Since 1855 the reports of cases and papers on the subject have been so numerous as to make it unprofitable to enumerate them. Among the most notable are those of Eisenmann, published in Canstatt's Jahresbericht for 1856; Roberts's classic work on Wasting Palsy, in 1858; the papers of Lockhart Clarke in 1866 and 1867,13 and of Swarzenski in 1867;14 Kussmaul's clinical lecture15 and Friedreich's treatise16 in 1873; and Eulenburg's article on "Progressive Muscular Atrophy" in Ziemssen's Cyclopædia of Practical Medicine, published in German in 1875 and in English in 1877. An important case, in consequence of the careful post-mortem study of the nervous tissues, is one recently reported by Wood and Dercam.17
13 Med.-Chir. Transactions, xlix., 1866, p. 171, and l., 1867, p. 489.
14 Die Progressive Muskelatrophie, Berlin.
15 "Ueber die fortschreidende Bulbärparalyse und ihr Verhältniss zur progressiven Muskelatrophie." Sammlung klinische Vorträge, liv.
16 Ueber progressive Muskelatrophie, über wahre und falsche Muskelhypertrophie, Berlin, 1873.
17 Therapeutic Gazette, March 16, 1885.
ETIOLOGY.—The cause of this affection in a large number of cases is quite unknown. That hereditation plays an important part seems well determined by numerous observations, among which may be mentioned those of Roberts, Friedreich, Hemptenmacher, Trousseau, Meryon, Eulenburg, Sr. and Jr., Naunyn,18 Hammond, and Osler.19 In the Farr family, reported by Osler, 13 individuals in two generations have been affected, 6 females and 7 males—a larger proportion of the former than is common in this disease. Of these 9 had died at date of publication of paper. With the exception of two, all occurred or proved fatal after the age of forty. Of the 10 instances in the second generation, 5 are the offspring of males and 5 the offspring of females. The disease has not yet appeared in the third generation, which promises between forty and fifty individuals, several of whom are over thirty years of age.
18 Berliner med. Wochenschrift, Nos. 42 and 43, 1873.
19 Archives of Medicine, vol. iv., No. 3, Dec., 1880.
The over-use of the muscles involved seems to be a well-determined cause in certain cases of true muscular atrophy. The following interesting illustrations are given by Eulenburg:20 Betz observed atrophy of the side three times in the cases of smiths and saddlers, who had to do heavy work with the right hand; Gull, in a tailor after excessive exertion; Hammond reports a case apparently due to excessive use of one thumb and finger in playing faro; Friedreich, one of a dragoon who may have exhausted his left hand in holding the bridle while riding; another in a morocco-leather worker, who used to press hard with his left hand; and a musician who played several hours a day on the bass viol. Schneevogt names two cases of primary atrophy of the shoulder-muscles, especially of the deltoid of the right side—one of a sailor who had to pump for days together on a leaking ship, and the other of the left side in a woman who always carried her child on the left arm while suckling it. Continued threshing and the handling of a musket have both been followed by it in the muscles called into play by these exercises. Roberts was able to trace the effects of over-muscular exertion in producing the disease in 35 out of 69 cases. As a determining cause, at least, therefore, we must admit the over-use of muscles.