Bruce H. Haughey
INTRODUCTION
Complete oncologic clearance of advanced cancer of the tongue may require a total glossectomy: the end result of this procedure in itself may cause life-threatening loss of function and marked reduction in quality of life. Reconstructive techniques aim to create a neotongue that potentially restores the fundamental functions of airway protection, swallowing, and articulation. In this context, free tissue transfer has evolved as a standard technique for reconstruction of the tongue. A variety of musculocutaneous and fasciocutaneous donor tissues have been described including gracilis, rectus abdominis, latissimus dorsi, radial forearm, and anterolateral thigh (ALT) flaps. Reconstruction with sensate fasciocutaneous flaps has also been proposed, seeking better functional results.
In my practice, the flap of choice for reconstruction of total glossectomy defects is the motor-innervated musculocutaneous latissimus dorsi flap. Acceptable outcomes for swallowing and speech intelligibility have been achieved with the use of this flap. Techniques of latissimus dorsi and ALT free flap reconstruction are described below. The descriptions herein assume and facilitate preservation of the larynx.
Anatomy and Physiology of the Tongue
The tongue is a unique anatomic structure with a complex array of extrinsic and intrinsic muscles and a rich neurovascular supply. The extrinsic muscles include the genioglossus, hyoglossus, styloglossus, and the palatoglossus. The genioglossus and hyoglossus insert into the tongue from their bony origins inferiorly, while the styloglossus and palatoglossus insert from superior and lateral. These muscles are responsible for positioning the tongue in protrusion, retraction, elevation, and depression movements. By contraction of the digastric muscles (via the hyoid bone) and the muscular diaphragmatic floor, created by mylohyoid, along with the suprahyoid muscles, these extrinsic muscles elevate the tongue toward the base of the skull, lifting it high into the oral cavity.
The intrinsic musculature of the tongue is arranged in two bundles of interwoven fibers. One bundle runs across the entire length of the tongue and consists of the superior longitudinal and inferior longitudinal muscle fibers, while the other contributes to the main bulk of the tongue and consists of vertical and transverse fibers. The intrinsic muscles, partly assisted by extrinsic muscles, contract to produce changes in the shape of the tongue, critically important for articulation and swallowing.
The groove behind the row of circumvallate papillae or sulcus terminalis divides the tongue into an anterior two-thirds, mobile or oral tongue, and a posterior one-third or the base of the tongue, with bilateral lingual tonsils. The oral tongue is instrumental in the production of intelligible speech. Fine coordination of its contractions and movements helps to manipulate and propel the food bolus toward the pharynx during the oral phase of deglutition. The posterior part of the base of the tongue provides the driving force for initiation of the pharyngeal phase of deglutition. The tongue contributes to the critical function of airway protection by its strategic location in the oral cavity and the oropharynx, above the epiglottis, and also by providing dynamic laryngeal support via the geniohyoid to the mandible and via the styloglossus to the base of the skull.
The hypoglossal nerve provides motor innervation to both the intrinsic and extrinsic muscles except the palatoglossus muscle, which is innervated by the pharyngeal branch of the vagus nerve. General sensory supply from the oral tongue is mediated by the lingual nerve and from the posterior third of the tongue by the glossopharyngeal nerve. Special taste afferents from the oral tongue and the base of the tongue also travel to the central nervous system via the lingual nerve and the glossopharyngeal nerve, respectively.
The extraordinarily unique, multifunctional properties of the human tongue create a predicament following total glossectomy that is difficult to overcome.
Goals of Reconstruction
After total glossectomy, the defect extends from the nadir of the vallecula forward and superiorly to include the entire tongue and partial or entire floor of the mouth. The lingual and hypoglossal nerves are sacrificed bilaterally. This results in loss of articulation, oral preparatory and propulsive phases of deglutition, the piston-like action of the base of the tongue for initiation of the pharyngeal phase of deglutition, and the sense of taste. To date, no reconstructive technique has been able to restore the functions incorporated in the complex musculature of a normal tongue. The aim, however, is to create a neotongue that is capable of simulating such actions to an extent that confers, after appropriate rehabilitation, acceptable though modified function and quality of life. The specific objectives of reconstruction are to
• Provide laryngeal protection to minimize the risk of aspiration
• Achieve flap contact with the palate via appropriate tissue bulk and shape
• Facilitate articulation and mastication via suitable shape of the tip and dorsum
• Assist swallowing via passive mobility of the flap, driven by surrounding muscles
• Provide motor innervation for potential active flap contraction
• Provide sensory innervation, if possible
Latissimus Dorsi Free Flap
Described by Tansini in 1896, the latissimus dorsi flap enjoys the distinction of being the first musculocutaneous flap described in the medical literature. As a versatile perforator flap, Quillen first reported its use in head and neck reconstruction in 1978, followed by Watson who described its application as a microvascular free flap in 1979. Conventionally, longitudinally oriented latissimus dorsi flaps have been described for use in head and neck reconstruction. A modification of this conventional technique has been designed and adopted at our institution for total glossectomy reconstruction (Fig. 8.1).
FIGURE 8.1 Design of a right latissimus dorsi musculocutaneous flap for total glossectomy reconstruction. The skin paddle is oriented perpendicular to the axis of the muscle fibers.
