Chapter 11 Forehead and Temple
RECONSTRUCTIVE PRINCIPLES
The forehead and temple constitute one-third of the face. This region includes the area from the natural frontal hairline superiorly and laterally, extending inferiorly to the zygomatic arch and curving above the superior aspect of the orbit to include the eyebrows and the nasal root. It is subdivided into five cosmetic units: central forehead, right and left lateral forehead (temple), and right and left eyebrow (Figure 11.1). There are several points to consider when evaluating this area including the inherent properties of the skin in the region, the underlying bone structure, the relaxed skin tension lines (RSTL) and wrinkles, the hair-bearing areas, the age of the patient, and the elastic properties of the surrounding tissue.
Adherence to the underlying frontalis musculature causes the thick skin of the central forehead to be relatively inelastic compared to the skin of the lateral forehead, which is more loosely attached to the underlying temporalis fascia, allowing comparatively easier manipulation. The underlying boney structure changes from convex centrally to concave laterally as seen in the surface anatomy. RSTL and natural wrinkles and furrows should be evaluated for potential hiding places for suture lines (Figure 11.2). The RSTLs are horizontal across most of the forehead, perpendicular to the underlying frontalis musculature, and curve in an inferior fashion laterally. The hair-bearing areas of the brows and the abutting scalp can help with camouflaging scar lines but can also limit flap design. In the younger patient, the skin is more elastic and the collagen thicker than in the older patient. The relative increased skin elasticity and regularity will cause greater wound expansion after excision of a lesion, leading to a longer suture line. At times after undermining a lesion, the elastic properties of the skin will declare the direction of least tension to close the wound, which can be different from the forces on the wound before undermining. Using your fingers or skin hooks to approximate the edges of an undermined defect will help determine the direction of closure, which avoids tension.
The frontalis, corrugator, and the superior aspect of the orbicularis oculi muscles make up the underlying musculature of the forehead (Figure 11.3). The frontalis muscle, lying just below the subcutaneous tissue, is a vertically oriented muscle that is continuous with the galea aponeurotica superiorly and interdigitates with the procerus, orbicularis oculi, corrugator supercilii, depressor supercilii, and skin of the eyebrow inferiorly. Frontalis contraction causes brow elevation and is responsible for cutaneous horizontal creases. The temporal branch of the facial nerve is responsible for the action of the frontalis with denervation resulting in unilateral brow ptosis and loss of forehead motion. The width of this muscle can be easily palpated and often noted clinically by the extent of the forehead crease. The corrugator supercilii muscle is a paired muscle originating at the medial end of the superciliary arch and inserting into the frontalis and skin of the brow. It acts via the temporal nerve to pull the brow together and downward, causing vertical glabellar frown lines. These muscles are often the target of botulinum toxin injections to ameliorate the rhytids between the eyebrows. The orbicularis oculi lies beneath the eyebrow. Its action assists in closure of the eye through temporal nerve innervation. The superficial musculoaponeurotic system (SMAS) envelops the frontalis muscle and then forms the galea aponeurotica.
The temporal branch of the facial nerve runs with the SMAS in the temple roughly along a line drawn 0.5 cm below the tragus to a point about 1.5 to 2.0 cm above the outer margin of the orbit where the branches enter the muscle from its deep aspect (Figure 11.4). This nerve is particularly vulnerable over the zygoma where it lies quite superficially just beneath the subcutaneous fat. Upon reaching the frontalis muscle, the temporal nerve courses along its undersurface with smaller nerve branches coursing more superficially.1,2 One should undermine in the superficial aspect of the subcutaneous plane with particular care over the zygoma when closing defects located in the region of the lateral forehead. When undermining around defects located on the central forehead and brow area, the ideal plane of dissection lies just superficial to the SMAS, covering the regional muscles if the defect is no deeper than the subcutaneous tissue. However, defects that violate the frontalis muscle require repair of the muscle and undermining in the avascular plane beneath the muscle overlying the periosteum.3
Sensory innervation of the central forehead originates from branches of the supraorbital and supratrochlear nerves. The pattern of division of these nerves into four or five branches is variable and often asymmetric: however, a common feature is the plane in which these nerves travel with respect to their location. These nerves exit their foramen centrally and quickly penetrate the musculature before continuing in the superficial subcutaneous plane. As one progresses laterally, these nerves course along the underside of the frontalis muscle before changing planes to the superficial subcutaneous plane.4 Consequently, horizontal closure on the central forehead will produce a temporary fan-shaped area of numbness superior to the closure (Figure 11.5). Patients should be made aware of this prior to any surgical incision in this area.
