Masticatory muscle silent periods in patients with MPD syndrome before and after treatment.

Masticatory muscle silent periods were compared in normal subjects and in patients with MPD syndrome before and after a variety of psychological, physiological, and pharmacological forms of therapy. All patients initially showed prolonged silent periods in one or more of the muscles. There was a direct relationship between prolongation and severity of symptoms. The temporalis (90.9%) and masseter (54.5%) were most frequently involved. In almost all instances the silent periods returned to the normal range following treatment.