Hair Graft Transplantation for Baldness

Introduction

Hair loss occurs in more than 60% of men and in approximately 10% of women. Although a lack of scalp hair can potentially increase the risk of actinic damage and skin cancer, male and female pattern baldness are conditions that are, with few exceptions, treated electively.

Balding is a major concern for many, and surgery to treat hair loss (ie, hair transplantation) is the most common cosmetic surgery procedure performed on men today. Yet, the market for hair transplantation is dwarfed by the immense market for products that treat hair loss without surgery. These products, which include shampoos, hair-care cosmetics, scalp massagers, laser combs, and many more, have no proven efficacy except for their ability to temporarily increase the volume of existing hair, resulting in a denser appearance than before. Exceptions are the 2 medications the US Food and Drug Administration (FDA) approved: minoxidil (Rogaine, available over the counter in the United States) and finasteride (Propecia, available by prescription only for men), which have limited but definite benefit.

Interest in hair transplantation will probably increase as knowledge that most modern hair-transplantation techniques can create virtually undetectable restoration spreads. To this day, hair transplantation remains the treatment of choice for most patients with hair loss.
History of the Procedure

In the 1950s, surgeons such as Orentreich, Stough, Ayres, and Rabineau pioneered the earliest hair-transplant procedures. Although these early procedures resulted in hair growth on bald scalps, they were characterized by obvious pluglike appearances. However, the early experiences formed the foundation for hair transplant procedures, that is, the donor dominance of hair-bearing scalp to grow hair after it is transplanted into another part of the scalp (or body) as an autograft.

The doll's-hair, or pluglike, appearance was the result of using grafts typically 4 mm in diameter. These plugs contained 15-20 hairs and were usually harvested with a circular punch, then transplanted into 4-mm circular recipient sites in the bald scalp. Once transplanted, hairs entered a 4-month dormant cycle (telogen), after which they began continued growth for as long as donor site hair grew. Scalp areas that contain hairs genetically programmed for permanence (ie, those on the sides and lower back portion of the head) were (and still are) donor areas.

From the 1950s until the early 1990s, plug-graft transplantation was, with few exceptions, the most common hair-transplant procedure. Small grafts, created by halving or quartering the formerly standard 4-mm plug grafts became popular in the early 1980s. Over the last 15 years, developments in hair transplantation have followed this evolution toward smaller grafts to mimic the way hair grows naturally on the scalp.

Until the last several years, with the popularization and further development of microscopic follicular-unit grafting, state-of-the-art hair transplantation involved transplanting a combination of minigrafts and micrografts. These 2 terms are open to definition, but a typical micrograft contains 1-2 hairs, whereas a minigraft contains 3-6 hairs. Combining these different-sized grafts by placing the micrografts along the hairline and the minigrafts further behind gives the surgeon a tool that potentially makes a hair transplant difficult to detect. Artistry, individualization of the specific procedure to the patient, and other variations in technique are of critical importance.

Today, using the state-of-the-art procedure of follicular-unit grafting and guided by sound aesthetic judgment, surgeons can achieve virtually undetectable hair restoration.
Problem

Some say, "A bad hair day is better than a no hair day." For millions of individuals, hair loss is a major problem associated with loss of self-esteem, insecurity, and even depression. Hair loss can range from early thinning or hairline recession to complete loss of hair along the top and upper sides of the head.

A full head of hair contains approximately 100,000 hairs. (People with red or blonde hair have somewhat more than this.) The loss of up to 30% of the number that was present during the peak of adolescence that occurs by middle age is part of the normal aging process. For thinning to become cosmetically noticeable, at least 50% of the hairs must have fallen out in a particular area. Loss of a smaller percentage than this generally does not result in the cosmetic appearance of hair loss. In addition to the loss of the number of hairs, the hair loss process causes individual hairs to thin, which further contributes to the appearance of hair loss.

The Norwood Classification System recognizes and categorizes the typical sequence of the hair loss process in men.1 Early in the process (types 1-3), the hairline recedes, typically led by frontotemporal recessions. In the latter stages (types 4-7), progression of hair loss at the vertex (crown) gradually meets and joins the progressive hairline recession, resulting in varying sizes (in both coronal and sagittal dimensions) of the confluent vertex with frontotemporal regions of baldness.

