ultrasonography. In addition, the ankle was rotated from 10° plantar-flexion to 20° dorsiflexion at 5 deg s(-1) with a dynamometer, and the ankle angle and torque were recorded. After normalizing the data (the initial points of angle and torque were set to zero), we calculated the peak torque and energy. Furthermore, angle-torque data (before and after normalization) were fitted with a second- and fourth-order polynomial, and exponential (Sten-Knudsen) models, and stiffness indices (SISOP, SIFOP, SISK) and AngleSLACK (the angle at which plantar-flexor passive torque equals zero) were calculated. The stretch reflex gain and offset were determined from 0-10° dorsiflexion at 50, 90, 120 and 150 deg s(-1). After logarithmic transformation, Pearson's correlation coefficients were calculated.. MAS, calf circumference, MG thickness, peak torque and SIFOP significantly decreased with injury duration (r log-log=-0.63, -0.69, -0.63, -0.53 and -0.55, respectively, P<0.05). The peak torque and SIFOP maintained significant relationships even after excluding impacts from muscle morphology.. Plantar-flexor elasticity in chronic SCI patients decreased with increased injury duration.

Topics: Adult; Ankle; Cross-Sectional Studies; Female; Humans; Lower Extremity; Male; Middle Aged; Muscle Spasticity; Muscle, Skeletal; Spinal Cord Injuries; Time Factors; Torque; Young Adult

Despite the impact of spasticity, there is a lack of objective, clinically reliable and valid tools for its assessment. This study aims to evaluate the reliability of various performance- and spasticity-related parameters collected with a manually controlled instrumented spasticity assessment in four lower limb muscles in children with cerebral palsy (CP).. The lateral gastrocnemius, medial hamstrings, rectus femoris and hip adductors of 12 children with spastic CP (12.8 years, ±4.13 years, bilateral/unilateral involvement n=7/5) were passively stretched in the sagittal plane at incremental velocities. Muscle activity, joint motion, and torque were synchronously recorded using electromyography, inertial sensors, and a force/torque load-cell. Reliability was assessed on three levels: (1) intra- and (2) inter-rater within session, and (3) intra-rater between session.. Parameters were found to be reliable in all three analyses, with 90% containing intra-class correlation coefficients >0.6, and 70% of standard error of measurement values <20% of the mean values. The most reliable analysis was intra-rater within session, followed by intra-rater between session, and then inter-rater within session. The Adds evaluation had a slightly lower level of reliability than that of the other muscles.. Limited intrinsic/extrinsic errors were introduced by repeated stretch repetitions. The parameters were more reliable when the same rater, rather than different raters performed the evaluation. Standardisation and training should be further improved to reduce extrinsic error when different raters perform the measurement. Errors were also muscle specific, or related to the measurement set-up. They need to be accounted for, in particular when assessing pre-post interventions or longitudinal follow-up. The parameters of the instrumented spasticity assessment demonstrate a wide range of applications for both research and clinical environments in the quantification of spasticity.

Topics: Adolescent; Cerebral Palsy; Child; Child, Preschool; Electromyography; Female; Humans; Leg; Muscle Spasticity; Muscle, Skeletal; Observer Variation; Range of Motion, Articular; Reproducibility of Results; Torque

This study examined the sensitivity of an instrumented spasticity assessment of the medial hamstrings (MEH) in children with cerebral palsy (CP). Nineteen children received Botulinum Toxin type A (BTX-A) injections in the MEH. Biomechanical (position and torque) and electrophysiological (surface electromyography, EMG) signals were integrated during manually-performed passive stretches of the MEH at low, medium and high velocity. Signals were examined at each velocity and between stretch velocities, and compared pre and post BTX-A (43 ± 16 days). Average change between pre and post BTX-A was interpreted in view of the minimal detectable change (MDC) calculated from previously published reliability results. Improvements greater than the MDC were found for nearly all EMG-parameters and for torque parameters at high velocity and at high versus low velocity (p<0.03), however large inter-subject variability was noted. Moderate correlations were found between the improvement in EMG and in torque (r=0.52, p<0.05). Biomechanical and electrophysiological parameters proved to be adequately sensitive to assess the response to treatment with BTX-A. Furthermore, studying both parameters at different velocities improves our understanding of spasticity and of the physiological effect of selective tone-reduction. This not only provides a clinical validation of the instrumented assessment, but also opens new avenues for further spasticity research.

Topics: Adolescent; Biomechanical Phenomena; Botulinum Toxins, Type A; Cerebral Palsy; Child; Child, Preschool; Dose-Response Relationship, Drug; Electromyography; Female; Follow-Up Studies; Humans; Injections, Intramuscular; Leg; Male; Muscle Spasticity; Muscle, Skeletal; Neuromuscular Agents; Reproducibility of Results; Time Factors; Torque; Treatment Outcome

Although it has been reported that strengthening exercise in stroke patients is beneficial for their motor recovery, there is little evidence about which exercise method is the better option. The purpose of this study was to compare isotonic and isokinetic exercise by surface electromyography (EMG) analysis using standardized methods. Nine stroke patients performed three sets of isotonic elbow extensions at 30% of their maximal voluntary isometric torque followed by three sets of maximal isokinetic elbow extensions with standardization of mean angular velocity and the total amount of work for each matched set in two strengthening modes. All exercises were done by using 1-DoF planner robot to regulate exact resistive torque and speed. Surface electromyographic activity of eight muscles in the hemiplegic shoulder and elbow was recorded. Normalized root mean square (RMS) values and co-contraction index (CCI) were used for the analysis. The isokinetic mode was shown to activate the agonists of elbow extension more efficiently than the isotonic mode (normalized RMS for pooled triceps: 96.0±17.0 (2nd), 87.8±14.4 (3rd) in isokinetic, 80.9±11.0 (2nd), 81.6±12.4 (3rd) in isotonic contraction, F[1,8]=11.168; P=0.010) without increasing the co-contraction of muscle pairs, implicating spasticity or synergy.

Topics: Adult; Aged; Aged, 80 and over; Elbow; Electromyography; Exercise; Exercise Therapy; Female; Humans; Isotonic Contraction; Male; Middle Aged; Muscle Spasticity; Muscle, Skeletal; Paresis; Robotics; Stroke; Torque

Spasticity, an increased resistance of a limb to movement, is associated with functional limitations and a major source of disability in neurological disorders, including multiple sclerosis (MS) and stroke. Despite the clinical significance of spasticity in brain and spinal cord injuries, it is often not clear whether the spasticity is due to reflex or non-reflex changes.. Reflex and nonreflex properties of the human knee joint were studied in eight MS patients with spasticity and ten healthy subjects. A digitally controlled joint driving device was used to apply small-amplitude, and band-limited white-noise perturbations to the knee to manifest the reflex and nonreflex properties. The subjects were asked to maintain a steady level of background muscle torque during the perturbation. A nonlinear delay differential equation model was used to characterize the reflex and intrinsic properties of the knee in terms of phasic stretch reflex gain, tonic stretch reflex gain, joint elastic stiffness, and coefficient of viscosity.. It was found that joint coefficient of viscosity and tonic stretch reflex gain of the spastic MS patients were significantly lower than those of normal controls. On the other hand, spastic MS patients showed higher phasic stretch reflex gains than normal controls and a trend of increased joint stiffness.. Simultaneous characterizations of changes in tonic and phasic reflexes and nonreflex changes in joint elastic stiffness and viscosity in neurological disorders may help us gain insight into mechanisms underlying spasticity and develop impairment-specific treatment.

Topics: Actigraphy; Adult; Elasticity; Female; Humans; Knee Joint; Male; Middle Aged; Models, Neurological; Multiple Sclerosis; Muscle Spasticity; Muscle, Skeletal; Nonlinear Dynamics; Physical Stimulation; Reflex, Stretch; Torque; Viscosity

The aim of this study was to assess the effects of neuromuscular fatigue on stretch reflex-related torque and electromyographic activity of spastic knee extensor muscles in hemiplegic patients. The second aim was to characterize the time course of quadriceps muscle fatigue during repetitive concentric contractions.. Eighteen patients performed passive, isometric and concentric isokinetic evaluations before and after a fatigue protocol using an isokinetic dynamometer. Voluntary strength and spasticity were evaluated following the simultaneous recording of torque and electromyographic activity of rectus femoris (RF), vastus lateralis (VL) and biceps femoris (BF).. Isometric knee extension torque and the root mean square (RMS) value of VL decreased in the fatigued state. During the fatigue protocol, the normalized peak torque decreased whereas the RMS of RF and BF increased between the first five and last five contractions. There was a linear decrease in the neuromuscular efficiency-repetitions relationships for RF and VL. The peak resistive torque and the normalized RMS of RF and VL during passive stretching movements were not modified by the fatigue protocol for any stretch velocity.. This study showed that localized quadriceps muscle fatigue caused a decrease in voluntary strength which did not modify spasticity intensity. Changes in the distribution of muscle fiber type, with a greater number of slow fibers on the paretic side, may explain why the stretch reflex was not affected by fatigue.

Topics: Adult; Aged; Electromyography; Female; Hemiplegia; Humans; Isometric Contraction; Knee; Knee Joint; Leg; Male; Middle Aged; Movement; Muscle Contraction; Muscle Fatigue; Muscle Spasticity; Muscle Strength; Pilot Projects; Quadriceps Muscle; Reflex, Stretch; Torque

Clinical assessment of spasticity is compromised by the difficulty to distinguish neural from non-neural components of increased joint torque. Quantifying the contributions of each of these components is crucial to optimize the selection of anti-spasticity treatments such as botulinum toxin (BTX). The aim of this study was to compare different biomechanical parameters that quantify the neural contribution to ankle joint torque measured during manually-applied passive stretches to the gastrocsoleus in children with spastic cerebral palsy (CP). The gastrocsoleus of 53 children with CP (10.9 ± 3.7 y; females n = 14; bilateral/unilateral involvement n = 28/25; Gross Motor Functional Classification Score I-IV) and 10 age-matched typically developing (TD) children were assessed using a manually-applied, instrumented spasticity assessment. Joint angle characteristics, root mean square electromyography and joint torque were simultaneously recorded during passive stretches at increasing velocities. From the CP cohort, 10 muscles were re-assessed for between-session reliability and 19 muscles were re-assessed 6 weeks post-BTX. A parameter related to mechanical work, containing both neural and non-neural components, was compared to newly developed parameters that were based on the modeling of passive stiffness and viscosity. The difference between modeled and measured response provided a quantification of the neural component. Both types of parameters were reliable (ICC > 0.95) and distinguished TD from spastic muscles (p < 0.001). However, only the newly developed parameters significantly decreased post-BTX (p = 0.012). Identifying the neural and non-neural contributions to increased joint torque allows for the development of individually tailored tone management.

