Location of the Crown
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.
Characteristics of the Crown
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.
Hair Loss Patterns in the Crown
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, let’s 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).
Challenges in Crown Restoration
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. Let’s 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 FU’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 patient’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.