Anterolateral Thigh Free Flap
The perforator-based ALT free flap emerged as an option for skin and soft tissue reconstruction after Song et al. described it in 1984. The use of the ALT flap for reconstruction of defects in the head and neck was first reported by Koshima et al. in a cohort of 22 patients. It gained widespread popularity for application in the Asian population, and Wei et al. have described outcomes for 475 patients, the largest series for head and neck reconstruction with the ALT available to date. The reduced application of the ALT flap in the Western population is attributed to a higher incidence of obesity, which causes excess thickness of adipose tissue in the thigh. Furthermore, variability in the vascular anatomy predisposes to difficult dissection. However, experience and expertise acquired by the microvascular surgeons to harvest and thin the flap have rekindled the interest in the application of the ALT flap for reconstruction in the head and neck in many centers.
HISTORY
Evaluation of medical comorbidities is an important component of preoperative history for free tissue transfers since these procedures subject the patient to prolonged anesthesia and fluid imbalance. Hematologic or hepatorenal abnormalities merit a thorough preoperative investigation and correction since these may affect the intraoperative blood loss, postoperative hematoma formation, and thus, the viability of flap. Conditions such as diabetes and active smoking cause small vessel obliteration and are known risk factors for microvascular complications, and necessary measures should be taken to avoid any compromise of the microvascular anastomosis. Preoperative correction of nutritional deficits helps optimize the healing process. Cigarette smoking, administration of more than 7 L crystalloids (approximately 6 mL/kg/h), and weight loss of over 10% prior to surgery have been found to be significant for the overall flap complication rate in our analysis of cases with free tissue transfer.
PHYSICAL EXAMINATION
Assessment of the general body habitus and performance status of the patient is important for any free flap reconstruction to design a plan for harvest, donor site closure, and functional preservation. Furthermore, a complete examination of the head and neck by the microvascular surgeon with prediction of the probable surgical defect following total glossectomy, and careful examination of the donor site are critical in decision-making. Previous traumatic or surgical scars in the head and neck, skin cancer and radiation damage are important considerations in planning the placement of incisions for resection and protection of suitable recipient vessels. Examination of skin and soft tissue bulk, presence of scar, and presence or absence of arterial pulses (axillary, femoral) also influence selection of the donor site. For example, a large, previous thoracotomy incision may have traversed the latissimus dorsi muscle.
INDICATIONS
The latissimus dorsi flap provides suitable bulk and volume for true total glossectomy defects that include the entire base of tongue and oral tongue in the resection. It is also an ideal mode of reconstruction where there is an anticipated need for motor innervation. The ALT flap is more suitable for reconstruction of total oral glossectomy defects and is the flap of choice when a sensate reconstruction is planned. It is also a more conveniently accessed donor site.
CONTRAINDICATIONS
Latissimus Dorsi Flap
Congenital absence of latissimus muscle associated with Poland anomaly or other familial defects of the shoulder girdle is an absolute contraindication. Patients with a scar on their back or with a preexisting disability of the back or shoulder girdle do not make ideal candidates for reconstruction with the latissimus dorsi flap. It is also relatively contraindicated in patients with a history of previous surgery in the axilla due to the risk of possible disruption of the proximal vascular supply to the muscle.
Anterolateral Thigh Flap
Absence of musculofasciocutaneous perforators from the descending branch to the skin paddle is an absolute contraindication to this flap (see below, Pitfalls). Previous injury or surgery of the upper thigh such as vascular bypass procedures are relative contraindications for reconstruction with the ALT flap. Also, atherosclerotic superficial femoral arterial occlusion may result in substantial collateral flow through the profunda femoris and its branches to the distal lower limb. If such a situation pertains, the patient should be evaluated by a vascular surgeon before proceeding to harvest an ALT flap. The presence of a thick saddle bag of adipose tissue in the thigh makes such patients less than ideal candidates for ALT reconstruction because of the excess tissue bulk transferred to the recipient site.
PREOPERATIVE PLANNING
Fundamental to preoperative planning is a thorough knowledge of the anatomy of the donor site, which is critical to the flap harvest and reconstructive technique. Pertinent anatomic details of the latissimus dorsi and ALT flaps are discussed below.
Anatomy of the Latissimus Dorsi Free Flap
The latissimus dorsi muscle originates from the spinous processes of the lower six thoracic vertebrae, posterior iliac crest, the thoracolumbar fascia, last four ribs, and inferior angle of scapula. It inserts at the medial aspect of the intertubercular groove of the humerus. The dominant blood supply of the flap arises from the thoracodorsal artery, which is one of the two branches of the subscapular artery. The latter is the largest branch of the axillary artery and originates from its third part, gives rise to the circumflex scapular artery before continuing as thoracodorsal artery. The thoracodorsal artery enters the upper border of the latissimus dorsi and divides within the muscle into superior and lateral branches. It also gives a branch to the serratus anterior muscle that needs to be ligated during flap harvest. In its inferior half, the muscle receives perforators from the thoracic intercostal and lumbar arteries. The overlying skin is nourished by multiple musculocutaneous perforators that are more abundant over the upper two-thirds of the muscle, making it the preferred site for harvest of the skin paddle.
Venous drainage of the muscle is via the venae comitantes that accompany the thoracodorsal artery during their course along the undersurface of the latissimus dorsi muscle, draining to the axillary vein. The artery may vary in diameter from 1 to 4 mm, and the diameter of the vein may range from 2.5 to 4.5 mm. The motor innervation to the latissimus dorsi is provided by the thoracodorsal nerve (middle subscapular nerve), derived from the posterior cord of the brachial plexus (C6, C7, and C8). The nerve travels distally with the vascular pedicle, but closer to the vein.
