The most familiar type of hair loss is called baldness and it is the state of lacking hair where it often grows, especially on the head. The most common form of baldness is a progressive hair thinning condition called androgenic alopecia that occurs in men and women. The degree and patterns of baldness can vary greatly depending on gender, age, genetics and sometimes on one’s medical condition.
Androgenetic alopecia: The most common areas of hair loss in men are frontal, temporal and vertex, while the most commonly affected areas in women are behind the hairline and the top of the scalp and occasionally a receded hairline and/or vertex. The hair in the back of the head is rarely affected by thinning and serves as the donor area for hair transplantation.
Androgenetic alopecia (AGA) is also known as male-pattern baldness and is the most common cause of hair loss. Approximately 50% of men are affected by the age of 50 and thinning of the hair can benign, the psycho-social ramifications of AGA can be significant. One of the hallmarks of androgenetic alopecia is the conversion of thick terminal hairs into miniaturized, vellus-like hairs. This process of miniaturization (i.e., shrinking of hair volume and growth length) is usually an indication that on is undergoing hair loss. The main mechanism for miniaturization relates to the shortening of the anagen phase, i.e., the hair becomes “lazy” and does not grow to its full term.
Female-Pattern Baldness
While hair loss in men is often a genetic condition thus a lifelong process, it is unclear what predisposes a female toward hair loss. Some females may start exhibiting hair loss as early as after puberty, while others have no signs of any unusual hair shedding until later in life when they enter menopause. In women as in men, the most likely cause of scalp hair loss is androgenetic alopecia: an inherited sensitivity to the effects of androgens (male hormones) on the hair follicles of the scalp.Alopecia areata: – The hallmark of this medical condition is circular patches of hair loss with 60% having their first incidence before the age of 20. The etiology for AA is unknown but has been attributed to a T-cell mediated immune attack on the hair follicle. AA can remain or resolve spontaneously without intervention. For limited cases of AA, intralesional steroids and topical minoxidil can be helpful. For more extensive cases, such as in cases of alopecia totalis (complete loss of scalp hair) and alopecia universalis (in which eyebrow, eyelash and body hair are absent), topical immune modulators may be required.
Anagen Effluvium
Hair is lost during the anagen phase due to conditions that affect the growth phase of the hair cycle like anti-neoplastic chemotherapeutic agents. The onset of hair loss is within weeks of exposure to the offending agent, and the condition should be entirely reversible within a few months after the cessation of the agent.
Telogen Effluvium
Telogen effluvium relates to shift of a significant percentage of hairs in the anagen (growing) phase to telogen (resting) phase, usually following a stressful event or sudden hormonal change. TE can occur about 8 to 10 weeks following certain inciting events like fever, postpartum, crash dieting/low protein diet, low thyroid levels, iron deficiency, cessation of oral contraceptive pills, prolonged anesthesia, malignant disease, renal failure, liver failure, acute anxiety and depression.
Cicatricial Alopecia
Any type of hair loss that involves scarring requires urgent treatment. Discoid lupus and lichen planopilaris account for a majority of the remainder of this category and also constitute inflammatory scarring alopecia and some experts believe it represents a burned-out condition of a formerly inflammatory scarring alopecia.
Traction Alopecia
A type of irreversible hair loss that arises due to traction or pull on one’s hair for an extended period of time most commonly arising from tight hair braiding in the African community. Another interesting group of people experiencing traction alopecia are the sikh population that do not cut their hair for religious religious reasons but instead tie it in a progressive knot under a turban. The outer fringe of hair is subjected to the highest degree of strain and is therefore the most commonly lost due to traction alopecia. Only when these individuals convert to western customs and shed their turban does the unique pattern of alopecia become a concern.
Trichotillomania
A psychological disorder characterized by obsessive-Compulsive Disorder (OCD) of pulling out one’s hair. On scalp biopsy, the classic signs of trichotillomania include pigment casts and trichomalacia. Interestingly, the periphery of the hair-bearing area can be typically spared, as it is the most uncomfortable to pull out. On physical examination, multiple hairs can be seen to be broken off out. On physical examination, multiple hairs can be seen to be broken off in irregular patches in varying lengths.
