Hair Loss: Hair Shaft Defects
Traction alopecia and trichotillomania continued...
Trichotillomania occurs when an individual plucks out their own hair. Often the hair on the scalp is plucked to leave bald patches, but the individual may focus on the eyelashes, eyebrows, pubic hair, or any other hair-bearing region. There is much argument about whether trichotillomania is a habit like nail biting, or a more psychological problem. Either way, affected individuals are usually not aware that they are plucking their hair, and when they are made aware of it they often find it very hard to stop.
Some individuals who pluck their hair also then eat it, a condition called trichophagia. This is a very dangerous condition that needs to be treated with some urgency. Hair is not digestible in the stomach and can build up into a hair ball. This can severely irritate the stomach lining, leading to severe ulceration. It is possible to die from trichophagia. Treating trichotillomania is difficult; therapists can probably help more than dermatologists.
The condition monilethrix makes hair fiber look like a string of beads. Along the length of a hair fiber there are nodes and constrictions making the edge of the fiber undulate. The beading that happens with monilethrix weakens the fiber.
Seen under a microscope, the hair fibers have lost their cuticle covering over the nodes while the constrictions keep their cuticle. The brittle hair easily breaks once it is exposed above the skin and the fibers rarely grow very long as a result. Breakage occurs in the weak constriction points along the fiber.
People with monilethrix have diffuse hair loss. Most frequently the hair loss is at the back of the scalp and neck and can leave the front of the head relatively unaffected. Monilethrix can also affect hair in other regions of the body.
Monilethrix most often occurs in childhood but young adults can also develop it. It is a genetically inherited disease and can run in families, although family members may be affected to different degrees of severity. The severity of monilethrix can also change with the seasons. It is often worse in winter and improves in summer. Monilethrix may spontaneously improve, although many people have monilethrix all their lives.
Overprocessing, cuticle stripping, and bubble hair
Overprocessing the hair is by far the most common cause of physical hair damage. Perming, straightening, bleaching, and dyeing the hair all involve harsh chemicals that can significantly affect the integrity of hair fiber. Using these cosmetic approaches too frequently or inappropriately can lead to irreversible damage to the hair fiber. The more hair fiber is damaged by these processes, the weaker it will be and the more likely it will break off.
The hair cuticle is a very strong outer sleeve of dead and highly keratinized cells that overlap each other like fish scales along the length of the hair fiber. The cuticle helps protect the softer inner cortex structure of the hair fiber from damage. The overlapping scales of the cuticle may become damaged and "flake up" if they are exposed to too much processing.