Myoclonus, cerebellar disorder, neuropathy, mitochondrial myopathy, and ACTH deficiency.

A 50-year-old Japanese woman with action myoclonus, cerebellar signs, neuropathy with axonal degeneration and onion-bulb formation, muscle atrophy with mitochondrial abnormalities, and isolated ACTH deficiency was reported. Her daughter had myoclonus epilepsy and cerebellar ataxia. Neuropathologic findings included atrophy of the dentate and inferior olivary nuclei, Purkinje's cell loss, and demyelination of the posterior columns and spinocerebellar and pyramidal tracts of the spinal cord, besides severe respirator changes. Lafora's bodies were absent. The present case should be included in the entity "myoclonus epilepsy associated with mitochondrial myopathy."