Rod Rezaee
INTRODUCTION
Historically, defects of the pharynx have posed challenges to the head and neck reconstructive surgeon due to the complex nature of pharyngeal function from the standpoint of breathing and swallowing. The pharyngeal mucosa and musculature must generate pressure to assist with bolus transfer but additionally must maintain a patent airway. An intricate array of neuromuscular and sensory reflexes in addition to cognitive control allow for this to take place. Any interruption in this reflex arc poses the potential for aspiration and significant dysphagia. The presence of cancer, or the treatment of the cancer, either surgical or nonsurgical, can increase the challenge for the reconstructive surgeon in order to maintain a patient’s basic function.
Total laryngopharyngectomy defects can be restored with a tubed flap design with no concern for aspiration and only concern for recreating a patent conduit connecting the tongue base to the esophagus. When the oncologic resection does not require removal of the larynx, the reconstructive challenge increases substantially. This is due to the added need not only to restore an intact watertight pharynx but to do so while preserving the ability to swallow and not impinge on the airway. To accomplish this goal, the reconstructive surgeon must carefully consider the needs of the patient as the decision is made on the donor site, design, and insetting of the flap.
The focus of this chapter is on reconstruction of the lateral pharyngeal defect using a free flap with an intact larynx.
HISTORY
It is critical to understand the patient’s history to help determine the needs of the flap selected for restoration of the pharynx. Location of the cancer, prior surgery, radiation, chemotherapy, age, laboratory values (hematocrit, thyroid-stimulating hormone), medical history, and nutritional status (prealbumin) all factor into the decision algorithm. Discussion of surgical approaches should be undertaken preoperatively with the ablative and reconstructive surgeons to determine an optimal plan for safe and effective extirpation and reconstruction. Since a lateral pharyngeal lesion and defect may extend cephalocaudad to include the hypopharynx to nasopharynx, transmandibular versus transcervical approaches are possible and can add an additional challenge for flap reconstruction (Fig. 11.1). This may have implications for the type of flap chosen especially when the mandible is intact and there is a high lateral defect.
FIGURE 11.1 This figure is a transoral view of a carcinoma of the pharynx (arrow).
Although modern free flap teams can provide reconstruction very efficiently, there are certain patient situations when primary closure or pedicle flaps, either supraclavicular island or pectoralis major myocutaneous flaps, may be chosen to shorten operative times and reduce the risk of additional potential operations in the setting of a rare free flap compromise. For instance, patients of advanced age, those with cardiac conditions, or those with aortic stenosis where added potential fluid shifts or operative time may increase the risk of perioperative events may be considered for regional tissue closure rather than free tissue repair. All patients benefit from a comprehensive multidisciplinary approach to designing a treatment plan. This also includes preoperative and postoperative assessment by the speech and swallowing team to achieve maximal functional outcomes.
PHYSICAL EXAMINATION
Physical examination requires attention to both the donor site and the recipient site. The donor site evaluation requires an Allen test on the upper extremity to ensure that there is an intact vascular palmar arch. Because the radial forearm free flap will be used for reconstruction, a careful examination of the volar surface of the forearm is important to ensure that there has not been trauma or prior surgery that may compromise the harvesting of the flap. It is important to plan the harvest of the forearm flap from the nondominant arm. The recipient site should be carefully evaluated to determine the size of the defect. This will help to determine the appropriate size of the skin flap reconstruction.
INDICATIONS
When I assess the lateral pharyngeal defect, I consider a number of factors in determining the need for a free flap. Prior radiation and surgery intuitively raises a concern about the quality and integrity of the local native tissues that I believe benefit from repair with vascularized grafts from a remote nonirradiated site (Fig. 11.2). If the defect connects to the neck, then flap reconstruction may be indicated especially if the defect is large or the quality of the tissue prevents a tension-free primary closure. Transoral defects from cancers removed in standard fashion or robotically that do not connect to the neck may be safely allowed to granulate or be closed with local flaps for carotid coverage. If there is communication with the neck and if there has been a radical neck dissection performed and I consider the carotid artery at risk either from wound breakdown externally or soilage from a potential salivary leak, free flap repair and regional coverage become important considerations. The carotid artery can become exposed internally or externally, and the risk of this must be assessed in the absence of the sternocleidomastoid muscle (SCM).