Topics: Adolescent; Ankle Joint; Biomechanical Phenomena; Botulinum Toxins, Type A; Case-Control Studies; Cerebral Palsy; Child; Child, Preschool; Electromyography; Female; Humans; Male; Muscle Spasticity; Neuromuscular Agents; Reproducibility of Results; Torque

The passive properties of the muscle-tendon unit are regularly assessed in individuals with cerebral palsy (CP). However, no information is available on the passive properties of adult muscle, and whether any differences exist between the paretic and control muscles. Eleven ambulant male athletes with spastic hemiplegic CP (21.2 ± 3.0 years) and controls without neurological impairment (age = 21.8 ± 2.2 years) completed two and one passive stretch session, respectively. During each session, the ankle was passively dorsiflexed until end range of motion (ROM), whilst recording passive ankle angle, torque and gastrocnemius medialis (GM) myotendinous junction (MTJ) displacement. In addition, GM cross-sectional area (CSA) and length were measured. Subsequently, in vivo stress and strain were determined to calculate elastic modulus. Passive stiffness, MTJ displacement and ROM of the paretic GM were not different from the control muscles. However, the elastic modulus of the paretic GM was two times stiffer than the control GM muscles. In conclusion, athletes with CP exhibit absolute passive muscle stiffness similar to the controls; however, the elastic modulus of the CP muscle was significantly greater. Therefore, throughout the same ROM a smaller GM CSA in CP athletes has to dissipate larger relative torque compared to the control muscles, consequently causing the muscle to elongate to the same extent as the non-paretic muscle under stretch.

Topics: Adult; Ankle; Ankle Joint; Athletes; Cerebral Palsy; Elastic Modulus; Electromyography; Humans; Male; Muscle Spasticity; Muscle Stretching Exercises; Muscle, Skeletal; Range of Motion, Articular; Torque; Young Adult

Spasticity and reduced strength are both primary neuromuscular impairments associated with cerebral palsy (CP). However, it is unclear whether spasticity or reduced strength is the strongest contributor to activity limitations.. To study whether involuntary activation of the biceps brachii muscle, in addition to reduced strength, contributes to limitations in upper limb activity in children with CP.. Fifteen children with unilateral CP (9 males and 6 females, age range 8-17 years) participated in this study. Involuntary activation, reflecting spasticity, was studied as biceps brachii activity during passive elbow extension at four isokinetic velocities (10, 90, 180 and 300°/s). Elbow flexion peak torque, reflecting strength, was measured during maximal voluntary isometric contraction, and concurrent biceps brachii activity was registered reflecting voluntary muscle activation. Bimanual upper limb activity was assessed in the performance domain using the Assisting Hand Assessment (AHA).. Both involuntary and voluntary muscle activation were related to activity, the former negatively, but voluntary activation showed the strongest relationship (Spearmans rho = .84). Involuntary muscle activation at 10, 90 and 180°/s was negatively related to muscle strength (Spearmans rho = -.63, -.58 and -.62, respectively).. Our results do not indicate that spasticity affects upper limb activity in addition to strength. Most likely, muscle weakness and spasticity jointly contribute to activity limitations, reflected by the strong relationship between the ability to voluntarily activate a muscle and activity performance.

Topics: Adolescent; Cerebral Palsy; Child; Elbow; Electromyography; Female; Humans; Isometric Contraction; Male; Muscle Spasticity; Muscle Strength Dynamometer; Muscle Weakness; Muscle, Skeletal; Torque; Upper Extremity

Most clinical tools for measuring spasticity, such as the Modified Ashworth Scale (MAS) and the Modified Tardieu Scale (MTS), are not sufficiently accurate or reliable. This study investigated the clinimetric properties of an instrumented spasticity assessment. Twenty-eight children with spastic cerebral palsy (CP) and 10 typically developing (TD) children were included. Six of the children with CP were retested to evaluate reliability. To quantify spasticity in the gastrocnemius (GAS) and medial hamstrings (MEH), three synchronized signals were collected and integrated: surface electromyography (sEMG); joint-angle characteristics; and torque. Muscles were manually stretched at low velocity (LV) and high velocity (HV). Spasticity parameters were extracted from the change in sEMG and in torque between LV and HV. Reliability was determined with intraclass-correlation coefficients and the standard error of measurement; validity by assessing group differences and correlating spasticity parameters with the MAS and MTS. Reliability was moderately high for both muscles. Spasticity parameters in both muscles were higher in children with CP than in TD children, showed moderate correlation with the MAS for both muscles and good correlation to the MTS for the MEH. Spasticity assessment based on multidimensional signals therefore provides reliable and clinically relevant measures of spasticity. Moreover, the moderate correlations of the MAS and MTS with the objective parameters further stress the added value of the instrumented measurements to detect and investigate spasticity, especially for the GAS.

Topics: Adolescent; Case-Control Studies; Cerebral Palsy; Child; Child, Preschool; Electromyography; Female; Humans; Joints; Lower Extremity; Male; Muscle Spasticity; Muscle, Skeletal; Range of Motion, Articular; Reproducibility of Results; Severity of Illness Index; Torque

Spasticity is a common complication with neurological diseases and CNS lesions. Instrumented systems to evaluate spasticity often cannot provide an immediate result, thus limiting their clinical usefulness. In this study we investigated the accuracy and reliability of the portable Neurokinetics RA1 Ridgidity Analyzer to measure stiffness of the ankle joint in 46 controls, 14 spinal cord injured (SCI) and 23 multiple sclerosis (MS) participants.. Ankle stiffness measures were made twice by two raters, at speeds above and below the expected stretch reflex threshold. Ankle torque was measured with the portable device and a stationary torque motor. Inter- and intra-rater reliability was assessed with the intra-class correlation coefficient (ICC).. Stiffness measures with the portable and stationary devices were significantly correlated for controls and MS participants (p < 0.01). Intra-rater reliability for the portable device ranged from 0.60-0.89 (SCI) and 0.63-0.67 (control) and inter-rater reliability ranged from 0.70-0.73 (SCI) and 0.61-0.77 (control). Ankle stiffness measures in SCI and MS participants were significantly larger than in controls for both slow (p < 0.05) and fast movements (p < 0.01), with stiffness being larger for fast compared to slow movements in SCI and MS participants (p < 0.05), but not in controls (p = 0.5).. The portable device correlated well with measures obtained by a torque motor in both controls and MS participants, showed high intra- and inter-rater reliability for the SCI participants, and could easily distinguish between stiff and control ankle joints. However, the device, in its current form, may be less accurate during rapid movements when inertia contributes to stiffness and the shape of the air-filled pads did not provide a good interface with the foot.. This study demonstrates that a portable device can potentially be a useful diagnostic tool to obtain reliable information of stiffness for the ankle joint.

Topics: Adult; Aged; Ankle Joint; Biomechanical Phenomena; Elasticity; Equipment and Supplies; Female; Humans; Male; Middle Aged; Monitoring, Ambulatory; Movement; Multiple Sclerosis; Muscle Spasticity; Muscle, Skeletal; Observer Variation; Reproducibility of Results; Spinal Cord Injuries; Torque

Prospective cohort study.. To determine incidence of contracture and develop prediction models to identify patients susceptible to contracture after spinal cord injury.. Two Sydney spinal cord injury units.. A total of 92 consecutive patients with acute spinal cord injury were assessed within 35 days of injury and 1 year later. Incidence of contracture at 1 year was measured in all major appendicular joints by categorizing range of motion on a 4-point scale (0-no contracture to 3-severe contracture), and in the wrist, elbow, hip and ankle by measuring range of motion at standardized torque. Multivariate models were developed to predict contracture at 1 year using age, neurological status, spasticity, pain and limb fracture recorded at the time of injury.. At 1 year, 66% of participants developed at least one contracture (defined as ≥1 point deterioration on the 4-point scale). Incidence of contracture at each joint was: shoulder 43%, elbow and forearm 33%, wrist and hand 41%, hip 32%, knee 11% and ankle 40%. Incidence of contracture determined by standardized torque measures of range (defined as loss of ≥10 degrees) was: elbow 27%, wrist 26%, hip 23% and ankle 25%. Prediction models were statistically significant but lacked sufficient predictive accuracy to be clinically useful (R(2)≤31%).. The incidence of contracture in major joints 1 year after spinal cord injury ranges from 11-43%. The ankle, wrist and shoulder are most commonly affected. It is difficult to accurately predict those susceptible to contracture soon after injury.

Topics: Adult; Cohort Studies; Contracture; Humans; Incidence; Joints; Middle Aged; Muscle Spasticity; Predictive Value of Tests; Prospective Studies; Range of Motion, Articular; Severity of Illness Index; Spinal Cord Injuries; Torque

Spasticity is a common disorder following spinal cord injury that can impair function and quality of life. While a number of mechanisms are thought to play a role in spasticity, the role of motoneuron persistent inward currents (PICs) is emerging as pivotal. The presence of PICs can be evidenced by temporal summation or wind-up of reflex responses to brief afferent inputs. In this study, a combined neurophysiological and novel biomechanical approach was used to assess the effects of passive exercise and modafinil administration on hyper-reflexia and spasticity following complete T-10 transection in the rat. Animals were divided into 3 groups (n=8) and provided daily passive cycling exercise, oral modafinil, or no intervention. After 6weeks, animals were tested for wind-up of the stretch reflex (SR) during repeated dorsiflexion stretches of the ankle. H-reflexes were tested in a subset of animals. Both torque and gastrocnemius electromyography showed evidence of SR wind-up in the transection only group that was significantly different from both treatment groups (p<0.05). H-reflex frequency dependent depression was also restored to normal levels in both treatment groups. The results provide support for the use of passive cycling exercise and modafinil in the treatment of spasticity and provide insight into the possible contribution of PICs.

Topics: Analysis of Variance; Animals; Benzhydryl Compounds; Chronic Disease; Disease Models, Animal; Electromyography; Female; H-Reflex; Modafinil; Muscle Spasticity; Muscle, Skeletal; Neuroprotective Agents; Physical Conditioning, Animal; Random Allocation; Rats; Rats, Sprague-Dawley; Reflex, Stretch; Severity of Illness Index; Spinal Cord Injuries; Time Factors; Torque

To investigate the methodology using a manual ankle joint resistive torque measurement device to evaluate the contribution of the neural component of ankle joint resistive torque in patients with stroke.. Within-subject comparison to compare the ankle joint resistive torque between fast and slow stretching conditions.. Ten patients with stroke participated in this study. The incremental ratio of ankle joint resistive torque at the ankle angular position of 5degrees dorsiflexion under the fast stretching condition in comparison to the slow one was calculated in each patient.. A significant increase (p<0.01) in the ankle joint resistive torque was demonstrated under the fast stretching condition in comparison to the slow one in all patients and the mean ankle joint resistive torque was 4.6 (SD=1.7) Nm under the slow stretching condition, while it was 8.4 (SD=4.1) Nm under the fast stretching condition at the ankle angular position of 5 degrees dorsiflexion. The incremental ratio ranged from 9.4-139.3% among the patients.. The results of this study demonstrated the potential advantage of the device to evaluate the contribution of the neural component of ankle joint resistive torque.

