NARP MITOCHONDRIOPATHY: AN UNUSUAL CAUSE OF PROGRESSIVE MYOCLONIC EPILEPSY

Abstract

Progressive myoclonic epilepsies (PMEs) are characterized by seizures, epileptic or nonepileptic myoclonus, cerebellar signs, and progressive neurologic deterioration.1 The main causes are Unverricht–Lundborg disease, Lafora disease, myoclonic epilepsy with ragged red fibers (MERRF), neuronal ceroid lipofuscinosis, and sialidoses, but other diseases, such as mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS), are rare.1 Conversely, the T8993G mitochondrial mutation associated with neurogenic muscle weakness, ataxia, and retinitis pigmentosa (NARP) syndrome has never been reported with a PME phenotype. The proband patient, a 46-year-old woman, was admitted for a complex neurologic syndrome that included myoclonus, epilepsy, ataxia, and peripheral neuropathy. Her mother had had flash-induced head-shaking episodes of possible epileptic origin that had never been investigated. One brother of the patient died at age 6 months of convulsive status epilepticus, and one sister died at age 5 months during an episode of refractory infantile spasms. The patient had two daughters; one died at age 3 weeks of unknown etiology, and the other, …