"Cerebral" lactic acidosis: defects in pyruvate metabolism with profound brain damage and minimal systemic acidosis.

Six patients are described with a combination of early onset of neurological symptoms, gross cerebral changes and elevated concentrations of pyruvate and lactate in cerebrospinal fluid. Although at least five of the six patients appear to have a generalised defect in pyruvate metabolism, reflected in deficient pyruvate dehydrogenase activity in cultured fibroblasts, systemic acidosis was not a problem clinically and blood pyruvate and lactate concentrations were only slightly raised. The localisation of significant clinical and biochemical problems to the central nervous system, coupled with the difficulties in making the diagnosis if analysis of cerebrospinal fluid (CSF) is not performed, lead us to term this condition "cerebral" lactic acidosis.