Anatomy of the Anterolateral Thigh Flap
For reconstruction following a total glossectomy, the ALT flap is usually harvested as either a perforator-based myocutaneous flap including portions of vastus lateralis muscle or a fasciocutaneous flap (Fig. 8.2).
FIGURE 8.2 Anatomy of a right ALT flap. Black line represents the intermuscular septum between rectus femoris and vastus lateralis. A, B, and C represent the likely location for proximal, middle (most common), and distal perforators, typically separated by 5 cm. LCFA, lateral circumflex femoral artery.
Fascial and Muscular Anatomy
The superficial fascia of the thigh forms a continuous layer over the thigh and consists of areolar tissue. It may be separated into two or more layers, between which are found the superficial vessels and nerves. The deep fascia of the thigh, the fascia lata, varies in thickness in different parts, being thicker in the superior and lateral aspect of the thigh. The muscles encountered during ALT flap harvest include the rectus femoris, vastus lateralis, and the tensor fascia lata. The rectus femoris arises from two tendons: one from the anterior inferior iliac spine and the other from the acetabulum. It occupies the middle of the front of the thigh and ends into a flattened tendon that inserts into the superior patella. The vastus lateralis is the largest part of the quadriceps femoris. It arises by a broad aponeurosis attached mainly to the superior part of the intertrochanteric line and to the anterior and inferior borders of the greater trochanter. The fibers run inferiorly over the lateral side of the thigh and thicken into a flat tendon for insertion into the lateral border of the patella. The tensor fascia lata occupies the lateral border of the thigh. It arises from the posterior part of the iliac crest, anterior superior iliac spine, and the deep surface of the fascia lata and gets inserted between the two layers of the fascia lata close to the junction of the middle and upper thirds of the thigh.
Vascular Anatomy
The ALT flap is based on the perforating vessels arising from the descending branch of the lateral circumflex femoral artery (LCFA). The LCFA is a branch of the profunda femoris artery and divides into ascending, descending, and transverse branches. The descending branch of LCFA is usually associated with two venae comitantes. It travels obliquely and inferiorly in the intermuscular groove between the rectus femoris and vastus lateralis along with the nerve to the vastus lateralis and terminates in the vastus lateralis just above the knee. The descending branch provides several perforators to the skin of the lateral thigh. These vessels pass in either a septocutaneous or myocutaneous pattern. The septocutaneous perforators run between the rectus femoris and vastus lateralis muscles and traverse the fascia lata to supply the skin of the lateral thigh as septocutaneous perforators. Alternatively, the perforators can traverse the vastus lateralis muscle tissue and the deep fascia and supply the skin as musculocutaneousperforators.
Septocutaneous perforators are highly inconsistent in their number and origin. The proportion of septocutaneous (vs. musculocutaneous perforators) varies from 10% to 60% across different clinical and cadaveric studies. By contrast, musculocutaneous perforators are more constant, present in 50% to 90% of cases. This variation in vascular anatomy is important to know since elevation of the ALT flap requires meticulous intra-muscular dissection for preservation of musculocutaneous perforators.
The average diameters of the vascular pedicle are reported to be 2.1 mm for the artery and 2.6 mm for the vein. These measurements may, however, range from 1.5 to 4 mm and from 1.5 to 5.0 mm, respectively, for the artery and the vein.
Classification of the Perforators
The perforators have been classified by Yu et al. for better identification during flap harvest.
1. Classification Based on the Pattern of Location: The cutaneous perforators are usually concentrated within a radius of about 3 cm around the midpoint of the line between the anterior superior iliac spine and superolateral patella. However, more perforators have been discovered that are spread over a larger part of the ALT flap. These are usually present in predictable locations about 5 cm apart and have been named as perforators A (most proximal), B (middle), and C (most distal); Perforators B are present most consistently.
2. Classification Based on the Origin: The cutaneous perforators have been classified as types I, II, and III based on their origin from the parent artery.
Type I: This is the most common type in which perforators originate from the descending branch of the lateral circumflex femoris artery and travel as septocutaneous or musculocutaneous perforators.
Type II: A single cutaneous perforator derives from the transverse branch of the lateral circumflex femoris artery and travels longitudinally within the vastus lateralis muscle for its entire length before it enters the fasciocutaneous flap.
Type III: A single perforator derives directly from the profunda femoris artery and pierces through the rectus femoris muscle to reach the fasciocutaneous flap.
Sensory Innervation
The lateral femoral cutaneous nerve is the dominant sensory nerve of the ALT. It is a direct branch of the lumbar plexus (L2, L3) and enters the thigh deep to the lateral aspect of the inguinal ligament near the anterior superior iliac spine. It consistently runs along the line connecting the anterior superior iliac spine and the superolateral patella in the deep subcutaneous tissue immediately above the fascia.
Nerve to the Vastus Lateralis Muscle
The nerve innervating the vastus lateralis muscle is intimately related to the descending branch of the lateral circumflex artery. Two particular variations of the anatomy of the nerve make it susceptible to interruption during harvesting of the ALT flap, thus increasing the risk of denervation of the muscle: One where the motor nerve courses through the vascular pedicle or another where it travels between the perforators supplying the flap. The frequency of the presence of at least one of these unfavorable variations had been reported to be 28% in one of the anatomical studies. However, denervation of the vastus lateralis appears to cause little or no functional loss.
