Chapter 108: Hair Transplantation

Although counterintuitive, there is the same number of hair follicles histologically in a bald scalp as there are in a normal hair-bearing scalp. The difference is that the follicles do not remain in the normal growth cycle within the bald scalp. Scalp hair originates from both ectodermal and mesodermal origins as do hairs on the rest of the body. A normal scalp contains around 100,000 to 150,000 individual hairs. A follicular unit typically contains two hairs; so, there are usually around 50,000 to 75,000 follicular units. It also contains the associated sebaceous glands, the insertions of the erector pili muscles, and the perifollicular nerve and vessel supply. The follicular unit is relevant to hair transplant, as single or multiple units are grafted during this process. Single follicular units containing one or two hairs are termed “micrografts” and those containing more hairs are termed “minigrafts.” The total number of scalp hairs is influenced by natural hair color, with blondes having more hairs and redheads having fewer hairs.1,2

2. Barrera A. Hair Transplantation. The Art of Micrografting and Minigrafting. St Louis, MO: Quality Medical Publishing; The process of hair growth has three, not four, phases: anagen, catagen, and telogen. The anagen phase is the active growth phase, and 90% of hairs are usually produced in this phase. It is the longest phase, lasting about 3 years in men and 5 to 8 years in women. The catagen phase (degradation phase) is the shortest, at 2 or 3 weeks, and prepares hairs for shedding by separation of the base from the dermal papilla. The telogen phase is the resting phase and lasts 3 to 4 months. Approximately 10% of hair is in this phase, and within it, 50 to 100 hairs are lost daily. Concurrent shortening of the anagen phase and lengthening of the telogen phase result in hair thinning and the subsequent development of baldness.1,2

There is a difference in the incidence of alopecia across races, although the mechanism of male pattern baldness remains the same in all groups. Whites are most commonly affected, followed by Asians and blacks. The lowest incidence is seen in American Indians. The reason for these apparent racial differences is not known and may reflect both genetic and environmental factors. In the United States, around 35,000,000 men and 21,000,000 women are affected by scalp hair loss. Onset typically commences in the third and fourth decades, with half of patients affected by the age of 50 years.1–4

4. Gan DC, Sinclair RD. Prevalence of male and female pattern hair loss in Maryborough. J Investig Dermatol Symp Proc 2005;10(3):184–189 Male pattern baldness that occurs at such a young age tends to be more severe in terms of extent and speed of hair loss. Male pattern baldness can be inherited in an X-linked autosomal dominant fashion, therefore coming from the maternal grandfather. Therefore, it is no coincidence that the patient’s grandfather is also affected. Not all cases will be inherited this way, however, as there is evidence for several non–X-linked autosomal dominant (variable penetrance) routes of inheritance. The mechanism of hair loss in male pattern baldness is thought to be due to the effects of dihydroxytestosterone (DHT) on the growth cycle of scalp hair follicles. However, it is not necessarily an excess of DHT that is responsible. A normal DHT can cause alopecia if the hair follicles are abnormally sensitive to its effects. Likewise, testosterone levels do not need to be elevated to cause androgenic alopecia. Testosterone is normally converted to DHT by the enzyme 5-alpha reductase which is found within the cells of susceptible hair follicles and skin. Therefore, an excess of any of these substances can be responsible for the effects observed in androgenic alopecia, and it is most likely that this patient has both normal testosterone and DHT levels. Treatment with 5-alpha reductase inhibitors, but not 5-alpha reductase itself, may be helpful in some cases to reduce the amount of DHT.1–3

The Norwood classification1 is very commonly used and describes the anatomic location and extent of male pattern baldness. It has seven subtypes (I–VII) ranging from mild to severe. It is difficult and unnecessary to memorize the precise details of the classification for daily practice. However, the underlying principles and extremes are worth knowing because male pattern baldness tends to follow relatively predictable patterns in terms of anatomic areas affected. It typically begins affecting only the hairline and frontotemporal areas (type I) and progressively affects the frontotemporal regions and the vertex. Type VII is the most extreme, affecting the hairline, vertex, and frontotemporal areas. Some patients first present with vertex baldness only. Within this classification, there is no subtype for either a normal scalp and hairline or complete baldness. The physiologic causes, age of onset, treatment, and outcomes are not part of this classification system either (Fig. 108.1).1,2 Type I Type II Type III Type III (vertex) Type IV Type V Type VI Type VII Fig. 108.1 Norwood male classification of alopecia.

