The description of the disease in the upper half of the body may be distinctly separated from that in the lower half, on account of the remarkable differences observed in the mode of the muscular degeneration. In the lower extremities and pelvis primary pseudo-hypertrophy is the rule; atrophy is almost invariably secondary, and below the hips is rarely excessive.33 In the upper part of the body primary atrophy is the rule for certain muscles, and succeeds rather early to the pseudo-hypertrophy which affects others. Only a few muscles habitually hypertrophy, and remain enlarged until a somewhat advanced period of the disease. The first in this group is the deltoid, which not unfrequently enlarges simultaneously with the gastrocnemii.34 In one case the triceps humeri, and after that the biceps, are the next most frequently hypertrophied,35 in some cases even together with atrophy of the deltoids (2d case Seidel). In exceptional cases all the muscles surrounding the shoulder-joint, especially those covering the scapula, are hypertrophied. Thus in the early case of Coste and Gioga36 the latissimus dorsi and trapezius were hypertrophied, together with the deltoids, and even the muscles of mastication and the tongue. In this case not only the quadratus lumborum, but also the recti abdominis muscles, were hypertrophied. In Chrostek's case the tongue was hypertrophied, although all the shoulder-muscles, and also the sterno-cleido-mastoids, were atrophied.37 In Duchenne's third case the temporal and masseter muscles were hypertrophied, while no alteration of size in any direction was observed in the arms or shoulders. In Duchenne's twelfth case all the muscles of the body, including the face, were hypertrophied, with the single exception of the pectorals. In Barth's second case, the left sterno-mastoid, the supra and infra spinali, together with the left deltoid, were hypertrophied.
33 The quadricipites femoris, as already noticed, are not unfrequently wasted.
34 See cases of Kaulich, hypertrophy of calves, thighs, deltoids; Heller, hypertrophy of all muscles of lower limbs, also of abdomen with deltoids; Benedikt (4th and 6th cases); Friedreich (1st case); Adams; Gowers (4th and 11th); Ross (2 cases); Brieger. In a case by Clarke (Med.-Chir. Trans., vol. lvii.) the deltoids were observed to be large seven years after the beginning of the disease. In a case by Duchenne the enlargement of the deltoids, by great exception, preceded that of the gastrocnemii by several months.
35 Cases of hypertrophy triceps or biceps: Seidel (2d), Rinecker, Griesinger, Wagner (2d, triceps without deltoid), Knoll, Rakowac, Pekelharing, Spielmann (atrophy deltoid).
36 Schmidt's Jahrb., Bd. xxiv. S. 196. Other cases are given by Wernich (hypertrophy of rhomboids), Barth, Gowers (11th).
37 Oesterreich Zeitschrift f. prakt. Heilk., 1871.
In the majority of cases, however, at the time the patient came under observation all the muscles above the quadratus lumborum were atrophied, except the deltoids. In the pectoral, which has never been found hypertrophied, the wasting process always sets in the earliest, and advances to the greatest extent. The pectoral muscle is thus the exact antithesis of the gastrocnemius, while the deltoid more nearly resembles the gastrocnemius than any other muscle of the upper extremity. After the pectoral the latissimus dorsi, then the trapezius scapular muscles (including the serratus magnus), those of the arm and fore arm, the muscles of the neck, are found more or less wasted by the time the disease is fully developed. The wasting is sometimes extreme, as in a case described by Gowers, where the patient maintained a permanently crouching attitude, the spinal column being in extreme cyphosis, all its processes projecting, from the extreme emaciation of the trunk.
In Eulenburg's adult case38 the atrophy began in the hands, and was regarded by him as a combination of true progressive muscular atrophy in the upper, with lipomatosis musculorum luxurians in the lower extremities.39
38 Virch. Arch., Bd. xlix., 1870.
39 Cases of atrophy (often excepting deltoids): 1st case by Seidel, "simultaneous paresis in upper and lower extremities in four years; atrophy of arms and thighs, with hypertrophy of calves and fore arms; in six years, primary atrophy sterno-cleido-mastoids and pectorals; secondary atrophy of deltoids."