A clinico-pathological study of chronic hereditary motor neuropathy.

Forty cases of chronic hereditary motor neuropathy (CHMN) were divided into five categories according to the distribution of muscle atrophy; they were proximal, facioscapulohumeral, bulbospinal, distal and scapuloperoneal forms. Their clinical features and laboratory data were analysed, and muscle biopsies from 32 of them were studied by histological, histochemical and electron microscopical methods. An attempt at quantitative assessment of the histological changes was also made. All muscle biopsies showed a mixture of neurogenic and 'myopathic' changes in varying proportions. They showed more 'myopathic' changes than Werdnig-Hoffmann's disease, amyotrophic lateral sclerosis and other neurogenic atrophies except Charcot-Marie-Tooth disease. There was marked variation in the average number of atrophied muscle fibers contained in grouped atrophy. Frequently, deranged internal structure of the muscle fibres was revealed both by histochemical and electron microscopical methods. Based on the evidence of heterogeneity of CHMN in respect of genetics, clinical features and histological changes, it was speculated that CHMN represents a group of diseases which involves primarily different parts of the motor units.