74 Demange, Rev. de Médecine, 1882, p. 247.
75 Friedreich, Progressive Muskelatrophie, p. 347, 1873.
The condition of the skin and its appendages is influenced decidedly by changes in the nervous system, either in the nerves, in the spinal ganglia, or in the central gray matter. Here it is the sensory nerves which convey the trophic influence, not the motor nerves, as in the cases hitherto considered; and when the lesion producing trophic changes in the skin is central, it is situated in the posterior cornua of the spinal cord or in the gray matter near the central canal. The glossy skin seen on the fingers after injuries to the nerves is a type of such atrophy from disturbance of trophic impulses. Glossy fingers present a smooth, shining appearance, are dry from the diminution in the secretion of sweat, feel soft and satin-like to the touch from the marked thinning of the skin, and frequently show a defective or irregular growth of the nails, which may be ridged, curved, or deformed.76 They are red and mottled from accompanying vaso-motor paralysis, and are usually hot and painful. Changes in the pigmentation of the skin and hair are recorded as a not infrequent accompaniment of severe neuralgia and as a result of great mental anxiety. Thus in several cases of supraorbital neuralgia the eyebrow on the affected side has turned white; in infraorbital neuralgia the beard has become gray; and in both the hair has been observed to fall out.77 The sudden turning white of the hair is ascribed to a swelling of the hair by air within it.78 In one case, frequently cited, the hair and nails fell out after a stroke of lightning.
76 Weir Mitchell, Injuries of Nerves. See also Vol. IV. p. 683.
77 Seeligmüller, Lehrbuch der Krankheiten d. Peripheren Nerven, p. 157, 1882.
78 Arch. f. Path. Anat., xxxv. 5, 575, Landois.
When a gland is cut off from its nervous connection with the cord or cerebral axis by section of its nerves, its function is impaired and its nutrition suffers, so that after a time it loses weight and undergoes a progressive total atrophy. This has been proven experimentally in animals in the submaxillary gland. It has been observed in the testicle in man after division of the spermatic nerve (Nélaton) and after destruction of the spinal cord by traumatic and idiopathic myelitis (Klebs, Föster).79 The sweat-glands are known to be under the control of a central nervous mechanism, as cases of hyperidrosis, anidrosis, and chromiodrosis prove;80 and an atrophy of them and of the sebaceous glands has been observed81 after nervous lesions.
79 Cited by Samuel, Realcyclop., loc. cit. See also Obolensky, Centralblatt für med. Wissen., 1867, 5, 497.
80 See Vol. IV. pp. 583-586.
81 See Vol. IV. pp. 683 et seq.