By Martin G. Unger, MD, FRCSC, ABHRS, FISHRS
Although hair transplantation alone is by far the most common method of hair restoration utilized in modern times, excision of bald scalp after either tissue expansion or scalp extension surgery can play a very useful and important role in hair restoration as well.
Scalp tissue has the ability to elongate or stretch after tension or pull has been placed on it for a period of time, similar to the elongation of “fish-net” nylon stockings when pulled from two sides. In humans, this phenomenon is called “mechanical creep”. When tissue is pulled or “stretched” for longer periods of time, two other changes occur – new tissue is formed and also adjacent tissue moves into the area (called recruitment of surrounding tissue). This combination of new tissue growth and recruitment is known as “biological creep”, and pregnancy with “stretching” of the abdominal skin is an every day example of this. In order to excise more bald skin, and make the area of baldness become smaller or be eliminated, certain surgical procedures will utilize either mechanical creep or biological creep or possibly both, to achieve this goal. Some of these hair replacement options are detailed below.
Chronic Tissue Expansion
Dr Ernest Manders, of Ann Arbor, Michigan, who is a personal friend of the author, is credited with first using this technique on the scalp in 1982. In this technique, also called volumetic expansion, one or more balloon-like structures, called tissue expanders, are surgically placed below the hair-bearing scalp skin to cause biological creep. Usually two weeks after the tissue expanders have been put in place, some salt water or saline is added to each expander, using a needle through the skin, to expand it. Saline is then added once or twice a week for 8-12 weeks until the hair-bearing scalp has been expanded the desired amount. Then, at a second operation, the saline is removed from the expander(s), the expander(s) removed, and then the desired bald scalp excised and replaced by the expanded hair-bearing scalp.
As the hair-bearing scalp expands, normally a hat or some sort of hair covering is needed in the last month or so to hide the area. For most patients, this short term inconvenience is well rewarded by the long term surgical improvements that are achieved.
This technique, which is a type of non-volumetric expansion, was designed by Dr Patrick Frechet of Paris, France, (also a personal friend of the author), in 1993. In the first operation an “extender”, a thin sheet of silastic material with a row of metal hooks at each end, is attached, after stretching it, to the under side of the hair-bearing scalp tissue on each side. Like a wide, stretched elastic band, the extender pulls the hair-bearing scalp from each side towards the middle of the head. After 30 days, a second operation is performed during which the extender is removed, bald scalp tissue is excised, and replaced by the hair-bearing scalp. Scalp extension always involves mechanical creep of the scalp tissue, however, it is unknown whether biological creep is also involved or not. The advantage of scalp extension is that the deformity caused by chronic tissue expansion in its final weeks is avoided.
Prolonged Acute Tissue Expansion (PATE)
The Unger PATE procedure was first published by the author in 1997 and is designed to achieve the maximum amount of mechanical creep. It is another example of non-volumetric expansion. In this technique, a tissue expander is placed under the hair-bearing scalp and then the scalp incision closed. The expander is then expanded with distilled water to a desired pressure for two minutes and then deflated for two minutes to complete one cycle. After eighteen to twenty cycles in the operating room, the maximum amount of mechanical creep has been reached. Having achieved this goal, the incision is re-opened, the tissue expander removed, and the desired amount of bald scalp is excised and replaced by hair-bearing scalp. The big advantage of this procedure is that in one operation, 136% more bald tissue can be removed than with conventional “scalp reductions”.
In order to achieve the very best results with hair restoration, ideally any of the above procedures, or alternately, repeated conventional scalp reductions, should be used to remove approximately half of the bald scalp tissue. Following this, since the bald area has been made much smaller, much less hair transplantation (either follicular unit transfer [FUT] or follicular unit extraction [FUE]) will be needed to successfully complete the balance of the hair restoration.