The location of the crown is actually a point of controversy. The area at the back of the head is rather ill defined in the first place; some people refer to it as the crown, some as the vertex. Others refer to the vertex as the highest point on the head. For purposes of this discussion, we will call the crown the area behind the highest point on the head; in others words, the area behind which the horizontal plane of the top of the head abruptly changes to a sloping, more vertical plane. In many people, it is a rather flattened region roughly the size of the palm of the hand. Obviously, from looking at Class VI and VII balding, we can see that the crown has the potential of becoming even larger with extensive balding. In short, the boundaries are vague when there is abundant hair in place, but the crown may become the largest bald area on the head with extreme hair loss.
In addition to its expansive size, there are other interesting aspects of the region we call the crown. Hair growth at the center of the crown is centrifugal; that is, the hair emerges from the scalp acutely and spirals in an outward direction. Sometimes there is a cowlick at the center of the spiral, which is more obvious in straight, coarse hair. Occasionally, there is a double spiral, which really makes things “interesting” for the hair transplant surgeon.
The presence of this swirl makes more sense when we examine the direction of growth of hair in other parts of the scalp. In the back and sides of the head (occipital and parietal regions), hair growth is down and to the back. At the temples, the hair abruptly changes its orientation from forward to down, and then back. From the crown area forward, including the top of the head and frontal region, and frontal hairline, the direction of growth is forward. So we see the crown as the center of the growth swirl, or the “merging” of these differing hair angles. The logistical and cosmetic importance of this will become clear as the discussion continues.
The Crown is involved in many of the hair loss patterns that we see clinically, and not just the Norwood, or classically “male” patterns; it is also part of the Ludwig, or typically “female” forms of pattern baldness. The crown may be affected in any of the three degrees of Ludwig presentations. (Notice that women can sometimes develop a Norwood, and men a Ludwig, type of balding). That being said, lets take a look at crown involvement in Norwood types of balding.
Norwood Class IV though VII all entail loss in the crown, but with increasing magnitude; Class II and III do not. However, we have additional groupings, the II Vertex and III Vertex; these are the same as the II and III, but with a “bald spot” at the crown. Again, the more advanced IV, V, VI, and VII patterns all represent at least some crown loss. However, there are the “A” variants, II through V, which involve only the front and top of the head, excluding the crown. Finally, some patients present with no frontal loss at all, just exclusive crown loss (the isolated bald spot).
Two essential groups of problems arise when dealing with crown balding. The artistic/aesthetic difficulties crop up when transplanting an area characterized by a swirling vortex of hair directions, often with thinner hair toward the middle. Also, this configuration amounts to a circular “part” which exposes the scalp, and any transplanted groups, to fairly close examination in social settings. Therefore, it is a technically challenging area in which to create appropriately placed and oriented recipient sites; and the correct size grafts must be placed in different regions of the crown.
The other major difficulties are related to supply and demand. The potential size alone of the crown can create an insatiable demand for donor hair, which, as we have seen, is limited. Lets consider the mathematics of this and other regions: the frontal area, from the hairline back to a line drawn across between the two temporal angles, measures an area of roughly 50 cm2. The top of the head, from behind the frontal area to the front border of the crown, may be about 150 cm2. The crown, as we pointed out can vary widely in size, but in a Class VI or VII patient can be as large as 175 cm2: a lot of area to cover! Doing the calculations, we see that, even if we transplant a minimal density (say, 15 FUâ€™s or about 35 hairs per cm2) to a fully bald crown (about 175 cm2), we have used roughly 2600 follicular unit grafts. If we go for a higher density, for example, 40 FU, then we have used 7000 grafts, more than the average person even has available in their donor area. Again, this is in the crown alone. This leaves the cosmetically important frontal area and hairline with essentially no donor hair for transplantation.
While the above example is an extreme one, it is used as an example to show just how much of the donor reserves can be exhausted by the injudicious attempt to fully restore the crown with high density. In a young, desperate man with new onset crown balding, it may be tempting to try to fill this area in with dense packing of grafts; this, however, could be to his long-term detriment. If the balding in the crown continues to expand, the patient and surgeon can find themselves “chasing” the balding with ever increasing circles of grafts, like the layers of an onion. Not only can this quickly deplete the donor area, but if the hair characteristics and donor density are unfavorable, he may find himself with an “island” of dense crown hair sitting amidst an ocean of bald scalp. Moreover, what is he to do if frontal balding ensues? The man who was desperate about his crown balding at age 24, is bound to be absolutely frantic when his hairline starts to recede at 28; this will be even more noticeable than the hair loss at the crown.
Often, especially in younger men, it is appropriate to use medical management with Propecia and/or Rogaine, which tend to be more effective in the crown area than frontally. This may help at least maintain the hair in the region; surgical planning can be done to include hairline restoration, and transplantation to the frontal area as far back as the crown. This will be a more beneficial use of donor reserves from a cosmetic standpoint. The crown can then be transplanted carefully and judiciously, perhaps with a lower density, and the advancement of the patientâ€™s hair loss can be observed over time. We must always be mindful that the large crown can drain the donor reserves, and that transplanted density is often best “spent” on the top, in the frontal area, and at the hairline.