is primarily caused by aging, a change in hormones, and a family history of baldness. As a rule, the earlier hair loss begins, the more severe the baldness will become. Hair loss can also be caused by burns, other thermal injuries, trauma, and prior surgeries. In these cases hair replacement surgery is considered a reconstructive treatment, and may be covered by some health insurance policies.

If you're considering hair replacement surgery, this web page will give you a basic understanding of the variety of procedures involved. It cannot answer all of your questions, since a lot depends on your individual circumstances

What is a hair cycle?

Hair growth goes through a cycle with three identified stages - catagen (transitional phase), telogen (resting phase), and anagen (growing phase). Approximately 90% to 95% of hairs are in the anagen phase, and 5% to 10% are in the telogen phase. In the scalp, the anagen phase lasts between 2 to 6 years, catagen between 2 to 3 weeks, and telogen between 2 to 3 months.

In the anagen phase, hairs grow at a rate of about 1cm per month which slows with age. Length of hair corresponds to the amount of time in the anagen phase. This explains why hair on the head is longer than hair on other parts of the body, such as the eyebrows which only spend 30-45 days in the anagen phase.

Catagen is the period of transition between the anagen phase and the telogen phase. Less than 1% of hairs are in this 2-3 week period at any one time. Changes take place in the structure of the hair follicle and at the end of catagen, telogen phase is entered.

Telogen phase is the resting phase of the hair follicle. At the end of the telogen phase, the hair follicles will reenter anagen phase and start growing again. Approximately 5-10% of scalp hair is in the telogen phase at any one time and these follicles are randomly distributed. It is during telogen hairs that hair is normally shed. Approximately 25-100 hairs are shed each day.

What causes hair loss?

There are many different causes of hair loss all with different treatments. We will cover the more common causes below. The most common cause of hair loss, or alopecia, is often referred to as male patterned baldness. More appropriately, this condition is termed androgenic alopecia, and can effect women as well as men. 25% of men aged 25 years have some degree of clinically apparent androgenic alopecia and over 40% of men will develop androgenic alopecia at some point in their life. Androgenic alopecia results from progressive shortening of the anagen cycle with resultant decreased time for hair growth. Hair loss usually begins with the frontoparietal scalp and then the vertex. Female-pattern baldness is similar but more diffuse, without complete baldness and maintaining the anterior hairline. Fortunately hairs on the sides and back of the scalp are androgen-independent and thus do not suffer from androgenic alopecia - it is these hairs which are used for hair transplants and why hair transplants last. Androgenic alopecia is genetically determined and its development is related to age and presence of hormones and the corresponding receptors.

The second most common form of alopecia is alopecia areata. This form of hair loss results in rapid loss of hair in circular or oval patches. It may be episodic or persistent. There is no definite reason why alopecia areata develops, but there is a genetic predisposition, and popular opinion favors an autoimmune disorder. Alopecia areata only affects 0.1% of people.

Approximately 3 months after surgery, childbirth, crash dieting, other stressful events, hair can enter an extended resting cycle referred to as telogen effluvium. Usually <50% of the scalp is affected and recovery is complete once the triggering event is resolved.

A wide range of medications can cause hair loss. The most widely known are chemotherapy drugs but other more common drugs including blood thinners and Vitamin A can cause hair loss. After taking the medications, hair growth is abruptly interrupted and growing hairs are shed after 1-4 weeks. This form of hair loss rapidly affects 80-90% of the scalp but complete recovery can be expected once the medication is stopped.

Certain infections can cause hair loss. Children may have hair loss caused by a fungal infection of the scalp. The infection is easily treated with antifungal medicines. Hair loss may occur as part of an underlying disease, such as lupus or diabetes. Since hair loss may be an early sign of a disease, it is important to find the cause so that it can be treated.

Finally, tightly pulling hair can cause hair loss. People who wear pigtails or cornrows or use tight hair rollers can pull the hair and cause traction alopecia. If the pulling is stopped before scarring of the scalp develops, the hair will grow back normally. However, scarring can cause permanent hair loss. Hot oil hair treatments or chemicals used in permanents may cause inflammation (swelling) of the hair follicle, which can result in scarring and hair loss.