Assessment of Recipient Vessel Availability
Evaluation of the history of previous treatment and physical examination of the entire head and neck will alert the reconstructive surgeon, especially in the setting of previous radiotherapy or neck dissection, to vessel abnormalities. Doppler ultrasonography or angiography in patients with known vessel depletion or carotid artery disease may be required to assess the adequacy of the external carotid artery and its branches for selection of an appropriate recipient vessel for microvascular anastomosis.
SURGICAL TECHNIQUE
Latissimus Dorsi Free Flap
Flap Design
The unique features of my latissimus dorsi flap design include transverse orientation of the skin paddle, demarcation of the skin paddle into two portions—one anterior and another posterior—incorporation of two lateral skin and muscle “wings” (Fig. 8.3), and incorporation of the motor nerve to the latissimus dorsi muscle.
FIGURE 8.3 Right latissimus dorsi free flap harvest. Two silk marker sutures placed on the sides of the muscle component to reference the in situ length–tension relationship.
The flap is fashioned in a way so that the musculature forms a transverse sling or “hammock” across the floor of the mouth, and the skin is sufficiently redundant so as to be sculpted vertically at the front of the mouth for articulation. The longitudinal dimensions of the flap allow adequate curvature and suspension of the midportion of the skin and muscle component at the isthmus of the oropharynx. This design facilitates creation of oral and pharyngeal portions of the skin paddle that partially simulate oral tongue and the base of tongue, respectively, in structure and function.
Flap Harvest
Harvesting of the latissimus dorsi flap requires a lateral decubitus and a 45-degree shoulder and trunk up position. By rotating the table toward the donor site, resection is facilitated and by rotating the table away from the donor site, harvest is facilitated. This avoids repositioning the patient during the procedure.
Prior to harvesting the flap, using the Doppler flowmeter, the course of the thoracodorsal artery may be marked from its origin from the subscapular artery to the point where it enters the muscle. The skin paddle is carefully marked on the back at the site of flap harvest. The axis of the skin paddle is oriented at a right angle to the underlying muscle fiber axis. The length of the skin paddle equals the distance measured from the anterior floor of the mouth or the mandibular arch, curving superiorly to the palate, and proceeding to the posterior aspect of the defect. The posterior end of the defect is usually the nadir of the vallecula. In cases requiring supraglottic laryngectomy, it may be either the base of the epiglottis or the anterior commissure. The curvilinear transverse dimensions of the flap may be approximated by measuring the width of the mandibular arch and multiplying by (π × d)/2, π assuming that the flap will be shaped as a semicircle in the mouth, to resemble the contour of dorsum of oral tongue. Alternatively, for measuring the transverse dimensions, a flexible ruler curved to the desired shape and position of the flap in contact with the hard palate may also be used.
For flap harvest, once scribed on the back, an incision is first made across the anterolateral aspect of the skin paddle, extended superiorly and follows the lateral free border of the muscle into the axilla. Here, the neurovascular pedicle is identified by blunt dissection through the axillary fascia and adipose tissue. Incisions are made on the inferior, medial, and superior aspects of the paddle down to the fascia of the latissimus dorsi muscle. Tacking sutures are then placed between the skin and underlying muscle. The musculature is sharply transected at the distal end of the flap and around the margins of the flap medially and laterally. The neurovascular pedicle is identified entering the muscle on its deep surface underneath, at the lateral border of the muscle, approximately 8 to 10 cm from the midpoint of the axilla. At this stage, two silk marker sutures may be placed across the muscle at a measured distance apart (8 to 10 cm) to allow accurate recreation of the resting length of muscle at inset (Fig. 8.3). The pedicle is dissected and traced into the axilla up to the origin point of the circumflex scapular artery. This requires ligation and division of the artery to the serratus anterior. Finally, the muscle is transected superiorly while carefully preserving the vascular pedicle that is later divided distal to the takeoff of the circumflex scapular artery from the subscapular artery (Fig. 8.4). The free flap is harvested with an intact motor nerve to latissimus dorsi (middle subscapular nerve or long scapular nerve) that is released sharply from its origin at the brachial plexus. The flap can be made sensate by harvesting an intercostal nerve from the chest.
FIGURE 8.4 Latissimus dorsi flap harvested with the musculocutaneous component, vascular pedicle, and thoracodorsal nerve exiting to the right.
In total glossectomy defects with mandibular resection, the flap may be harvested with the lateral scapular border or the tenth or eleventh rib. These provide a source of vascularized bone for reconstruction of the mandibular ramus in the same surgical sitting.
Closure of the Donor Site. Hemostasis is secured, and suction drains are inserted. The reapposition of the skin edges of the wound defect at the donor site on the back is usually accomplished as a three-limbed closure, resembling a Y shape (Fig. 8.5). Interrupted deep 2-0 sutures are followed by skin closure. Tension is avoided at the skin level of the donor site defect, to prevent wound dehiscence.
FIGURE 8.5 Three-limbed Y-shaped closure of the donor site after latissimus dorsi flap harvest on the right.