Topics: Adult; Ankle Joint; Equipment Design; Exercise Therapy; Female; Hemiplegia; Humans; Male; Middle Aged; Muscle Spasticity; Range of Motion, Articular; Stroke; Stroke Rehabilitation; Torque; Young Adult

After spinal cord injury (SCI), alterations in intrinsic motoneuron properties have been shown to be partly responsible for spastic reflex behaviors in human SCI. In particular, a dysregulation of voltage-dependent depolarizing persistent inward currents (PICs) may permit sustained muscle contraction after the removal of a brief excitatory stimulus. Windup, in which the motor response increases with repeated activation, is an indicator of PICs. Although windup of homonymous stretch reflexes has been shown, multijoint muscle activity is often observed following imposed limb movements and may exhibit a similar windup phenomenon. The purpose of this study was to identify and quantify windup of multijoint reflex responses to repeated imposed hip oscillations. Ten chronic SCI subjects participated in this study. A custom-built servomotor apparatus was used to oscillate the legs about the hip joint bilaterally and unilaterally from 10° of extension to 40° flexion for 10 consecutive cycles. Surface electromyograms (EMGs) and joint torques were recorded from both legs. Consistent with a windup response, hip and knee flexion/extension and ankle plantarflexion torque and EMG responses varied according to movement cycle number. The temporal patterns of windup depended on the muscle groups that were activated, which may suggest a difference in the response of neurons in different spinal pathways. Furthermore, because windup was seen in muscles that were not being stretched, these results imply that changes in interneuronal properties are also likely to be associated with windup of spastic reflexes in human SCI.

Topics: Adult; Aged; Ankle Joint; Electromyography; Female; Hip Joint; Humans; Knee Joint; Leg; Male; Middle Aged; Motor Neurons; Muscle Spasticity; Paralysis; Posture; Range of Motion, Articular; Reflex, Abnormal; Spasm; Spinal Cord Injuries; Torque; Young Adult

Despite numerous investigations, the impact of tizanidine, an anti-spastic medication, on changes in reflex and muscle mechanical properties in spasticity remains unclear. This study was designed to help us understand the mechanisms of action of tizanidine on spasticity in spinal cord injured subjects with incomplete injury, by quantifying the effects of a single dose of tizanidine on ankle muscle intrinsic and reflex components.. A series of perturbations was applied to the spastic ankle joint of twenty-one spinal cord injured subjects, and the resulting torques were recorded. A parallel-cascade system identification method was used to separate intrinsic and reflex torques, and to identify the contribution of these components to dynamic ankle stiffness at different ankle positions, while subjects remained relaxed.. Following administration of a single oral dose of Tizanidine, stretch evoked joint torque at the ankle decreased significantly (p < 0.001) The peak-torque was reduced between 15% and 60% among the spinal cord injured subjects, and the average reduction was 25%. Using systems identification techniques, we found that this reduced torque could be attributed largely to a reduced reflex response, without measurable change in the muscle contribution. Reflex stiffness decreased significantly across a range of joint angles (p < 0.001) after using tizanidine. In contrast, there were no significant changes in intrinsic muscle stiffness after the administration of tizanidine.. Our findings demonstrate that tizanidine acts to reduce reflex mechanical responses substantially, without inducing comparable changes in intrinsic muscle properties in individuals with spinal cord injury. Thus, the pre-post difference in joint mechanical properties can be attributed to reflex changes alone. From a practical standpoint, use of a single "test" dose of Tizanidine may help clinicians decide whether the drug can helpful in controlling symptoms in particular subjects.

Topics: Adrenergic alpha-2 Receptor Agonists; Adrenergic alpha-Agonists; Adult; Ankle Joint; Clonidine; Elasticity; Humans; Muscle Spasticity; Muscle, Skeletal; Physical Stimulation; Range of Motion, Articular; Receptors, Adrenergic, alpha-2; Reflex; Spinal Cord Injuries; Torque

Although spasticity has been defined as an increase in velocity-dependent stretch reflexes and muscle hypertonia during passive movement, the measurement of flexor muscle paresis may better characterize the negative impact of this syndrome on residual motor function following incomplete spinal cord injury (iSCI). In this longitudinal study Tibialis Anterior (TA) muscle paresis produced by a loss in maximal voluntary contraction during dorsiflexion and ankle flexor muscle coactivation during ramp-and-hold controlled plantarflexion was measured in ten patients during subacute iSCI. Tibialis Anterior activity was measured at approximately two-week intervals between 3-5 months following iSCI in subjects with or without spasticity, characterized by lower-limb muscle hypertonia and/or involuntary spasms. Following iSCI, maximal voluntary contraction ankle flexor activity was lower than that recorded from healthy subjects, and was further attenuated by the presence of spasticity. Furthermore the initially high percentage value of TA coactivation increased at 75% but not at 25% maximal voluntary torque (MVT), reflected by an increase in TA coactivation gain (75%/25% MVT) from 2.5+/-0.4 to 7.5+/-1.9, well above the control level of 2.9+/-0.2. In contrast contraction-dependent TA coactivation gain decreased from 2.4+/-0.3 to 1.4+/-0.1 during spasticity. In conclusion the adaptive increase in TA coactivation gain observed in this pilot study during subacute iSCI was also sensitive to the presence of spasticity. The successful early diagnosis and treatment of spasticity would be expected to further preserve and promote adaptive motor function during subacute iSCI neurorehabilitation.

Topics: Adult; Aged; Ankle; Ankle Joint; Electromyography; Humans; Longitudinal Studies; Male; Middle Aged; Movement; Muscle Contraction; Muscle Spasticity; Muscle Tonus; Muscle, Skeletal; Pilot Projects; Recovery of Function; Spinal Cord Injuries; Torque; Young Adult

The aim of this study was to examine the repeatability of and relationships among spasticity, co-contraction of agonist-antagonist, and muscle strength in children with cerebral palsy (CP). Eight children with spastic diplegic CP (five males, three females; Gross Motor Function Classification System [GMFCS] Levels I-III; mean age 10y 2mo [SD 2y 9mo], range 6-13y) and nine children in a comparison group (six males, three females; mean age 8y 10mo [SD 2y 4mo], range 6y to 12y 6mo) were assessed twice to examine repeatability of Composite Spasticity Scale, soleus stretch reflexes, electromyography (EMG) co-contraction ratio, and torque recorded during maximal isometric voluntary contraction of ankle dorsiflexors and plantarflexors. Sixty-one children with spastic CP, (54 diplegic, seven hemiplegic; 32 males, 29 females; GMFCS levels I-III; mean age 10y 8mo [SD 2y 9mo], range 6-15y) were then assessed to delineate possible correlations among these measures. Intraclass correlation coefficients (0.78-0.97) showed high data repeatability in both groups. Children with spastic CP demonstrated significantly larger soleus stretch reflex/M-response areas smaller torques, but larger EMG co-contraction ratios during both voluntary dorsiflexion and plantarflexion (all p<0.05). Children with spastic CP who had larger soleus stretch reflex/M-response areas demonstrated larger plantarflexion co-contraction ratio (r = 0.28), and produced smaller plantarflexion and dorsiflexion torques (r = -0.48 and -0.27 respectively). However, no correlation was noted between soleus stretch reflex and clinical spasticity. Our findings demonstrated that hyperactive soleus stretch reflex affected torque production of ankle muscles. Moreover, the severity of spasticity may not be fully described by either stretch reflex or tone measure alone.

Topics: Adolescent; Cerebral Palsy; Child; Electromyography; Female; Humans; Male; Muscle Contraction; Muscle Spasticity; Muscle Weakness; Muscle, Skeletal; Reflex, Stretch; Reproducibility of Results; Statistics as Topic; Torque

Instead of hyper-reflexia as sole paradigm, post-stroke movement disorders are currently considered the result of a complex interplay between neuronal and muscular properties, modified by level of activity. We used a closed loop system identification technique to quantify individual contributors to wrist joint stiffness during an active posture task.. Continuous random torque perturbations applied to the wrist joint by a haptic manipulator had to be resisted maximally. Reflex provoking conditions were applied i.e. additional viscous loads and reduced perturbation signal bandwidth. Linear system identification and neuromuscular modeling were used to separate joint stiffness into the intrinsic resistance of the muscles including co-contraction and the reflex mediated contribution.. Compared to an age and sex matched control group, patients showed an overall 50% drop in intrinsic elasticity while their reflexive contribution did not respond to provoking conditions. Patients showed an increased mechanical stability compared to control subjects.. Post stroke, we found active posture tasking to be dominated by: 1) muscle weakness and 2) lack of reflex adaptation. This adds to existing doubts on reflex blocking therapy as the sole paradigm to improve active task performance and draws attention to muscle strength and power recovery and the role of the inability to modulate reflexes in post stroke movement disorders.

Topics: Adaptation, Physiological; Adult; Aged; Feedback, Physiological; Female; Follow-Up Studies; Humans; Male; Middle Aged; Models, Biological; Muscle Contraction; Muscle Spasticity; Muscle Weakness; Paresis; Posture; Psychomotor Performance; Reflex; Reflex, Abnormal; Stroke; Stroke Rehabilitation; Torque; Weight-Bearing; Wrist Joint

To examine the role of reflex activity in spasticity and the relationship between peak passive torque, Ashworth Scale (AS), and Spasm Frequency Scale (SFS) of the knee flexors and extensors during the measurement of spasticity using an isokinetic dynamometer in children with spinal cord injury (SCI).. Eighteen children with chronic SCI and 10 children of typical development (TD) participated. One set of 10 passive movements was completed using an isokinetic dynamometer at 15, 90, and 180 degrees per second (deg/s) while surface electromyographic data were collected from the vastus lateralis (VL) and medial hamstrings (MH). Spasticity was clinically assessed using the AS and SFS.. There were no significant differences in peak passive torque of the knee flexors and extensors at any velocity for children with SCI compared to children with TD. Children with TD demonstrated significantly more reflex activity of the MH during the assessment of knee flexor spasticity at all movement velocities than did children with SCI. Children with TD demonstrated significantly more reflex activity of the VL during the assessment of knee-extensor spasticity with movements at 180 deg/s. The relationship between peak passive torque, AS, and SFS was significant during movements at a velocity of 90 deg/s only.. The role of increased reflexes in spasticity needs further examination. Isokinetic dynamometry may be measuring a different aspect of spasticity than the AS and SFS do in children with SCI.

