[A case of chorea-acanthocytosis onset with at age 86].

An 86-year-old woman was admitted to our hospital for orobuccolingual dyskinesia. She did not take any medication. Her relatives had no similar symptoms nor consanguineous marriage. Although orobuccolingual dyskinesia was improved by administration of haloperidol for a while, orobuccolingual dyskinesia with biting of tongue and lips, chorea and muscular atrophy in the legs, seizures and dementia appeared half a year after the onset. The decrease of cMAP suggested axonopathy in the extremities by a nerve conduction study. The serum level of CK was normal. The EEG showed generally slow wave activities. A head MRI showed mild atrophy of the bilateral caudate nuclei and frontal lobes with scattered old lacunars in the deep white matter. She was diagnosed as having chorea-acanthocytosis (ChAc) because acanthocytes (10-20%) appeared in the peripheral blood. The normal lipoprotein levels and Kell antigen expression excluded the possibilities of Bassen-Kornzweig syndrome and McLeod syndrome. In all reported cases of ChAc, she was the oldest onset patient. ChAc is warranted in a patient presenting with orobuccolingual dyskinesia with biting, in spite of elderly onset.