Hyperammonemic encephalopathy after induction chemotherapy for acute lymphoblastic leukemia.

The syndrome of hyperammonemic encephalopathy occurs in patients who have received high-dose cytoreductive therapy for the treatment of hematologic malignancy. It is characterized by acute alteration in mental status and respiratory alkalosis associated with markedly elevated plasma ammonium levels in the absence of any identifiable cause and frequently results in cerebral edema, coma, and eventually death. Although the etiology of this syndrome is yet to be determined, it seems to be invariably multifactorial in nature. Optimal therapy remains elusive, and the critical step is increased awareness of the syndrome by measurement of plasma ammonia levels in patients with neurologic symptoms, leading to accurate diagnosis and the rapid implementation of therapy.