vendex and Dystonia

To evaluate if hyperreflexia (exaggerated reflexes) due to disinhibition is associated with dystonia in Complex Regional Pain Syndrome (CRPS).. Stretch reflexes at the wrist were assessed in healthy controls (n=10) and CRPS-patients with dystonia (n=10). Subjects exerted a wrist flexion torque of 5% of maximum voluntary contraction torque (T(MVC)) to a manipulandum which applied ramp-and-hold stretches to the wrist flexors. Since reflex responses scale with background contraction, controls additionally performed the task at 1% and 3% T(MVC) to attain similar torques as patients who have reduced T(MVC). The M1 onset and the magnitudes of the short latency M1 and long latency M2 were assessed using the electromyographic signals (EMG) of the flexor carpi radialis. EMG of the extensor carpi radialis was recorded to monitor cocontraction.. Compared to controls, patients had a substantially reduced T(MVC). Ramp velocity had a significant effect on M1 onset time and magnitude.. Since M1 magnitude decreased with flexion torque, no significant difference was found between patients and controls at 5% T(MVC), while comparison at similar absolute torques (controls at 1% T(MVC)) resulted in significantly smaller M1 magnitudes for patients with dystonia.. This study suggests that CRPS-patients with dystonia are not hyperreflexive.

Topics: Adolescent; Adult; Case-Control Studies; Complex Regional Pain Syndromes; Dystonia; Electromyography; Female; Humans; Male; Middle Aged; Muscle Contraction; Muscle, Skeletal; Pain Measurement; Reflex, Abnormal; Reflex, Stretch; Torque; Wrist Joint; Young Adult

In dystonia, both sensory malfunctioning and an abnormal intermuscular low-frequency drive of 3-7 Hz have been found, although cause and effect are unknown. It is hypothesized that sensory processing is primarily disturbed and induces this drive. Accordingly, experimenter-controlled sensory input should be able to influence the frequency of the drive. In six genetically confirmed myoclonus-dystonia (MD) patients and six matched controls, the low-frequency drive was studied with intermuscular coherence analysis. External perturbations were applied mechanically to the wrist joint in small frequency bands (0-4, 4-8 and 8-12 Hz; 'angle' protocol) and at single frequencies (1, 5, 7 and 9 Hz; 'torque' protocol). The low-frequency drive was found in the neck muscles of 4 MD patients. In these patients, its frequency did not shift due to the perturbation. In the torque protocol, the externally applied frequencies could be detected in all controls and in the two patients without the common drive. The common low-frequency drive was not be affected by external perturbations in MD patients. Furthermore, the torque protocol did not induce intermuscular coherences at the applied frequencies in these patients, as was the case in healthy controls and in patients without the drive. This suggests that the dystonic 3-7 Hz drive is caused by a sensory-independent motor drive and sensory malfunctioning in MD might rather be a consequence than a cause of dystonia.

Topics: Adult; Afferent Pathways; Aged; Dystonia; Electromyography; Female; Humans; Male; Middle Aged; Muscle Contraction; Muscle, Skeletal; Myoclonus; Physical Stimulation; Proprioception; Time Factors; Torque; Wrist

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