Malignant cerebral edema secondary to hyperammonemia in setting of acquired carnitine deficiency

A 34-year-old woman with a remote history of Roux-en-Y bariatric surgery and pancreatitis with residual sphincter of Oddi dysfunction was hospitalized with 1 week of progressive confusion. Initial examination was nonlateralizing, but revealed lethargy and asterixis. The initial ammonia level was elevated (362 mu mol/L [normal 11-32 mu mol/L]), whereas liver function tests, hepatitis panel, acetaminophen levels, blood alcohol, drug screen, urinalysis, complete blood count, blood cultures, and comprehensive metabolic panel were normal. Abdominal CT revealed diffuse fatty liver. Within 24 hours, repeat ammonia was >600 mu mol/L despite treatment with lactulose. Continuous renal replacement therapy was started with minimal improvement in ammonia levels and progressively worsening mentation requiring intubation. Continuous EEG revealed severe encephalopathy. Head CT revealed diffuse cerebral edema. Follow-up brain MRI corroborated CT findings and revealed transtentorial herniation (figures 1 and 2). Hypertonic saline, mannitol boluses, and extraventricular drain placement all were done for elevated intracranial pressure management without any clinical improvement. Given the patient's history (bariatric surgery and pancreatitis) suggesting an increased risk of malabsorption, along with current refractory idiopathic hyperammonemia, an acquired carnitine deficiency was considered, and empiric supplementation of L-carnitine was initiated, resulting in a dramatic reduction of ammonia levels (to 55 mu mol/L) 24 hours after supplementation. Total (11 nmol/mL [normal 34-78 nmol/mL]) and free (1 nmol/mL [normal 25-54 nmol/mL]) carnitine levels obtained before empiric treatment returned confirming severe carnitine deficiency. Despite improving ammonia level, clinical deterioration continued, the patient was transitioned to comfort measures, and the patient died 48 hours later.