Altered Mental Status Due to Hyperammonemia Syndrome and PRES in a 31-Year-old Bone Marrow Transplant Recipient.

Hyperammonemia syndrome and posterior reversible encephalopathy syndrome (PRES) are potentially devastating diagnoses in transplant patients. Their underlying etiologies and pathophysiologies remain incompletely understood, and while they are separately well-documented complications in posttransplant patients, they have not been described concurrently. Here we present a case of both hyperammonemia syndrome and PRES causing rapid mental status decline in a 31-year-old bone marrow transplant recipient. The patient had extensive testing to rule out other diagnoses and made a full recovery after correction of her hyperammonemia. Further research is needed to elucidate the underlying mechanisms of these disease processes; however, clinicians should keep both diagnoses in mind when treating transplant patients with acute neurologic changes.