(734) Cerebral Edema Management in a 5-Year-Old Boy With Ornithine Transcarbamylase Deficiency

Introduction: X-linked Ornithine Transcarbamylase (OTC) Deficiency is the most common urea cycle disorder. If not managed, it results in hyperammonemia, cerebral edema, and eventually death. Patients are commonly diagnosed during the neonatal period, but late-onset presentations have been rarely described when nitrogen turnover is increased due to impaired enzyme activity. We present a rare case of late-onset OTC deficiency with marked cerebral edema on presentation.

Description: A 5-year-old male presented to a local ED with somnolence and a tonic-clonic seizure after 2 days of fever and non-bilious, non-bloody emesis. He was tachycardic, tachypneic, and hypertensive upon arrival. He had a bicarbonate of 9, a PaCO2 of 5, normal pH, lactic acid of 5.6, base deficit of 23, an anion gap of 32, and a beta-hydroxybutyrate of 7. He was intubated given GCS of 3. Head CT was concerning for cerebral edema, he was given 3% hypertonic saline. On arrival to the PICU, ammonia was 920. He was started on D12.5% IV fluids, intralipids, and an ammonia scavenger and underwent hemodialysis. Head imaging in the first 12 hours of admission did not demonstrate cerebral edema. Approximately 18 hours after admission, he developed Cushing’s triad and repeat head CT was notable for edema. An intracranial pressure (ICP) bolt was placed by neurosurgery, and initial ICP was in the 30s. For the next 8 days elevated ICPs were managed with 3% hypertonic saline, mannitol, and a pentobarbital infusion. After 6 days imaging showed resolution of his cerebral edema. MRI demonstrated multiple ischemic areas. His exam was significant for neurologic deficits requiring rehabilitation, but he was able to breathe independently, move all extremities, and follow commands prior to discharge. He was diagnosed with X-linked Ornithine Transcarbamylase Deficiency.

Discussion: Metabolic diseases should be considered in patients who present in extremis with hyperammonemia regardless of age. Cerebral edema in OTC deficiency can be prolonged and result in significant neurologic sequelae and even death but can be managed with typical ICP therapies with potential for good recovery. There should be consideration of ICP monitor placement and active ICP management in patients with presumed metabolic crisis when cerebral edema is a known consequence.