For women, the development of androgenic alopecia is classified into 3 stages. The typical pattern of hair loss in women is progressive diffuse thinning in an oval area along the top of the scalp. Hair loss along the hairline is usually spared.
Frequency

The incidence of hair loss in men approaches 60% by the age of 60 years. In women, this incidence is considerably lower, that is, approximately 10% at a similar age.

Among racial groups, whites have the highest incidence of hair loss, African Americans have lowest incidence, and Asians have an incidence between the two.
Etiology

Hair loss in men almost always is due to androgenic pattern baldness, which is usually referred to as male pattern baldness (MPB). Although the exact cause of pattern balding is unclear, the trait is transmitted by means of a polygenic type of inheritance. Anecdotal reports indicate a stronger link to men on the maternal side of the family than on the paternal side. MPB is a progressive process that continues for the rest of an individual's lifetime. The eventual degree of hair loss is typically more advanced with a younger age of onset.

In women, most hair loss is also genetic, though women have an increased incidence of hair loss caused by medical conditions, such as hormonal imbalance, trichotillomania, and poststress telogen effluvium. As with MPB, female-pattern androgenic hair loss is progressive.
Pathophysiology

In men, pattern baldness has been established as an androgen-mediated miniaturization process of genetically susceptible hair follicles. Women with pattern baldness are presumed to undergo the same process.

Pattern baldness requires linking of the hormone dihydrotestosterone (DHT) to susceptible hair follicles. In the body, DHT is created when the enzyme 5-alpha reductase converts testosterone. This conversion takes place in the bloodstream and locally in the scalp and other body tissues. DHT acts on genetically susceptible hair follicles to cause miniaturization of the hair, which eventually leads to follicle death.
Presentation

MPB follows a classic pattern that is best illustrated by using the Norwood Classification System, which ranges from type 1 (minimal frontotemporal recession) to type 7 (loss of all but a small rim of hair).1 Types 2-6 categorize the typical progression of hair loss.

The clinical presentation in women differs somewhat from that of men. In women, hair loss along the hairline is typically spared, with thinning throughout the top and upper sides of the head is more diffuse in women than in men.

In the author's office, preoperative screening consists of a health-history questionnaire that includes questions about easy bruising, anesthesia problems, allergies, mitral valve prolapse or other conditions necessitating preoperative antibiotics, and all current medications (including herbal remedies). Study results have confirmed the superiority of good history taking and physical examination compared with any blood screening test for determining a patient's medical suitability for surgery.
Indications

Nearly all men and most women who have androgenic or inherited pattern baldness can be treated with hair transplantation. As in all other elective cosmetic surgeries, the most important patient selection criterion in hair transplantation is the individual's motivation. Results of hair transplantation are usually most dramatic when the procedure is performed on individuals with advanced degrees of hair loss. In general, the greater degree of hair loss, the larger number of grafts transplanted.

Hair transplantation may not be the most effective therapy for some medical causes of hair loss; in some instances, it exacerbates the condition. Therefore, workup to rule out other treatable causes of hair loss is important, especially in women, in whom nongenetic etiologies for the hair loss are more common than in men.

In addition to MPB and female pattern baldness, a variety of conditions can be successfully treated with hair transplantation. Scarring of the scalp due to trauma or surgery and hair loss due to traction (seen with extended wearing of hair pieces or trichotillomania) can be repaired with hair transplantation. Finally, hair transplantation can be successfully used to restore hair to the eyebrows; eyelashes; beard, mustache, or goatee area; and even to areas of the body, such as the pubis or chest.
Relevant Anatomy
The scalp is divided into 5 layers, which are easily remembered by the mnemonic SCALP, which represents, in order from outermost to innermost layer, the skin, connective subcutaneous tissue, galea aponeurosis, loose connective tissue, and periosteum over the cranium.

The skin contains all the epidermal appendages, including hair follicles, which extend into the connective subcutaneous layer. In areas that have undergone hair loss, thinning of the outer 2 layers usually occurs. This situation can be appreciated when one compares the thickness of the scalp in recipient areas to that in donor areas.

