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Avoiding Pitfalls in Planning a Hair Transplant (part 2)

Patient Assessment

Donor Supply

In performing a hair transplant, the physician must balance the patient?s present and future needs for hair with the present and future availability of the donor supply.  It is well known that one?s balding pattern progresses over time. What is less appreciated is that the donor zone may change as well.   

The patient?s donor supply depends upon a number of factors including the physical dimensions of the permanent zone, scalp laxity, donor density, hair characteristics, and most importantly, the degree of miniaturization in the donor area – since this is a window into the future stability of the donor supply.

The size of the donor area is determined by both its width (height) and its length.  When assessing the potential width of the donor area, doctors usually assess the lowermost point that the balding will reach, i.e. the top part of the permanent zone.  However, it is equally important to pay attention to the inferior margin as well.  It is common for the hair to thin significantly at the nape of the neck as a person ages, producing an “ascending hairline.”  Since this can significantly diminish the width of the donor area, any evidence that this process may occur should be taken into account in the planning.  Loss of the temporal points is another process that has a significant impact on the donor supply. Not only does it foreshorten the potential length of the donor strip but it often portends very significant baldness.   

Scalp laxity is another variable that affects the amount of available donor hair.  Very tight scalps significantly limit the amount of donor hair that can be removed through strip harvesting.  The constraint imposed by a tight scalp is not always apparent in the first session, but can plague the hair restoration down the line; therefore, it should be evaluated carefully in the initial patient assessment. A very loose scalp can present its own set of problems, as patients with very loose scalps often heal with widened donor scars. [18]   

The average donor density of a Caucasian is about 225 hairs/cm2. This can easily be measured using a hand-held instrument called a densitometer. (2) When the density of a Caucasian is below 180, a hair transplant should be undertaken with great caution. In this author?s opinion, when the maximum donor density is below 150/hair mm2, a person should generally not be transplanted, as there will not be enough donor hair to make the procedure cosmetically worthwhile and the risk of a visible donor scar is too great. (3) Exceptions would be an older person with very limited expectations and in races where the normal density is lower (i.e. Asians and Africans). 

Hair characteristics, particularly hair shaft diameter, are as important as the absolute number of hairs in determining the outcome of a procedure.  The amount of transplantable hair is related to both the number of movable hairs (determined by the size of the donor area, scalp laxity and donor density), multiplied by the hair shaft cross sectional area.  Since each hair in a person with coarse hair can have over 5 times the volume as a person with fine hair, the estimate (or actual measurement) of hair shaft diameter is important in determining the overall donor supply.  

Miniaturization, the progressive diminution of hair shaft diameter and length (the result of the action of DHT on the hair follicle) produces thinning on the front, top and crown of the scalp and is the hallmark of androgenetic alopecia.  But the back and sides of the scalp can miniaturize as well and when a significant portion of a patient?s donor area is miniaturized, the hair in this area can be rendered useless for a hair transplant. (Figures 1 and 2)

This condition, called diffuse unpatterned hair loss (or DUPA), is the most common type of hair loss seen in women and it is not uncommon in men.  It goes without saying, that every patient, male or female, in whom a transplant is being considered, should be evaluated for donor miniaturization using densitometry to make sure that the donor hair to be transplanted is stable. 

Recipient Demand

One should never assume that a person?s hair loss is stable. Hair loss tends to progress over time.  Even patients who show a good response to finasteride will eventually lose more hair.  It is always best to consider the reasonable worst-case scenario when assessing how bald the patient may become, so that the finite donor hair can be allocated properly. Although the Norwood classification is very helpful in staging the hair loss, it doesn?t take into account actual scalp dimensions. Just like the donor site, the recipient area should actually be measured.  Even within a single Norwood class, there is a vast difference between a patient with a narrow forehead and one with a very broad head with respect to the actual surface that needs to be covered, and thus the number of grafts required for the restoration. 

Designing the Hairline 

Hairline Position

In the adolescent, the hairline sits just above the upper brow crease formed by the upper border of the frontalis muscle directly below it.  The position of the normal adult male hairline is approximately 1.5cm above this crease at the midline). A common error is to place the newly transplanted hairline at the adolescent position, rather than one appropriate for an adult. Although the younger patient, first experiencing hair loss, may put considerable pressure on the doctor to place hair in the lower position, the physician should not yield to this demand. 

Under normal circumstances, as a patient ages, his density decreases and the natural hairline will move back somewhat.  However, a transplanted hairline is immutable. Therefore, when the transplanted patient continues to thin or bald (which he invariable will) the fixed low frontal hairline will begin to look out of place, since it is natural for a person with decreased overall hair volume to have a slightly receded hairline, rather than one that is still in the adolescent position. 

Hairline Shape

A similar logic applies when choosing the shape of the hairline.  As a male passes from adolescence to adulthood, his broad, flat hairline evolves into a more tapered shape with some recession at the temples.  A persistent low, broad hairline is enjoyed by those who also maintain their adolescent density. This situation is not present in those who are suffering from androgenetic alopeica; therefore, a transplanted flat hairline will not “age well” over time and will look unnatural as the patient?s overall density decreases and particularly as the crown begins to thin. 

If a person is older, has maintained a high donor density, and has a small risk of extensive hair loss, a broader hairline is possible.  However, this is not this case for the person who is starting to bald at a young age, since he has a significant risk of extensive baldness and, more importantly, the extent of his future hair loss can not be known at the time the surgery is planned. 

Graft Distribution

The nuances of graft distribution and the multitude of problems that result from distributing grafts improperly are beyond the scope of this writing; however, there are two main but related themes that the hair transplant surgeon should be cognizant of when deciding where to place grafts. The first is to set a target area of coverage that takes into account the patient?s future balding pattern, as well as, his total donor hair supply.  The second is to forward weight the grafts, rather than distributing them evenly over the top of the scalp.

