CT and MR Imaging in 3 Patients with Hyperammonemia Due to Ornithine Transcarbamylase Deficiency

ABSTRACT

CT and MR appearance of the brain in three children with ornithine transcarbamylase (OTC) deficiency are described. They showed clinical signs of vomiting and convulsion and were diagnosed by measurement of plasma ammonium, amino acids, acid-base balance, and urinary orotic acid levels. CT and MR were performed within one month from the onset of the symptom. CT and MRI demonstrated brain swelling with small ventricles and diffuse low density of white matter, which indicated cerebral hypoperfusion secondary to elevated intracranial pressure. With more prolonged survival hyperammonemia may cause cerebral atrophy. CT and MR appearance in these cases resembled a hypoxic brain damage and this finding should be included in the differential diagnosis.