Hair disorders result in the production of defective hair fibers. These disorders damage the outer cuticle layer and may expose the inner cortex to various hair treatments like curling, relaxing, pressing or coloring. The exposure to these strong hair treatments weakens the overall strength of the hair fiber.

Gradual weakening of the hair fibers is involved in hair shaft defects and hair disorders like pili torti and monilethrix.

Pili Torti
Pili torti(trichokinesis, corkscrew hair) is the general name for rigidly twisted hair. The twisting of the hair fiber occurs at focal points along its length. There may be several twists in one hair fiber.

In this hair shaft disorder the cuticle layer remains intact and is not stripped away as in Trichorrhexis nodosa. But the rigid twisting of the hair fiber through 180 degrees creates stress, which leads to fractures in the cuticle and internal cortex layer of the hair shaft.

Causes
The common cause of pili torti is genetics, and usually develops in early childhood. Genetic pili torti is most frequently found in people with thin, blond hair.

However, occasionally an individual may develop the hair disorder later in life.

The acquired causes of twisted hair fibers are due to damage of the skin from burns or other forms of scarring. Pili torti is sometimes diagnosed in some people who are suffering from anorexia nervosa or taking some drugs, like retinoids.

Effects
Scalp hair is most commonly affected by pili torti. But in extreme cases the hair disorder is seen in eyebrows, eyelashes and other hair growing areas of the body. A single twisted hair cannot be termed as pili torti, but when there are innumerable twisted hair fibers in the scalp or other region of hair only then is the condition called pili torti.

The pili torti hair disorder can be seen in a number of hair dystrophies and is associated with several syndromes such as Menkes kinky hair syndrome or twisting hair dystrophy.

In Menkes kinky hair syndrome apart from the formation of twisted hairs, the hair tends to be lightly pigmented and may demonstrate unusual colors in young people, such as white, silver, or grey. In twisting hair dystrophy there are half and three-quarter twists of the hair at irregular intervals rather than the 180º turns as seen in true pili torti.

Treatment
There are no treatments or professional hair care products for pili torti, but sometimes the condition can improve spontaneously after a period of time.

Monilethrix
Another common hair disorder is monilethrix. Distinctive, regular beaded hairs and hair fragility characterize monilethrix. This hair shaft disorder can occur alone or in association with trichorrhexis nodosa. The affected hairs demonstrate a beaded structure of alternating elliptical nodes and constrictions (internodes). The internodes are prone to severe weathering. The hair tends to fracture between the nodes, where weathering occurs.

Causes
Monilethrix is a genetically inherited disease, though the effects may vary from person to person in a same family. Children and young adults are most affected by Monilethrix, but the severity tends to diminish as the individual grows older. The severity of monilethrix also depends on seasonal changes. It is often worse in winter and sometimes improves in summer.

Apart from the hair disorder, seasonal changes also affect hair loss to some extent.

Effects
The hair beading in monilethrix weakens the fiber which leads to diffusive hair loss. Most frequently the hair loss is at the back of the scalp and neck whereas the front of the head remains relatively unaffected. Monilethrix can also affect other hair growing regions of the body. It can also be associated with defects in the eyes (cataracts), teeth, and nails, as the structure of these organs are of similar properties to that of the hair follicles.

Treatment and professional hair care products
There are no effective treatments or professional hair care products for this severe hair disorder, but hair loss can be camouflaged with a wig. Retinoids and minoxidil may be helpful in some cases. It has been observed that the hair disorder can spontaneously improve with age.