Nuclear magnetic resonance spectroscopy in glutaryl-CoA dehydrogenase deficiency

Nuclear magnetic resonance (NMR) spectroscopy is a safe, noninvasive method that is the preferred technique for in vivo analysis of specific chemical compounds in localized brain regions. Besides quantification of compounds, NMR spectroscopy allows the detailed analysis of neurotransmitter, glucose and lactate metabolism following peripheral infusions of stable isotopically labelled precursors. The latter has been successfully applied to patients with different neurological disease states not including glutaryl-CoA dehydrogenase (GCDH) deficiency. In contrast, single patients with GCDH deficiency who were neurologically unremarkable have been studied with conflicting results. One patient was shown to have an increase in intracerebral creatine and phosphocreatine concentrations, while the second studied had unremarkable levels. In a 15-year-old patient, we were able to demonstrate elevated levels of intracerebral lactate and elevated choline/N-acetylaspartate ratios, indicating potentially increased myelin turnover and reduced neuronal integrity in periventricular white matter. Interestingly, spectra in basal ganglia were within normal limits. Systematic studies to address well-defined questions in GCDH deficiency are urgently needed. In particular, analysis of in vivo neurotransmitter metabolism following administration of isotopically labelled precursors in patients with GCDH deficiency, both when metabolically stable and when unstable, may help to advance our understanding of the pathophysiology of GCDH deficiency.