Idiopathic palatal myoclonus.

Two cases with idiopathic palatal myoclonus without other neurological deficits were described. They did not have any other neurological deficits other than myoclonus of branchial muscles. In these cases, the myoclonus disappeared during natural or induced sleep. In Case 1, the myoclonus ceased transiently when the patient was calculating or receiving an injection. In Case 2, the myoclonus disappeared with intravenous injection of saline as a placebo. Detailed examinations, including brain CT, MRI and multiple evoked potentials, showed normal results. The myoclonus in Case 2 disappeared after we had explained that her disease was benign. Since the clinical features and laboratory data in idiopathic palatal myoclonus are quite different from those in palatal myoclonus with other neurological deficits, idiopathic palatal myoclonus is considered to be a separate syndrome. Invasive examinations or excessive medications should be avoided because of its benign prognosis.