vendex and Brain-Injuries

This study sought to determine whether factors other than stretch reflex excitability contribute to velocity dependent passive plantarflexor resistive torque following brain injury.. In patients with acquired brain injury increased resistance to passive muscle lengthening commonly results from abnormal muscle contraction, secondary to disinhibition of descending motor pathways, in addition to rheologic changes within the musculo-tendinous unit. Hyper-excitable tonic stretch reflex responses (spasticity) have traditionally been considered to be the main factor influencing resistance that is velocity dependent.. Ten adults with brain injury and eighteen age matched controls were studied. A computer controlled torque measurement system was utilised to evaluate resistance to dorsiflexion stretches at two velocities (5 degrees and 25 degrees s(-1)). Only stretches which did not evoke muscle contraction were included in the data analysis. The mean difference and 95% confidence limits in passive plantarflexor resistive torque at two stretch velocities, measured over a defined portion of the test movement, were compared between subject groups.. A velocity dependent increase in passive plantarflexor resistive torque was evident when the ankle was dorsiflexed past the neutral position in both subjects with brain injury and controls. However, the mean difference was approximately 10 times greater in neurologically impaired limbs compared with control values.. These data indicate that an important component of velocity dependent resistance to passive muscle lengthening in adults with brain injury can be mechanical, and unrelated to stretch induced reflex muscle contraction.. Increased resistive torque during rapid muscle lengthening may represent a compensatory adaptation for reduced distal motor control following brain injury. A velocity dependent increase in passive plantarflexor resistive torque has the potential to improve stability during gait and provide mechanical resistance to sudden external perturbations.

Topics: Adult; Ankle Joint; Brain Injuries; Elasticity; Female; Humans; Male; Middle Aged; Muscle Hypertonia; Muscle, Skeletal; Reflex, Stretch; Reproducibility of Results; Rotation; Sensitivity and Specificity; Stress, Mechanical; Torque

Pediatric gait disorders are often chronic and accompanied by various complications, which challenge rehabilitation efforts. Here, we retrospectively analyzed the feasibility of overground robot-assisted gait training (RAGT) using a joint-torque-assisting wearable exoskeletal robot. In this study, 17 children with spastic cerebral palsy, cerebellar ataxia, and chronic traumatic brain injury received RAGT sessions. The Gross Motor Function Measure (GMFM), 6-min walk test (6 MWT), and 10-m walk test (10 MWT) were performed before and after intervention. The oxygen rate difference between resting and training was performed to evaluate the intensity of training in randomly selected sessions, while the Quebec User Evaluation of Satisfaction with assistive Technology 2.0 assessment was performed to evaluate its acceptability. A total of four of five items in the GMFM, gait speed on the 10 MWT, and total distance on the 6 MWT showed statistically significant improvement (p < 0.05). The oxygen rate was significantly higher during the training versus resting state. Altogether, six out of eight domains showed satisfaction scores more than four out of five points. In conclusion, overground training using a joint-torque-assisting wearable exoskeletal robot showed improvement in gross motor and gait functions after the intervention, induced intensive gait training, and achieved high satisfaction scores in children with static brain injury.

Topics: Brain Injuries; Child; Feasibility Studies; Gait; Humans; Oxygen; Retrospective Studies; Robotics; Torque; Wearable Electronic Devices

Pediatric hemiplegia, caused by a unilateral brain injury during childhood, can lead to motor deficits such as weakness and abnormal joint torque coupling patterns which may result in a loss of independent joint control. It is hypothesized that these motor impairments are present in the paretic lower extremity, especially at the hip joint where extension may be abnormally coupled with adduction. Previous studies investigating lower extremity isometric joint torques in children with spastic cerebral palsy used tools that limited data collection to one degree of freedom, making it impossible to quantify these coupling patterns. We describe the adaptation of a multi-joint lower extremity isometric torque measurement device to allow for quantification of weakness and abnormal joint torque coupling patterns at the hip in the pediatric population. We also present preliminary data in three children without hemiplegia to highlight how the presence of atypical femoral bony geometry, often observed in childhood hemiplegia, can be accounted for in the Jacobian transformations and affect joint torque measurements at the hip.

