Progressive hemiatrophy of the face is treated elsewhere. The following case of progressive hemiatrophy of the entire body may be mentioned here: A boy, aged fourteen, dislocated his ankle, which in a few days became swollen, red, hot, and painful. The inflammation extended up the leg, but did not involve the knee, and soon subsided. After a short time the foot began to atrophy. The atrophy extended up the leg, and involved the thigh; it then progressed to the trunk and the arm, and lastly to the face on the affected side, until in the course of two years there had developed a unilateral atrophy of the entire body. Muscles, fat, and bones were all affected, but no difference in the skin or hair of the two sides was noticed. Fibrillary tremors were present in the muscles. The electric reactions were not altered, but were gradually lost. There was a hypersensitiveness to touch and to cold, but no other sensory disturbance. The boy was alive and fairly well when the case was reported.82 It is unique.
82 Heuschen, Schmidt's Jahrbuch., vol. cxcviii. p. 130.
These various instances of atrophy cannot be ascribed to simple disuse, since they differ markedly in their pathological changes and in the rapidity of their progress from such atrophy. Nor are they to be referred to vaso-motor disturbances, since in many cases no vascular changes are evident. Their distribution in the body often corresponds exactly with that of peripheral nerves, and they accompany nerve lesions too frequently to be explained on any theory of coincidence. There are many authorities, however, who refuse to ascribe them to a lesion of trophic nerves.83 In regard to the degeneration of nerves it is said that each nerve axis-cylinder is a part of the nerve-cell from which it arises, and hence destruction of the cell or division of the cylinder, by disturbing the unity of existence, results in the death of the part. The fibre shares all the changes of nutrition which the nerve-cell undergoes, and if separated from it necessarily perishes. To this it is replied that trophic paths and motor paths are distinct at some points in their course, at least in the central nervous system, since each can be affected alone. Erb, who has studied this subject carefully,84 believes that trophic are distinct from motor centres in the spinal cord, but that both impulses may be conveyed by the same axis-cylinder in the peripheral nerves—a middle ground which is widely accepted. It is now known that each axis-cylinder is made up of several fibrils, so that this theory gains probability. This would also explain the occurrence of atrophy in the muscles, the trophic centres being affected when the muscle atrophies, and unaffected when it is paralyzed without atrophy. Mayer, however, denies this explanation of the muscular atrophy, holding that the motor system, cell, nerve, and muscle-fibre, forms a nutritive as well as functional unit, and that the simple suspension of function, by interfering with the special conditions of nutrition attendant upon physiological excitement, is competent to cause a pathological change. To this it is replied that the parts of the motor system are not interdependent, since disease of the muscle does not produce degeneration of the nerve and of the cell, and the fact of a degeneration in a peripheral direction alone is evidence of central trophic influence. The attempt to ascribe trophic changes in the skin, nails, and hair to vaso-motor disturbance has been equally unsuccessful in covering all the observed cases.
83 See Handfield Jones, St. George's Hospital Reports, 1868, vol. iii. pp. 89-110; Sigmund Meyer, Hermann's Handbuch d. Physiol., ii. Th. 2, “Trophische Nerven,” 1879; Gowers, Diseases of the Brain, 1885, p. 4.
84 Arch. f. Psych., v. S. 445, 1875; also Ziemssen's Cyclo., vol. xiii. p. 117 (Amer. trans.); also Deut. Arch. f. klin. Med., v. S. 54.
FIG. 58.
Diagram of the Arrangement and Connection of Motor and Trophic Centres and Fibres in the Spinal Cord and Motor Nerve (after Erb): a, motor fibre of spinal cord from the brain to d, the motor cell, which is joined to the muscle m by the motor nerve; b, trophic cell in the spinal cord for the muscle, to which it is joined by the trophic fibre bʹ; c, trophic cell in the spinal cord for the motor nerve, to which it is joined by the trophic fibre cʹ; s, a fibre bringing sensory (reflex) impulses to the cell.
If d is destroyed, the fibres from b and c perish with it, and the result is paralysis and atrophy of the muscle and degeneration in the motor nerve—e.g. poliomyelitis anterior. If b is destroyed, the muscle atrophies, and paralysis is a secondary result—e.g. progressive muscular atrophy. If c is destroyed, the nerve degenerates, and paralysis and atrophy of the muscle are secondary results—e.g. neuritis with reaction of degeneration. If a is destroyed, voluntary power is lost, but reflex power remains, and no atrophic changes occur—e.g. lateral sclerosis. If the motor nerve is cut between d and m, the result is the same beyond the division as when the motor cell is destroyed.