Palatal myoclonus during sleep.

Standard polysomnographic recordings were carried out in three patients with verified diagnoses of palatal myoclonus (PM). Findings showed that PM continued during sleep; its frequency and amplitude varied consistently with different sleep stages. Gradual decrease in rate and amplitude, together with amplitude irregularities, occurred as sleep progressed from light to deep non rapid eye movement sleep. The most characteristic change was seen during rapid eye movement sleep. Here the PM occurred in the form of clusters of two to four high-amplitude movements at rather variable intervals.