P98 – 3040: Early diagnosis of maple syrup urine disease (MSUD) by means of neonatal EEG and MRI in a newborn with encephalopathy

Abstract

Objective Early diagnosis of maple syrup urine disease (MSUD) by means of neonatal EEG and MRI in a newborn with encephalopathy. Methods This male neonate was born after an uneventful pregnancy as the first child of non-consanguineous parents. Familial medical history is negative with respect to congenital defects, seizures or developmental delay. At day 9 he was referred to our center because of feeding problems, vomiting and lethargy. He progressively developed an encephalopathy with seizures, intermittent opisthotonic posturing and Kussmaul breathing. Elevated ammonia levels were detected in blood. EEG showed multifocal epileptic activity together with bursts of a monophasic negative theta rhythm (comb-like rhythm) in the rolandic and parasagittal regions. Brain imaging by MRI showed intramyelinic edema in the myelinated regions on Diffusion Weighted Images: cerebellar white matter, brainstem, posterior limb of internal capsule and both thalami. Results High ammonia levels are indicative for a metabolic encephalopathy. Monophasic negative theta rhythm on EEG, as well as intramyelinic edema on MRI are rare, but pathognomonic diagnostic clues for Maple Syrup Urine Disease (OMIM: 24800). MSUD is a disorder of the branched-chain amino-acid metabolism leading to a progressive neonatal encephalopathy. Early presenting symptoms are aspecific, including feeding problems, vomiting, lethargy, opisthotonic posturing and seizures. Accumulation of the leukotoxic metabolites (2-ketoacids and branched-chain amino acids leucine, valine and isoleucine) finally leads to coma and central respiratory failure, which can be prevented by dietary measures. Conclusion Neonatal encephalopathy and neonatal seizures require comprehensive diagnostic measures, comprising a full metabolic blood screen, longitudinal neurophysiological monitoring and brain imaging, preferably by means of MRI. Electroencephalographic and MRI features typical for MSUD have been rarely reported together. Based on this case report, we discuss the unique EEG pattern before and after MSUD treatment.