Phosphorus magnetic resonance spectroscopy of patients with mitochondrial cytopathies demonstrates decreased levels of brain phosphocreatine.

The hypothesis that brain mitochondria are directly affected in several phenotypes associated with disordered oxidative phosphorylation was tested using phosphorus 31 (31P) magnetic resonance spectroscopy. Abnormal phosphorylation potentials in skeletal muscle have been demonstrated by 31P magnetic resonance spectroscopy in patients with mitochondrial cytopathies (heritable disorders of oxidative phosphorylation), but abnormalities of phosphorylation potentials in other organs have not been documented. Several lines of evidence suggest that these mutations may affect mitochondria in nonmuscle tissue. In this study we found that phosphocreatine-to-ATP ratios in brain were significantly reduced and that calculated brain ADP concentrations, phosphorylation potentials, and percentage of maximal rate of ATP synthesis were significantly altered in the 5 patients examined. This study indicates a primary abnormality of mitochondrial function in the brain, even in the absence of clinically evident cerebral dysfunction.