A possible mechanism for selective cerebellar damage in partial pyruvate dehydrogenase deficiency.

In patients with partial deficiencies of pyruvate dehydrogenase, cerebellar ataxia has been the most prominent and sometimes the only neurologic abnormality. It is not clear how this generalized enzyme deficiency (with activity 15 to 30 percent of normal in several tissues) might lead to clinical signs referable to a limited part of the nervous system. We therefore compared the normal activity of pyruvate dehydrogenase with the normal rate of pyruvate oxidation in different parts of animal brains and then calculated the effect on pyruvate oxidation of partial deficiencies of the enzyme. The data indicate that pyruvate oxidation could be impaired in an area of anterior cerebellar vermis by deficiencies of pyruvate dehydrogenase too mild to affect pyruvate oxidation in the other areas of the brain we examined.