The nasolabial flap has been commonly described and used for facial soft tissue reconstruction since the 19th century. However, the first recorded description dates back to an Indian surgeon, Sushruta, in 600 bce . The ease of harvest, robust blood supply, and versatility of the flap lends itself to multiple applications. When based axially, it can be carried on the facial artery as an inferiorly based flap, or angular artery as a superiorly based flap. For most applications on the face, random pattern harvest is favorable and allows a thinner, more pliable flap to match the recipient site soft tissue.
The nasolabial region anatomy is surprisingly more complex than it seems. The nasolabial crease runs linearly from 1 cm superior and just lateral to the ala of the nose to 1 cm lateral to the oral commissure. Several reports and anatomic studies have demonstrated the presence of muscle fibers from the zygomaticus major that insert in the dermis of this crease. The vascular supply of this region is derived from perforating branches of the facial artery inferiorly, and angular artery superiorly. This flap is most commonly harvested without its underlying named vessel to maintain thinness, although axial pattern flaps can extend length considerably. The nasolabial crease serves as the major anatomic marker for linear orientation of the flap.
The nasolabial flap may be used as a random or axial pattern flap and can be pedicled superiorly or inferiorly. Preoperative history and physical examination is critical in determining the flap variant to be used. Prior facial incisions, scars, and local flap harvest sites may preclude its use if the subdermal vascular plexus has been disturbed. Previous surgery, neck dissection, and/or radiation therapy resulting in facial or angular artery compromise may limit the use of axial pattern flaps or extended flaps. There are several reports of successful standard random pattern nasolabial flaps in patients with concomitant ipsilateral radial neck dissection and facial artery sacrifice.
A pinch test can be used to assess flap width to be harvested starting 2 to 3 mm lateral to the nasolabial crease extending laterally into the cheek. The optimal width of the base of the flap should be approximately 2 cm. This ensures adequate capture of the subdermal vascular plexus and associated perforators, but any wider may limit the arc of rotation. The length of the flap should be within the boundaries of the nasolabial fold for acceptable donor site closure. It is important to limit width medial to the medial canthus to prevent eyelid distortion during donor site closure. In excessively long flaps, the perfusion pressure to the distal aspect may not be adequate for viability. This point is particularly important when harvesting a thin flap that does not include the named axial vessel.
A suture or unfolded surgical sponge may be used to design the overall dimensions of the flap. Gauze or suture is used to simulate the flap length and rotated around the proposed base to determine its reach into the recipient site. Adequate length should be incorporated to allow for a tension-free inset. The arc of rotation can exceed 90° with careful undermining around the base of flap.
After marking as outlined, harvest of the flap commences by completing the skin incisions while maintaining the base of the flap wider than its distal extension. A distal to proximal harvest with monopolar cautery or a scalpel can be completed expeditiously within the subcutaneous fat. Care should be taken to not disrupt the muscles of facial expression and stay superficial to the superficial musculoaponeurotic system (SMAS). Because the distal one-third to one-half of the flap will most likely be used for the planned reconstruction, maintaining the desired thickness is critical. A thick, but narrow flap is difficult to inset because the recipient bed (facial skin, intraoral mucosa) will be considerably thinner. This offset in thickness can result in tenting of the flap and internal compression when insetting, leading to venous obstruction. Maintaining a thin layer of subcutaneous fat distally ensures random pattern subdermal plexus capture, while allowing appropriate thickness match for reconstruction.
As the dissection proceeds proximally, the flap harvest may be completed in a deeper plane. Including the angular or facial vessels; however, necessitates dissection in a supraperiosteal plane, which is generally not required. It is important to avoid the temptation to back-cut the base of the flap to increase rotational arc or avoid a standing cutaneous cone as this will compromise the vascularity of the distal third.
Donor site closure
Because the donor site is central on the face, a meticulous tension-free closure is required to prevent unfavorable scarring or facial distortion. Skin flaps should be sharply raised in a supra-SMAS plane, taking care to raise more length laterally than medially. This maneuver is best accomplished with facelift or Dean’s scissors. Once the flaps can be closed tension free, deep dermal closure is completed with slowly resorbing monofilament suture (3-0 or 4-0 poliglecaprone 25) and skin with 5-0 or 6-0 nylon. Occasionally, the deep subcutaneous tissues require suspension to the orbitozygomatic periosteum to prevent scar widening or nasofacial groove flattening. This factor is important in wider flaps or where the donor site closure is tight. It is important to minimize undermining near the oral commissure and medial canthus because this will laterally distort these structures if closed under tension.
The nasolabial flap may be harvested as a perforator based flap or island flap, which may be advantageous for nasal reconstruction. By completely islanding the flap, a skin paddle can be tunneled subcutaneously to reconstruct nasal or cheek cutaneous defects not in continuity with the planned donor site. Monarca and colleagues prospectively compared the use of traditional pedicled nasolabial flaps versus nasolabial island flaps in nasal ala reconstruction and demonstrated improved patient esthetic satisfaction scores and lower incidence of flap complications in the island group. When harvesting an island flap, it is important to carry the dissection in the supraperiosteal plane to include the facial artery and its perforators, because the subdermal plexus will be disrupted circumferentially. Failure to do so compromises vascular flow. Alternatively, a similar result can be obtained, particularly for intraoral reconstruction, by harvesting a standard thin pedicled nasolabial flap and carefully de-epithelializing the base. Although not a true island flap, it allows for subcutaneous tunneling into the oral cavity and complete donor site closure.