[Myoclonic epilepsy with ragged-red fibers: report of one case].

Myoclonic epilepsy with ragged-red fibers (MERRF) is one of the mitochondrial encephalomyopathies. This article presents a nine-year-old boy who had been noted to have psychomotor retardation since infancy, and had progressive myoclonic epilepsy since he was four. The myoclonic epileptic seizures were refractory to the conventional anticonvulsants. The brain MRI, echocardiography and brainstem auditory-evoked-potential showed negative findings, but electroencephalography showed episodic generalized spike wave complexes. Oral glucose lactate stimulation test revealed abnormal elevation of lactic acid, and muscle biopsy showed ragged-red fibers. Subsarcolemmal accumulations of mitochondria with abnormal cristae in the muscle cells were noted under electronmicroscopic study. The patient was administered coenzyme Q 90 mg per day orally, with dramatic improvement in myoclonic seizures. The patient is still being followed up as an outpatient.