Alopecia areata is an autoimmune condition in which hair is randomly lost from small areas of the body, particularly the scalp. It is an inherited condition that can present at any age. It can affect the entire scalp in more extreme cases (alopecia totalis) or even the entire body (alopecia universalis).1 If this patient was a few years older and had a history of progressive hair loss to the vertex and frontotemporal areas rather than a single patch, then a diagnosis of androgenic alopecia would be more likely, particularly if he was generally fit and well and had siblings with the same condition. Androgenic alopecia involves the conversion of healthy, thick terminal hairs to clear, microscopic vellus hairs. If the patient had learning difficulties with mental illness and had presented with itchiness of the scalp and recent-onset patchy baldness without signs of head lice or inflammation, then a diagnosis of traumatic alopecia could be considered, especially if examination showed evidence of broken hairs in the scalp. In this scenario, patients sustain traumatic alopecia as a result of self-harm by pulling out sections of hair. This condition is more specifically called trichotillomania, and affected individuals feel compelled to pull their hair. Cicatricial alopecia refers to a diverse range of conditions that destroy the hair follicle and replace them with scarring. This normally results in permanent hair loss. Lichen planopilaris refers to hair loss in patients with the inflammatory condition called Lichen planus that progresses to affect the scalp.1–3

Finasteride is a 5-alpha-reductase inhibitor that has been used to treat benign prostatic hypertrophy and male pattern baldness. It is an oral (not topical) medication taken once daily in 1-mg doses. It is most effective on the vertex and frontal region in male pattern baldness and less effective in the temporal region. Side effects are uncommon. The major caveat is that it must be used indefinitely to maintain a response. Topical solutions of 2 and 5% minoxidil are also used as treatment for baldness. Minoxidil is an antihypertensive medication that causes vasodilation that can also stimulate hair growth. Minoxidil may be useful in both men and women, but at present there is no strong evidence to show a measurable improvement in female hair loss with finasteride. This must also be used indefinitely to maintain a response.1,2

inducing hair growth. Laser therapy has been promoted as a preventative measure against androgenic alopecia. It is believed that it can help thicken hair and induce growth of existing follicles. Common lasers used for managing alopecia are within the red/infrared spectrum and have wavelengths of between 600 and 900 nm. The mechanism of action of the lasers is not well understood. Theories include provision of an increased blood supply, direct stimulation of hair follicles, an increased and more productive anagen phase, and decreased local DHT levels. The Food and Drug Administration (FDA) has approved the use of laser for hair loss, but this is based on safety rather than efficacy. Large placebo-controlled trials are lacking. Some smaller studies have shown a benefit of laser on hair growth as have some systematic reviews of case reports, case series, cohort studies and randomized controlled trials (RCTs).1,2 One meta-analysis containing three RCTs showed that laser treatment promoted hair density in androgenic alopecia.2 Laser was originally found to be effective in treating hair loss when used on laboratory mice to initiate skin cancer using a 694-nm ruby laser; hence, its discovery as a modality of treating hair loss was purely accidental rather than a planned deduction.3

The average number of scalp hairs per unit centimeter is 200. This equates to around 100,000 to 150,000 total hairs. A good visual result can be achieved with a density of around 50 hairs per unit centimeter. This equates to around 25 follicular units per unit centimeter. To treat large areas of hair loss, a few thousand grafts may be required to achieve the required hair density and this is one of the main reasons why the procedure is so time consuming to perform.1