Topics: Adolescent; Age Factors; Child; Child, Preschool; Disability Evaluation; Electromyography; Female; Humans; Knee; Male; Muscle Contraction; Muscle Spasticity; Muscle Strength Dynamometer; Muscle, Skeletal; Neurologic Examination; Paralysis; Predictive Value of Tests; Range of Motion, Articular; Spinal Cord Injuries; Torque

Although spasticity is a common symptom in children with cerebral palsy, weakness may be a much greater contributor to disability. We explore whether a treatment that reduces spasticity may also have potential benefit for improving strength. Ten children with cerebral palsy and spasticity in the ankle plantar flexor muscles were treated with oral baclofen for 4 weeks. We tested voluntary ability to activate ankle plantar flexor muscles using the ratio of the surface electromyographic signal during isometric maximal voluntary contraction to the M-wave during supramaximal electrical stimulation of the tibial nerve and tested muscle strength using maximal isometric plantar flexion torque. Mean maximal voluntary neuromuscular activation increased from 1.13 +/- 1.02 to 1.60 +/- 1.30 ( P < .05) after treatment, corresponding to an increase in 9 of 10 subjects. Mean maximal plantar flexion torque did not change. We conjecture that antispasticity agents could facilitate strength training by increasing the ability to voluntarily activate muscle.

Topics: Administration, Oral; Adolescent; Ankle Joint; Baclofen; Cerebral Palsy; Child; Child, Preschool; Dose-Response Relationship, Drug; Drug Administration Schedule; Electric Stimulation; Electromyography; Female; Follow-Up Studies; H-Reflex; Humans; Isometric Contraction; Male; Muscle Relaxants, Central; Muscle Spasticity; Muscle Strength; Muscle Weakness; Neuromuscular Junction; Range of Motion, Articular; Tibial Nerve; Torque

Despite intensive investigation, the origins of the neuromuscular abnormalities associated with spasticity are not well understood. In particular, the mechanical properties induced by stretch reflex activity have been especially difficult to study because of a lack of accurate tools separating reflex torque from torque generated by musculo-tendinous structures. The present study addresses this deficit by characterizing the contribution of neural and muscular components to the abnormally high stiffness of the spastic joint.. Using system identification techniques, we characterized the neuromuscular abnormalities associated with spasticity of ankle muscles in chronic hemiparetic stroke survivors. In particular, we systematically tracked changes in muscle mechanical properties and in stretch reflex activity during changes in ankle joint angle. Modulation of mechanical properties was assessed by applying perturbations at different initial angles, over the entire range of motion (ROM). Experiments were performed on both paretic and non-paretic sides of stroke survivors, and in healthy controls.. Both reflex and intrinsic muscle stiffnesses were significantly greater in the spastic/paretic ankle than on the non-paretic side, and these changes were strongly position dependent. The major reflex contributions were observed over the central portion of the angular range, while the intrinsic contributions were most pronounced with the ankle in the dorsiflexed position.. In spastic ankle muscles, the abnormalities in intrinsic and reflex components of joint torque varied systematically with changing position over the full angular range of motion, indicating that clinical perceptions of increased tone may have quite different origins depending upon the angle where the tests are initiated.Furthermore, reflex stiffness was considerably larger in the non-paretic limb of stroke patients than in healthy control subjects, suggesting that the non-paretic limb may not be a suitable control for studying neuromuscular properties of the ankle joint. Our findings will help elucidate the origins of the neuromuscular abnormalities associated with stroke-induced spasticity.

Topics: Aged; Ankle; Ankle Joint; Biomechanical Phenomena; Functional Laterality; Humans; Leg; Middle Aged; Movement Disorders; Muscle Hypertonia; Muscle Spasticity; Muscle, Skeletal; Neurologic Examination; Paresis; Predictive Value of Tests; Range of Motion, Articular; Reflex, Abnormal; Reflex, Stretch; Stroke; Tendons; Torque

To examine the usefulness of a biomechanical measure, resistance torque (RT), in quantifying spasticity by comparing its use with a clinical scale, the modified Ashworth scale (MAS), and quantitative electrophysiological measures.. This is a correlational study of spasticity measurements in 34 adults with traumatic brain injury and plantarflexor spasticity. Plantarflexor spasticity was measured in the seated position before and after cryotherapy using the MAS and also by strapping each subject's foot and ankle to an apparatus that provided a ramp and hold stretch. The quantitative measures were (1) reflex threshold angle (RTA) calculated through electromyographic signals and joint angle traces, (2) Hdorsiflexion (Hdf)/Hcontrol (Hctrl) amplitude ratio obtained through reciprocal inhibition of the soleus H-reflex, (3) Hvibration (Hvib)/Hctrl ratio obtained through vibratory inhibition of the soleus H-reflex, and (4) RT calculated as the time integral of the torque graph between the starting and ending pulses of the stretch.. Correlation coefficients between RT and MAS scores in both pre-ice (0.41) and post-ice trials (0.42) were fair (P = 0.001). The correlation coefficients between RT scores and RTA scores in both the pre-ice (0.66) and post-ice trials (0.75) were moderate (P

Topics: Adult; Biomechanical Phenomena; Brain Injuries; Cryotherapy; Electrophysiology; Humans; Muscle Spasticity; Torque

The aim of this study was to estimate the strength of spastic muscles using Biodex System 3 within a group of patients with hemiparesis in after-stroke population. Measurements of the moments of force in elbow flexors and extensors of both spastic and non-spastic limbs were conducted under isostatic conditions. We analysed the values obtained for both limbs in order to determine the spasticity level on an Ashworth scale (0-4). The subjects were 10 patients with hemiparesis and varying spasticity selected from an after-stroke population. The analysis showed that spastic muscles activated less force than non-spastic muscles of the same patient. Furthermore, in a spastic limb, higher values of force were noted in the flexors than in the extensors of the elbow. In a non-spastic limb, the values of force were higher in the extensors of the elbow joint than in flexors. It is worth adding that the dynamics of force exposure, defined by a gradient of force, was much lower in spastic muscles than in non-spastic ones. Objective estimation of muscle force can be done by measuring the moments of force in particular groups of muscles upon the isokinetic contraction appearing. The repeatability of measurements may enable the kind of kinesitherapy to be determined as well as the assessment of the effectiveness of exercises in regard to force increase and dynamics of spastic muscles.

Topics: Elbow Joint; Female; Humans; Male; Muscle Contraction; Muscle Spasticity; Muscle, Skeletal; Paresis; Stroke; Stroke Rehabilitation; Torque

We developed a neuromusculoskeletal model to simulate the stretch reflex torque induced during a constant angular velocity elbow extension by tuning a set of physiologically-based parameters. Our model extended past modeling efforts in the investigation of elbow spasticity by incorporating explicit musculotendon, muscle spindle, and motoneuron pool models in each prime elbow flexor. We analyzed the effects of changes in motoneuron pool and muscle spindle properties as well as muscle mechanical properties on the biomechanical behavior of the elbow joint observed during a constant angular velocity elbow extension. Results indicated that both motoneuron pool thresholds and gains could be substantially different among muscles. In addition, sensitivity analysis revealed that spindle static gain and motoneuron pool threshold were the most sensitive parameters that could affect the stretch reflex responses of the elbow flexors during a constant angular velocity elbow extension, followed by motoneuron pool gain, and spindle dynamic gain. It is hoped that the model will contribute to the understanding of the underlying mechanisms of spasticity after validation by more elaborate experiments, and will facilitate the future development of more specific treatment of spasticity.

Topics: Adaptation, Physiological; Biomechanical Phenomena; Elbow Joint; Models, Biological; Motor Neurons; Movement; Muscle Spasticity; Muscle, Skeletal; Nonlinear Dynamics; Reflex, Stretch; Torque

This pilot study examined the effects of neuromuscular electrical stimulation (NMES) therapy on upper limb impairment in children with cerebral palsy, specifically addressing spasticity, heightened passive resistance to wrist rotation, coactivation, and weakness.. Eight subjects, aged five to 15 years, with spastic hemiparesis subsequent to brain injury, participated in three months of NMES therapy, targeting the wrist flexor and extensor muscles. Maximum voluntary wrist extension range of motion against gravity, spasticity, passive torque, maximum voluntary isometric torque, and coactivation were recorded prior to, during, and at the conclusion of the therapy.. Seven of the eight subjects demonstrated a significant (>15 degrees) improvement in wrist extension range of motion against gravity following the NMES treatment, with an average gain of 38 degrees. Differences in spasticity (0.01 +/- 0.14 N-m, p = 0.80) and passive torque (0.03 +/- 0.11 N-m, p = 0.52) were not significant for these subjects. Isometric wrist extension torque, however, did increase significantly (p < 0.01), accompanied by a reduction in flexor coactivation (p < 0.01).. Evidence suggests that the NMES treatment protocol affected wrist extension by improving the strength of the wrist extensor muscles, possibly through decreased flexor coactivation. Further studies are required, however, to determine whether electrical stimulation itself or other facets of the therapy paradigm played the key role in improvement.

Topics: Adolescent; Brain Injuries; Cerebral Palsy; Child; Child, Preschool; Electric Stimulation Therapy; Electromyography; Female; Hand Strength; Humans; Male; Muscle Spasticity; Muscle Weakness; Paraparesis, Spastic; Pilot Projects; Range of Motion, Articular; Torque; Treatment Outcome; Upper Extremity; Wrist Joint

To assess test-retest reliability of the peak resistance torque and slope of work methods of spasticity measurement of the knee flexors and extensors in children with cerebral palsy (CP).. Test-retest reliability study.. Pediatric orthopedic hospital.. Fifteen children with CP.. Knee extensor and flexor spasticity was assessed with an isokinetic dynamometer using passive movements at 15 degrees, 90 degrees, and 180 degrees/s taken 1 hour apart.. Peak resistive torque and work were calculated. The relative and absolute test-retest reliability was calculated by using intraclass correlation coefficients (ICCs) and Bland-Altman plots, respectively.. Relative reliability was good (ICC>.75) for slope-of-work and peak resistance torque measurements at a velocity of 180 degrees/s, whereas reliability of peak torque measurements was decreased (ICC<.51) at slower velocities for both muscle groups. The 95% limits of agreement of Bland-Altman plots contained most data points for both methods, but the width of the limits of agreement were wide.. The measurement of spasticity of the knee extensors and flexors in children with CP using peak-resistance torque at 180 degrees/s and the slope of work method has acceptable relative test-retest reliability. However, the absolute reliability of spasticity data should be considered cautiously.

