Hair Color, Wave & Scalp Depth

It is also important to note that as the contrast between hair and skin color increases, the more visual impact each hair will have. In areas in which there will be fewer hairs, such as the hairline, the visual impact of each individual hair will have a greater potential to detract from the illusion of both density and naturalness. This contrast becomes more marked as the calculated density increases or as the hair shaft diameter increases. Therefore, one might strongly consider "cherry-picking" more finely textured single hairs for the hairline and fractionating FU (to reduce the average number of hairs per graft immediately posterior to the single hairs) especially when the patient has high contrast, high-calculated density, and greater hair shaft diameter.

As a patient ages, the hair often begins to lose its pigment. This is because tyrosinase activity decreases in the follicular melanocytes. As this metamorphosis occurs the contrast between the hair and skin changes. This can work in favor of the individual with prior high contrast, but slightly against the individual who previously benefited from his darker skin.

As noted earlier, there is a wide variation in scalp hair color in any single individual. There also may be variations in hue depending on whether the hair is medullated or not. The absence of pigment or "white" hair is particularly important to the graft production phase of the transplant. "White" hairs reflect or transmit all light waves and have no color. It is difficult to see a white hair in the yellow adipose tissue and technically much more difficult to dissect them into grafts. The risk to these white hairs increases as the size of the graft decreases. Grey hairs, on the other hand, although not particularly common, have color and are easily seen against the yellow adipose background.

Scalp hairs typically begin to lose their pigmentation first in the temporal areas. Individuals with predominantly white hair also often retain a larger percentage of pigmented hairs in the occipital region. This has significance because it is technically easier to dissect small grafts such as FU and single hair grafts, when hair pigment is present. Because harvests from the temporal areas in individuals with predominately white hair, will often contain a greater percentage of white hair, the graft production phase can be technically more challenging from this harvest if one is only using FU. Keene has recently suggested immersing donor tissue containing white hair in a .2% methylene blue solution before preparing grafts.* The methylene blue stains the follicles and surrounding tissue to different degrees and allows for far visualization of the FU. Unfortunately, this technique only works well with "slivers" of donor tissue that are one FU wide, so it is not helpful with the initial "slivering" One must be careful of employing blue stains because blue stain applied to yellow tissue has the potential to absorb all wave lengths of light resulting in black. Although methylene blue has been used previously in vivo, all stains have potential toxic effects to the stained hairs and the patient, not to mention significant hurdles achieving FDA approval. More recently Cole has described a technique using monochromatic wavelengths of light, refraction, and color subtraction to create contrast between white hairs and the surrounding tissue. (See Chapter 11). It is, however, a step in the right direction. However, harvests from the temporal area as well as the occipital region, results in a nice mixture of future hair color for the frontal recipient region.* Harvests limited to the occipital region might result in cosmetically inappropriate amounts of darker hair in the recipient area at a point when the majority of the adjacent temporal hairs are grey or white. A harvest from both the occipital region and the temporal area produce a potentially more natural mix of hair color in the frontal areas as the patient ages.

WAVE OR HAIR "BODY"

It is possible to clarify these principals in a graph form (Fig. 13#). One can see the equation for a straight-line y = mx, results in much less surface area coverage than the equation for a curly hair, which becomes more sinusoidal ({such as y = sin t (wavy hair) or y = 2 sin t + cos 2t (kinky hair))}. To more clearly understand these concepts, add additional straight lines to the graph of straight hairs and additional sinusoidal lines to the graph of curly hair or kinky hair. The addition of these lines corresponding to the equation of curly and kinky hair with varying points of origin, results in considerably more coverage of the surface of the paper than a similar number of straight lines with varied points of origin. Or merely consider the amount of shaded surface on the chart, which is covered by the corresponding lines.

This chart is at the end of the chapter

SCALP DEPTH