Brain cortical activation during guitar-induced hand dystonia studied by functional MRI

Focal hand dystonia in musicians is a strongly task-related movement disord er. Typically, symptoms become apparent only when players execute specific overpracticed skilled exercises on their instrument. We therefore examined five guitarists with functional MRI during dystonic symptom provocation by means of an adapted guitar inside the magnet. The activation patterns obtai ned in comparable nondystonic guitarists and in the study patients when per forming normal-hand exercise served as references. A 1.5-T system equipped with echo-speed gradients and single-shot echoplanar imaging software was u sed. Data acquisition was centered on the cortical motor system encompassed in eight contiguous slices. Dystonic musicians compared with both control situations showed a significantly larger activation of the contralateral pr imary sensorimotor cortex that contrasted with a conspicuous bilateral unde ractivation of premotor areas. Our results coincide with studies of other d ystonia types in that they show an abnormal recruitment of cortical areas i nvolved in the control of voluntary movement. However, they do suggest that the primary sensorimotor cortex, rather than being underactive in idiopath ic dystonic patients, may be overactive when tested during full expression of the task-induced movement disorder. (C) 2000 Academic Press.