Acute ammonia intoxication 37 years after ureterosigmoidostomy.

Ureterosigmoidostomy causes hyperammonemia, which can, especially in the presence of hepatic disease, lead to metabolic encephalopathy and coma. In the case reported here, acute hyperammonemic encephalopathy developed 37 years after the operation, and responded promptly to oral neomycin therapy, with clinical and electroencephalographic resolution. Magnetic resonance imaging of the brain, not previously reported in this disorder, showed symmetric lesions of the white matter.