In general, the most popular site for hair harvest is the occipital region. This is commonly used because the donor follicles have decreased or absent DHT and are therefore not influenced by hormonal factors usually associated with hair loss. In addition, providing that the hair is kept above a certain length, the donor scar can be well hidden in this area. The precise level of harvest from the occiput will vary according to age and extent of alopecia. In younger patients such as this man, the donor site is at the junction of the middle and caudal thirds of the vertical distance between the posterior upper healthy fringe and lower hairline (Fig. 108.2). Posterior fringe Donor area for mature patient Lower hairline 50% 50% A B Posterior fringe Donor area for younger patient Lower hairline 33% 33% 33% Fig. 108.2 Donor-site locations. In older patients, the harvest site is placed higher at the midpoint of the healthy fringe and lower hairline. In this patient, who already has frontotemporal hollowing, temple grafts should be avoided. The vertex and parietal regions are not common donor-site areas.1-4

There are a number of ways to harvest hair for hair transplantation and the factors that must be considered include speed of harvest, risk of damage to follicular units, and donor-site scarring. Traditional harvest techniques involve taking a strip of hair (strip excision) with a standard scalpel as a full-thickness graft and then splitting this into smaller mini- and micrografts for transfer. Triple-blade and quadruple-blade knives have been developed so that 2-mm parallel incisions can be made more quickly and accurately to harvest thinner strips of hair-bearing skin. A laser can be used to harvest the skin as an alternative to a blade but appears to offer no advantages. Because of the problems with donor-site scarring, the technique of follicular unit extraction has been developed. This is a technique that involves harvesting single follicular units individually using a small diameter punch (<1 mm diameter). The advantage of this technique is that linear harvest scars are avoided and instead the harvested areas heal by secondary intention with no visible scarring. The limitations of the technique are that it is blind; so, it risks inadvertent transection of the follicle, it is slow, and it is technically demanding. It may be best suited to treatment of smaller areas in patients who are keen to wear their hair short. It is, however, gaining popularity as powered surgeon/ technician handpieces are becoming available and also an automated robot has been developed for this process.1–4

To achieve a natural look after hair transplant surgery, the hairline must be re-created carefully and the grafts should be placed in different formations. The angle of orientation is critical to get right and this varies according to anatomic location. At the anterior hairline, angles of 45 to 60 degrees should be used for hair placement. Posterior to the hairline, the angles should be increased to 75 or 80 degrees. In general, the hairs should be placed to reflect the direction of hair growth if they are to look natural (Fig. 108.3). The anterior hairline should start 7 to 9 cm above the glabella (not 5 cm) and the lateral extent should be in line with the lateral canthus. Grafts can be micro (containing one or two hairs) or mini (containing three to eight hairs). Ideally, a combination of these should be used. Grafts may be placed into small slits or holes. Placing smaller grafts in slits is a good approach, as this is simple and preserves adjacent hair follicles. However, slits do not allow larger grafts to spread out and may give a tufted or “dolls head” appearance. In this instance, it may be preferable to place these in holes instead of slits. In general, a mixture of micrografts and minigrafts should be used. For example, at the anterior hairline, finer grafts are placed first with larger grafts behind them. A combination of slits and holes is probably best to obtain a natural result.1–5

Following a hair transplant, it is important to wash the hair early, but this must be done with a pouring technique using a light mix of shampoo with warm water and no scalp massage, which may risk inadvertent removal of the grafts. Normal hair washing can be resumed after 2 weeks once the grafts have taken. The head is typically wrapped in a turban with a nonstick base layer such as Telfa. Hair transplant is performed as an outpatient procedure without an overnight stay, but it takes a significant length of time to perform; so, it is important to ensure that patients are well hydrated and fed before discharge. They should be accompanied home by a friend or family member. A follow-up appointment should be made for 1 week. There is no reason for patients to have a 2-week course of antibiotics after this surgery.1–4