Topics: Adolescent; Cerebral Palsy; Child; Female; Humans; Isometric Contraction; Knee; Male; Muscle Spasticity; Muscle, Skeletal; Range of Motion, Articular; Rehabilitation; Reproducibility of Results; Torque

To assess the feasibility of using magnetic resonance imaging (MRI) and resistance to passive movement to evaluate spastic muscle.. T2-weighted MRI scans of the upper arm were obtained at rest and after the performance of upper-arm exercise. In addition, resistance to passive movement was measured subjectively (Modified Ashworth Scale [MAS]) and objectively by an isokinetic device while the arm was moved at varying speeds (stretch reflex torque).. Research laboratory.. Six hemiplegic stroke survivors (single group) with spasticity in the elbow flexors and extensors.. Not applicable.. Strength, stretch reflex torque, MAS, MRI-derived muscle cross-sectional area (CSA), and transverse relaxation time (T2).. The affected sides exhibited spasticity (as assessed through MAS), with the extensors displaying a range of 0 to 3, and the flexors between 1 and 1+. The affected muscle groups were significantly weaker than the unaffected muscle groups (extensors: 61% less, flexors: 65% less; P< or =.05). The affected CSA of the triceps was 25% smaller than that of the unaffected side (P=.01), but the biceps muscle group was similar (5% less on the affected side, P> or =.05). There was a tendency (P=.07; effect size, .48) for the resting T2 to be higher in affected versus unaffected biceps, but triceps values were similar (P> or =.05). Both muscle groups showed an increase in T2 after exercise ( approximately 30%, P< or =.05); however, the affected sides did not show an increase (P> or =.05). For both muscle groups, the affected side had a greater stretch reflex torque, with the range of torque values being greater than the range of MAS scores.. MRI and quantitative resistance to passive movement may be useful in the evaluation of spasticity. This is clinically relevant for the development and evaluation of antispasticity treatments.

Topics: Arm; Feasibility Studies; Female; Hemiplegia; Humans; Magnetic Resonance Imaging; Male; Middle Aged; Movement; Muscle Spasticity; Muscle Strength; Muscle Strength Dynamometer; Muscle, Skeletal; Pilot Projects; Stroke; Survivors; Torque

Spasticity is defined/assessed in resting limbs, where increased stretch reflex activity and mechanical joint resistance are evident. Treatment with antispastic agents assumes that these features contribute to the movement disorder, although it is unclear whether they persist during voluntary contraction.. To compare reflex amplitude and joint resistance in spastic and normal limbs over an equivalent range of background contraction.. Thirteen normal and eight hemiparetic subjects with mild/moderate spasticity and without significant contracture were studied. Reflex and passive joint resistance were compared at rest and during six small increments of biceps voluntary contraction, up to 15% of normal maximum. A novel approach was used to match contraction levels between groups.. Reflex amplitude and joint mechanical resistance were linearly related to contraction in both groups. The slopes of these relations were not above normal in the spastic subjects on linear regression. Thus, reflex amplitude and joint resistance were not different between groups over a comparable range of contraction levels. Spastic subjects exhibited a smaller range of reflex modulation than normals because of decreased maximal contraction levels (weakness) and significant increases of resting contraction levels.. Spasticity was most evident at rest because subjects could not reduce background contraction to normal. When background contractions were matched to normal levels, no evidence of exaggerated reflex activity or mechanical resistance was found. Instead, reduced capacity to modulate reflex activity dynamically over the normal range may contribute to the movement disorder. This finding does not support the routine use of antispastic agents to treat the movement disorder.

Topics: Adult; Aged; Case-Control Studies; Elbow Joint; Female; Hemiplegia; Humans; Isometric Contraction; Male; Middle Aged; Muscle Spasticity; Muscle, Skeletal; Reflex, Stretch; Rest; Torque

To compare the effectiveness of constant-torque prolonged muscle stretching (PMS) treatment in the inhibition of ankle hypertonia with that of constant-angle PMS treatment.. Before-after comparison.. A university-affiliated teaching hospital.. Thirty subjects with hemiplegia and hypertonia in the calf muscles.. Ankle plantarflexors were stretched using a motor-driven stretching device capable of operating in either a constant-angle or a constant-torque mode for 30 minutes of PMS treatment.. Clinical scales, including the Modified Ashworth Scale (MAS) and passive range of motion (ROM), and biomechanic assessments were used to evaluate the viscoelastic components of the ankle plantarflexors before and after PMS treatment.. Both constant-angle and constant-torque PMS treatments significantly improved the clinical scale (MAS, ROM) assessment results and reduced the viscoelastic components of the ankle joint ( P <.05). The degree of change in the viscoelastic components was more evident in subjects with constant-torque PMS than in those with constant-angle PMS ( P <.05).. The present biomechanic assessments indicate that both PMS treatment modes reduced the viscous and elastic components of hypertonic muscles. The proposed constant-torque PMS treatment was more effective than the conventional constant-angle stretching technique.

Topics: Adult; Aged; Biomechanical Phenomena; Female; Humans; Leg; Male; Middle Aged; Muscle Hypertonia; Muscle Spasticity; Muscle, Skeletal; Physical Therapy Modalities; Torque; Treatment Outcome

To examine test-retest reliability of the Timed Up & Go (TUG) test, its ability to differentiate subjects with chronic stroke from healthy elderly subjects, and its associations with ankle plantarflexor spasticity, ankle muscle strength, gait performance, and distance walked in 6 minutes in subjects with chronic stroke.. Cross-sectional study.. University-based rehabilitation center in Hong Kong, China.. Ten healthy elderly subjects and 11 subjects with chronic stroke.. Not applicable.. Time taken to complete the TUG test was recorded. Plantarflexor spasticity and ankle muscle strength were assessed, respectively, by the Composite Spasticity Scale and a load-cell together with electromyography. Gait parameters and walking endurance were measured respectively by walkway system (GAITRite II) and 6-minute walk test. Intraclass correlation coefficients (ICCs) were calculated as measures of reliability, and all correlation analyses were conducted using Spearman correlation coefficients.. The TUG test showed excellent reliability (ICC>.95). Subjects with chronic stroke had significantly more spastic and weaker plantarflexors, slower walking speeds, and poorer walking endurance when compared with healthy elderly subjects (all P<.003). The strength of the affected ankle plantarflexors (rho=-.860, P<.01), gait parameters (rho range, .620-.900; P<.05), and walking endurance (rho=-.960, P<.01) correlated with TUG scores.. The TUG scores were reliable, were able to differentiate the patients from the healthy elderly subjects, and correlated well with plantarflexor strength, gait performance, and walking endurance in subjects with chronic stroke.

Topics: Aged; Analysis of Variance; Chronic Disease; Cross-Sectional Studies; Disability Evaluation; Electromyography; Female; Humans; Lower Extremity; Male; Middle Aged; Muscle Spasticity; Recovery of Function; Reproducibility of Results; Statistics, Nonparametric; Stroke; Stroke Rehabilitation; Torque

To determine the minimum number of measurements required to obtain a reliable estimate of upper-extremity spasticity using biomechanic assessment across multiple testing trials and dates.. Single-center, longitudinal study with repeated measurements of spastic upper-extremity torque measures taken 1 week apart.. A hospital-based laboratory with an isokinetic testing system.. Sixteen subjects more than 6 months poststroke with upper-extremity spasticity.. Elbow flexor hypertonia was assessed with a custom-made manipulandum attached to a 6-axis load cell and a Biodex System 3 isokinetic testing machine. Movements into extension were imposed at 4 speeds: 6 degrees /s, 30 degrees /s, 60 degrees /s, and 90 degrees /s.. The resistive torque and electromyographic response to these imposed movements were measured. The torque response at the slowest speed (6 degrees /s) was attributed solely to the passive elements of the elbow and was subtracted from the torque response at the higher speeds (30 degrees /s, 60 degrees /s, 90 degrees /s), leaving only reflex torque. The reflex torques at 30 degrees /s, 60 degrees /s, and 90 degrees /s were used for further analysis. Peak torque, peak joint stiffness, and onset angle of reflex torque responses were found; repeatability and daily variability of these measures were statistically examined. The variabilities due to the subject, test day, and trial number were computed. The overall reliability of each parameter at the 3 higher test speeds using different testing schemes was also calculated.. Ninety percent reliability in the measurement of all parameters was obtained after at least 2 days of testing during which 3 tests a day were performed. The variability in between-subjects measurements was at least 4 times greater than the intertrial variability when testing at the highest speeds; daily variability that was up to 50% of the intersubject variability was also observed. The biomechanic measures correlated well with the Ashworth Scale (Spearman rho=.84, P<.005), a clinical measure of hypertonia.. We recommend at least 2 test dates to account for the daily variability in the spastic reflex response and to ensure reliable spasticity measurements.

Topics: Adult; Biomechanical Phenomena; Elbow; Electromyography; Female; Humans; Longitudinal Studies; Male; Middle Aged; Muscle Spasticity; Reflex, Stretch; Reproducibility of Results; Statistics, Nonparametric; Stroke; Torque

To use a portable muscle tone assessment device to measure spasticity after a botulinum toxin type A (BTX-A) injection.. Before-after trial.. Hospital.. Ten chronic stroke patients with upper-limb spasticity.. BTX-A was injected in the biceps brachii.. The biomechanic parameters, viscous component, and averaged viscosity derived from the acquired reactive resistance and angular displacements, as well as the reflex electromyographic threshold of biceps brachii, were used for spasticity evaluation.. A statistically significant decrease in averaged viscosity and a significant increase in reflex electromyographic threshold (P<.05) both indicated reduction in spasticity owing to BTX-A intervention. There was no clear reflex electromyographic activity detected at lower stretch frequencies.. Our portable design allows for the convenient use of the device for quantifying spasticity in clinics. All quantitative measurements suggest that BTX-A decreases spasticity within 2 weeks of injection. Our portable muscle tone measurement device may be useful for the clinical assessment of elbow flexor spasticity.

Topics: Adult; Aged; Biomechanical Phenomena; Botulinum Toxins, Type A; Elbow; Electromyography; Female; Humans; Injections; Male; Middle Aged; Muscle Contraction; Muscle Spasticity; Neuromuscular Agents; Recovery of Function; Statistics, Nonparametric; Stroke; Torque

Spasticity has been defined as a motor disorder characterized by a velocity-dependent increase in tonic stretch reflex (muscle tone). Muscle tone consists of mechanical-elastic characteristics, reflex muscle contraction and other elements. The aims of this study were to determine whether to assess spasticity quantitatively, and to characterize biomechanical and electromyographic spasticity assessment parameters. These assessment parameters were described by investigating the correlation between clinical measures and the response to passive sinusoidal movement with consecutive velocity increments. Twenty post-stroke hemiplegic patients and twenty normal healthy volunteers were included in the study. Five consecutive sinusoidal passive movements of the ankle were performed at specific velocities (60, 120, 180, and 240 degrees/ sec). We recorded the peak torque, work, and threshold angle using a computerized isokinetic dynamometer, and simultaneously measured the rectified integrated electromyographic activity. We compared these parameters both between groups and between different velocities. The peak torque, threshold angle, work, and rectified integrated electromyographic activity were significantly higher in the post-stroke spastic group at all angular velocities than in the normal control group. The threshold angle and integrated electromyographic activity increased significantly and linearly as angular velocity increased, but the peak torque and work were not increased in the post-stroke spastic group. Peak torque, work, and threshold angle were significantly correlated to the Modified Ashworth scale, but the integrated electromyographic activity was not. The biomechanical and electromyographic approach may be useful to quantitatively assess spasticity. However, it may also be very important to consider the different characteristics of each biomechanical parameter.

