Associative Motor Cortex Plasticity is Reduced on the Non-Affected Side in Focal Hand Dystonia

Maladaptive plasticity has been implicated in the pathophysiology of focal dystonia. In support of this, we have recently shown that associative motor cortical plasticity induced by an external stimulation protocol is greatly enhanced and its somatotopic organization lost on the affected side in patients with writer's cramp (WC). However, it remains unknown whether these abnormalities are related to the dystonic phenotype or to an underlying pathogenetic disposition. We therefore studied the non-affected side in nine WC patients. In addition, the non-dominant hand of nine healthy control subjects was examined. D…