An episode of geniospasm in sleep: toward new insights into pathophysiology?

Polysomnography and needle electromyography were performed on three members of a family with hereditary geniospasm. Electromyography showed simultaneous bilateral discharges exclusively in the mentalis muscle. In one subject we documented a paroxysm of geniospasm during sleep phase 2. This activity ceased with the onset of REM sleep. In view of the mechanism of REM atonia and the bilateral chin EMG discharges, our findings support a supranuclear origin of the peculiar mentalis muscle paroxysms. 2007 Movement Disorder Society