Extent of Coverage

The problem of deciding how much bald scalp a hair transplant should cover can be illustrated as follows.  As an example, take a patient whose total number of follicular unit grafts available to harvest is around 5,500.  The front part of the scalp has a surface area of about 50 cm2.  The top or mid-scalp has an area of about 150 cm2 and the vertex or crown about 175 cm2. However, the size of the bald crown can vary dramatically depending upon the extent of hair loss, reaching over 200cm2 in a Norwood Class VII patient. 

If the front and top of the scalp were transplanted using all of the patients donor hair, the transplanted density would be only 5,500grafts/200cm2 or 27.5 grafts/cm2 (less than 1/3 the density of the patient?s original hair). If the crown were covered as well, that would be 5,500 grafts/400cm2 or 12.5 grafts/cm2 (only 15% the density of the patient?s original hair).  Using various manipulations, such as creating different densities in different parts of the scalp, a skilled surgeon can make 1/3 of the overall density look like a substantial amount of hair. However, working with only 15% of the original density, can make the job of creating a natural look significantly more difficult, if not impossible.    

The way to avoid having a hair transplant with a look that is too thin, or see-through, is to limit the extent of coverage to the front and mid-scalp until an adequate donor supply and a limited balding pattern can be reasonably assured -  an assurance that can only come after the patient ages.  Until that time, it is best to avoid adding coverage to the crown.  

Another problem with transplanting the crown early is that as the crown expands additional hair will be needed to follow the expanding area of baldness outward, just to keep the first hair transplant looking natural. This may require considerable amounts of hair that will not be available to cover the front and mid-scalp if that were too bald as well. On the other hand, if the hair transplant was limited to the vertex transition point or VTP (see figure above), the restoration would look natural without further surgery no matter how far the hair loss in the crown progressed. The reason is that the front and top of the scalp represent a complete cosmetic unit, with the VTP as the natural posterior boundary – so it is natural for hair to cover this region of the scalp but not beyond.  

Density Gradients

Another way for surgeons to prevent a thin, see-through look is to avoid distributing the grafts evenly over the transplanted area. It goes without saying that only 1-hair grafts should be used at the hairline, with larger grafts behind them, but there are additional ways to produce the gradations of density to mimic the way hair grows in nature.  Specifically, the greatest density should be in the front part of the scalp (shown in brown) and particularly in the frontal forelock area (shown in dark brown).

The greater density in the front of the scalp forelock area can be created in two ways; by placing the recipient sites closer together in this location and by using larger follicular units in the area (i.e. 3- and 4- hair units rather than 1s and 2s).  These techniques may be use in combination to achieved greater density but, as will be discussed in the following section, if done to excess, may compromise growth.  

Summary

Follicular unit transplantation is a powerful hair restoration technique that allows the surgeon to create natural hair patterns and produce results that mimic nature. The success of the procedure depends greatly on proper patient selection, accurately assessing the patient?s donor supply, and distributing the grafts in a way that is appropriate for a person who will continue to age and eventually thin over time. With thoughtful planning, major mistakes can be avoided and our patients will be able to achieve the full benefit of this remarkable procedure. 

References

1. Orentreich N: Autografts in alopecias and other selected dermatological conditions. Annals of the New York Academy of Sciences 83:463-479, 1959.
2. Bernstein RM, Rassman WR, Szaniawski W, Halperin A: Follicular Transplantation. Intl J Aesthetic Restorative Surgery 1995; 3: 119-32.
3. Bernstein RM, Rassman WR: Follicular Transplantation: Patient Evaluation and Surgical Planning. Dermatol Surg 1997; 23: 771-84.
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7. Bernstein RM, Rassman WR, Rashid N, Shiell R: The art of repair in surgical hair restoration – Part II: The tactics of repair. Dermatol Surg 2002; 28(10): 873-93.
8. Bernstein RM, Follicular Unit Hair Transplantation. In: Robinson JK, Hanke CW, Siegel DM, Sengelmann RD, editors: Surgery of the Skin, Elsevier Mosby, London UK. 2005.
9. Unger WP, Shapiro R. Hair Transplantation. New York: Marcel Dekker, Inc. 2004.
10. Bernstein RM, Rassman, WR. Follicular Unit Transplantation. In: Haber RS, Stough DB, editors: Hair Transplantation, Chapter 12. Elsevier Saunders, 2006: 91-97.
11. Norwood OT. Male pattern baldness: classification and incidence. So. Med. J 1975; 68:1359-1365.
12. Haas AF, Grekin RC: Antibiotic prophylaxis in dermatologic surgery. J Am Acad Dermatol 1995; 32: 155-76.
13. Otley CC. Perioperative evaluation and management in dermatologic surgery. J Am Acad Dermatol 2006; 54: 119-27.
14. Gandelman M, Bellio R, Barretto M: Beta-blockers and local anesthetics with vasoconstrictors: A dangerous association. Intl J Aesthetic Restorative Surgery 1995; 3 (2): 143-45.
15. Bernstein RM, Rassman WR: Limiting epinephrine in large hair transplant sessions. Hair Transplant Forum International 2000; 10(2): 39-42.
16. Skidmore RA, Patterson JD, Tomsick, RS: Local anesthetics. Dermatol Surg 1996; 22:511-522.
17. Phillips KA, Menard W: Suicidality in body dysmorphic disorder: A prospective study.  Am J Psychiatry, 2006; 163:1280-82. 
18. Bernstein RM, Rassman WR. The scalp laxity paradox. Hair Transplant Forum International 2002; 12(1): 9-10.