Neurologic syndromes in hyperammonemic disorders.

This article reviews the neurologic manifestations of hyperammonemic disorders. A variety of inborn errors of metabolism, as well as transient neonatal or acquired hepatic dysfunctions, are identified as causes of hyperammonemia. The pathogenesis of hyperammonemia in these disorders is outlined. Catastrophic hyperammonemia and hyperammonemic coma are described; algorithms to establish specific diagnosis are suggested. Symptoms of less severe ammonia intoxication, which also occur in more common diseases, are described. The need to consider hyperammonemia as a potential etiology for these symptoms is emphasized. Finally, the neurotoxicity of ammonia is discussed.