Napapon Sailasuta1, Andrea L. Gropman2,
1Clinical MR Spectroscopy, Huntington Medical Research Institutes, Pasadena, CA, United States; 2Neurology, Children's National Medical Center, Washington D.C., United States; 3University of Southern California, Keck School of Medicine, Los Angeles, CA, United States; 4Rudi Schulte Research Institute, Santa Barbara , CA, United States
Despite effective treatment of hyperammonemia, children and adult survivors of ornithine transcarbamlyase deficiency (OTCD) a frequent enzyme defect of the hepatic urea cycle, exhibit a wide variety of neurological, neuropsychological, neuroimaging and neurochemical abnormalities. Most recently, in addition to proton MRS abnormalities o sub-clinical hepatic encephalopathy, residual deficits in glutamate neurotransmission have been identified by non-invasive 13C MRS studies after loading tests with 1-13C and 2-13C glucose. The results point to a hitherto unrecognized defect in cerebral glucose metabolism. Successful therapies of this new lesion may improve long term neurological outcome for this and other defects of urea synthesis.