FIGURE 11.2 This photograph demonstrates the design for the radial forearm free flap. There is a cutaneous skin paddle for reconstruction of the pharynx and a second monitor skin paddle to evaluate the viability of the flap.
With an intact SCM, consideration can be given to pexing the medial aspect of the SCM to the prevertebral fascia when possible to potentially serve as a salivary diversion in the event of a fistula. Similarly, a flap can be designed such that a deepithelialized portion or additional soft tissue can be harvested to protect the carotid artery and provide a tissue barrier for protection between the pharyngeal reconstruction and the great vessels.
CONTRAINDICATIONS
There may be considerations in some settings where the radial forearm may not be ideal or feasible. For instance, I have had patients in whom rheumatologic conditions exist or severe Raynaud disease where the potential for added dexterity or vascular morbidity may not be reasonable. Additionally, a number of patients through the years have had the radial arteries harvested for prior cardiac surgery eliminating the radial forearm as a donor site. Prior free flaps or trauma may also preclude its use. In these patients, other potential fasciocutaneous sites must be considered, such as the lateral arm, rectus, anterolateral thigh (ALT), or scapula.
PREOPERATIVE PLANNING
My primary considerations in choosing a free tissue donor site include the size of the defect, rigidity of the cervical skin, donor vessel selection, and patient body habitus (Fig. 11.3). Secondary considerations are prior surgeries and prior oncologic treatments in addition to the patient’s nutritional status. Ideally, I think of the best repair for a lateral pharyngeal defect to be a radial forearm flap for a number of reasons. Its thin pliable nature allows for an excellent tissue match for the lateral defect such that there is less difficulty aligning the thickness of the skin and mucosal anastomotic line, especially if it extends a distance onto the cervical spine region and posterior pharyngeal wall. While a thicker flap can certainly be used for closure, I have found that the thicker flaps can be the cause of airway and pharyngeal obstruction postoperatively that may later require attention to allow for decannulation and restoration of PO intake.
FIGURE 11.3 This photograph demonstrates a typical pharyngeal defect. Note that the cranial nerves have been preserved to assist with functional restoration.
For example, if a bulkier flap is used, such as an ALT flap in a heavier-set individual and one in which there is a musculocutaneous perforator, it may be more difficult to close the neck if the native neck tissues are contracted from prior surgery or radiation. One can certainly consider a perforator ALT flap to minimize the need for harvest of the vastus lateralis or consider primary thinning of the subcutaneous adipose tissue, but the forearm gives such versatility with its inherent likeness to the pharyngeal mucosa and musculature in thickness that I believe it should be given first consideration for the lateral defect. A large proximal volume of skin and/or subcutaneous tissue may be included to be deepithelialized for carotid coverage and improved contour of the neck or externalized for a monitoring segment or repair of an external skin defect in a contracted neck. Additionally, its long vascular pedicle, ability to be neurotized, and potential use of the cephalic venous system give the reconstructive surgeon more options in both the vessel-replete and vessel-depleted necks. Its length allows for reach to the transverse cervical or contralateral neck, and the cephalic provides for a reasonable match for the external jugular vein when present. The paired venae comitantes can often be traced proximally in the arm to a unified larger vein or can be taken just distal to a bridging vein between them which may allow for a larger caliber anastamosis in those patients where the comitantes are small. The drawback through the years has been the donor site morbidity and need for a secondary surgical site to harvest the skin graft. I have not found the donor site morbidity and tendon exposure to be significant with meticulous attention to preservation of the paratenon during harvest and prevention of desiccation of the paratenon while awaiting skin graft repair. In many cachectic patients, the ALT flap resembles the forearm in thickness and quality and therefore may be the donor site of choice in those patients.
