Periodic hyperammonemic encephalopathy associated with a ureterosigmoidostomy.

Ureterosigmoidostomy, a urinary diversion procedure performed for treatment congenital urologic defects or bladder cancer, may be associated with hyperammonemia. A delayed periodic encephalopathy, characterized by dysarthria, ataxia, and coma, developed in a 44-year-old woman who had undergone this procedure. Hyperammonemia-associated neurotoxicity resolved after surgical revision of the ureterosigmoidostomy to a uretero-ileostomy. Therefore, a treatable episodic encephalopathy may occur in association with hyperammonemia in patients who have undergone ureterosigmoidostomy.