Chronic progressive external ophthalmoplegia. Clinical, electrophysiological, histochemical and ultrastructural studies of 14 cases

Clinical, histochemical and ultrastructural findings concerning 14 cases with diagnosis of Chronic Progressive External Ophthalmoplegia are described. According to the clinical features the patients have been rated in two groups: the first including subjects with isolated ptosis or ptosis with external ophthalmoplegia and the second including subjects with a spreading of the muscular deficit and involvement of the neck and limbs. The most frequent histological and histochemical features are type I fibre atrophy, ragged-red fibres, DPNH-diaphorase reaction disorders and abnormal accumulation of lipids into the fibres. Electron microscopy reveals myofibrillar disorganization and clusters of polymorphous, abnormal mitochondria. In five cases mitochondria contain a variety of crystalline inclusions. Correlations between clinical data and histochemical and ultrastructural findings are discussed. Mitochondrial abnormalities are postulated to be a characteristic physiopathological pattern in CPEO.