Trichorrhexis nodosa

Definition:

A defect in the hair shaft characterized by thickening or weak points (nodes) that cause the hair to break off easily. This group of conditions contributes to the appearance of hair loss, lack of growth, and damaged-looking hair.

Causes, incidence, and risk factors:

Trichorrhexis may have a genetic basis but appears to be precipitated by environmental factors. Among black children the hair may appear not to grow but microscopic examination shows that the hair shafts have nodes or swellings near the scalp which fracture easily. The hair actually grows but is broken before it can become long. Among whites the defect appears at the ends of the hair shaft with splitting of the ends, thinning and whitish discoloration.

These conditions are directly related to environmental causes such as "perming", blow drying, aggressive brushing, and excessive chemical exposure.