Soleus H-reflex tests in causalgia-dystonia compared with dystonia and mimicked dystonic posture.

Dystonia in the causalgia-dystonia syndrome is characterized by a fixed dystonic posture. To identify involvement of central pathophysiologic mechanisms, we analyzed soleus H-reflex tests in five patients with causalgia-dystonia. Soleus H-reflex test results in these patients differed from those in healthy controls but were similar to those in purely dystonic patients and healthy controls mimicking dystonic posture. The results suggest involvement of supraspinal mechanisms in the abnormal posture of causalgia-dystonia.