The shape of the forehead is affected by various hard and soft tissue components. The forehead is framed by the hairline superiorly, the brows inferiorly and the bony temporal lines to the sides. The projection of the forehead is controlled by the thickness of the frontal bone and its degree of convexity and smoothness. The height of the forehead is judged by the vertical distance from the hairline to the brow.
Forehead reduction may consist of either a hard or soft tissue approach depending upon the dimensional excesses. If the forehead is vertically long, a soft tissue reduction is needed. If the forehead has horizontal or width excesses then a bone reduction technique is needed.
Hairline Advancement Forehead Reduction
The vertically long or high forehead can be significantly improved in many patients. The vertical length of the forehead is typically judged to be too long if the distance from the eyebrows to the frontal hairline exceeds about 6.5 cms. This is obviously a subjective judgement on the part of the patient but most will feel their forehead is too long beyond this linear measurement. But when the length of the forehead violates the 1/3 rule (bigger than the lower middle and lower facial thirds) it will be typically thought of as being too long or high.
Shortening the height of the forehead is done by a hairline lowering procedure located at the frontal hairline with variable extensions along or into the temporal hairline. This is a scalp advancement which is done by undermining and mobilizing the entire scalp all the way back to the nuchal ridge of the occiput. Combined with galeal releases the frontal hairline may be capable of being lowered 2 to 3 cms in many patients.
But how much the hairline can be moved is heavily influenced by the natural elasticity of the scalp. The thinner the scalp is the less mobile it will be no matter how much undermining and galeal releases are done. This is an important preoperative assessment which may lead one to consider a two-stage approach to achieve the desired new hairline position. A first-stage scalp expander placed at the upper occiput/crown area creates an assured maximal amount of scalp mobilization when done six to eight weeks later.
Bony Forehead Reduction
A more infrequent cause of a prominent forehead is frontal bossing. This is an overgrowth of bone of the forehead, usually the upper portion, which makes it stick out often beyond the projection of the brow bones. The disproportion of the strong upper forehead makes the forehead look imbalanced in addition to being too large. In an adult, the only method of frontal bossing reduction is removal of bone through burring. How much the frontal bossing can be reduced is a function of the thickness of the outer cortex of the skull. Removing more than the outer cortex of the frontal bone risks dural exposure/disruption.
A unique form of a forehead protrusion is that of the forehead horns. While the term horns usually implies a pathology due to a keratinized growth from the skin, forehead horns in forehead surgery refers to an overgrowth of bone. This overgrowth uniquely occurs in the upper forehead and is often bilateral, hence the name horns. This is not to be confused with an osteoma which does not present in a paired or bilateral presentation and is an outcropping of new bone growth not just part of the normal development of the frontal bone. These paired upper forehead bony mounds may appear like two very distinct paired protrusion or may also have a ‘dumbbell’ appearance if a ridge of bone connects between the two of them. Through a hairline approach direct access to then can be done for a burring reduction.
Another treatment option for forehead horns is to build up the forehead around and over them with a bone cement material. This would be a better option if the forehead is generally recessed and a smoother and more projecting forehead is an aesthetic improvement.
When the forehead is too wide reduction of the anterior temporal line is needed. The temporal line is the transition between the outer edge of the bony forehead and the attachment of the temporalis fascia/muscle. This is a raised bony line that is easily seen on any skull model and goes from the lateral brow the whole way to the back of the head.
Beyond the tissue differences that the temporal line represents, it is equally important that a near 90 degree contour change occurs between the front and side of the forehead. This is important in some cases of forehead reshaping where a less wide or less square forehead is desired. The anterior temporal line is reduced by burring to round off the corner of the forehead. This usually requires some release of the upper fascial attachments.
Reduction of the temporal line is an important surgical technique to narrow forehead width as well as make a rounder and less rectangular shape.
Dr Barry Eppley