Myoclonus of Muscles of the Eye, Face, and Throat

CASES of palatal myoclonus, sometimes known as palatal "nystagmus," have been described since 1886.1The disorder is defined as constant rhythmic movements of the palate and pharynx, varying in rate and amplitude, the rate being between 50 and 180 per minute. The movements may be synchronous with those of other organs, such as the larynx, eyeballs, and diaphragm.2Once a patient has acquired this disorder, the movements continue inexorably until death, although in some patients the movements may be halted during voluntary innervation, such as phonation and swallowing. The movements continue unchanged during sleep, respiratory and cardiac dysrhythmias, and general and local anesthesia. The myoclonic movements involve the palate most commonly, and the pharynx, larynx, eyeballs, corner and floor of the mouth, and diaphragm, in that order of frequency. The intercostal muscles and extremities have been reported to be affected in rare instances.3 The palatal movements are