Progressive External Ophthalmoplegia: Evidence for a Disorder in Pyruvate-Lactate Metabolism

Chronic progressive external ophthalmoplegia, in addition to the myopathy of the external ocular muscles, often involves abnormalities in facial and limb muscles, cerebellum, spinal tracts, myocardium, endocrine glands, hearing, and retina. 1-4 Recent electron microscopical studies 5,6 show abnormal mitochondria in muscle, retina, and cerebellum. Biochemical accompaniments of this defect have not yet been discerned. The signs and symptoms of four patients with chronic progressive external ophthalmoplegia and retinal pigmentary changes are summarized in Table 1. The most prominent evidence of myopathy was found in patients 1 and 3. Figures 1 and 2 show the morphological changes in the left deltoid muscle in patient 3. Repeated examinations of venous plasma pyruvate and lactate concentrations were performed in these patients under standardized conditions. Venous stasis was avoided, and the samples were precipitated immediately with iced perchloric acid. Venous plasma pyruvate and lactate concentrations were normal in patients 2 and 4, who