Electroencephalographic Findings in Ornithine Transcarbamylase Deficiency

Abstract

A 3-day-old infant presented with anorexia, irritability, hypotonia, and seizures. Blood ammonia was 2115 pmol/L and amino and organic acid analyses were consistent with ornithine transcarbamylase deficiency. Liver biopsy confirmed only 1% enzyme activity. The patient was treated with hemodialysis. An electroencephalogram (EEG) revealed multifocal independent spike-and-sharp-wave discharges. After initial stabilization he was placed on a low-protein diet with citrulline and phenylbutyrate. Conjugating agents (arginine, sodium benzoate, and sodium phenylacetate) have been added during periods of metabolic decompensation. Although developmentally delayed, the patient has shown signs of clinical improvement and EEG activity has likewise improved with only mild background slowing and no evidence of epileptogenic activity at 4 years of age. A second infant presented at 3 days of age with a similar history, blood ammonia of 1382 μmol/L, and metabolic studies indicative of ornithine transcarbamylase deficiency. EEG showed multifocal independent ictal and interictal discharges. Electrographic abnormalities persisted despite lowering of blood ammonia with hemodialysis and conjugating agents. The patient continued to decline clinically and died on the 7th hospital day. EEG changes parallel the clinical course of ornithine transcarbamylase deficiency and may serve as an objective marker of the effectiveness of therapeutic interventions. (J Child Neurol 1999;14:533-536).