Disappearing palatal myoclonus.

Two patients had palatal myoclonus that disappeared. In one, the palatal myoclonus disappeared completely during all stages of natural sleep only to return again when he awoke, persisting as long as he remained awake. In the other patient, palatal myoclonus was continuous for 2 years, became erratic for 6 months, and then disappeared completely, although she could induce it voluntarily. These cases demonstrate that palatal myoclonus is not always: independent of the sleep-waking cycle, persistent throughout life, and independent of cortical control.