Topics: Adult; Aged; Ankle; Biomechanical Phenomena; Electromyography; Female; Humans; Male; Middle Aged; Muscle Spasticity; Regression Analysis; Stroke; Torque

To develop a method for assessment of spasticity, in which the whole range of motion (ROM) at a wide variation of speeds is applied.. Cross-sectional design to study construct validity.. Research department affiliated with a rehabilitation hospital in The Netherlands.. Nine patients with complete spinal cord injury recruited from the rehabilitation hospital.. Not applicable.. Thirty to 45 stretches over the whole ROM were applied to the triceps surae muscle at varying velocities measuring from 30 degrees to 150 degrees/s. Electromyographic responses were measured in order to assess reflex excitability. The torque over the ankle joint was measured during the whole stretch. The angle and velocity at which the reflex was initiated was also determined.. The electromyographic responses increased significantly at increasing stretch velocities (P<.001). The applied maximum angles are reproducible (intraclass correlation coefficient, .81) and provide representative torque responses.. The assessment method of spasticity using full range passive movements provides objective outcomes. The angular velocity is responsible for an exponential increase in amplitude of the electromyographic response.

Topics: Adult; Cross-Sectional Studies; Electromyography; Female; Humans; Lower Extremity; Male; Muscle Spasticity; Range of Motion, Articular; Reflex, Stretch; Reproducibility of Results; Spinal Cord Injuries; Torque

Data from the pendulum knee test has been used to develop two active models that use external torques to closely match the experimental knee trajectories of subjects with spasticity due to cerebral palsy. These data were collected from three subjects who are identical triplets; two of whom have clinically measurable spasticity. A passive model that accurately describes the knee trajectory of the nonspastic subject serves as the passive plant for two active models. One of these models allows direct application of external torques, and the second provides additional torque as the result of velocity feedback. Both active models and the passive model use separate parameters of stiffness and damping for the agonist and antagonist muscles.

Topics: Cerebral Palsy; Computer Simulation; Diagnosis, Computer-Assisted; Elasticity; Electromyography; Humans; Knee Joint; Male; Models, Neurological; Muscle Contraction; Muscle Spasticity; Muscle, Skeletal; Reflex, Stretch; Torque; Triplets

To determine what biomechanic characteristics of knee joint motion and walking show potential to quantitatively differentiate spasticity and dystonia in cerebral palsy (CP).. Descriptive measurement study.. University hospital.. Seventeen pediatric and adult patients with CP.. Not applicable.. We measured the resistance of the knee joint at different velocities and positions, maximum muscle activation during external motion, amplitude of knee tendon reflexes, maximum isometric flexion and extension torques, velocity of walking, and knee kinematics during the gait cycle. Patients were classified into 2 groups (dystonia or spasticity) if at least 2 of 3 physicians agreed that a prominent component of dystonia was present.. Patients with dystonia had a greater degree of co-contraction and an increased resistance to external motion at slow velocities. The tendon reflexes were almost normal in patients with dystonia, whereas they were increased in patients with spasticity. Muscle strength was more impaired in patients with dystonia, probably as a result of greater muscle co-contraction. They also walked slower, with smaller knee ranges of motion, during the stance phase of walking.. The measurement of resistance and of muscle activation during passive motion and tendon reflexes shows potential to differentiate dystonia from spasticity in CP patients with a mixed form of hypertonia. More studies are needed to confirm these results.

Topics: Adult; Biomechanical Phenomena; Cerebral Palsy; Child; Dystonia; Gait Disorders, Neurologic; Humans; Isometric Contraction; Knee Joint; Muscle Spasticity; Range of Motion, Articular; Reflex, Abnormal; Tendons; Torque; Walking

Topics: Acceleration; Elbow Joint; Humans; Isometric Contraction; Muscle Rigidity; Muscle Spasticity; Range of Motion, Articular; Reflex, Stretch; Stroke; Torque

Spastic equinovarus deformity of the ankle in adults with acquired brain injury can severely limit the achievement of rehabilitation goals. This study examined changes in triceps surae muscle extensibility, passive resistive torque and soleus stretch reflex responses in 10 adult brain injured subjects undergoing serial casting to correct ankle equinovarus deformity.. Goniometric measurement of maximal passive dorsiflexion was used to evaluate extensibility of the triceps surae muscles. Computer controlled ankle dynamometry and surface electromyography were used to identify passive resistive torque and soleus stretch reflex onset angle in response to stretches at two velocities.. The mean casting period was 5 weeks. Casting was discontinued in one subject due to failure to achieve measurable gain in ankle range over three consecutive cast changes. Median improvements in maximal ankle dorsiflexion, with the knee flexed or extended, of 30 degrees and 15 degrees, respectively, were achieved in the remaining nine subjects (p < 0.0001). The median passive ankle range in response to a displacing torque of 10 Nm increased 4.3 degrees over the intervention period (p < 0.0001). Consistent soleus reflex activity in response to passive stretches at 25 degrees x s(-1) was elicited in only four subjects. A trend for the stretch reflex onset to move further into the available range was demonstrated in these subjects.. In the present study, serial casting contributed to significant change in triceps surae extensibility and passive resistive torque, corresponding with improved maximal passive ankle dorsiflexion range and an increase in the angle achieved with a displacing torque of 10 N.m. Increased stretch reflex threshold was observed in some subjects. The use of pre-determined outcome criteria and careful measurement of responses to this intervention were important to prevent premature discontinuation of casting when gains were slower than expected.

Topics: Adolescent; Adult; Casts, Surgical; Female; Humans; Isometric Contraction; Male; Middle Aged; Muscle Spasticity; Muscle, Skeletal; Range of Motion, Articular; Reflex, Stretch; Sensitivity and Specificity; Torque

To determine whether increased reflexes are related to functional impairment in children with spasticity.. Descriptive measurement study.. Rehabilitation department in Poland.. Sixteen able-bodied children and 29 children with spasticity.. Not applicable.. Measurement of modulation function of knee tendon reflexes by isometric knee extension, maximum isometric knee flexion, and extension torques, and scoring of ambulation in patients.. In able-bodied children, the reflex modulation function increased with voluntary knee extension, reached maximum at 5% to 20% of voluntary extension, and then decreased. The reflex modulation function in patients fell into 2 major categories. In the majority of affected limbs, the modulation function was inverse, with maximum reflex response at relaxation, and decreased with an increase of voluntary extension. In the remaining limbs, the shape of the reflex modulation function was normal, although other parameters changed. Isometric torques decreased more in flexion (65%) than in extension (39%). A torque decrease was a result of cocontraction more often during knee flexion (65%) than in knee extension (24%). The larger the reflexes, the more flexion torque decreased and ambulation deteriorated. This pattern occurred in patients with inverse modulation function but not in those with normal modulation function. The reciprocal inhibition from knee flexors to extensors could be affected in patients with inverse modulation function and cocontraction during flexion, whereas other mechanisms occurred in other patients.. The experimental design has potential as a quantitative measure of abnormal control in children with spasticity and can lead to more precise treatment selection criteria.

Topics: Adolescent; Case-Control Studies; Child; Child, Preschool; Disability Evaluation; Disabled Children; Electromyography; Female; Humans; Isometric Contraction; Knee; Knee Joint; Male; Muscle Spasticity; Muscle, Skeletal; Reflex, Stretch; Tendons; Torque; Walking

Extensor spasms, which are a significant component of spasticity in spinal cord injury (SCI), were investigated in an attempt to identify the role that hip proprioceptors play in triggering an extensor reflex response. In ten SCI subjects, a controlled hip extension movement was imposed on one leg while the knee and ankle were held in an isometric position using an instrumented leg brace. Isometric joint torques of the hip, knee, and ankle were measured following a constant velocity (30 degrees /s), 45 degrees -75 degrees extension movement of the hip that was applied using the motor of a Biodex rehabilitation/testing system. Electromyograms (EMGs) from four to eight muscles were also recorded during the ten movement trials. The stereotypical torque response to an imposed hip extension consisted of hip flexion, knee extension, and ankle plantarflexion, although all components were not observed in every subject. EMGs indicated coactivation at the knee and ankle joints, with extensor activity generally outlasting flexor activity. These observations are consistent with clinical descriptions of extensor spasms. In contrast, the response to imposed hip flexion, which was observed in six of the ten subjects, comprised hip extension, knee flexion and ankle extension. This difference between the response to hip flexion and the response to extension indicates a specificity of the reflex, suggesting that organized pathways for coordinating leg movements are involved.

Topics: Adolescent; Adult; Aged; Ankle Joint; Electromyography; Hip Joint; Humans; Knee Joint; Middle Aged; Muscle Contraction; Muscle Spasticity; Muscle, Skeletal; Proprioception; Range of Motion, Articular; Reflex; Spinal Cord Injuries; Thigh; Torque

The linearity of the relationship between torque and electromyographic (EMG) activation has been widely debated for years, yet remains unresolved. Despite limitations and possible inaccuracies, an assumption of linearity is often made to simplify the relationship between these variables for computational and descriptive purposes. Although typically derived from isometric test conditions, these relationships have also been extrapolated, perhaps invalidly, to conditions where joint velocity and length are changing. The purpose of this study was to examine the degree of linearity between hamstring and quadriceps torques and their respective EMG signals, and to compare the slopes of these relationships in normal and spastic muscles at varying muscle lengths and conditions. We hypothesized that relationships would be linear for all muscles tested in both subject groups; however, slopes would differ across the two muscles, the three muscle lengths tested, and the two subject groups. We further hypothesized that the degree of linearity during an isotonic task would be less than for the isometric one, particularly for patients with spasticity who may demonstrate abnormal responses to changes in muscle length. Results indicated that torque--EMG relationships were linear for all subjects during isometric contractions, regardless of group, muscle, or knee angle. However, the degree of linearity was significantly less in CP in both conditions; and within the CP group, was less during isotonic compared to isometric conditions. Slope values differed between muscles at some lengths, across muscle lengths in the quadriceps, and subjects with CP showed consistently lower slopes for all quadriceps values. These data in general support the robustness of the linear assumption in isometric conditions for the knee musculature, caution against extrapolation to isotonic conditions particularly for those with movement abnormalities, and suggest that slope differences may provide valuable insights into pathology and warrant further investigation.

