Primary writing tremor and myoclonic writer's cramp.
Four patients with primary writing tremor had a focal, task-specific tremor that responded to anticholinergic drugs. Physiologic features included EMG activity alternating in antagonist muscles, 5- to 20-microV cerebral potentials evoked by stretch of pronator teres, and no C-reflexes. Another patient had myoclonic jerks of the forearm on attempts to write ("myoclonic writer's cramp") that also responded to anticholinergic drugs; EMG activity appeared synchronously or alternating in antagonist muscles. These disorders have features of dystonia and enlarge the spectrum of writer's cramp.
D000328:Adult; D000368:Aged; D005260:Female; D006225:Hand / Q000503:physiopathology*; D006236:Handwriting; D006801:Humans; D008875:Middle Aged; D009120:Muscle Cramp / Q000150:complications* / Q000503:physiopathology; D014202:Tremor / Q000150:complications* / Q000503:physiopathology