Racial and Ethnic Differences in Hair Follicles and How They Affect Hair Transplants
In measuring densities in over 5,000 patients, we have observed the average donor area to have approximately 1 follicular unit/mm2. Although the donor densities of our balding patients may not be representative of the general population, this number is extremely helpful in making clinical judgments with regard to our surgery. It is interesting that similar density measurements were obtained histologically by Headington. In addition, we find that each follicular unit contains, on the average, 2 hairs, yielding a density of 2 hairs/mm2.
These numbers, however, actually refers to the average Caucasian patient. We find that follicular characteristics, in fact, vary significantly between the different races. The following table compares some easily measurable aspects of the follicular unit in three different races.
The genetic differences in the follicular unit may have adaptive value. It is possible that in Africans, the low density in high follicular groups with darkly pigmented hair enhances photoprotection and minimizes heating of the skin. The curly hair, in tight groups of three, may act like scaffolding that holds the hair off the surface of the scalp (to cool it) and in a tight meshwork (that blocks the sun).
We transplant Asian hair in much the same manner as Caucasian hair, except that in Asians with coarse, straight hair and light skin, it is critical to use a larger percentage of single hair follicular units in the transition zone. Because of the heavy weight of each individual hair, more “bulk” may be achieved in the front part of the scalp, but placing too many units in the anterior portion may limit coverage in other areas, due to the inherently low donor density.
With African hair, modifications must be made in the dissection of the implants in order not to damage the follicular units, which tend to be larger and curved. Slightly larger recipient sites must be created to accommodate the larger implants, and they must be spaced further apart. The very low follicular density would appear to severely limit the success of the transplant, but in fact, the three haired units produce “kinky” hair that more than compensates for the low numbers of groups, and enables patients with this hair type to achieve among the best cosmetic results.
Skin and hair color contrast among the different races also greatly impacts the surgery. For persons of Scandinavian descent, with blonde hair and light skin color, the illusion of more fullness may be achieved even though the hair might be very fine in diameter. The fine diameter hair also permits larger follicular units to be placed further forward in the transition zone. An “Afro” hair style on a black haired person with very dark skin will give the appearance of greater fullness, as the dark skin color fills in any gaps between the hair. This is in contrast to an Asian?s black, straight hair which often overlies light skin and appears less dense due to the light color showing through.
Hairline design should also be tailored to the specific racial backgrounds of the patient. In certain families of southern Asia and those of Middle Eastern descent, the hairline tends to be flatter than the hairline of Northern European individuals. These patients often bald in a diffuse pattern, with a juvenile hairline that persists well into middle age. This poses significant problems in selecting a restoration plan which meets both the short and long-term goals of the patient. There are so many other racial and ethnic elements that affect the aesthetics of coverage, the surgeon should have great familiarity with the normal hair patterns and characteristics specific to each group before attempting the transplant.
In hair restoration surgery the physician?s goal should always be directed toward finding ways to most accurately mimic nature. The more one?s own interpretation deviates from the template set by nature, the less natural the results will be. It is hoped by these authors that as a result of this writing, many of the “aesthetic judgments” described above will be viewed as logical solutions to the supply/demand dilemma that all of us face when trying to restore a person?s hair.
Robert M. Bernstein, MD, F.A.A.D.
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