[Etiology and clinical aspects of palatal myoclonus].

Palatal myoclonus is a movement disorder consisting of rhythmic myoclonus of the soft palate, pharynx, larynx, and other muscles derived from the embryonal branchial arches. These movements are continuous and involuntary, and the patients are, in general, unaware of them. In the majority of patients, palatal myoclonus persists for life. In oculopalatal myoclonus, the eyes can be involved in the form of a nystagmus. Often a clicking noise in one or both ears is the initial symptom which can be heard by the examiner. A variety of etiologies have been linked to palatal myoclonus. The most common defined cause is a stroke. The variable delay between the proposed cause and the appearance of the disorder causes difficulties in determining the exact etiology. Pathologic findings show a transsynaptic hypertrophic degeneration of the inferior olivary nucleus which is due to a lesion of a specific, inhibitory, anatomic pathway. This somatotopic pathway leaves the contralateral dentate nucleus, passes through the superior cerebellar peduncle, and crosses the posterior commissure before joining the central tegmental tract and descending to the ipsilateral inferior olive. Treatment of palatal myoclonus is only occasionally effective. Some patients have responded to tryptophan, carbamazepine, and trihexyphenidyl. Surgical attempts have not been successful. - In the present paper the authors report on a case of an oculopalatal myoclonus following Leber's optic atrophy which involved the brain stem.