Hair Transplantation

The most common form of hair loss for both men and women is androgenetic alopecia (AA) and the most common reason for performing hair transplantation is for the surgical correction of male pattern baldness (MPB). However, hair transplantation is available for women with female pattern hair loss (FPHL); eyelash, eyebrow, moustache, beard, and pubic transplantation; and cicatricial alopecia secondary to trauma, burns, rhytidectomy, and inactive inflammatory dermatoses. Current techniques allow for the superior removal, dissection, and placement of hair to yield natural looking results. Available donor hair cannot only come from the back of a permanent fringe of hair bearing scalp, but from other body areas such as the chest, back, and arms, while at the same time leaving, in most cases, undetectable scars.

It is beyond the scope of this chapter to describe in detail the vast amount of knowledge that has developed in this field in such a relatively short period of time since the first punch grafts were performed in the 1950s. This chapter is aimed at the practicing physician who may or may not be performing transplants and desires to learn more about the current state of the art in the field of hair restoration with its many applications both medically and surgically to help people that suffer from hair loss.

P.C. Cotterill Private Practice,

21 Bedford Road, Toronto, ON M5R 2J9, Canada e-mail: paul@drcotterill.com

MPB occurs because of a combination of genetics, hormones, and time. MPB is androgen dependent and has a polygenic or multifactorial form of inheritance [1], hence the term, androgenetic alopecia (AA) to describe MPB. Although MPB can be passed on from either side of the family, there is a slightly higher risk through the maternal side. The typical scalp possesses between 90,000 and 140,000 terminal hair follicles, of which 84–90% are in the anagen (growing) phase. Scalp hairs in anagen grow at a rate of 0.35 mm/day, for 3–4 years. Approximately, 10% are in telogen (resting) phase, lasting 3–4 months. There is also a very short catagen (involution) phase lasting 3 weeks in 2% of scalp hairs. In humans, hair growth is asynchronous such that at any one time 50–150 hairs/day are shed as they cycle into telogen. In any area of the scalp a human needs to lose at least 50% of the hair to begin to have the appearance of hair loss. In those affected with AA there is a gradual conversion of terminal hairs (miniaturization) to fine, short, soft, hypopigmented vellus hairs. At the genetically predisposed hair follicle, free testosterone is reduced by the enzyme, 5-alpha reductase, to dihydrotestosterone (DHT). DHT then accumulates in the hair follicle and allows the chemical pathways that produce specific proteins that ultimately lead to hair follicle miniaturization and the eventual total loss of that hair. The role of androgens is less clear with FPHL. Women with FPHL, compared to men with MPB, have less androgen receptor proteins, and 5-alpha reductase enzymes but more estrogen producing aromatase enzymes [2]. This difference can help explain why women have a milder expression of AA compared to men and tend to maintain the frontal hairline.

The specific pattern of hair loss in men with MPB makes diagnosis generally easy. The individual affected

first notices an increased shedding of scalp hair with an increasing amount of vellus hairs as the process of miniaturization occurs. Norwood’s classification [3] of seven types of MPB, while not describing all common patterns of hair loss, is frequently used (Fig. 13.1).

The most common presentation for women with FPHL shows preservation of the frontal hairline with generalized thinning, but not total balding, behind the hairline. The thinning may be limited to the frontal

scalp, but in many cases, can also include the rest of the scalp, including the occipital region, which is often spared in men. Ludwig’s three grades of thinning [4] have been classically used to describe the pattern of FPHL (Fig. 13.2). More recently, Olsen [5] has described a Christmas tree pattern of thinning to the top of the scalp with frontal accentuation (Fig. 13.3) and is seen as the most common presentation affecting 70% of women with FPHL.

Fig. 13.1 Norwood classification of the common types of male pattern baldness [3]

Fig. 13.3 Christmas tree pattern of thinning showing preservation of the hairline and frontal accentuation

13.3Modern Hair Transplantation and Terminology

Traditional hair transplantation, employing circular punch grafts of 3–4 mm in diameter containing up to 25 hairs or more is largely accredited to Orentreich. In 1995, he published a paper that described the use of small autografts to treat various types of alopecias. The term, “donor dominance” was coined by Orentreich to describe how hair, taken from the permanent rim of scalp in a male with MPB, will continue to grow when transplanted to an alopecic area [6]. In the 1980s, Nordstrom and Marritt [7, 8] introduced oneto twohaired “micrografts,” cut down from larger grafts, to refine and soften the frontal hairline to take away from the “plugginess” associated with large circular punch grafts. Later, it was shown that upon close inspection

of the scalp, hairs could be seen to be emerging in bundles of one, two, three, and rarely four to five hairs surrounded by a common adventitia (Fig. 13.4). This integral bundle of hair is termed a follicular unit (FU). From this observation came the idea of removing and dissecting out FUs using magnification to allow proper visualization of FUs with the aim of keeping them intact. The advent of follicular unit transplantation (FUT) has led to the superior results now obtainable with modern hair transplantation techniques. A big advantage of FUT over traditional punch grafting, is that a natural result can be achieved even with one session on an otherwise alopecic area. Circular punch grafts were initially, “cut to size,” trimming these larger grafts into smaller ones or using parts of two adjacent punch grafts, without paying attention to keeping FUs intact. A number of confusing terms has arisen to describe the various types of grafts. Table 13.1 gives a description of some of the more commonly used terms.

Fig. 13.4 View of scalp hairs emerging in bundles. A two-haired Fu and a three-haired FU are circled