Humans are born with approximately 100,000 hair follicles on their scalp. Scalp hair only constitutes a small fraction (100,000–150,000 follicles) of the total count for the body (approximately 5 million follicles).
Alopecia, or hair loss, is the medical term for the loss of hair from the head or body. Unlike intentional aesthetic depilation, alopecia is involuntary and often unwelcomed. However, sometimes hair loss may be caused by a psychological compulsion to pull out one’s own hair (trichotillomania) or the unforeseen consequences of voluntary hairstyling routines causing mechanical hair loss (traction alopecia) from excessively tight braids often seen in African-Americans. There are many medical conditions that can cause temporary or permanent hair loss. Hair transplant is successful and possible in many cases except when the skin may be affected with a condition that would reject transplanted hair and for which reason the surgeon needs to evaluate scalp before proceeding with surgery.
When hair loss occurs in only one section and appears as bald patches, it is known as alopecia areata; and when complete hair loss on the body manifests including the eyebrows and eyelashes, the condition is called alopecia universalis. This condition is different from the total hair loss that follows chemotherapy. In alopecia universalis, the return of hair growth is unpredictable, while patients who lose their hair after undergoing chemotherapy are most likely to regrow their hair and do not require a hair transplant.
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. 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. However, in some situations of female diffuse hair loss or retrograding hair loss in the male, the occipital areas could be affected, which robs those individuals of the possibility for a hair transplant (Fig. 1.3).
It was previously believed that baldness was inherited from the maternal side only. However, it is now generally accepted that both parents contribute to their offspring’s likelihood of hair loss. Although baldness is not as common in women as in men, the psychological effects of hair loss, such as altering one’s self-image and self-esteem, tend to be much greater in women than men.