How is male patterned baldness (androgenic alopecia) classified?

Hamilton, an anatomist, recorded his observations of more than 300 men and graded their patterns of hair loss in 1949. Dr. O'tar Norwood, a dermatologist and distinguished hair transplant surgeon, expanded Hamilton's classification after conducting his own study of 1,000 men. The Norwood classification, published in 1975, is the most widely used classification for hair loss in men. It defines two major patterns and several less common types. In the regular Norwood pattern, two areas of hair loss - a bitemporal recession and thinning crown - gradually enlarge and coalesce until the entire front, top and crown (vertex) of the scalp are bald.

Type I: No or very minimal hairline recession along the anterior border in the frontotemporal region.

Type II: The anterior border of the hair in the frontotemporal region has symmetrc triangular areas of recession which extend no further posteriorly than 2 cm anterior to a line drawn in a coronal plane at the level of the external auditory meatus.

Type III: The triangular areas in Type II extend posterior of the coronal plane which is 2 cm anterior to the external auditory meatus. This is the minimal level considered to represent baldness.

Type III Vertex: Most of the hair loss is seen on the vertex. Frontal hair loss may be similar to Types I or II but should not exceed Type III. This type is most commonly seen with advancing age.

Type IV: Hair loss on the vertex associated with frontal loss more severe than Type III, but the frontal and vertex areas are separated by a distinct band of hair.

Type V: Greater hair loss than Type IV with only a sparse band of hair separating the frontal and vertex areas. The hair left on the occipital and parietal areas begins to form the shape of a horseshoe when viewed from above (also true for Types VI and VII).

Type VI: The frontal and vertex areas of hair loss are contiguous with greater lateral and posterior areas of denudation.

Type VII: The most severe form of male pattern baldness. Only a narrow sparse horseshoe-shaped band of hair is left extending from the ears posteriorly to the occiput.

In addition, Types II through V can also be designated with a Type A variant. The major features of the type A variant are: 1) the entire anterior hairline border recedes in unison without leaving the midfrontal peninsula of hair and 2) there is no simultaneous balding of the vertex. The two minor features are 1) scattered sparse hairs frequently persisting in the entire area of balding and 2) the horseshoe shaped fringe of hair that remains on the sides and back tends to be wider and reaches higher on the head. These variants exist only in about 3% of the population studies.

Type IIA: The hairline is anterior to the coronal plane 2 cm anterior to the external auditory meatus.

Type IIIA: The hairline has receded back to a point between the limit of Type IIA and the level of the external auditory meatus.

Type IVA: The hairline has receded beyond the external auditory meatus but has not reached the vertex.

Type VA: The area of denudation includes the vertex. Hair loss more severe than Type VA cannot be distinguished from Types VI or VII.

Are medicines available for hair loss?

Topical minoxidil (Rogaine) and oral finasteride (Propecia) are the only treatments for male patterned baldness that have been approved by the US FDA. Their use is indicated

in men older than 18 years with mild to moderate hair loss. Several well controlled studies have proven the efficacy of these medications. After 3-6 months of use, slowed hair loss, stabilization, or increased scalp coverage can be appreciated with either medication and results are clearly evident by 1 year. Dense regrowth is uncommon and neither medication can regrow hair in completely bald areas. Early intervention, when thinning is first noticed and hairs are incompletely miniaturized, produces the best results. Treatment must be continued indefinitely to maintain the benefits. Stopping treatment results in a return to pretreatment status by 6 months with minoxidil and by 12 months with finasteride.

For female pattern baldness, 2% topical minoxidil is the only FDA-approved medication. Its use is indicated in women older than 18 years with mild to moderate hair loss. Women who are pregnant or nursing should not use minoxidil.

The Best Candidates For

Hair replacement surgery can enhance your appearance and your self-confidence, but the results won't necessarily match your ideal. Before you decide to have surgery, think carefully about your expectations and discuss them with your surgeon.

It's important to understand that all hair replacement techniques use your existing hair. The goal of surgery is to find the most efficient uses for existing hair and consulting a , visit hair loss expert Dr. Verret on the web.