Causes of trichorrhexis

hair shafts affected by trichorrhexis nodosa contain small white nodes at irregular intervals throughout the length of the shaft. The number of nodes may vary from one to several, depending on the length of the hair. These nodes represent areas of curricular cell disruption, which allows the underlying cortical fibers to separate and fray. The cortical fibers splay outwards and fracture, giving the node the microscopic appearance of 2 brooms or

paintbrushes thrust together end to end by their bristles. Complete breakage often occurs at these nodes.

the cause of  trichorrhexis 

 stressed hairstyles, the application of heat, and prolonged exposure to ultraviolet light. Head rolling and banging; habit tics; trichotillomania; and the scratching and pulling associated with pruritic dermatology  such as seborrheic dermatitis and pediculosis capitis, can also result in sufficient damage, salt water, shampooing, setting, perming, bleaching, and dyeing of hair.

Also,The underlying structural weakness of the hair shaft may result from impaired keratin formation. Hairs weakened by impaired keratin formation are seen in argininosuccinic aciduria, trichothiodystrophy, and Menkes disease.

Menkes disease is a sex-linked recessive disorder characterized by a defect in the metabolism of copper, resulting in low serum copper levels. The enzymes involved in keratin formation are copper dependent. Therefore, patients with this disorder have an inherent defect in keratinization, resulting in a twisting of hairs (pili torti) as well as weakened hairs and trichorrhexis nodosa. 

Trichorrhexis nodosa has also been described in a case of hypothyroidism.

In another syndrome with dysmorphic features, including cleft palate, hypotrichosis with trichorrhexis nodosa, 

hypohidrosis, oligodontia, and ridging of nails, a heterozygous germline mutation, Ala111Thr, in the P63 .

A recent study in Japan (Journal of Dermatology, February 1995) has shown that on many factors which may hurt someone's hair with trichorrhexis, mechanical bending is the most damaging. In this study, even very gentle curvature of the hair, using a pair of tweezers, has resulted in multiple fractures of the hair shaft. Keeping this in mind when any information that you do with your daughter's hair (wash, rinse, combing, etc.) will help minimize the damage. Start now to teach him about his hair. She does not yet, but as you lovingly explain why you do the things you do, it will gradually understand and take care of her own hair.