Positron emission tomography (PET) and proton magnetic resonance spectroscopy (MRS) identified an increase in rate of cerebral glycolysis (PET) and cerebral lactate (MRS) in 2 children with defective mitochondrial respiration and congenital lactic acidosis studied at the Universitat zu Koln, Germany, and the University Hospital, Nijmegen, The Netherlands. These changes were not apparent in a child with lactic acidosis and normal respiratory chain activity. Defects of oxidative phosphorylation may cause increases in glycolysis and accumulation of cerebral lactate. 
COMMENT. PET and MRS have been used to demonstrate the metabolic changes associated with defective mitochondrial respiration in the brain without resort to diagnostic muscle biopsy. For further discussion of MRS in mitochondrial disorders, see Progress in Pediatric Neurology II, 1994, p454.