Outcome of thiamine treatment in a child with Leigh disease due to thiamine-responsive pyruvate dehydrogenase deficiency.

[pyruvate dehydrogenase deficiency]

We describe a child with severe psychomotor retardation , peripheral neuropathy and bilateral abnormal signal in basal ganglia on magnetic resonance imaging , consistent with Leigh disease . Fibroblast pyruvate dehydrogenase assayed with routine method was normal . However , because of neurological improvement after treatment with thiamine , pyruvate dehydrogenase activity was studied again with thiamine pyrophosphate concentration adjusted to the normal human tissue level and found to be deficient . We report here on diagnostic difficulties and clinical follow-up of this patient .