(Atrophy of the hair)
Definition. Idiopathic or symptomatic changes in the hair characterized by dryness, brittleness, splitting and diminution of size.
The division of these cases into idiopathic and symptomatic types is purely arbitrary, and simply signifies that the former presents no known causes while the latter may be due to constitutional or local diseases. Fragilitas crinium, trichorrhexis nodosa, monilethrix, leptothrix, tinea nodosa and piedra are the principal varieties ordinarily classed under this general head, and will be briefly considered.