Indication

The paramedian forehead flap (PFF) is a workhorse in facial reconstruction. Although it may close any wound on the central face, its best application is to the distal nose (tip, ala, and columella) where tissue thickness and sebaceousness are closely matched by forehead skin.² The PFF is ideal for recreating the convexity and projection of the nasal tip. Subtotal nasal tip and/or alar defects may be candidates for the PFF. Proximal wounds on the nasal dorsum, sidewall, nasal root, and medial canthus have inherently thinner skin and may be incongruous for the much thicker PFF unless a substantially deep defect is present.

Anatomy

The primary and secondary vascular supply to the PFF is the supratrochlear (internal carotid system) and dorsal nasal artery (external carotid system), respectively. The supratrochlear artery (SA) is reliably located at the medial border of the eyebrow, 1.5–2 cm from the facial midline. At the medial eyebrow, a glabellar crease (if present) delineates where the SA crosses the superior orbital rim to enter the forehead (Figure 8.1). Below the orbital rim, the SA lies deep to the periorbital muscles (orbicularis oculi and frontalis). Above the rim, however, the SA pierces the frontalis muscle and ascends superficially into the forehead, sandwiched between the frontalis muscle below and the subcutis above. Consequently, to preserve the SA near the orbital rim, dissection must be below the frontalis muscle and deep fascia.

Figure 8.1 Supratrochlear artery location 1.5 cm lateral from midline at the medial eyebrow, marked by a lateral glabellar crease.

Flap Design

The ideal PFF is an aesthetic covering that restores normal contour and symmetry without creating a shapeless blob. Table 8.1 discusses the critical design issues in a PFF. The covering provided by a PFF requires a stable nasal infrastructure (cartilage support and mucosal lining). Structural cartilage grafts (SCG) to prevent nasal valve collapse and alar rim contraction are usual considerations in PFF repairs. More neglected, however, are SCG that restore contour to the nasal supratip. Contour grafts should be considered in patients that have thick nasal tip skin and supratip defects (Figure 8.2). Without a contour graft in these patients, a PFF alone may be insufficient to restore normal tip projection.³

TABLE 8.1 ISSUES IN PFF DESIGN FOR DISTAL NOSE DEFECT (NASAL TIP AND/OR ALA)

Figure 8.2 Supratip defect in a woman with inherently thick nasal tip skin who would benefit from a contour cartilage graft.

Measurements of the defect must be accurate, neither over- nor undersized for the wound. The PFF template should be measured after the residual subunit has been outlined, but prior to the excision of any remaining skin (Figure 8.3). This avoids an artificially enlarged dimension from a retracted wound edge. A template should also reflect the 3-dimensional nature of the nose, especially if a defect extends to the infratip, columella, and ala (Figure 8.4a). If the vestibular mucosa is missing, the PFF may be extended and turned down to provide nasal lining. The soft nasal triangle, however, is best approached with second intention as the PFF, even when skeletonized, will never match the thin, soft concavity in this area (Figure 8.4b). Whenever possible, the unaffected contralateral side should be used as a template to restore symmetry. A right-sided nasal tip and ala wound, for example, should be repaired based on the normal left tip and ala.

Figure 8.3 PFF template designed to include the eventual removal of nasal tip subunit; pedicle base is 1 cm in width.

Figure 8.4 (a) Complex Mohs defect of the nasal tip, soft triangle, and medial ala, necessitating a 3-dimensional design. (b) Paramedian forehead flap designed to cover complex nasal tip and ala defect except for the nasal soft triangle, which is best recreated with second intention healing (see Figure 8.13b for long-term results).

The vertical height of the forehead (from orbital rim to anterior frontal hairline) will determine the potential reach of this flap, and may be estimated by using a suture. If the vertical length is inadequate (short forehead height relative to distal defect), then the modifications listed in Table 8.2 will significantly extend a flap’s distal reach.

TABLE 8.2 MODIFICATIONS TO THE PARAMEDIAN FOREHEAD FLAP FOR EXTENDED REACH

Design considerations for the pedicle include its position and width. Identifying the SA pedicle may be done clinically, by using the anatomic landmarks mentioned earlier, or definitively by confirming with a manual Doppler (8–10 MHz frequency). The pedicle width, therefore, rarely needs to be greater than 1.5 cm.⁴ Wider pedicles in fact are counterproductive and restrict flap mobility as well as vascular integrity (by increasing torque and compression on the artery during flap rotation). This author routinely develops a pedicle base of 1.0 cm (Figure 8.3). Pedicle positioning should be contralateral to the predominant side of the wound to minimize pedicle twisting during movement. The right SA, for example, should be the PFF pedicle for a predominantly left-sided nasal defect.

Anesthesia

The PFF may be safely performed as an outpatient procedure. Tumescent anesthesia is useful by rapidly anesthetizing large areas with minimal patient discomfort. Local anesthesia (local infiltration and nerve blocks) may be supplemented by oral benzodiazepines (lorazepam, midazolam) and oral analgesics. Rarely, conscious sedation may be needed and are safely performed by dermasurgeons.^5,6 Appropriate credentialing for advanced cardiac life support and sedation are essential for the latter modalities.

