Neuhauser et al. (1983) described 2 unrelated families in which a total of 5 members had recurrent encephalopathy affecting cerebellar and extrapyramidal structures. Affected individuals had onset in infancy or early childhood of acute encephalopathic episodes following presumably ... Neuhauser et al. (1983) described 2 unrelated families in which a total of 5 members had recurrent encephalopathy affecting cerebellar and extrapyramidal structures. Affected individuals had onset in infancy or early childhood of acute encephalopathic episodes following presumably viral infections. The episodes were characterized by lethargy, poor coordination, tremor, involuntary movements, and loss of coordination and voluntary motor skills. All psychomotor abilities were fully regained after these initial episodes; however, the attacks were recurrent during childhood, and all patients later developed residual neurologic impairment, including hypotonia, areflexia, extensor plantar responses, choreoathetoid movements, ataxia, intention tremor, and variable dysarthria.