Topics: Adolescent; Biomechanical Phenomena; Cerebral Palsy; Child; Electromyography; Female; Humans; Knee; Leg; Male; Movement; Muscle Contraction; Muscle Spasticity; Muscle, Skeletal; Torque

The effect of functional electrical stimulation (FES) training on body composition, assessed by computed tomography, and the effect of spasticity, assessed by both objective and subjective measures, are evaluated. Fifteen motor-complete spinal-cord-injured men participated in the study. Eight of the 15 subjects undertook FES cycling 3 times weekly for 6 months. Whole body computed tomography scans evaluated changes in body composition. Simultaneous Modified Ashworth Scale and electromyography (EMG) measurements, resistive torque (Kin-Com) and EMG measurements, and self-ratings with Visual Analogue Scale during four consecutive days were used to evaluate changes in spasticity. Lower extremity muscle volume increased by an average of 1300 cm3 (p < 0.001) in the training group compared to the control group, who experienced no change. Otherwise no changes in body composition were seen. Significant correlations (Spearman) were found between individual EMG activity recordings and movement-provoked Modified Ashworth Scale ratings in 26% of the test situations, irrespective of group and time. The objective and subjective evaluation of movement-provoked passive (viscoelastic) and active (spasticity-related) resistance remained unchanged.

Topics: Adult; Body Composition; Electric Stimulation Therapy; Electromyography; Humans; Linear Models; Male; Middle Aged; Muscle Spasticity; Quadriplegia; Statistics, Nonparametric; Tomography, X-Ray Computed; Torque; Treatment Outcome

To quantify velocity dependent and position related properties of increased muscle tone measured during a constant velocity stretch.. Elbow flexors were vertically stretched under four different velocities (40, 80, 120, and 160 degrees /s) through a 75 degrees range of motion in 12 patients with hemiparesis, 16 with parkinsonism, and 12 normal controls. From reactive torque measurement, a linear second order model was adopted to dissociate velocity dependent viscous and velocity independent elastic components. The averaged speed dependent reflex torque (ASRT)--defined as the deviation of measured torque from baseline torque--was used to quantify the viscous component of hypertonia. Velocity sensitivity of ASRT (VASRT) and segmented ASRT (SASRT), derived from the slope of the regression line among ASRT velocity plots and from segmentations of reactive torque, respectively, were used to differentiate the increased muscle tone of spasticity and rigidity.. ASRT and VASRT were significantly higher in both spasticity and rigidity than in normal controls. SASRT analysis showed three different position related patterns among spasticity, rigidity, and normal groups: spasticity showed progressively increasing muscle tension relative to position; rigidity showed increased (relative to the norm) but constant muscle tone over the entire stretch range; the normal control group showed a consistently low reactive torque over the entire range.. Velocity dependence analysis indicates that rigidity and spasticity have approximately equal velocity dependent properties. For differentiating these two types of hypertonia, position dependent properties my be employed.

Topics: Adult; Aged; Biomechanical Phenomena; Diagnosis, Differential; Elbow; Female; Humans; Male; Middle Aged; Muscle Rigidity; Muscle Spasticity; Muscle, Skeletal; Paresis; Parkinsonian Disorders; Posture; Torque

The relation between spasticity and strength in individuals with cerebral palsy (CP) has not been extensively researched. Knee and ankle spasticity and strength were quantified in a retrospective analysis of 60 individuals with spastic diplegic CP (mean age 12 years, range 3 to 38) and a group of 50 individuals without disabilities (WD group; mean age 12 years, range 4 to 36). Spasticity was measured using a KinCom dynamometer that stretched the passive knee flexors or ankle plantarflexors at different speeds and recorded the amount of resistive torques. For the strength tests, the participant performed a maximum contraction of the knee flexors/extensors and ankle plantarflexors/dorsiflexors throughout their range of motion at a speed of 10 degrees/s on the dynamometer. Pearson's correlation coefficient was used to determine if a relation existed between spasticity and strength within the same muscle group and in opposing muscle groups at the knee and ankle joints. A t-test was performed to determine if greater spasticity and less strength existed at the ankles compared with the knees in those with CP. Results show that there was no relation between spasticity and strength either within the same muscle group or at opposing muscle groups at the knee and ankle joints in persons with CP. Individuals with spastic diplegic CP were more involved (greater spasticity, less strength) distally at the ankles compared with the knees. The findings conflict with the literature, which contains several assumptions, one of which is that a spastic muscle is a strong muscle and that spasticity causes weakness in the opposing muscle group. We found no relation between spasticity and strength in individuals with CP. Our findings support the literature, which states that individuals with spastic diplegic CP are more involved distally compared with proximally in the lower extremities.

Topics: Adolescent; Adult; Ankle; Biomechanical Phenomena; Cerebral Palsy; Child; Child, Preschool; Humans; Knee; Muscle Contraction; Muscle Spasticity; Reference Values; Reproducibility of Results; Retrospective Studies; Torque

Muscle resistance was evaluated by measurement of movement-provoked torque performed during simultaneous thigh muscle EMG recordings in individuals with a motor complete spinal cord injury (SCI). Fifteen men with a motor complete (ASIA grade A or B) cervical injury participated in the study. The activity started at an average of 0.11 seconds after the start of the provoking movement as evidenced by EMG recordings. However, no activity at all was found before the end of the movement provocation for 0.3 seconds in >60% of the test situations, whereas muscle torque was recorded in all cases. Significantly higher resistive muscle torque (p = 0.049) was provoked during extension movement compared with that of flexion. On the contrary, the maximum muscle activity was significantly higher (p = 0.009) during flexion movement compared with that during extension, with no differences between muscle groups. The resistive muscle torque seems to measure the passive viscoelastic component rather then the active spastic component of the movement-provoked muscle resistance in our group of motor complete SCI individuals.

Topics: Adult; Electric Stimulation; Electromyography; Humans; Injury Severity Score; Knee Joint; Linear Models; Male; Middle Aged; Muscle Contraction; Muscle Spasticity; Prospective Studies; Quadriplegia; Range of Motion, Articular; Reproducibility of Results; Sampling Studies; Sensitivity and Specificity; Time Factors; Torque

To establish (1) whether associated reactions could contribute to contracture formation and (2) whether the presence of spasticity was essential for their expression, after stroke.. Subjects were 24 hemiparetics within 13 months of a stroke, unselected for contracture or spasticity.. Associated reactions were identified by the presence of muscle activity in the affected biceps brachii and quantified as the amount of affected elbow flexor torque produced during a moderate contraction of either the contralateral biceps brachii or the contralateral quadriceps muscles. Contracture was measured as loss of elbow joint range of motion and spasticity as the presence of abnormal reflex activity.. Associated reactions were present in at least one testing condition in seven subjects. During contractions of the contralateral biceps brachii, the median amount of elbow flexor torque produced was 0.39 (interquartile range, IQR 2.5) Nm while during contractions of the contralateral quadriceps muscle it was 0.19 (IQR 1.6) Nm. Associated reactions were not associated with contracture (p = 0.39) which was present in over half of the subjects. The incidence of associated reactions was about the same as that of spasticity, but the two were not related (p = 0.61).. Even though associated reactions were present in 29% of the subjects during moderate contraction of the contralateral muscles, they were not large, nor were they associated with contracture or spasticity, suggesting that this phenomenon is not usually a major problem for everyday function after stroke.

Topics: Adult; Aged; Aged, 80 and over; Arm; Contracture; Disabled Persons; Electromyography; Female; Humans; Incidence; Male; Middle Aged; Muscle Contraction; Muscle Spasticity; Paresis; Range of Motion, Articular; Reflex, Abnormal; Severity of Illness Index; Stroke; Tomography, X-Ray Computed; Torque

Mechanical changes underlying spastic hypertonia were explored using a parallel cascade system identification technique to evaluate the relative contributions of intrinsic and reflex mechanisms to dynamic ankle stiffness in healthy subjects (controls) and spastic, spinal cord injured (SCI) patients. We examined the modulation of the gain and dynamics of these components with ankle angle for both passive and active conditions. Four main findings emerged. First, intrinsic and reflex stiffness dynamics were qualitatively similar in SCI patients and controls. Intrinsic stiffness dynamics were well modeled by a linear second-order model relating intrinsic torque to joint position, while reflex stiffness dynamics were accurately described by a linear, third-order system relating half-wave rectified velocity to reflex torque. Differences between the two groups were evident in the values of four parameters, the elastic and viscous parameters for intrinsic stiffness and the gain and first-order cut-off frequency for reflex stiffness. Second, reflex stiffness was substantially increased in SCI patients, where it generated as much as 40% of the total torque variance, compared with controls, where reflex contributions never exceeded 7%. Third, differences between SCI patients and controls depended strongly on joint position, becoming larger as the ankle was dorsiflexed. At full plantarflexion, there was no difference between SCI and control subjects; in the mid-range, reflex stiffness was abnormally high in SCI patients; at full dorsiflexion, both reflex and intrinsic stiffness were larger than normal. Fourth, differences between SCI and control subjects were smaller during the active than the passive condition, because intrinsic stiffness increased more in controls than SCI subjects; nevertheless, reflex gain remained abnormally high in SCI patients. These results elucidate the nature and origins of the mechanical abnormalities associated with hypertonia and provide a better understanding of its functional and clinical implications.

Topics: Adult; Ankle Joint; Female; Humans; Linear Models; Male; Middle Aged; Movement; Muscle Contraction; Muscle Spasticity; Muscle Tonus; Muscle, Skeletal; Posture; Range of Motion, Articular; Reference Values; Reflex; Spinal Cord Injuries; Torque

Ankle spasticity and strength in 27 children with spastic diplegic cerebral palsy (CP) (mean age 9 years, range 3 to 18 years) and a group of 12 children without CP (comparison group) (mean age 9 years, range 5 to 18 years) were observed. To measure spasticity, a KinCom dynamometer dorsiflexed the passive ankle at five different speeds and recorded the resistive plantarflexion torques. Work values for the torque-angle data were calculated at each speed. Using this data, linear regression was used to measure spasticity. To measure strength, the dynamometer rotated the ankle from maximum dorsiflexion to maximum plantarflexion at a speed of 10 degrees/s while the child performed a maximum plantarflexion concentric contraction. The movement was reversed to record maximum dorsiflexion. Maximum torques and work by the plantarflexors and dorsiflexors were calculated. The group with CP had significantly more spasticity in the plantarflexors and significantly less strength in the plantarflexors and dorsiflexors than the group without CP. Results provide objective information quantifying ankle spasticity and strength in children with CP.