Flap Inset
After the recipient vessels are skeletonized and prepared in the neck, the pedicle is detached, and the flap is brought to the neck for performing the microvascular anastomosis. Once the arterial and venous anastomosis is completed and excellent flow is ensured, the nerve graft to the latissimus dorsi is brought into the field. It is anastomosed to the hypoglossal nerve on the side ipsilateral to the microvascular anastomosis. The nerve anastomosis is performed by end-to-end epineural neurorrhaphy using three to four 9-0 nylon sutures. This procedure potentially confers to the neotongue, the ability to elevate superiorly toward the palate thus facilitating better swallowing rehabilitation. Occasionally, an interposition nerve graft harvested from the greater auricular or sural nerve may be needed to bridge the distance between the donor nerve and the recipient hypoglossal nerve.
For flap reconstruction, access to the oral cavity and the oropharynx is available from a stepped mandibular osteotomy or a pull-through approach via the neck created by the oncologic resection. During the flap inset, the paddle is rotated such that the skin is oriented with its long axis parallel to the midline. The contouring of the flap tissue is accomplished with a series of suturing and multidimensional folding maneuvers in order to reconstruct the tip and body of the neotongue.
The distal margins of the flap are sutured across the anterior edge of the remnant of the base of the tongue, the mucosa of the vallecula, or the base of the epiglottis. Suturing of the flap to the region of the base of the epiglottis is recommended since it allows for normal downward folding movements during deglutition. Posterolaterally, the flap is sutured to the left and right pharyngeal walls. The two wings of skin and muscle, incorporated at the midpoint of the flap, are set into the tonsil fossae. The direct suturing of the muscle flap to the recipient site muscle may require a tonsillectomy. The muscle is inset as a transverse sling across the isthmus of the oropharynx by suturing it to the remnant of the medial pterygoid, masseter, or superior constrictor muscle depending on the availability (Fig. 8.6A). This maneuver creates an antigravity suspension of the flap from the left to the right skull base, and also a potentially dynamic reinnervated muscle sling to aid in uplifting the flap with swallowing efforts.
FIGURE 8.6 A. Latissimus dorsi free flap inset. Transverse sling created at oral–oropharyngeal isthmus by suturing of muscle flap to medial pterygoid and masseter muscle. B. Triangular wedge-shaped area marked anteriorly for de-epithelialization and imbrication for creation of neotongue tip.
In the mouth, the flap is sutured laterally to the alveolar ridges and the cut edges of the mucosa of the floor of the mouth, from posterior to anterior, using an advancement technique. Redundant flap tissue in the anterior midline is elevated superiorly with a skin hook, and the unattached margins of the flap are sutured vertically in the midline. This maneuver helps create a glossomandibular sulcus and a cupula of tissue in the anterior aspect of the flap in order to raise the tissue superiorly, for neotongue-to-hard palate contact. Two suspension sutures are placed between the flap tissue and the hard palate to enable correct positioning of the tissue. The anterior flap epithelium is thereafter, de-epithelialized, imbricated, and the margins of the de-epithelialized segment are approximated together with 3-0 Vicryl to create the neotongue tip (Fig. 8.6B). This maneuver traps a core of dermis, which helps in providing bulk and stiffening of the tip (Fig. 8.7).
FIGURE 8.7 De-epithelialization of the anterior wedge.
Finally, the anterior aspect of the floor of the mouth mucosa is closed with 3-0 Vicryl sutures. The muscle flap is further anchored transversely across the floor of the mouth to the anterior digastric bellies if preserved (Fig. 8.8). This gives an excellent tightening of the anterior floor of the mouth component. The mandibular osteotomy is repaired by approximation of the mandibular segments with placement of a precontoured and predrilled reconstruction plate. The anterior belly of the digastric is also reattached to the mandible beneath the flap for reinforcing antigravity support.
FIGURE 8.8 Margins of de-epithelialized segment sutured together to trap a core of dermis and create a “cupula” anteriorly for neotongue to hard palate contact.
Additional support for muscle flap bulk with a transverse Gore-Tex sling below the mandible from one angle to another is recommended to prevent gravitational prolapse of the flap from the oral cavity into the neck. Placement of a heavy monofilament suture between the hyoid bone or thyroid cartilage and anteriorly to the mandible can assist in swallowing and protection of the glottis.
Flap Inset After Total Glossectomy and Supraglottic Laryngectomy. In cases where a supraglottic laryngectomy has been performed with total glossectomy, the distal margins of the flap are sutured to the thyroid perichondrium and/or cartilage. Anterior suspension of the laryngeal remnant from the mandible with left and right 2-0 monofilament nylon suture is desirable since this maneuver tilts and transposes the glottis forward beneath the posterior flap and provides static support for minimization of aspiration during swallowing.
Anterolateral Thigh Flap
Flap Design
The intermuscular septum between the rectus femoris and the vastus lateralis muscle is marked by drawing a line between the anterior superior iliac spine and the superolateral border of the patella. The cutaneous perforators are mapped by use of a handheld Doppler probe. They are usually present around the midpoint of the line representing the intermuscular septum within a circle of 3 to 5 cm radius (Perforator B). Perforators A and C can be present at locations further from the midpoint as described earlier (Fig. 8.9).
FIGURE 8.9 An intraoperative photograph showing identification of perforators during harvest of a left ALT flap.
After completion of the total glossectomy, the exact dimensions of the defect are measured to finalize the design of the flap. The flap is deliberately marked with its center located in the area with maximum number of cutaneous perforators. The long axis is kept parallel to the axis of the thigh. The skin paddle may be fashioned to incorporate laterally, two wings of skin for suspension, similar to the technique described for the latissimus dorsi myocutaneous flap.
