Two task-specific dystonias in one hand.

BACKGROUND: Dystonia is characterized by involuntary muscle contractions that lead to abnormal postures and/or repetitive movements. Task-specific dystonia only manifests during a specific activity. CASE REPORT: We report a case of a female with writer's cramp who developed a second task-specific hand dystonia (tremor and abnormal posturing of the hand while using a computer mouse) many years after the initial onset. DISCUSSION: This observation is in agreement with the concept that task-specific hand dystonia is induced by repetitive, skilled hand movements in those who have an intrinsic vulnerability towards developing "dystonic" motor programs.