[Writer's cramp].

Writer's cramp is classified as a focal dystonia. Abnormal sensory-motor integration is characteristic and loss of inhibition is seen in many levels, including cortex, spinal cord, and peripheral nerves. Altered, irregular firing pattern of the basal ganglia, as well as push-pull system of the motor loop, probably play an important role in the pathophysiology of dystonia. First therapeutic step is providing the information of pathophysiology to the patients and advicing them to reduce the amount of writing. According to severity, local lidocaine block or medication is used in Japan.