Topics: Brain Injuries; Child; Hemiplegia; Hip Joint; Humans; Isometric Contraction; Lower Extremity; Monitoring, Physiologic; Torque

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

Extensive neuromotor development occurs early in human life, and the timing of brain injury may affect the resulting motor impairment. In Part I of this series, it was demonstrated that the distribution of weakness in the upper extremity depended on the timing of brain injury in individuals with childhood-onset hemiparesis.. The goal of this study was to characterize how timing of brain injury affects joint torque synergies, or losses of independent joint control.. Twenty-four individuals with hemiparesis were divided into 3 groups based on the timing of their injury: before birth (PRE-natal, n = 8), around the time of birth (PERI-natal, n = 8), and after 6 months of age (POST-natal, n = 8). Individuals with hemiparesis and 8 typically developing peers participated in maximal isometric shoulder, elbow, wrist, and finger torque generation tasks while their efforts were recorded by a multiple degree-of-freedom load cell. Motor output in 4 joints of the upper extremity was concurrently measured during 8 primary torque generation tasks to quantify joint torque synergies.. There were a number of significant coupling patterns identified in individuals with hemiparesis that differed from the typically developing group. POST-natal differences were most noted in the coupling of shoulder abductors with elbow, wrist, and finger flexors, while the PRE-natal group demonstrated significant distal joint coupling with elbow flexion.. The torque synergies measured provide indirect evidence for the use of bulbospinal pathways in the POST-natal group, while those with earlier injury may use relatively preserved ipsilateral corticospinal motor pathways.

Topics: Adolescent; Adult; Brain Injuries; Child; Elbow Joint; Female; Hand Joints; Humans; Isometric Contraction; Male; Muscle Weakness; Paresis; Shoulder Joint; Torque; Upper Extremity

Extensive neuromotor development occurs early in human life, but the time that a brain injury occurs during development has not been rigorously studied when quantifying motor impairments.. This study investigated the impact of timing of brain injury on the magnitude and distribution of weakness in the paretic arm of individuals with childhood-onset hemiparesis.. A total of 24 individuals with hemiparesis were divided into time periods of injury before birth (PRE-natal, n = 8), around the time of birth (PERI-natal, n = 8), or after 6 months of age (POST-natal, n = 8). They, along with 8 typically developing peers, participated in maximal isometric shoulder, elbow, wrist, and finger torque generation tasks using a multiple-degree-of-freedom load cell to quantify torques in 10 directions. A mixed-model ANOVA was used to determine the effect of group and task on a calculated relative weakness ratio between arms.. There was a significant effect of both time of injury group (P < .001) and joint torque direction (P < .001) on the relative weakness of the paretic arm. Distal joints were more affected compared with proximal joints, especially in the POST-natal group.. The distribution of weakness provides evidence for the relative preservation of ipsilateral corticospinal motor pathways to the paretic limb in those individuals injured earlier, whereas those who sustained later injury may rely more on indirect ipsilateral corticobulbospinal projections during the generation of torques with the paretic arm.

Topics: Adolescent; Adult; Age Factors; Brain Injuries; Child; Electromyography; Female; Humans; Isometric Contraction; Male; Muscle Fatigue; Muscle Weakness; Paresis; Torque; Upper Extremity

Jockey head injuries, especially concussions, are common in horse racing. Current helmets do help to reduce the severity and incidences of head injury, but the high concussion incidence rates suggest that there may be scope to improve the performance of equestrian helmets. Finite element simulations in ABAQUS/Explicit were used to model a realistic helmet model during standard helmeted rigid headform impacts and helmeted head model University College Dublin Brain Trauma Model (UCDBTM) impacts. Current helmet standards for impact determine helmet performance based solely on linear acceleration. Brain injury-related values (stress and strain) from the UCDBTM showed that a performance improvement based on linear acceleration does not imply the same improvement in head injury-related brain tissue loads. It is recommended that angular kinematics be considered in future equestrian helmet standards, as angular acceleration was seen to correlate with stress and strain in the brain.

Topics: Acceleration; Animals; Athletic Injuries; Brain Injuries; Computer Simulation; Computer-Aided Design; Craniocerebral Trauma; Equipment Design; Finite Element Analysis; Head Protective Devices; Horses; Humans; Models, Biological; Rotation; Sports Equipment; Stress, Mechanical; Torque; Wounds, Nonpenetrating

