Familial nocturnal facio-mandibular myoclonus mimicking sleep bruxism.

A mother and son presented with a multi-decade history of nocturnal tongue biting and bleeding. In both patients, video polysomnographic recordings documented bursts of electromyographic activity originating in the masseter and spreading to orbicularis oris and oculi muscles, present only during sleep. Faciomandibular myoclonic activity during sleep mimics sleep bruxism and may be familial.