LEIGH-SYNDROME - PYRUVATE-DEHYDROGENASE DEFECT - A CASE WITH PERIPHERAL NEUROPATHY

Pyruvate dehydrogenase deficiency is one of the most common causes of encephalopathy associated with lactic acidosis and is known to account for congenital lactic acidosis, recurrent ataxia, and infantile Leigh syndrome. Hitherto, however, peripheral neuropathy has not been regar ded as a presenting symptom of pyruvate dehydrogenase deficiency. Here , we report on a boy who presented peripheral neuropathy with severe l imb hypotonia, absent deep-tendon reflexes, and reduced motor nerve co nduction velocities at 8 months of age. Persistent hyperpyruvicemia wi th normal lactate/pyruvate molar ratios in plasma were highly suggesti ve of a pyruvate dehydrogenase deficiency, and the determination of py ruvate dehydrogenase activity in circulating lymphocytes led to the di agnosis of pyruvate decarboxylase (PDH-E1) deficiency in the proband. Based on this observation, we suggest that pyruvate dehydrogenase defi ciency should be considered in the diagnosis of peripheral neuropathy in infancy, especially when associated with persistent hyperpyruvicemi a, normal lactate/pyruvate molar ratios in plasma, and recurrent episo des of drowsiness and hypotonia of unknown origin.