Eric J. Moore
INTRODUCTION
Defects involving the soft palate are usually the by-products of ablative surgery for squamous cell carcinoma of the tonsil fossa or the mucosal lining of the soft palate, during ablative surgery for minor salivary gland neoplasms, or less commonly from posttraumatic, iatrogenic, or congenital defects. The soft palate plays a critical role in velopharyngeal closure during speech and swallowing, and the success of reconstruction of the soft palate defect is judged primarily on the ability to adequately obliterate the velopharyngeal opening on the side of the defect while maintaining free mobility of the remaining functional soft palate.
Small defects of the soft palate and tonsil fossa can be left to heal by second intention or be closed primarily. The distensibility of the soft palate tissues and the excellent vascularity usually result in a successful outcome with either of these options. However, larger defects, particularly those involving more than 50% of the soft palate or those that communicate with the neck will require reconstruction. While regional pedicled flaps and micro-vascular free flaps have been employed frequently for large defects of the oropharynx, an intermediate level of defect that is too large to close primarily but does not cross the midline extensively can be reconstructed with the use of local pedicle flaps. There are many random and local pedicle flaps that have been described to close defects of the palate. Many of these have applications in primary or secondary closure of cleft palate defects, and they have been adapted for use in reconstruction of oncologic defects of the soft palate. The following section describes the use of the three local pedicle flaps that can be used to close defects of the soft palate: The buccal adipose tissue pad flap, the inferiorly based facial artery musculomucosal (FAMM) flap, and the reverse facial–submental artery island flap. Familiarity with these flaps will allow the surgeon to close intermediate-size defects in the oropharynx without the complexity of creating a separate donor site in a more distant area of the body.
HISTORY
I take a routine history from the patient and focus on determining if the patient has a history of infection, bleeding, an oral mucosal disease, or surgery or radiation of the oral mucosa that may represent a contraindication to reconstruction using a local flap. I am also careful to note that a history of active smoking can impact flap survival. This is particularly true of random flaps.
PHYSICAL EXAMINATION
The physical examination should include a careful surveillance of the oral cavity and the defect in order to ensure that a local flap is an appropriate reconstructive option. Additionally, I like to inspect the donor site and determine if prior surgery or scar in the area may preclude or complicate the surgical reconstruction.
INDICATIONS
Buccal Adipose Tissue Pad
The use of the buccal adipose tissue pad as a pedicle flap was first described by Egyedi in 1977. He advocated its use for closure of oroantral and oronasal fistulae. In that description, a split-thickness skin graft was placed on the oral side, but later descriptions recognized the skin graft as unnecessary since the flap rapidly muco-salizes when placed into the oral cavity. The buccal adipose tissue pad is described as a central body at the posterior maxilla and upper buccinator with four extensions: buccal, pterygoid, superficial, and deep temporal. The adipose tissue pad is prodigious in infants and supports the cheeks during sucking. In adults, it serves to aid in sliding of the masticatory muscles from themselves and the zygomatic arch and mandibular ramus. It is relatively conserved in adults, even in the setting of cachexia. The buccal adipose tissue pad is amply supplied with blood from the maxillary artery, the superficial temporal artery, and the facial artery. It is thinly encapsulated, and the capsule should be preserved with flap harvest to aid in epithelialization and to prevent devascularization. Although the pterygoid extension between the pterygoid musculature and mandibular ramus can be mobilized with flap elevation, mainly the buccal portion is used in reconstruction of the palate.
Facial Artery Musculomucosal Flap
Random buccal flaps have been used for decades to close soft palate defects. Pribaz in 1991 combined the knowledge of random buccal flaps, musculomucosal buccal flaps, and pedicled melolabial flaps to describe an axial buccal flap based on the facial artery that he called the FAMM flap. The added vascularity and the thicker tissue that is transferred with this flap compared to random buccal mucosal flaps make it a versatile local tissue flap to augment oral cavity and oropharyngeal defects.
The buccinator muscle lies just under the mucosa and submucosa of the buccal area. Lateral to the buccinator muscle lie the buccal adipose tissue pad, masseter muscle, ramus of the mandible, buccopharyngeal fascia, terminal buccal branch of the facial nerve, and facial artery and vein. The buccinator is supplied with blood from the buccal artery and branches of the facial artery. Abundant venous drainage flows to the internal maxillary veins and pterygoid plexus posteriorly and to the facial vein anteriorly. After the facial artery crosses the mandible, it runs a tortuous course around the oral commissure under the risorius, zygomaticus major, and lateral orbicularis oris muscles. The artery lies lateral to the buccinator and levator anguli oris muscle. It gives rise to an inferior and superior labial artery that lie medial to the lateral orbicularis oris muscle. The artery continues superiorly as the angular artery. Because of the rich anastomoses between the left and right facial artery and internal maxillary branches, the FAMM flap can be based inferiorly (anterograde) off the more proximal facial artery or superiorly (retrograde) off the distal facial artery. The inferiorly based FAMM flap is favorable for defects of the soft palate, as the pedicle can lie posterior to the maxillary tuberosity and molar teeth (see Fig. 9.1).
