Progressive Muscular Dystrophy of the Extra-ocular Muscles in a Negro.

ABOUT 150 cases of progressive muscular dystrophy involving the extra-ocular muscles have so far been recorded in the literature. As far as can be ascertained, this condition has never been described in a Negro. The myopathies are characterized by a primary dystrophy of voluntary muscle. Kiloh and Nevin (1951) reviewed the problem of progressive dystrophy of the external ocular muscles and concluded that the pathology directly affected the muscles and was not due to a degeneration of the oculomotor nuclei. They reported that a family history of the condition may be obtained in about half the cases. Progressive muscular dystrophy usually begins with a progressive ptosis; later the movements of the extra-ocular voluntary muscles become restricted, resulting in a partial or complete external ophthalmoplegia. These manifestations are usually bilateral and symmetrical. When the ophthalmoplegia is complete the ocular axes are divergent, and the ocular movements are equally restricted in all fields of gaze in both eyes. Although the disease is slowly progressive, it may spontaneously regress at any stage. In 25 per cent. of cases the orbicularis oculi muscles show weakness which may progress to complete paralysis (Nevin and Kiloh, 1958). 10 per cent. of cases also show evidence of weakness of the muscles of the face, neck, and shoulder girdle (Nevin and Kiloh, 1958; Teasdall and Sears, 1960), the facial weakness being always more marked in the orbicularis oculi. Hyperthyroidism, premature baldness, testicular atrophy, and cataracts have all been described as possible associated features of the condition (Teasdall and Sears, 1960). The intra-ocular muscles are not usually involved in the condition-the pupils are equal and react to light directly, consensually, and to accommodation. Microscopic examination reveals muscle fibre degeneration of a non-specific nature, with a marked increase in fibrous and collagen tissue. There is also an increased number of sarcolemmal nuclei.