Idiopathic Hyperammonemia Associated With Cerebral Arteriovenous Malformation: A Potentially Treatable Form of Impaired Mental Function

• A patient with a cerebral arteriovenous malformation and a seizure disorder complained of impaired mental function. He had recurrent idiopathic hyperammonemia with no evidence of renal, hepatic, or pulmonary disease. Mental function improved in this patient with reduction of blood ammonia level. Impaired mental function as a complication in patients with cerebral arteriovenous malformations has been reported. To our knowledge, this particular syndrome has not previously been delineated in the extensive literature on cerebral arteriovenous malformations. The factors underlying this disorder are unknown.