The subcutaneous layer is well vascularized and contains the main penetrating branches of the named main arteries that travel primarily along the external surface of the galea. The importance of staying superficial along the connective subcutaneous tissue layer (when one makes slit recipient sites to avoid compromising circulation) has only recently become apparent. The scalp has an excellent blood supply. The supraorbital, supratrochlear, superficial temporal, postauricular, and occipital arteries are the primary vessels, and they typically travel with the veins.

The galea aponeurotica is a nonelastic layer that connects the frontalis muscles anteriorly with the occipitalis muscle at its posterior aspect. The temporoparietal fascia, in which the superficial temporal artery travels, is also connected to the galea. The galea sliding over the loose connective tissue layer allows for most scalp mobility. This loose connective tissue layer and the periosteum below have minimal sensory innervation.

The sensory innervation of the scalp closely follows the vascular supply. At the anterior aspect, the supraorbital and supratrochlear nerves provide sensation to the anterior half of the scalp. On occasion, sensation to the frontal scalp can diminish for several weeks when a large number of graft recipient sites are made along the hairline. The occipital nerve serves the posterior half of the scalp, whereas the supraauricular and superficial temporal nerves contribute innervation from the sides.

Perhaps no anatomic feature of the scalp is more important with regard to hair transplantation than the microscopic distribution of hair. Scalp hairs usually do not grow individually; they most often grow in tiny follicular-unit bundles, which usually contain 2-3 hairs and occasionally 1 or 4 hairs. A follicular-unit contains these 1-4 terminal hairs, a sebaceous gland element, and insertions of the arrector pili muscles, all wrapped in an adventitial tissue sheath. These follicular units are dispersed throughout the scalp, where non–hair-bearing skin constitutes up to 50% of the total tissue. By transplanting only these follicular units and dissecting away the 50% of unnecessary non–hair-bearing tissue, the most natural-appearing results can be attained.
Contraindications

Perhaps the most difficult part of being a surgeon is knowing when not to operate. In elective cosmetic surgery, sound judgment must certainly be exercised.

Individuals must be motivated to undergo hair transplantation. Although the author does not conduct a formal psychological evaluation by means of lengthy questionnaires and examinations, some surgeons use this method. During the consultation, the present author generally reads to the individual to ensure that he or she is mature enough to decide to undergo the planned procedure. A prospective patient who has realistic motivations and expectations before the procedure is likely to be happy after the procedure. Honest and thorough preprocedural consultation is perhaps the most important part of the process.

Poor medical health is a potential contraindication for elective surgery of any kind. Individuals cannot be taking anticoagulants (eg, Coumadin, aspirin) before the procedure. Good surgical judgment must be exercised when one considers surgery in individuals with potentially complicating medical conditions. Age is not a medical contraindication. The author has performed procedures on men in their late 70s. Ensure that such patients provide medical clearance from their internist.

Perhaps no single hair-loss condition calls for more conservatism in judgment than premature MPB. Teenagers and men in their early 20s are particularly self-conscious about hair loss because most of their peers still have full heads of hair. These young men often hold unrealistic expectations, desiring a youthful hairline that will not be appropriate as they age. Worse, early surgical correction uses a large number of donor hairs, which will be sparse in the future, potentially resulting in an unnatural look and a disappointed patient.

In general, attempt to delay the procedure in individuals in their 20s or younger, though the author has performed procedures in select individuals as young as 20 years. When counseling young men about hair loss, the author advises a conservative approach to give patients time to consider hair transplantation. If the patient and surgeon agree on transplantation, restore a relatively high hairline and instruct the patient to use minoxidil for the crown region. Perhaps in the future, as effective medical therapies that end or substantially slow MPB progression become available, a less conservative approach can be taken.

For a number of medical conditions that are associated with or that can cause hair loss, treatment with hair transplantation is not appropriate. Examples are the active phases of alopecia areata, lupus, and infections. Scalp conditions, such as vitiligo and psoriasis, must be evaluated because hair transplantation can aggravate them.


http://emedicine.medscape.com/article/839753-overview