ULTRASTRUCTURE OF MUSCLE IN WERDNIG-HOFFMANN DISEASE

The ultrastructure of denervated muscle from 7 cases of Werdnig-Hoffmann disease (hereditary spinal muscular atrophy of infancy) is described. The diagnosis was established by the clinical finding of amyotrophy and hypotonia in an infant, and electromyographic studies, when performed, showed evidence of denervation in the voluntary muscles. In 3 cases the diagnosis was confirmed at necropsy. Electron microscopy showed changes of denervation in the sarcolemmal nuclei, the sarcolemmal sheath and in the band structure of the muscle fibre. Of particular importance was the demonstration of division of the sarcolemmal nuclei in denervated muscle fibres. The gradual disintegration of the myofibrillar architecture due to a progressive loss of myofilaments was studied. The changes reported are compared with those described in previous reports of the ultra-structure of muscle in cases of Werdnig-Hoffmann disease and Kugelberg-Welander disease, and with those found in denervation atrophy produced experimentally in animals. © 1969.