Acute brainstem dysfunction in neonatal hyperammonemia with ornithine transcarbamylase deficiency: A case report

Background Ornithine transcarbamylase deficiency (OTCD) is the most common urea cycle disorder that causes episodic hyperammonemia. Many newborns with OTCD present with nausea, delirium, lethargy, and seizure during a metabolic attack; however, brainstem failure as a complication has been rarely reported. Case report A 4-day-old boy developed progressive lethargy and apnea. Neurological examination when he was 5 days old revealed the absence of brainstem responses and the disappearance of systemic deep tendon reflexes with flaccid limbs, and a blood test revealed hyperammonemia (2178 µg/dL). Continuous hemodiafiltration therapy was started immediately, and whole-brainstem reflexes and systemic tendon reflexes reappeared. Subsequent genetic testing revealed a pathogenic variant of the OTC gene (p.D126G). Brain magnetic resonance imaging (MRI) at 11 days of age showed no diffuse brain edema but transient mild swelling of the basal ganglia, hyperintensity of the deep region of the paracentral sulcus and basal ganglia on T1-weighted and fluid-attenuated inversion recovery images, and symmetric restricted diffusion along the pyramidal tract. Of interest was that MRI showed no abnormalities in the brainstem other than in the cerebral peduncles. Conclusion This is the first detailed report of chronological recovery from brainstem dysfunction in a newborn with OTCD.