subacute necrotizing encephalomyelopathy

a type of encephalopathy of unclear clinical and pathological criteria, causing neuropathologic damage like that of the Wernicke-Korsakoff syndrome. It occurs in two forms: the infantile form is caused by mitochondrial energy metabolism protein mutations and pyruvate carboxylase complex mutations and is characterized by degeneration of gray matter with necrosis and capillary proliferation in the brainstem; hypotonia, seizures, and dementia; anorexia and vomiting; slow or arrested development; and ocular and respiratory disorders, with death usually before age 3. The adult form usually first manifests as bilateral optic atrophy with central scotoma and colorblindness, followed by a quiescent period of up to 30 years and then late symptoms such as ataxia, spastic paresis, clonic jerks, grand mal seizures, psychic lability, and mild dementia. Called also subacute necrotizing encephalopathy and Leigh disease.