Hemimasticatory and hemifacial spasm: a common pathophysiology?

The case is described of a 60-year-old woman with a 4-year history of left hemimasticatory spasm. Detailed electrophysiological studies are compared with those from 6 patients with typical idiopathic hemifacial spasm. On the basis of comparable patterns of EMG activity in the 2 conditions, it is concluded that they may have both a common pathophysiology and a peripheral site of involvement.