Execution

Prior to the first incision, all design elements should be measured and remeasured, and anesthesia must be complete. The execution sequence for this author is (1) cartilage support and nasal lining restoration (if needed), (2) flap harvesting and pedicle mobilization, (3) defect preparation, (4) flap preparation and inset, (5) donor site closure, and (6) postoperative care.

Cartilage and Lining Restoration

Cartilage grafts (CG) and nasal lining are essential ingredients for a stable nasal architecture. CG are either structural (native cartilage present but additional CG needed for support) (Figure 8.5) or restorative (replacing missing cartilage). Structural cartilage grafts serve to (1) support heavy flap tissue, (2) maintain airway patency of the internal nasal valve (priority in nasal reconstruction), (3) minimize scar contraction, and (4) restore contour projection (nasal tip). CG may be auricular (antihelix or concha; Figure 8.6), nasal (septum), or costal in nature. Auricular cartilage harvest is easiest and may be performed from an anterior or posterior approach. Anterior incisions are more accessible but scars are more visible than posterior incisions. Antihelical cartilage is excellent for long, straight segments whereas conchal cartilage is ideal for grafts that demand more curvature and substance.^7,8 The subject of nasal lining is beyond the scope of this chapter. General options, however, for smaller mucosal defects (< 1 cm) include (1) turnover hinge flap, (2) turndown of a forehead flap extension, (3) full-thickness skin graft (FTSG), and (4) bipedicle vestibular skin advancement flap. Larger lining restoration may require (1) turnover forehead flap, (2) septal mucoperichondrial hinge flap, (3) composite septal chondromucosal pivotal flap, or (4) larger FTSG vascularized by an overlying PFF.⁹

Figure 8.5 Cartilage graft placed close to the alar rim for structural stabilization and support of the overlying PFF.

Figure 8.6 Anterior approach to auricular cartilage harvesting. Conchal skin is elevated, and cartilage with perichondrium removed for grafting.

Flap Harvesting and Pedicle Mobilization

The PFF may be mobilized at its superior edge to include just the skin and subcutis or down to underlying galea. The former approach facilitates flap debulking during inset but results in greater bleeding. A subcutaneous level is preferred if the flap is in hair-bearing scalp to expose terminal hair bulbs for depilation. The level of undermining, however, delves deeper into the subgaleal plane as one approaches the eyebrow to preserve the SA. The transition from subcutis to subgalea should occur at least 3 cm above the orbital rim. Undermining past the orbital rim should be under direct visualization as the SA is at risk of transection. Occasionally, subperiosteal release of the arcus marginalis and brow complex is required to enhance flap extension (Table 8.2). The PFF should now overlie the defect without tension (Figure 8.7).

Figure 8.7 PFF lies without tension, draping to patient’s columella.

Flap Preparation and Inset

Prior to any suturing, the flap thickness must be revised to fit the defect. Aggressive debulking except for a thin subdermal layer is possible because of the excellent vascularity of the SA (Figure 8.8). Constant reference to the defect is mandatory to prevent excessive thinning. Flap inset begins with interrupted epidermal sutures to secure its leading edge with the defect. If dermal-buried sutures are placed, this author prefers Poliglecaprone 25 (Monocryl, Ethicon) because of its minimal tissue reaction, a desirable feature on the sebaceous nasal tip.¹⁰ Dermal sutures contribute to flap security and minimize incision line separation. The proximal flap as it abuts the nasal dorsum is not sutured until pedicle division.

Figure 8.8 The distal forehead flap may be substantially debulked except for a thin subdermal fat layer.

Donor Site Closure

Donor areas are approximated as much as possible and any remaining wound heals by second intention (Figure 8.9). Patients may be reassured that this open portion will be significantly smaller because of inevitable wound contraction (Figure 8.10). Tissue expansion and complex scalp flaps should be avoided as they often lead to excessive morbidity on both donor and recipient tissue without cosmetic benefits. At most, unilateral or bilateral W-plasties along the frontal hairline may be considered for complete closure of the forehead wound. These W-plasties act as bilateral advancement and rotation flaps, with the W design to camouflage incision scars and preserve hairline continuity.⁴ Broad scalp paresthesia may be a price of donor site closure.

Figure 8.9 Second intention wounds at the midline or paramedian forehead heal exceptionally well. More lateral forehead wounds, however, are less predictable and usually result in poor donor site cosmesis.

Figure 8.10 One-year postoperative scar from primary closure and second intention healing of PFF donor site.

Postoperative Care

Postoperative bleeding at the sides of the exposed pedicle is common and may be prevented with meticulous electrocoagulation and a Surgicel or Surgicel Nu-Knit wrap of the exposed pedicle. This oxidized cellulose gauze promotes hemostasis and its removal causes less discomfort than Vaseline gauze.¹¹ Visual fields are blocked with pressure dressings and the wearing of glasses is usually not possible without preoperatively customized devices.