Flap Harvest
The remote location of the donor site from the head and neck defect allows adoption of the simultaneous two-team approach for flap harvest. Proper positioning of the leg facilitates dissection during harvest of the ALT free flap. The ideal position is with slight knee flexion and internal rotation at the hip. The skin incision is initially made on the anteromedial side of the marked skin paddle and is deepened until the fascia lata is reached. The incision is carried through the fascia lata, including it in the flap. Identification of the perforators to the skin requires blunt lateral mobilization of the flap. Once the vessels are located, the skin incisions are completed circumferentially. Subfascially, the dissection is continued toward the septum between the rectus femoris and the vastus lateralis muscles to explore whether the perforator is septocutaneous or myocutaneous. These are traced further proximally until the main pedicle is reached. The pedicle is located by continuing the dissection between the rectus femoris and vastus lateralis muscles in patients with septocutaneous perforators and through the vastus lateralis muscle in patients with myocutaneous perforators.
The musculocutaneous perforator gives off small branches to the vastus lateralis muscle from the lateral and posterior sides of the vessel and rarely from the anterior aspect. Thus, the course of the perforator is traced by incising the muscle over the perforator followed by ligation of the branches to the muscle from lateral and posterior sides. The perforator is then traced to the descending branch of the LCFA and is further dissected proximally along the descending branch according to the pedicle requirement. A small cuff of muscle may be left around the perforators to facilitate the speed of the harvest.
Ligation of the transverse branch of the LCFA and the branch to the rectus femoris muscle can allow harvesting of a longer pedicle. This may be required for reaching the contralateral neck vessels, if due to previous surgery or irradiation, the ipsilateral neck lacks suitable vessels for anastomosis.
It is important to trace the perforator to the vessel of origin because occasionally, types II and III perforators may be encountered. Type II perforator requires a careful and tedious intramuscular dissection to free the perforator from the vastus lateralis for its entire length. The perforator originates from the transverse branch of the LCFA, and upon entering the muscle superiorly runs in an inferior direction necessitating dissection out of the muscle or extensive muscle harvest. The type III perforator runs to the skin through the rectus femoris and is thus anterior in location. It has both a small caliber and a short pedicle length. When faced with type III perforator, the plan to proceed further with flap harvest should be aborted in favor of other reconstructive options.
In the presence of myocutaneous perforators (the majority), portions of vastus lateralis muscle are included in the flap. It is preferable to elevate the flap such that the muscle is thicker proximally and thinner distally. The thicker portion at the base of the flap can be used to bulk the posterior part and dorsum of the neotongue, while the thinner end can be used to augment the tip. In order to make the flap sensate, the lateral femoral cutaneous nerve of the thigh may be harvested. The nerve is identified below the anterior superior iliac spine when the superior incision of the flap is made. It is possible to harvest an additional 5 cm of nerve by continuing the subcutaneous dissection proximal to the inguinal ligament.
Closure of the Donor Site. Hemostasis is secured, and the wound defect is closed after insertion of suction drain. The drain is carefully placed in the intermuscular space to avoid accumulation of fluid between muscle groups and in the subcutaneous space. In cases where intramuscular dissection has been done to identify the perforators, repair of the muscle segment by loose approximating stitches results in better preservation of function. The donor site can usually be closed primarily without requiring a skin graft. Primary closure of the donor site for a skin paddle as wide as 9 to 12 cm has been reported to be accomplished, but the use of a skin graft is generally recommended for defects exceeding 8 cm.
Flap Inset
Before insetting the flap, the subcutaneous component may require thinning, particularly in the obese patient. Reduction of bulk to the desired thickness requires meticulous dissection under magnification to identify the pattern of the perforators and avoid injuring them. The main perforator usually gives off a few branches that traverse suprafascially, deep in the adipose layer and then to the subdermal plexus. Identification of these branches precedes thinning of the flap. It is advised to preserve 2 mm of adipose tissue on the dermis to ensure that the subdermal plexus is not damaged. Thicker flaps are usually preferred for reconstruction following total glossectomy.
The microvascular anastomosis is carried out in the routine fashion followed by nerve anastomosis in patients undergoing a sensate flap reconstruction. Care should be taken to avoid twisting the pedicle while insetting the flap. The edges of the flap are sutured posteriorly and inferiorly to the base of the tongue or base of the epiglottis, depending on availability. Posterolaterally, the flap is sutured to the pharyngeal mucosa. The lateral skin and fascial processes, if incorporated in the flap design, are elevated and anchored into the tonsil fossae to provide antigravity support. Anteriorly, the edges of the flap are sutured to the gingival mucosa. Additional tissue on the flap may be de-epithelialized and folded beneath the skin paddle to reinforce the floor of the mouth reconstruction. However, in total glossectomy, optimum bulk of tissue is preserved during harvest to restore the height and volume of the neotongue.
Similar to my technique for latissimus dorsi flap inset, advancement sutures can be placed laterally between the edges of the flap and the gingival mucosa. This enables cupula formation anteriorly thus assisting with creation of the neotongue tip. Suture placement with 3-0 Vicryl preferably taking large bites and spacing at every 5 mm is recommended for watertight closure and better wound healing (Fig. 8.10).
