As regards premature idiopathic alo pecia, women are less frequently affected than men. In many cases this form of alopecia seems to be hereditary.
Study of 300 cases. Conclusion that baldness is more common in men than in women. It seems to be more common in unmarried men. Most patients are found to lead in-door lives, and belong to the intellectual class. Usually the loss of hair begins before the thirtieth year. In women it usually constitutes a gen eral thinning; in men it affects the top of the head. Dandruff is usually a factor in the causation; heredity is also active. When complicating diseases are present, they are usually those that affect the general nutrition. G. T. Jackson (Med. Record, May 26, 1900).
Excessive mental work, excesses, and a bad hygiene of the scalp seem to be factors in its development. (Brocq.) Pressure of the anterior temporal, pos terior temporal, and occipital arteries by a stiff hat has been mentioned as a cause of this form of baldness. (F. A. King.) The escape of the little tuft of hair above the forehead has been attributed to the fact that the supra-orbital arteries escape from pressure by their passage between the two frontal eminences.
(Jackson.) - The blood-supply to the scalp is con veyed by the frontal, temporal, and occipital arteries, situated just where a tight hat would press on them and bring about a gradual starvation of the hair follicles. A woman, on the other hand, wears her hat resting lightly on top of the head, bringing no pressure whatever on the arteries, and thus escapes bald ness. The maximum of hat-pressure in a man comes on the frontal arteries, and in consequence we find baldness gener ally commences on the regions supplied by those vessels. M. C. Black (Indian Lancet, Apr. 16, '98).
Alopecia is a symptom resulting from many different sources of irritation of peripheral nerves. The commonest and therefore the most important of these causes is dental irritation, as shown in three hundred consecutive cases. Jae quet (Annales de Berm. et de Svph., Feb. and March, 1902).
That frequent washing of the head encourages loss of hair is the opinion of the majority of dermatologists.
Pathology. — In alopecia following acute and chronic general diseases the hairs are no longer formed; their roots become atrophied, and they finally fall out. The alopecia of convalescence is due to disturbance of nutrition of the tissues.
Premature idiopathic alopecia is due to a fibrous transformation of the derma, which strangles in its meshes the ele ments found in the scalp, especially the hair-follicles. As to the pathogenesis, alopecia may be considered a specific microbic affection.
The specific microbacillus of fatty seborrhcea, when introduced into the pilosebaceous follicle, produces four constant results: (a) sebaceous hyperse cretion; (b) sebaceous hypertrophy; (c) progressive papillary atrophy; (d) death of the hair. These phenomena result from seborrhceic infection upon smooth regions as well as upon the hairy ones. The vertex is the seat of election of this infection. Common baldness is only a chronic fatty seborrhcea of the vertex. Not only is follicular seborrhceic infec tion indispensable in the production of baldness, but this seborrhccic infection remains intense, pure, and permanent until the baldness is fully and perma nently established. (Sabouraud.) Seborrhea cheese is due to a micro bacillus which had already been dis covered, but not rightly interpreted by L'nna. This microbacillus forms a mass in the upper third of the hair-follicle, between the surface of the skin and the point where the sebaceous gland opens into the follicle. This mass is the oily cylinder which may be extracted from the follicle by pressure on the skin. Secondary infections may be superadded to seborrhcea of the face, giving rise to acne or furunculosis. On the scalp it causes seborrhceic alopecia.
Ordinary alopecia create is closely re lated to seborrhcea. Any patch of alo pecia areata is the seat of an intense localized seborrhmic infection, both pre vious to the loss of hair and while the latter persist.