Clinical utility of brain MRS imaging of patients with adult-onset non-cirrhotic hyperammonemia

Adult-onset non-cirrhotic hyperammonemia (NCH) is a rare, but often fatal condition that can result in both reversible and irreversible neurological defects. Here we present five cases of adult-onset non-cirrhotic hyperammonemia wherein brain magnetic resonance spectroscopy (MRS) scans for cerebral glutamine (Gln) and myo-inositol (mI) levels helped guide clinical management. Specifically, we demonstrate that when combined with traditional brain magnetic resonance imaging (MRI) scans, cerebral Gln and mI MRS can help disentangle the reversible from irreversible neurological defects associated with hyperammonemic crisis. Specifically, we demonstrate that whereas an elevated brain MRS Gln level is associated with reversible neurological defects, markedly low mI levels are associated with a risk for irreversible neurological defects such as central pontine myelinolysis. Overall, our findings indicate the utility of brain MRS in guiding clinical care and prognosis in patients with adult-onset non-cirrhotic hyperammonemia.