FIGURE 8.10 Multidimensional technique for ALT flap inset used for reconstruction of total oral glossectomy defect. A. The flap is laid in transversely and sutured bilaterally from posterior to anterior using advancement technique. B. Suturing the redundant anterior flap edges to each other vertically in the midline creates anterior neotongue height. The midline of the remaining superior free margin is anchored to the vertical suture line to form a three-point junction. Arrows indicate the direction of tissue displacement. C. Fashioning of right-and left-sided, anterolaterally directed cones that are de-epithelialized (stippled area) and sutured together in the midline thus creating a neotongue. Curved arrows indicate arc of rotation of flap corners, to be sutured together in the midline following de-epithelialization.
A transverse Gore-Tex or preserved acellular cadaver dermis sling underneath the oral portion of flap and anchored to the mandible is useful to prevent tissue sagging. Gore-Tex is biologically well tolerated, although there is concern for possible infection or soft tissue reaction, alternatively acellular cadaveric skin graft may be used. When acellular cadaveric dermis is chosen, it is less rigid and more elastic compared to Gore-Tex. Laryngeal suspension from the mandible with sutures between the hyoid and holes drilled on both sides of the mentum is performed after completion of the flap inset.
Flap Inset After Total Glossectomy of the Oral (Anterior Two-Third) Tongue. In patients who undergo total oral glossectomy that includes no more than 1 cm of tongue base, the final steps of multidimensional folding technique are modified for recreation of the tip of the new oral tongue. After posterior inset across the tongue base and after ensuring adequate height for flap to palate contact, the midline anterior free edge of the skin paddle is depressed inferiorly to create a three-point junction. The right and left corners are sutured onto themselves to form anterolaterally directed cones. These cones are de-epithelialized, swung anteriorly, and sutured together in midline, thus entrapping dermis to stiffen and confer some bulk to the neotongue tip (Fig. 8.8).
POSTOPERATIVE MANAGEMENT
The patient is cared for in an observational unit and preferably kept sedated for 2 to 3 days to avoid neck movement–related shearing stresses on the microvascular anastomoses. Vigilant monitoring of the vital signs, flap viability, nutritional status, and the donor site is essential along with care of the tracheostomy tube and donor site wounds. Donor sites are managed with negative pressure drains and the neck with passive drains.
In patients with latissimus dorsi flap reconstruction, the arm is abducted and flexed often with pillows, to avoid any undue stretch or tension on the donor site wound repair. For tracheostomy management and dietary resumption see “Results.”
COMPLICATIONS
The early complications at the recipient site may include anastomotic occlusion, more commonly venous, leading to flap loss. Secondary hemorrhage, infection and, occasionally, wound breakdown and fistula formation may also occur.
Latissimus Dorsi Free Flap
At the donor site, hematoma and wound dehiscence may occur as early complications. The large area of tissue dissection may precipitate late seroma formation. This can be prevented by placing deep tacking sutures between the back skin flaps and the rib cage, pressure dressings, and maintenance of functional suction drains. Inadvertent injury on the lateral chest wall to the long thoracic nerve of Bell may result in “winged scapula.”
Anterolateral Thigh Flap
The ALT flap is considered by some to be more prone to venous occlusion or compression of the pedicle, but this is probably due to dissection of small intramuscular perforators versus leaving a more generous muscle cuff. Under these circumstances, loss of the flap due to compression of the muscular perforator may be avoided by reexploration and release of wound pressure. For small caliber perforators, inclusion of the muscle cuff around the vessel is recommended. As with other fasciocutaneous flaps, marginal necrosis may occur in cases where there has been excessive thinning.
Complications at the donor site are reported to be infrequent but include pain and functional morbidity. Extensive fascial elevation of the flap is believed to contribute to prolonged muscular weakness and fatigue. A higher incidence of complications has been demonstrated to correlate with extent of injury to the vastus lateralis and the need for a skin graft when larger flaps are used. In order to avoid the use of a skin graft, a V–Y perforator–based advancement flap has also been described. The quadriceps femoris muscle is largely composed of the vastus lateralis muscle fibers, and injury of the nerve to the vastus lateralis may compromise the quadriceps function. Quadriceps muscle testing has demonstrated significant deficits in motor function and motion of the range of the knee after flap harvest with an abnormality in gait analyses. A careful knowledge of nerve anatomy and possible variations along with complete skeletonization of the pedicle is believed to preserve the muscle. However, in some cases, the ALT flap cannot be harvested without sacrifice of the nerve.
Seroma formation may occur as in the postoperative period and can be prevented by placement of large bore suction drains. Delayed healing is possible, and contour deformity is customary but mild and easily concealed.
RESULTS
Latissimus Dorsi Flap
The latissimus dorsi myocutaneous free flap provides a large bulk of tissue for neotongue formation with limited donor site functional or cosmetic morbidity. The decrease in the muscle’s functions in adduction of the arm, extension, or medial rotation is not a source of significant compromise in the arm movement in the presence of active shoulder girdle muscles. The donor site can usually be closed primarily and does not usually require a skin graft.
The muscle flap provides a reliable and good caliber vascular pedicle with constant anatomical relationships. It can be harvested with portions of rib or scapula for bony reconstruction. The flap can be made sensate and when harvested with its motor nerve can potentially be made to contract for better functional results. Patients are usually decannulated 2 to 3 weeks following surgery, and muscle tissue bulk minimizes the risk of fistula formation. Swallowing rehabilitation can begin soon after decannulation.
