Juvenile neuroaxonal dystrophy: clinical, electrophysiological, and neuropathological features.

We describe 2 brothers with progressive myoclonus epilepsy that began in the second decade and was associated with cerebellar ataxia and intellectual deterioration. Electroencephalographic and cerebral evoked potential studies showed findings associated with myoclonus epilepsy. Neuropathological examination of 1 of the brothers, who died at age 23 years, revealed widespread changes of neuroaxonal dystrophy without pigment deposition in the basal ganglia. We propose the term juvenile neuroaxonal dystrophy (JNAD) to distinguish this condition on clinical grounds from infantile neuroaxonal dystrophy on the one hand, and on clinical and pathological grounds from Hallervorden-Spatz disease on the other hand. JNAD, while exceedinly rare, must be considered in the differential diagnosis of the progressive myoclonus epilepsies.