Central motor conduction in cervical dystonia with cervical spondylotic myelopathy

Objectives: It has been known that cervical dystonia develops secondarily to spinal cord injuries as secondary dystonia. However, little is known about the pathophysiological mechanism. Patients and methods: We examined motor and sensory conduction in six patients with symptomatic cervical dystonia by transcranial magnetic stimulation (TMS). All of the patients exhibited unilateral head rotation. They had symptoms corresponding to cervical myelopathy and felt discomfort in the neck, shoulders or arms before involuntary movement occurred. Results: Although the overall central motor conduction time (CMCT) was not different from that of normal controls, contralateral CMCT was significantly delayed compared to ipsilateral CMCT (p < 0.05). The results of somatosensory evoked potential study demonstrated that contralateral central conduction time (CCT) was not significantly different from ipsilateral CCT. Conclusion: These findings indicate that there is a selective interference with the contralateral corticospinal tract in patients with symptomatic cervical dystonia.