SURGICAL TECHNIQUE
Keys to successful reconstruction of the lateral pharyngeal wall involve having an intimate understanding and respect for the balance of providing a sealed pharyngeal conduit while minimizing the effect on maintaining a patent airway and ability to swallow without aspiration. Care must be taken to size the flap appropriately not only in thickness but in overall dimensions. For instance, an oversized flap may produce redundancy that occludes the airway or obstructs the esophageal inlet. I keep in mind not only the primary size of the skin paddle but also potential edema that will occur for a period of time especially in those who have had radiation or those who will be going through radiation. Conversely, sizing a skin island too small may cause excess tension on the suture lines that could predispose to fistulization or flap and pharyngeal mucosal ischemia. My preferred suture is a 3-0 horizontal lubricated polyglactin suture to achieve a tension-free watertight closure. Over and undertying knots can lead to fistulization either by inducing ischemia along the suture line or by being too loose allowing for egress of saliva through an “air knot” or through sutures placed at too wide an interval. Although already precoated, I have the surgical scrub run the suture through a Xeroform gauze to minimize the friction as the suture is passed through the radiated tissue and ischemic flap. My thoughts are to minimize the chance of enlarging the size of the hole already created by the needle and the suture via a “sawing” mechanism akin to a Gigli saw used for cutting bone. While a theoretical advantage, I prefer the smooth feeling as I place and draw the suture through the tissue. Care must also be taken while making adjustments in suture length while tying the knot, making certain to keep the anastomotic line in a neutral plane while trying to prevent sudden repetitive bursts of force if the suture line is pulled upward or torqued in various directions while tying (often seen when tying is performed by a more junior level assistant). I also prefer polyglactin due to its absorption profile from a time standpoint (approximately 3 weeks) and hydrolysis degradation. This theoretically reduces the inflammatory response seen in sutures undergoing protein degradation and may allow for improved healing of the anastomotic line.
I begin the inset along the posterior pharyngeal wall and work cephalad toward any oro/nasopharyngeal component and caudad to transition to the esophageal inlet (Fig. 11.4). I periodically assess the length of the remaining pharynx and flap so as to make adjustments with length mismatch gradually over the course of many stitches, rather than having to reduce a large mismatch over the course of a few stitches. Care must be taken to prevent excess redundancy in the pyriform sinus in order to minimize the chance of a reservoir that could inhibit future swallowing and serve as a potential source of aspiration. Superiorly, one must work transcervically in those patients not opened with a mandibular split. I find it helpful to have an assistant retract the mandible and place the patient in slight Trendelenburg position to aid in reaching the highest point of the reconstruction. There are instances where the robot could be considered to aid in transoral repair and inset in a hybrid fashion in those patients not split or those whose tissues are rigid from prior therapy. The final line is the anterior aspect of the pharynx where I ultimately convert from a horizontal mattress with the knot directed into the lumen and on the flap side of the anastomosis to a modified Connell-type suture for the final centimeter of closure. The exact suture material and type of suture used are surgeon dependent but should be everting and tension distributing. If a mandibular swing is employed, care must be taken at the trifurcation point between the base of tongue/posterior floor of the mouth and superolateral pharyngeal wall, which is a natural watershed area that requires special attention. I use sutures that include all three walls of closure to allow for proper tissue coaptation at this site.
FIGURE 11.4 This photograph demonstrates the radial forearm free flap positioned into the defect. The adipose tissue lining the vascular pedicle of the radial forearm free flap is used to cover the great vessels during the healing process.
If the flap used is bulky or myocutaneous in nature, I usually consider using support sutures through the fascia or horizontal sutures through muscle to reduce the tension on the flap from the forces of gravity. In some instances, a large flap may allow for a second “bolstering” layer to the anastomotic lines. In other circumstances, it may preclude closure of the contracted neck skin, thus requiring thinning of the flap or split-thickness skin grafting. If thinning is performed, my preference is to do so while the flap is revascularized to minimize potential damage to primary or secondary perforators to the skin.
