45 Ibid., 1867.
46 This excludes the adult cases of Eulenburg, where "progressive atrophy of the upper extremities combined with pseudo-hypertrophy of the lower;" the case of Barth, an amyotrophic lateral sclerosis; the case of Müller, a dementia paralytica; and the case of Billroth, where the lesion was localized in the hamstring muscles of one thigh.
This great preponderance in the male sex is the first of three striking peculiarities which distinguish the clinical history of the disease. The second is its strangely-marked hereditary character. This is not, and indeed hardly could be, shown in a direct line, since the patients are incapable of marriage, or even die before arriving at maturity. But several brothers in a family are usually afflicted. There was, it is true, no trace of heredity in Duchenne's 13 cases, but this author himself recognizes the frequency of hereditary influence in those observed by others. Out of 81 cases analyzed by Friedreich, two or more members of one family were attacked thirty-five times. Thus, the first clinical report, that made by Meryon, described four brothers in one family and two in another. Coste, Griesinger, Wernich, Benedikt, Adams, Russel, Gowers, each relate cases of two members in one family; Heller, Wagner, Billroth, Seidel, have seen three: Moore47 describes three cases out of a family of seven, consisting of five boys and two girls. Two of the cases I myself have seen were brothers. Gowers48 relates five cases in the families of two sisters who married two brothers. This same writer refers to three other families in which two brothers were affected; to a fourth family described by Clifford Albutt, where two brothers were paralyzed, the third child dying of Hodgkin's disease; finally, to the family of a clergyman, himself living to the age of seventy-four, having always had large calves, and out of whose eight children two boys and one girl were affected.
47 Lancet, 1880.
48 Loc. cit., Appendix.
The families invaded by this singular disease are often remarkably large, and even where several children are affected, many others, even boys, escape. The morbid inheritance is always through the mother, "thus through the ovum—a condition unknown in diseases of the nervous system" (Gowers). This peculiarity belongs to only one other disease, hæmophilia, also almost limited to males. The third fact, which from its all but universality is shown to be of fundamental importance, is that the disease begins during infancy or early childhood. It has been shown that more than two-thirds of all cases began before the age of six. Whether there is ever an intra-uterine origin is still doubtful (Friedreich). This early invasion, often coinciding with the first efforts to walk or to use the muscles which are first attacked, distinctly separates pseudo-hypertrophic paralysis from all diseases which can be traced to definite accidents or to perversion of functions. It implies a profound perversion of nutrition, or rather a misdirection of developmental force.
PATHOLOGICAL ANATOMY.—The anatomical lesions of pseudo-hypertrophic paralysis are to be sought first in the muscles, afterward in the spinal cord, upon which so many peripheric lesions of the nervo-muscular system have recently been shown to depend. The argument from analogy, therefore, has of itself almost sufficed to create a conviction that some disease of the central nervous organs must exist as the real basis of pseudo-muscular hypertrophy.49 Nevertheless, as will presently be shown, the present evidence in favor of such hypothesis is extremely small.
49 This conviction is fully expressed by Hammond, loc. cit.
Muscular Lesions.—In the muscles, however, the anatomical changes are profound and varied. They may be divided into three kinds—those affecting the muscular fibre itself; those touching the connective tissue; and, finally, the fat deposited in this.
The lesions of these different elements are variously combined with each other in different muscles, and also at different stages of the disease. Thus, in the muscles of the trunk and upper extremities affected with primary atrophy the increase of fat is always moderate and quite insufficient to compensate the wasting of the contractile mass, while in the gastrocnemii and gluteal muscles the hypertrophied masses are often found to consist entirely of fat, traversed by bands of connective tissue, and indistinguishable from a lipoma.