In our institutional review of eleven tongue reconstructions with microvascular latissimus dorsi myocutaneous free tissue transfers, one flap failure occurred. Acceptable rates of restoration to oral alimentation, speech intelligibility, and decannulation were observed. Vertical movement of the flap, possibly attributed to successful reinnervation of the latissimus muscle, and initiated voluntarily by the patient, has been documented by video-oropharyngography.
Anterolateral Thigh Flap
The ALT flap is pliable and conforms appropriately to the three-dimensional defect in the oral cavity and oropharynx subsequent to total glossectomy. When endowed with sufficient adipose tissue, it fills the oral cavity and pharynx well enough to provide surface-to-surface contact for swallowing (Fig. 8.11). It offers the advantage of having good caliber vessels and a medium length pedicle. It also has the potential of being used as a sensate flap that has been associated with a higher degree of patient satisfaction; however, the sensory recovery of the neotongue has not been demonstrated to directly translate into better speech and swallowing function.
FIGURE 8.11 Neotongue following ALT reconstruction 2 months postoperatively.
PEARLS
• Latissimus dorsi free flap: The key to a successful latissimus dorsi free flap reconstruction for total glossectomy includes the following:
Preoperative surface marking of the lateral border of the latissimus dorsi is recommended (Fig. 8.2).
The muscle contour is palpated and marked after arm elevation. This is important for correct positioning of the skin paddle.
Proximal positioning of the donor area avoids a long pedicle (Fig. 8.2). This obviates harvest of excessive muscle and prevents a cumbersome flap inset at the recipient site.
The length–tension relationship of muscle can be optimized by careful reinstatement of the resting length of the latissimus dorsi fibers in the recipient site. Failure of muscle contraction will occur if this principle is ignored, that is, shortening the fibers to less than the resting length inhibits adequate contraction. Measured suture placement on the back (Fig. 8.3) at the level of the intended oropharyngeal sling before harvest accomplishes this goal.
• ALT free flap: Dissection and preservation of at least one intact perforator from the lateral circumflex artery to the skin is required to maintain the viability of the flap. To achieve this, along with an adequate knowledge of the perforator anatomy and possible variations, the following keys are helpful.
Make the first aspect of the incision on the anterior skin paddle border and proceed in the subfascial plane posteriorly with careful blunt dissection to search for the perforators. Infrequently, anomalous anatomy may be encountered, and search for perforators may need to be directed anteriorly from the groove between the rectus femoris muscle and the vastus lateralis. The skin paddle is accordingly redesigned medial to the incision.
Confirm the course of the musculocutaneous perforators in the vastus lateralis muscle by incising the muscle just superficial to the perforators to ensure safe dissection. Maintain 5 mm of muscle on either side of the perforator.
In septocutaneous perforators, preservation of a small cuff of fascia around the perforator and intermittent topical use of Xylocaine assist safe dissection.
PITFALLS
• Latissimus dorsi free flap
Adequate exposure of the harvest site near the midline of the back requires careful lateral positioning and prepping of the patient.
Additional assistance is required for controlling the position of the arm to facilitate appropriate access. In the obese patient, presence of excessive axillary adipose can make identification of the vascular pedicle tedious, requiring a greater depth of dissection and substantial retraction of soft tissue. Prolapsed tissue may be hazardous, obscuring the pedicle, leading to inadvertent damage before identification.
The overall flap thickness may limit maneuverability and sculpting of the tissue in situ.
• ALT free flap
Dissection of the vascular pedicle poses a major challenge during ALT flap harvest because of the anatomical variability both in origin and course of the perforators supplying the flap. Presence of type II perforator is rare (about 4%) but, when present, may complicate the dissection.
Absence of cutaneous perforators on which the flap needs to be based has been reported in up to 5% of cases. In addition to the perforators, the course of the descending branch of the lateral circumflex artery may also vary. Occasionally, it is buried inside the vastus lateralis or is absent. When faced with a situation of unsuitable vascular anatomy, the surgeon should be prepared to abandon the flap and either explore the contralateral thigh or employ an alternative donor site.
In the Western population, another source of problem in dissection of vascular pedicle arises from the usually ill-defined septum between the vastus lateralis and rectus femoris muscles. Its presence is indicated by only a line of adipose tissue. Absence of its identification obscures an important landmark because mostly, all reliable perforators are located lateral to the septum.
Presence of excessive subcutaneous adipose tissue makes the dissection cumbersome and also creates difficulty in handling the bulky flap during inset.
INSTRUMENTS TO HAVE AVAILABLE
• Standard head and neck surgical set
• Microvascular surgery instruments
ACKNOWLEDGMENT
I gratefully acknowledge the contributions of Parul Sinha.
SUGGESTED READING
Song YG, Chen GZ, Song YL. The free thigh flap: a new free flap concept based on the septocutaneous artery. Br J Plast Surg 1984;37:149–159.
Haughey BH, Fredrickson JM. The latissimus dorsi donor site. Current use in head and neck reconstruction. Arch Otolaryngol Head Neck Surg 1991;117:1129–1134.
Haughey BH. Tongue reconstruction: concepts and practice. Laryngoscope 1993;103:1132–1141.
Koshima I, Fukuda H, Yamamoto H, et al. Free anterolateral thigh flaps for reconstruction of head and neck defects. Plast Reconstr Surg 1993;92:421–428, discussion 429–430.
Wei FC, Jain V, Ortho MC, et al. Have we found an ideal soft-tissue flap? An experience with 672 anterolateral thigh flaps. Plast Reconstr Surg 2002;109:2219–2226.