I prefer to inset the flap first when possible. In my opinion this minimizes trauma and movement of the flap pedicle while insetting. If ischemic time lengthens due to a difficult inset, I will revascularize and finish the inset after. I choose to neurotize flaps to allow for potential sensory input for the patient that may aid in detecting bolus or residual presence during swallow. A potential nerve donor is the local glossopharyngeal contribution. Vessel selection is a vast topic, but consideration may be given to allow for adequate draping of the pedicle to create a favorable geometry taking into consideration future neck movements that could predispose to a kink or obstruction of the vessels. Quality of vessels, size, location, and flap selected all play roles in the decision of which are chosen for recipient site. Please refer to those chapters dedicated to this subject as it is a critical part of the algorithm that has a direct impact on successful patient outcomes.
POSTOPERATIVE MANAGEMENT
The flap viability must be checked routinely. This may be performed with pinprick or Doppler evaluation. Postoperatively, the patient remains NPO for 7 days unless there has been prior radiotherapy in which case the patient remains NPO for 14 days. I prefer to perform a barium swallow evaluation prior to initiation of an oral diet. This ensures that there is no evidence of fistula or aspiration. The donor site is managed with a splint for 5 to 7 days. This helps to ensure that the skin graft used to reconstruct the donor site heals completely. After the skin graft is healed, I prefer to have the patient begin occupational therapy to ensure that strength and flexibility are regained in the donor site hand.
COMPLICATIONS
The main concern for a flap surgeon is vessel thrombosis leading to flap loss. Thankfully, with meticulous attention, success rates are in excess of 98% at my center and many high-volume major medical centers. Other concerns include fistula formation especially in those patients who have undergone prior radiotherapy. While present in some series in excess of 30%, if not recognized and managed appropriately, fistula formation can lead to flap compromise via inflammatory response, infection, external skin dehiscence, vessel exposure, and salivary contamination. Exposure and rupture of the carotid artery, either internal or externally, can occur, and one should be cognizant of the location of the great vessels in relationship to the fistula and skin breakdown. Hematoma formation, drug reaction, and perioperative cardiopulmonary complications must be identified and managed appropriately. The head and neck team must be vigilant with twice daily team rounds monitoring wounds and managing these complicated patients. Drains and flap checks must be done around the clock.
RESULTS
The radial forearm free flap provides an excellent method for reconstruction of the defect in the lateral pharyngeal wall. The pliable soft tissue associated with this donor site provides excellent restoration of the anatomy. The donor site is reliable and is associated with minimal donor site morbidity. In my experience, this donor site is a very popular approach for reconstruction of this defect. Although I have not used sensory innervation, this may improve the function, although there is a paucity of data to support this contention. The long vascular pedicle associated with this donor site is ideal for salvage surgery and for use in the vessel-depleted neck. I found that this donor site is my first choice for defects in the lateral pharyngeal wall.
PEARLS
• Thin pliable fasciocutaneous flaps such as the radial forearm or ALT (in thin individuals) are ideal donor sites for lateral pharyngeal reconstruction.
• Be mindful not to over or undersize the skin paddle.
• Consider the potential exposure of the carotid artery when insetting and draping the flap pedicle in the neck.
• Watertight closure is essential, paying careful attention to proper knot placement and tension.
PITFALLS
• Oversized flaps may inhibit functional outcomes for patients and may prevent decannulation and feeding tube removal.
• Lateral pharyngeal fistulization poses a risk to the carotid artery from contamination and exposure standpoint.
• Excess wound tension can predispose to fistula formation.
INSTRUMENTS TO HAVE AVAILABLE
• General head and neck surgical tray
• Microvascular surgical instrumentation
SUGGESTED READING
Sumer BD, Gastman BR, Nussenbaum B, et al. Microvascular flap reconstruction of major pharyngeal resections with the intent of laryngeal preservation. Arch Otolaryngol Head Neck Surg 2009;135(8):801–806.
De Almeida JR, Park RC, Genden EM. Reconstruction of transoral robotic surgery defects: principles and techniques. J Reconstr Microsurg 2012;28(7):465–472.