FIGURE 9.1 Design of the inferiorly based FAMM flap.
Reverse Facial–Submental Artery Island Flap
The traditional submental artery flap was first described by Martin in 1993, and the reverse flow facial–submental artery flap was studied anatomically and presented as a new flap by Rojananin et al. in 1996. Possibly because of reports of venous congestion, it did not gain popularity immediately, but multiple reports of large series using this flap to reconstruct oral and oropharyngeal defects have been published in this decade.
After the facial artery leaves the posterior submandibular gland, it gives off the submental branch before it courses over the mandibular notch to continue superiorly into the face. The submental branch runs on the superficial surface of the mylohyoid muscle either deep to the anterior belly of the digastric muscle (70%) or superficial to it (30%). Perforators from the artery come off proximal to the anterior belly of the digastric muscle, through it, and distal to it before piercing the platysma and supplying the overlying submental skin. The facial vein, which has no valves, runs posterior to the facial artery over the mandible, superficial to the submandibular gland, to join the retromandibular vein. The artery and vein have multiple anastomosing branches to arterial and venous vessels in the face. Because of this rich communicating system, there is no significant change in mean intra-arterial pressure in the submental artery after proximal occlusion of the facial artery. Basing the submental artery island flap on this retrograde flow allows a more beneficial axis of rotation and pedicle length to allow the flap to reach the soft palate.
Previous or concurrent neck dissection can interrupt the facial arterial blood supply to the submental island flap both proximally and distally and to the FAMM flap proximally. The anterograde FAMM flap may have adequate blood supply through collateral flow through the inferior labial artery even if the proximal facial artery is ligated. A Doppler should be used intraoperatively to ensure adequate blood supply during the elevation of the flap in this setting.
If the submental island flap is to be used, care must be taken during the neck dissection to preserve the blood supply of the submental artery and the venous outflow. Although this flap has been used in conjunction with a level I neck dissection, the dissection is more tedious. In the situation where there is a high expectation of metastatic cancer in the submental and submandibular triangle, the use of an alternative flap might be prudent. Previous neck dissection does not typically affect the ability to harvest the buccal adipose tissue and FAMM flaps successfully.
CONTRAINDICATIONS
The contraindications for the buccal adipose tissue pad flap, FAMM, and reverse submental island flap are limited to prior surgery that may have impacted the blood supply or tissue flap. In general, these are reliable flaps that have few contraindications.
PREOPERATIVE PLANNING
Careful preoperative history of previous treatment in the head and neck and careful preoperative examination of the oral cavity, oropharynx, and neck will prevent the surgeon from underestimating the extent of the defect or choosing an unfavorable reconstructive option. Even with this planning, the ultimate extent of the defect and the reconstructive challenge cannot always be anticipated preoperatively, and the reconstructive surgeon should discuss several options with the patient and have several reconstructive flaps in mind. As with any ablative and reconstructive surgery, careful communication should be maintained between the ablative and reconstructive team if they are not the same.
SURGICAL TECHNIQUE
Buccal Adipose Tissue Flap
With an oral retractor in place to provide exposure, a horizontal incision is made in the buccal mucosa adjacent to the maxillary molars and below the orifice of the parotid duct. The buccal adipose tissue may prolapse into the incision, or the surgeon may need to bluntly dissect through the buccinator muscle to expose the capsule of the adipose tissue pad. This is mobilized with blunt dissection. Care is taken not to interrupt the capsule as this keeps the buccal adipose tissue pad intact and preserves vascularity, a surface to mucosalized, and the integrity of the flap. After adequate length is obtained, the flap is rotated into or transposed to the defect keeping the lateral soft tissue pedicle intact. The flap can be expanded to a width of approximately 3 cm by gentle manipulation, and then, the capsule of the flap is sutured to the edges of the defect with resorbable sutures. No attempt is made to skin graft the defect, as the surface will mucosalize. If the flap is transposed, it is not tunneled into the defect—the pedicle can be divided in a second stage or left to atrophy. The buccal incision is irrigated and closed loosely around the pedicle.
FAMM Flap
The submucosal course of the facial artery in the buccal area is mapped with a handheld Doppler. For lateral defects in the oropharynx, an inferiorly based flap is designed with a pedicle width of approximately 1 cm and a maximal flap width of 2.5 cm. The maximal length of the flap is approximately 9 cm. The distal portion of the flap is incised through the mucosa and buccinator muscle, taking care to keep the superior edge of the incision inferior and lateral to Stenson orifice. The facial artery is ligated and divided. Dissection proceeds from distal to proximal with care to include the facial artery in the flap. The flap can be converted to an island flap by carefully removing the proximal mucosa, or it can be harvested as a mucosa pedicled flap. Branches of the facial artery are clipped and divided as necessary until adequate mobilization allows rotation or transposition of the flap into the defect. The flap is inset with resorbable horizontal mattress sutures to the edges of the defect (see Fig. 9.2). After irrigation and hemostasis of the donor site, it is closed in layers including the buccinator muscle followed by the mucosa.