Blood supply to this region is provided by both the internal and external carotid systems. The internal carotid artery supplies the eyelids, upper nose and nasal dorsum, the forehead, and the scalp through its ophthalmic arterial branch. The ophthalmic artery branches into the supraorbital and supratrochlear arteries, which exit the skull with their corresponding nerves and veins through the supraorbital and supratrochlear foramen, respectively. Upon exiting the skull these arteries perforate the frontalis muscle and run in the subcutaneous tissue. The supraorbital foramen can be located clinically by palpation of the bony supraorbital ridge at the vertical mid-pupillary line. The supratrochlear artery courses medial to the supraorbital artery. This artery serves as the axial blood supply for the midline forehead flap. The external carotid artery branches from the common carotid and is the principal artery that supplies blood to the face. The superficial temporal artery is the terminal branch of the external carotid artery. It runs within and then above the SMAS layer of the lateral forehead. Just above the uppermost-attached portion of the ear, the artery branches into the parietal and frontal (anterior) branches (Figure 11.6). The forehead, brow, and scalp receive their arterial supply through these branches of the superficial temporal artery.1
As with defects in any location, it is best to systematically consider the reconstruction options: second intention healing, primary closure, random tissue flaps, pedicle flaps, full- and split-thickness skin graft, and Burow’s graft. Within this framework, the size, depth, and location of the defect and the patient’s anatomy will dictate which reconstructive option is best.5
Second intention healing is a method of wound management that can provide excellent cosmetic results in certain areas.6 Wounds on concave surfaces, such as the lateral forehead, heal with a better cosmetic result than wounds located on convex surfaces, such as the central forehead.7 The frontal bossing of the central forehead lends itself to healing with step-off or contour irregularities and stellate or hypertrophic scars. On the lateral forehead, wounds healing by second intention contract and result in flat or slightly depressed hypopigmented scars. In this area, hypertrophic scarring is rare and distortion of the brow, lateral canthus, and hairline is unusual even with large wounds.8 When needed, guiding sutures may be placed to direct the contraction of the scar to optimize cosmetic results or to change the vectors of the contracting scar away from or toward another anatomic region.9 Advantages of second intention healing include the low risks of hematoma formation or infection if proper care is administered. The likelihood of nerve damage or facial distortion associated with wound edge undermining and wound closure is reduced greatly.
Cosmetic factors to consider when selecting a patient for second intention healing include skin color, surrounding photo-damage, and the patient’s age. Since the scar will most likely be hypopigmented, darker skinned individuals or those with the surrounding dyschromia of photoaging will have a scar less likely to match their skin. Younger patients tend to have a better skin match after secondary intention healing than older patients, who frequently have ruddy complexions with telangiectasia, lentigines, and other colored growths that would contrast the white color of the healed site (Figure 11.7). The depth of the wound is another determining factor in choosing between first and second intention reconstruction. Shallow wounds are more likely to blend into the surrounding skin with smooth borders and will heal more quickly than full-thickness defects in the same location. Surprisingly, deep wounds with exposed bone at the base have been shown to heal safely and effectively by second intention.10 If bone is exposed, sanding the outer table of frontal bone or cranium will promote faster healing and granulation tissue formation.11 For larger defects on the upper forehead or scalp of balding men, a random tissue flap to cover the defect with exposed bone and back-grafting over the secondary defect can provide excellent coverage and cosmesis.12
Figure 11.7 White discoloration of skin grafts and second intention healing can be very unsightly on the forehead.
The kinetics of second intention healing are important when educating the patient on wound care and predicting the time needed for healing. If a partial-thickness wound exists, reepithelialization of the wound is needed for healing. Adnexal structures provide this reepithelialization. It is important to remember that the healing time needed for reepithelialization of a wound is not only proportional to the size of the wound, but also to the density of adnexal structures plentiful on the face. Preexisting scars and prior radiation therapy will decrease the number of adnexal structures and slow reepithelialization.
The healing of full-thickness wounds is also influenced by a number of other factors including the size and location of the wound, the method of wounding, and the presence of wound contaminants. During the first period of healing, the lag phase, there is little to no change in the size of the wound, and it can actually enlarge slightly because of the elasticity of the surrounding skin. Later, during the exponential phase, healing occurs at a more constant rate. The healing time for full-thickness wounds is not directly proportional to the size of the wound; rather it has a logarithmic relationship to the surface area of the wound. Therefore larger wounds take only slightly longer to heal than smaller wounds. Identical wounds made on the face and leg will heal at different rates. Wounds in acral locations take longer to heal because of a variety of factors including venous dependency, a decreased number of blood vessels, and fewer adnexal structures. The rate of wound closure is independent of wound shape. The relationship of healing time to shape is best described as being dependent on the diameter of the largest circle that can be contained within the wound margins.13
Horizontal and vertical primary closures are the mainstays of reconstruction on the forehead. Vertical closures are especially well suited in the glabella and central forehead where they can be hidden. Similarly horizontal closures can be camouflaged by the RSTL that run across the forehead superior to the eyebrow (Figure 11.8). The radial orientation of closures on the lateral forehead and temple will utilize the greatest amount of tissue movement as well as follow the RSTL of the crow’s feet (Figure 11.9). In order to determine the best direction of closure in these areas, skin hooks can be used to approximate the skin edges in different directions.
