POSITRON EMISSION TOMOGRAPHY AND MAGNETIC-RESONANCE SPECTROSCOPY OF CEREBRAL GLYCOLYSIS IN CHILDREN WITH CONGENITAL LACTIC-ACIDOSIS

Congenital lactic acidosis with neurological symptoms may be due to a variety of disorders of energy metabolism. We investigated whether pos itron emission tomography (PET) and proton magnetic resonance spectros copy (H-1 MRS) are capable of demonstrating specific changes to facili tate diagnosis. A corresponding increase of cerebral lactate (with MRS ) and rate of glycolysis (with PET) was observed in 2 children with bi ochemical evidence of defective mitochondrial respiration. No such inc rease was noted in a child with lactic acidosis due to stress and exer cise but normal respiratory chain activity, and in a control case with an epilepsy syndrome without evidence of primary changes of energy me tabolism. The results suggest that defects of oxidative phosphorylatio n may cause a massive increase of glycolysis to cover energy requireme nts, with corresponding accumulation of lactate in brain tissue. This mechanism can now be demonstrated in vivo and, with further experience , may potentially be used as a diagnostic marker of respiratory chain disorders in brain tissue.