As a method of alopecia reduction for surgical hair restoration, scalp expansion surgery using a balloon-type device implanted under the scalp is called volumetric expansion. Scalp expansion using implanted physical instrumentation is called nonvolumetric expansion or scalp extension. The expansion and excision of bald scalp creates the conditions for subsequent approximation of hair-bearing scalp to cover the area of bald scalp excision. The man most likely to benefit from bald scalp excision and hair-bearing scalp advancement is a man (1) who has enough hair at the sides and back of the head to provide adequate coverage after bald scalp excision, and (2) does not have rapidly progressive male-pattern hair loss.
Although hair transplantation is by far the most commonly performed type of surgical hair restoration procedure some patients may be candidates for scalp reduction or scalp flaps. Some surgeons advocate the use of these procedures in some patients, and the procedures may be choices recommended by a surgeon in selected patients. The scalp reduction of scalp flap procedures can be performed with or without scalp expansion.
Skin has an enormous capacity to expand in response to under-the-skin pressure. The degree to which scalp tissue can expand in response to under-the-scalp pressure is seen naturally in people who have untreated hydrocephalus or large epithelial tumors of the scalp. A more common example of skin expansion in response to under-the-skin pressure is the remarkable ability of skin to "stretch" during pregnancy.
Volumetric Scalp Expansion
The basic principles of volumetric scalp expansion are to (1) expand the bald scalp over a period of time with a balloon-type device implanted under the scalp, (2) collapse and withdraw the device when scalp expansion reaches a predetermined extent, (3) excise the excess scalp skin, (4) advance hair-bearing scalp to cover the area of bald scalp excision, and (5) suture the hair-bearing scalp to complete the correction of male-pattern hair loss.
An implantable balloon-type scalp skin expander was first used for medical purposes about 25 years ago to facilitate surgical removal of a tattoo. By the early 1980s the technique of tissue expansion and bald scalp excision was being pioneered at Hershey (Pennsylvania) Medical Center for treatment of massive scalp defects in children. By the mid-1980s the technique was being used by physician hair restoration specialists to treat selected patients with male-pattern hair loss.
Volumetric scalp expansion begins with the insertion of a Silastic (non tissue reactive) envelope beneath the scalp. The envelope is inserted into the subgaleal plane, a space of loose tissue between the overlying scalp and the blood vessel-rich tissue underneath. The subgaleal space is nearly devoid of blood vessels, so insertion of the envelope causes little bleeding and does not compromise blood or nerve supply to the scalp. As a rule, envelopes are inserted on right and left sides of the head to fit the distribution of bald scalp.
About two weeks after insertion of the device(s), a small amount of saline fluid is injected into the envelope(s) through self-sealing ports to begin inflation of the devices and to begin the process of scalp expansion. Injections of saline are repeated at intervals over succeeding weeks and the scalp responds by expanding. If there are scalp expanders on opposite sides of the head they may be injected in alternate weeks.
Volumetric scalp expansion causes a visible change in head shape as the device(s) inflate. Friends and relatives can be prepared for this temporary change. Strangers may be less prepared. Hats or other head covering can be worn to make the change in head shape less apparent. A good relationship between patient and physician hair restoration specialist can prepare the patient for managing any psychological, emotional or social problems that may arise during the temporary period of scalp expansion.
When scalp expansion is judged to be satisfactory the devices are drained and removed. The patient is taken to an operating room for (1) gathering expanded bald scalp into a "pleat" for excision, (2) excising the pleated bald scalp, (3) advancing hair-bearing scalp to cover the areas of excised bald scalp, and (4) suturing the hair-bearing scalp to create a total or near-total correction of hair loss.
Individual patients may require follow-up treatment such as "fill-in" hair transplantation and use of hair restoration pharmaceuticals (minoxidil or finasteride) to achieve the maximum cosmetic improvement. "Fill-in" hair transplantation may be made more difficult and costly by scalp expansion and excision, however; bald scalp excision and hair-bearing scalp approximation may reduce the number of donor follicles that can be harvested in a single transplantation session, thus increasing the time and dollar investment of "fill-in" hair transplantation.
Patients can usually shower and shampoo the day after surgery, not waiting until sutures are removed. Healing takes place over the following two to six weeks. Postoperative bleeding and infection are potential complications of volumetric scalp expansion and bald scalp excision. Sometimes a postoperative scar forms at the site of hairline suturing. A scar can be revised later to make it inapparent, but revision is more technically difficult when the scar is a so-called "slot defect" that forms where two previously non-adjacent areas of scalp are sutured together.
Nonvolumetric Scalp Expansion
Nonvolumetric scalp expansion is accomplished with a physical device. Expansion may be over a period to time (one to three months) using a stretchable band implanted in the subgaleal space under constant tension. Scalp expansion may also be accomplished during a scalp reduction procedure using a skin-stretching device.
Advantages cited for the implanted nonvolumetric scalp expander include:
- 50% increase in the amount of bald scalp removed in scalp reduction
- fewer procedures are needed to accomplish a final result
- reduced "stretchback" of scalp skin and subsequent scarring
- reduced postoperative hair loss
- early development of postoperative scalp laxity
Potential complications and side effects of nonvolumetric scalp expansion include:
- mild to severe pain during the first 24 hours after the scalp-expanding device is implanted
- occasional bruising or edema in scalp over the implanted device
- reduction in the number of donor grafts that can be harvested per session later for "fill-in"
- hair transplantation should this be needed to achieve the desired hair restoration goal
- postoperative scarring at the site where hair-bearing scalp is sutured together - most difficult to revise when the scar is a so-called "slot defect" the forms at the site where two previously non-adjacent scalp areas are now joined by suturing
- postoperative drainage and delayed wound healing for up to several weeks
- rarely, infection in the tissue around the implanted device