A previously healthy 10-year-old girl suffered sudden, binocular visual deterioration. During the next few years her neurologic and visual condition progressively worsened and she developed hypertension, seizures, ataxia, and lactic acidemia, leading to death at the age of 16 years. Bilateral optic disk pallor was followed by the loss of the foveal reflex and pigmentary maculopathy, manifested as disorganization of the retinal layers, loss of ganglion cells, degeneration of the photoreceptors and nuclei, and irregular infiltration of the retina by pigment epithelial cells. The optic nerves and tracts showed central axonal loss. Bilateral, multifocal symmetric areas of cerebral atrophy and necrosis of the neuropil and neurons in the cerebral cortex, basal ganglia, and thalamus were observed; neurons persisted in the dorsal medulla, despite neuropil degeneration.