Topics: Adolescent; Ankle Joint; Biomechanical Phenomena; Cerebral Palsy; Child; Child, Preschool; Female; Humans; Male; Muscle Spasticity; Muscle, Skeletal; Prospective Studies; Torque; Weight-Bearing

Quantitative evaluation of muscle tone in post-stroke patients; correlation of biomechanical indices with conventional clinical scales and neurophysiological measures; characterization of passive and neural components of muscle tone.. Mechanical stretches of the wrist flexor muscles of 53 post-stroke patients were imposed by means of a torque motor at constant speed. Patients were clinically studied using the Ashworth scale for spasticity and the Medical Research Council score for residual muscle strength. The neurophysiological measures were Hoffmann reflex latency, Hmax/Mmax ratio, stretch reflex threshold speed (SRTS), stretch reflex (SR) latency and area, passive (ISI) and total (TSI) stiffness indices.. Hmax/Mmax ratio, SR area, ISI and TSI values were significantly higher in patients, while SRTS was significantly lower. TSI, SRTS and SR area were highly correlated to the Ashworth score.. This EMG-biomechanical technique allows an objective evaluation of changes in muscle tone in post-stroke patients, providing easily measurable, quantitative indices of muscle stiffness. The linear distribution of these measures is particularly indicated for monitoring changes induced by treatment. The apparatus seems suitable to characterize neural stiffness, while difficulties were found in isolating the passive components, because of the occurrence of tonic EMG activity in most spastic patients.

Topics: Adult; Aged; Biomechanical Phenomena; Electromyography; Electrophysiology; Female; H-Reflex; Humans; Male; Middle Aged; Muscle Contraction; Muscle Spasticity; Muscle Tonus; Muscle, Skeletal; Reaction Time; Stroke; Torque; Wrist Joint

Despite its potential importance in hand dysfunction, spasticity in the finger muscles following stroke has not been well described. To explore this area, we assessed the role of finger flexor spasticity, along with that of passive mechanical forces, in resisting finger movement in 13 chronic stroke subjects. Subjects were tested with a device that stretched the extrinsic finger muscles through imposed rotation of the metacarpophalangeal (MCP) joints. Both maintained and constant-velocity stretches were imposed. For the constant-velocity stretches, eight of the 13 stroke subjects exhibited strong stretch reflexes, as determined by electromyography and net work. The net work of this reflex response, calculated from the integral of the torque-angle plots, increased proportionally with increasing velocity, indicating a contribution from flexor muscle spasticity. Conversely, nine of the 13 stroke subjects did not possess distinctly greater passive, mechanical resistance to MCP rotation than control subjects. While extensor spasticity was not observed, stretch of the extrinsic finger flexors also produced some reflex activity in the finger extensors concomitant with reflex excitation of the flexors. These findings suggest that resistance to muscle stretching following stoke is mediated primarily by neurological rather than biomechanical disturbances, although changes in muscle fiber length may exaggerate the resistance.

Topics: Aged; Electromyography; Female; Finger Joint; Humans; Male; Middle Aged; Movement; Muscle Contraction; Muscle Spasticity; Muscle, Skeletal; Paralysis; Reflex, Stretch; Stroke; Torque; Wrist Joint

We examined ankle clonus in four spastic subjects to determine whether this oscillatory behavior has the properties of a limit cycle, and whether it is driven by peripheral sensory input or by a spinal generator. Using Floquet Theory and Poincare sections to assess reflex stability, we found that cycle-to-cycle variability was small, such that the Floquet multipliers were always less than unity. Furthermore, the steady-state periodic orbit was not dependent on the initial position of the ankle. Both of these findings, coupled with strong correlations between the size of the applied load and the frequency of ankle movements and electromyogram burst frequency suggests that clonus behaves as a locally stable limit cycle driven from peripheral receptors. To better understand how nonlinear elements might produce stable oscillatory motion, we simulated the ankle stretch reflex response. We found that delays in the pathway caused the reflex to come on during the shortening phase of movement, so the additional reflex torque required to sustain oscillatory ankle movements was quite small. Furthermore, because the resistance to stretch is largely due to passive mechanics whose properties are quite stationary, the system is robust to small perturbations within the reflex pathway.

Topics: Adult; Ankle; Biomechanical Phenomena; Computer Simulation; Electromyography; Humans; Male; Models, Biological; Muscle Spasticity; Nonlinear Dynamics; Periodicity; Range of Motion, Articular; Reflex, Stretch; Signal Processing, Computer-Assisted; Spinal Cord Injuries; Torque

To assess resistance to passive isokinetic movements at specified speeds and range of motion, as a measure of muscular tonus.. A group of 12 subjects with complete traumatic spinal cord injury and a group of 12 able-bodied subjects were analysed, distinguishing the level of spasticity in the SCI group. Maximum eccentric peak torque was observed in passive isokinetic flexion (F) and extension (E) knee movement in displacements of 30, 60 and 120 per second.. The Student t-test showed that the average torque in the injured group was significantly higher than in the control group (F= 120 degrees per second, P<0.001). Variance analysis showed that the lower level presented lower torque levels (E=60 and 120 degrees per second, P<0.032), while those in the higher level presented higher torque levels (F and E=60 and 120 per second, P<0.032) when compared to the control group. In the control group the Student t-test (P<0.0006) showed a significantly different muscle behavior (Flexion>Extension Torque).. By using isokinetic assessment it was possible to quantify hypertonic spasticity in a group of subjects with spinal cord injury, distinguishing groups with higher and lower levels of spasticity as compared to a control group.

Topics: Adolescent; Adult; Analysis of Variance; Biomechanical Phenomena; Female; Humans; Knee Joint; Male; Muscle Spasticity; Spinal Cord Injuries; Torque

In this investigation the authors quantified changes in ankle plantarflexor spasticity and strength following selective dorsal rhizotomy (SDR) and intensive physical therapy in patients with cerebral palsy (CP).. Twenty-five patients with cerebral palsy (CP group) and 12 able-bodied volunteers (AB controls) were tested with a dynamometer. For the spasticity measure, the dynamometer was used to measure the resistive torque of the plantarflexors during passive ankle dorsiflexion at five different speeds. Data were processed to yield a single value that simultaneously encompassed the three key elements associated with spasticity: velocity, resistance, and stretch. For the strength test, the dynamometer rotated the ankle from full dorsiflexion to full plantarflexion while a maximum concentric contraction of the plantarflexors was performed. Torque angle data were processed to include the work done by the patient or volunteer on the machine. Plantarflexor spasticity values for the CP group were significantly greater than similar values for the AB control group prior to surgery but not significantly different after surgery. Plantarflexor strength values of the CP group were significantly less than those of the AB control group pre- and postsurgery. Postsurgery strength values did not change relative to presurgery values.. The spasticity results of the present investigation agreed with those of previous studies indicating a reduction in spasticity for the CP group. The strength results did not agree with the findings of most previous related literature, which indicated that a decrease in strength should have occurred. The strength results agreed with a previous investigation in which knee flexor strength was objectively examined, indicating that strength did not decrease as a consequence of an SDR. The methods of this investigation could be used to improve SDR patient selection.

Topics: Adolescent; Ankle Joint; Cerebral Palsy; Child; Female; Humans; Knee Joint; Male; Muscle Contraction; Muscle Spasticity; Physical Therapy Modalities; Prospective Studies; Rhizotomy; Torque

To develop an effective selection procedure for lower limb functional neurostimulation (LLFNS) for standing in paraplegia.. The selection procedure and exclusion criteria were based on the previous experience for two clinical centres with experience of LLFNS.. Two Regional Spinal Injuries units in southern England.. 254 fully rehabilitated paraplegics living in the community.. Patients were invited to participate in the programme, and if suitable to subject themselves to a rigorous staged selection procedure from which they could withdraw at any time.. Functionally successful home standing using closed-loop surface electrical stimulation.. 57/254 patients were suitable on paper and were accessible. 19 of these (CI = 10-28) were interested in the project and attended one of the spinal centres for details. Twelve (CI = 5-19) of these fulfilled the selection criteria and started on the training programme; and 10 of them completed the muscle training programme successfully. Seven patients (CI = 2-12) achieved closed-loop standing in the laboratory and four patients (CI = 1-8) did so at home.

Topics: Adult; Anxiety; Bone Density; Depression; Electric Stimulation Therapy; Female; Humans; Leg; Male; Middle Aged; Muscle Spasticity; Muscles; Paraplegia; Patient-Centered Care; Personnel Selection; Physical Endurance; Prostheses and Implants; Regional Blood Flow; Torque

The goal of this investigation was to quantify changes in hamstring muscle spasticity and strength in children with cerebral palsy (CP) as a function of their having undergone a selective dorsal rhizotomy.. Nineteen children with CP (CP group) and six children with able bodies (AB group) underwent testing with a dynamometer. For the spasticity measure, the dynamometer measured the resistive torque of the hamstring muscles during passive knee extension at four different speeds. Torque-angle data were processed to calculate the work done by the machine to extend the knee for each speed. Linear regression was used to calculate the slope of the line of best fit for the work-velocity data. The slope simultaneously encompassed three key elements associated with spasticity (velocity, resistance, and stretch) and was considered the measure of spasticity. For the strength test, the dynamometer moved the leg from full knee extension to flexion while a maximum concentric contraction of the hamstring muscles was performed. Torque-angle data were processed to calculate the work done on the machine by the child. Hamstring spasticity values for the CP group were significantly greater than similar values for the AB group prior to surgery; however, they were not significantly different after surgery. Hamstring strength values for the CP group remained significantly less than those for the AB group after surgery, but were significantly increased relative to their presurgery values.. The results of spasticity testing in the present investigation agreed with those of previous studies, indicating a reduction in spasticity for the CP group. The results of strength testing did not agree with those in the previous literature; a significant increase in strength was observed for the CP group.

Topics: Adolescent; Cerebral Palsy; Chi-Square Distribution; Child; Child, Preschool; Electromyography; Female; Hemiplegia; Humans; Knee Joint; Linear Models; Male; Monitoring, Intraoperative; Muscle Contraction; Muscle Spasticity; Muscle, Skeletal; Physical Therapy Modalities; Prospective Studies; Reproducibility of Results; Rhizotomy; Torque

The modulation of the short latency stretch reflex of the soleus muscle during walking was investigated in seven spastic multiple sclerosis (MS) patients and nine healthy control subjects. Ankle joint stretches were applied by a system which can rotate that ankle joint in any phase of the step cycle during treadmill walking. The torque related to the muscle fibres contracting prior to the stretch and the passive tissues around the ankle joint were measured as the "non-reflex torque". At the same time the short latency stretch reflex-mediated EMG response was measured. The findings show that the stretch reflex modulation was impaired in spastic patients during walking. The stretch reflex modulation was quantified by a modulation index of an average 50% (range -5 to 100%) in the patients and 93% (78-100%) in the control subjects (P < 0.05). The passive stiffness of the ankle joint was at the same time increased in the patients (P < 0.05). It is proposed that the impaired modulation of the stretch reflex along with increased ankle joint stiffness contribute to the impaired walking ability in spastic MS patients.

Topics: Adult; Electromyography; Female; Gait; Humans; Joints; Leg; Male; Middle Aged; Multiple Sclerosis; Muscle Spasticity; Muscle, Skeletal; Reaction Time; Reflex, Stretch; Torque; Walking