FIGURE 9.2 Inset of the FAMM flap.
Reverse Facial–Submental Artery Flap
The flap is designed with the superior skin incision approximately 1 cm below the inferior edge of the mandible. The inferior, medial, and lateral edges of the incision are then designed based on the extent of the defect. The flap can reliably include the entire submental skin, with the area of the flap primarily determined by the laxity of this skin and the ability to close the neck primarily. The superior edge of the flap is incised, and dissection proceeds down through the platysma to identify and preserve the marginal branch of the facial nerve overlying the facial artery and vein. The medial incisions are then performed, and the flap is raised below the subcutaneous adipose tissue and platysma and over the mylohyoid muscle from medial to lateral until the ipsilateral midline is reached. Although not advocated by all authors, the ipsilateral anterior belly of the digastric muscle should be included in the flap to prevent venous congestion. The facial artery is traced proximally, and downward retraction on the submandibular gland exposes the submental artery behind the gland and the submental vein on its lateral surface.
The proximal facial artery and vein are ligated with care to ensure that the division point is proximal and lateral to the origin of the submental vessels. The flap is then mobilized with division and clipping of the small vascular branches that penetrate the submandibular gland. The reverse flow vascularity of the flap is confirmed, and then the flap is fully mobilized on the distal facial vessel pedicle and gently passed beneath the marginal mandibular nerve to advance the reach of the pedicle. The flap can then be passed intraorally through a mucosal incision in the buccal sulcus. Care is taken to ensure that the pedicle is not kinked or stretched, and then the skin edges of the flap are contoured and sutured to the mucosal edges of the defect with resorbable mattress sutures in a water tight fashion. The donor site is irrigated and closed primarily over a drain.
POSTOPERATIVE MANAGEMENT
The patient is instructed on oral care with saline rinses and antibiotic mouthwash twice daily. Enteral nutrition is provided until the mucosal defect is healed to prevent fistula formation and to discourage dehiscence of the flap. The patient is allowed to begin an oral diet once the risk of healing complications has subsided. This period is variable depending on the extent of the defect, the type of reconstruction used, previous treatment effects, and the age of the patient and the preoperative swallowing function.
COMPLICATIONS
Careful design and meticulous technique prevent most complication associated with these flaps. The arterial supply to these flaps is robust, so arterial insufficiency is rare. Venous insufficiency can occur, particularly with the submental island flap. Venous insufficiency is reduced by including the anterior belly of the digastric muscle in the flap design. Venous insufficiency is manifest by bluish discoloration, the flap becoming tense, and eventual skin necrosis and flap dehiscence. In the event of venous congestion, the wound can be explored for hematoma, kinking of the pedicle, or tension on the pedicle. Therapy for venous congestion can include using leeches on the flap, but a new reconstructive treatment may be necessary if the venous congestion cannot be promptly remedied.
RESULTS
The results for these three local flaps are excellent. The blood supply and the tissue are hearty, so the healing is reliable.
PEARLS
• Defects in the oropharynx that involve up to 50% of the palate and are too large to close primarily or to heal by second intention can be managed by using local pedicle flaps.
• Lateral defects of the oropharynx are amenable to buccal adipose tissue pad flaps and FAMM flaps.
• The inferior (anterograde flow) FAMM flap is better suited to a defect in the oropharynx than the superior (retrograde flow) pedicle.
• Larger defects in the oropharynx can be closed with the reverse flow facial–submental artery flap.
• If neck dissection of the submandibular area is performed in conjunction with the submental flap, careful planning and execution are necessary to preserve vascular flow to the flap and venous return.
PITFALLS
• Previous surgery in the distribution of the facial artery may jeopardize the blood supply to the FAMM flap and submental flap.
• Failure to perform careful blunt dissection of the capsule of the buccal adipose tissue pad flap will jeopardize the blood supply and make the flap more difficult to inset.
INSTRUMENTS TO HAVE AVAILABLE
• Standard head and neck surgical set
• Oral maxillofacial surgical tray with Dingman retractor
SUGGESTED READING
Tideman H, Bosanquet A, Scott J. Use of the buccal fat pad as a pedicled graft. J Oral Maxillofac Surg 1986;44:435–440.
Pribaz J, Stephens W, Crespo L, et al. A new intraoral flap: facial artery musculomucosal (FAMM) flap. Plast Reconstr Surg 1992;90(3):421–429.
Baumann A, Ewers R. Application of the buccal fat pad in oral reconstruction. J Oral Maxillofac Surg 2000;58:389–392.
Vural E, Suen J. The submental island flap in head and neck reconstruction. Head Neck 2000;22:572–578.
Zhang B, Wang JG, Chen WL, et al. Reverse facial-submental artery island flap for reconstruction of oropharyngeal defects following middle and advanced-stage carcinoma ablation, Br J Oral Maxillofac Surg 2011;49:194–197.