Abnormal sensorymotor integration in a Task-specific dystonia after ACA infarction

초록

Introduction: Focal hand dystonia is characterized by excessive involuntary contraction of the muscles controlling hand during the performance of a specific task, leading to loss of movement precision and selectivity, which is usually found in subjects with lesion of basal ganglia circuit. We report a rare case of task-specific focal hand dystonia caused by the left anterior cerebral artery (ACA) infarction. Case: A 72-year old male with right hemiplegia following left ACA infarct was transferred to Dept. of P&RM for intensive rehabilitation program. He had alert mental status but his cognitive function was impaired (13 on MMSE, 5 on FAB). Motor function of the hemiplegic side was Hand III, Arm II, Leg II by Brunnstrom stage. His sensory was intact. Deep tendon reflex and muscle tone were normal. On command, he could grasp and release his right fingers by free hand and he had no dystonia at rest. However after he grasped an object with his palm, he was unable to release it. Brain MRI revealed acute left ACA infarction. At the right FDI muscle recording, reduced amplitude was evoked by simple pulse magnetic stimulation and decreased intracortical inhibition (ICI) by paired pulsed magnetic stimulation. SEP study revealed delayed latency & reduced amplitude in right median nerve stimulation. After 4 months of rehabilitation program, his motor function improved to hand IV, Arm V, Leg II by Brunnstrom stage, K-BBS (from 2 to 24 points), and K-MBI (from 4 to 57 points). But task-specific focal hand dystonia still remained. Conclusion: We report a rare case which has a task specific hand dystonia, induced by left ACA infarction. Pathophysiology of task specific dystonia remains unclear, but modern scientific studies suggest reduced inhibition at different levels of the sensorimotor integration.