Etiology

The nature and cause of alopecia areata are unknown. On the one side, there are those who maintain that it is a purely trophoneural affection; and on the other, those who are equally satisfied that it is of microbin origin. The specific microbe, however, has not been determined with any certainty, and the chief support of the parasitic theory lies in the fact that the disease frequently appears in certain series of cases as if it were spread by contagion. Perhaps both theories are right, and-that two entirely different diseases exist, included under the same name - one of them nervous in origin, and the other parasitic.

Fragility of the hair, seen oftentimes about the beard, is explained by the attack of fungi, or by such causes as lead to insufficient nourishment of the hair, whereby its fibres are ill-formed, and tend to undergo degeneration.

Senile baldness is due to an atrophy of the structures generally; it commences on the crown of the head, the hair first turning gray; the scalp is dry, thinned, loses its subcutaneous fat, and the follicles become indistinct. In some people this change takes place at an early age, it is either an hereditary or physiological peculiarity.


General thinning, of the hair is most likely to occur under conditions which lower the vital energy of the patient. The scalp generally is scurfy and dry. This is in all probability due to the sluggish action which goes on. The usual sebaceous matter is not secreted; the follicles become choked by retained fatty and epithelial matter, and the formation of the hair is interfered with. This is also the case in eruptive disease and in syphilis.


The loss of hair in all these cases is an evidence of the working of some debilitating cause, it is not remediable to the most perfect extent without the use of constitutional remedies.

The hair in cases of thinning and baldness is often dry, brittle, and twisted or split up. This results from the peculiar absence of moisture; in its turn from the diminished activity of the circulation of the scalp; in its turn again, from the general debility of the system.

The various other alterations in physical aspect come under the head of Parasitic Disease.