MUSCLE P-31-NMR IN A MITOCHONDRIAL ENCEPHALOMYELOPATHY DUE TO A SPECIFIC DEFECT IN PYRUVATE-DEHYDROGENASE

P31 NMR spectroscopy is useful for the diagnosis of some myopathies an d it is necessary to further specify its range of application. Mitocho ndrial myopathies show one or more abnormalities, yielding a heterogen eity of results that may correspond to their biochemical heterogeneity . We here report on a rare mitochondrial disease due to a defect in th e protein X of the pyruvate dehydrogenase complex. The abnormalities o bserved by muscle P31 NMR were mainly low phosphocreatine (PCr) and hi gh inorganic phosphate at rest and too small acidification with exerci se. The patient thus showed 2 of the main abnormalities described, alo ne or in association, in mitochondrial myopathies. The rate of PCr rec overy was normal. P31 NMR thus seems sensitive in this precise defect and can help the clinician for the diagnostic process. it is however t oo early to conclude whether P31 NMR abnormalities are specific for pr ecise mitochondrial defects. This search for diagnostic specificity co uld also benefit from other NMR approaches.