Changes take place in the hair. Sometimes it simply changes color; at other times it falls out or ceases to grow. The beard or hair of the head will thus be gray or white upon one side, or in one or two locations of one side and not of the other; or the hair may be absent or simply thinned out. Peculiar limitations in the extent to which the hair is affected are sometimes observed. In one of Romberg's cases, for example, complete absence of the eyelashes from the inner angle of the eye to the middle of the lids was noted; the hair was very thin, and in some parts altogether wanting, and the left eyebrow was almost entirely devoid of hair. The changes which take place in the color of the hair in some severe cases of chronic trigeminal neuralgia will be recalled in this connection. I have known of several instances in which a few locks of hair were turned gray or white on the neuralgic side. Anstie, author of the work on Neuralgia, was a sufferer from supraorbital neuralgia, and the eyebrow of the same side contained a white tuft. Facts of this kind serve to corroborate and emphasize the view that unilateral facial atrophy is a tropho-neurosis.
Anidrosis, or absence of perspiration, on the atrophied side of the face is a nearly constant phenomenon. In one of Bannister's cases, a printer, attention was first called to the patient by the fact that in working a hand printing-press in the hot weather he perspired only on the right side of his face. The left side remained perfectly dry, no matter how warm the temperature or hard the labor. This hemidrosis, or unilateral sweating, was confined only to the right side of the forehead, the right cheek, side of the nose, and lip. On the chin it encroached a little on the left. Under the chin and in the throat there was a little excess of perspiration on the right side; on other portions of the body no difference was noted. Nicati12 considers a combination of symptoms, several of which were present in a recorded case—namely, lowered temperature, stoppage of perspiration, and wasting of the side of the face—as indicating a paralysis of the sympathetic nerve in what he calls its second or more advanced stage. In true facial hemiatrophy, however, other phenomena of such paralysis are wanting. Brunner13 gives a case in which perspiration, tears, mucous secretions, and temperature were all diminished on the affected side, and in which were also present exophthalmos and dilatation of the pupil. The cervical sympathetic in this case was irritated by a tumor. I agree with Bannister, however, that while we cannot exclude the possibility of the participation of the sympathetic in hemiatrophy of the face, the evidence is not sufficiently positive. Mechanical interference with the sweat-glands by pressure or otherwise has been suggested. The true view to take would seem to be that the perspiratory disorder is due to the same central or peripheral neurotic affection which gives rise primarily to the atrophy. Eulenburg says that the secretion of the sebaceous follicles is in most cases diminished or stopped on the atrophied side, while the sweat-glands often act in a normal manner; but his experience does not seem to correspond with that of the majority of other observers.
12 Sur Paralysie du Nerf sympathetique-cervical, Lausanne, 1873, quoted by Bannister.
13 St. Petersburger Med. Zeitschr., ii., 1871, quoted by Bannister.
Seguin, Dreschfeld, and others have found no notable differences in surface temperature between the two sides of the face. In one of Bannister's cases the temperature was tested in both ears, and a difference of six-tenths of a degree Fahrenheit in favor of the ear of the unatrophied side was found, that of the left ear being 97.6°, and that of the right 98.2°. This examination was repeated on another occasion with nearly the same result.
Weakness of pulsation in the carotid of the affected side has been observed. Sometimes the power to blush is lost on the affected side, but this may return. In one instance the cheek, having been reddened by electrical stimulation, so remained for an hour or more.
Paræsthesiæ, such as pain, numbness, and stinging sensations, are not uncommon. A diminution of the general tactile sensibility of the skin of the affected side has been observed by Tanturri14 and by Vulpian,15 and perhaps by others, but anæsthesia is not commonly present.
14 Il Morgagni, 1872, quoted by Bannister.
15 L'Appareil vaso-moteur, ii. p. 430.
Eulenburg and Guttmann found atrophy of the muscles supplied by the motor branch of the fifth nerve—namely, the masseter and temporal. The changes which take place in the muscles of the affected side are, so far as can be judged, not of the character of fatty degeneration. Probably a general and uniform shrinkage of calibre of muscular fibres and bundles occurs. Certainly, this would seem to be true of the muscles supplied by the portio dura. The muscles on the atrophied side respond to both the faradic and galvanic currents, reactions of degeneration not being present. The absence of the reactions of degeneration in the facial muscles shows that normal muscular fibres remain. In one reported case the facial muscles seemed at first to react more readily than in normal conditions. The muscles of the upper lip sometimes appear to have wasted, preventing full closure of the mouth on this side. Fibrillary twitchings have been observed only very rarely. Voluntary control over the muscles of the affected side is not impaired.