A case of acquired progressive kinking of the hair is described. There were abnormalities of both hair structure and growth. The structural change was an occasional kink or half-twist of the shaft, and the growth change, a shorter anagen phase with catagen apparently occurring as a random event such that in a population of affected hairs about a third entered catagen for every 1.5 cm increment of hair growth.
Coupe RL, Johnston MM. Acquired Progressive Kinking of the HairStructural Changes and Growth Dynamics of Affected Hairs. Arch Dermatol. 1969;100(2):191-195. doi:10.1001/archderm.1969.01610260067012