An experimental anatomic study performed on elderly cadaveric skulls.. (1) To determine the pin penetration depths in outer table of skull at different torques in the elderly population during halo pin insertion and (2) to validate a safe range of torque for use in this population.. The elderly are at an increased risk of falls, which can lead to cervical fractures. The halo pins used to stabilize these injuries present unique problems in this population owing to osteoporosis, and intracranial pin penetration should always be avoided.. A halo ring was used to insert pins in 4 standard positions on 10 elderly cadaveric skulls. Incremental torques were used to drive the pin into the outer table, and the penetration of each pin was measured using computed tomography imaging at each stage.. Eight to Twelve in-lb of torque was not sufficient to fully penetrate the outer table of the skull. Only at 16 in-lb of torque was the outer table penetrated, and only anterolaterally, hence the posterolateral outer table is more resistant to penetration than the anterolateral outer table.. Despite age-related bone changes in the elderly, it is still safe to use 8 in-lb of torque when inserting pins for a halo vest. However, as the anterolateral outer table is weaker than the posterolateral outer table, a new pin design with broader shoulders should be used anterolaterally to ensure maximal patient safety.

Topics: Accidental Falls; Age Factors; Aged; Aged, 80 and over; Aging; Brain Injuries; Cadaver; Cervical Vertebrae; Compressive Strength; Craniotomy; External Fixators; Female; Humans; Iatrogenic Disease; Intraoperative Complications; Male; Monitoring, Intraoperative; Osteoporosis; Skull; Spinal Fractures; Stress, Mechanical; Torque

Increased calf muscle stiffness is a common impairment following acquired brain injury. This study examined the immediate effects of cyclic ankle stretching at two stretch velocities on calf stiffness in individuals with hemiparesis (n=17) and control subjects (n=10).. Cyclic ankle stretching was applied for 3min at velocities of 5 degrees s(-1) and 25 degrees s(-1) using a purpose-built dynamometer. Surface electromyography was employed to ensure stretches were passive. Peak plantarflexor resistive torque was derived from torque-angle curves. Comparisons were made between groups, velocities, and between limbs for hemiparetic subjects.. At baseline, mean peak plantarflexor resistive torque was greater in the affected limbs of hemiparetic subjects than their contralateral limbs (P<0.001), however there was no significant difference between groups. Plantarflexor resistive torque was reduced in all limbs following cyclic stretching regardless of stretch velocity (P<0.005). Two distinct patterns of response were observed in hemiparetic subjects. In nine cases the affected limb responses did not differ from the contralateral limb or control data. In the remaining eight cases mean peak plantarflexor resistive torque in the affected limb was greater than the contralateral limb and control values. In this subgroup, peak plantarflexor resistive torque was significantly affected by stretch velocity and showed the greatest reduction following cyclic stretching.. Cyclic stretching has been shown to produce a short term reduction in calf stiffness in a subgroup of individuals with hemiplegia. Further investigation is required to elaborate the characteristics of those most likely to respond optimally to this intervention.

Topics: Adult; Aged; Ankle Joint; Brain Injuries; Elastic Modulus; Female; Humans; Male; Middle Aged; Muscle Contraction; Muscle Hypertonia; Muscle, Skeletal; Stress, Mechanical; Torque; Young Adult

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

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

This study provides a detailed analysis of disturbances in the kinematics and dynamics of the acceleration phase of multijoint arm movements in six patients with chronic hemiparesis. Movements of the dominant and nondominant limbs were also examined in three control subjects. Subjects performed rapid movements from a central starting point to 16 targets located equidistantly around the circumference of a circle. Support of the upper limb was provided by an air-bearing apparatus, which allowed very low friction movements in the horizontal plane. We found that patients retained the capacity to modulate, in response to target direction, the initial direction of movements performed with the paretic limb. However, in comparison to the nonparetic limb or control subjects, movements of the paretic limb were misdirected systematically. An inverse dynamics analysis revealed an abnormal spatial tuning of the muscle torque at the elbow used to initiate movements of the paretic limb. Based on electromyographic recordings, similar spatial abnormalities were also apparent in the initial activations of elbow muscles. We argue that these spatial abnormalities result from a systematic disturbance in the control signal to limb muscles that cannot be attributed to previously identified mechanisms such as weakness, spasticity mediated restraint, or stereotypic muscle activation patterns (muscle synergies). Instead, our analysis of movement dynamics and simulation studies demonstrate that the spatial abnormalities are consistent with an impaired feedforward control of the passive interaction torques which arise during multijoint movements. This impaired control is hypothesized to reflect a degradation of the internal representation of limb dynamics that occurs either as a primary consequence of brain injury or secondary to disuse.

Topics: Adult; Aged; Arm; Biomechanical Phenomena; Brain Injuries; Electromyography; Female; Humans; Joints; Male; Middle Aged; Motor Activity; Movement; Paresis; Psychomotor Performance; Reference Values; Stroke; Torque