T2

Transoral T1, selected T2

Transoral, with mid T2-T4

facial degloving Transoral, with limited mandibulectomy Transoral with midline glossotomy Transcervical with lower T2-T4

facial degloving Transcervical with T3-T4

lip/chin split Transcervical with Any stage lingual release

All Locations

Upper gingiva, hard and/or soft palate

Lower gingiva, adjacent FOM or labial/

buccal region Central tongue or oropharynx with/without midline mandibulotomy Any Location with/without mandibulotomy or mandibulectomy Any location with/without mandibulotomy or mandibulectomy Oropharynx, hypopharynx, base of tongue aBy virtue of limited mandibular invasion but overall tumor < 4cm. Abbreviation: FOM, floor of mouth.

the contralateral neck and, hence, onward toward the mastoid tip should a bilateral access be necessary. The neck incisions are always placed two fingerbreadths below the inferior border of the body of the mandible in its mid portion (closer to the mandible near the midline) to avoid damage to the marginal mandibular branch of the facial nerve, and can extend well below such for a substantial "apron," even to a trach site, should access to lower echelons of cervical nodes be indicated (1-4,7,30). For a standard submandibular type of unilateral apron flap, access to the Level I and Level II nodes is straightforward, although an inferiorly placed apron is often necessary to reach the Level III or IV nodes. From the neck incision, the immediate subcutaneous tissues and platysma are divided and a plane of dissection is established superiorly toward the mandible, over the lateral capsule of the submandibular gland and the adjacent anterior and posterior bellies of the digastric muscle. By staying at this depth and suture ligating the distal stumps of the facial artery and vein (only if necessary for oncologic purposes or if a free-tissue transfer and recipient vessels are unnecessary) to the overlying platysma (Hayes Martin maneuver), damage to the marginal mandibular nerve can be prevented.

Tumors of the buccal mucosa and lateral alveolar arch may commonly result in metastases along the perivascular nodes that follow the facial artery and vein (28). In such cases these nodes must be removed, and require the surgeon to visually identify, with the assistance of a nerve stimulator if desired, the marginal mandibular nerve to preserve that structure while the facial artery and vein are skeletonized of associated lymphatic structures.

Once the inferior border of the mandible is exposed, a subperiosteal plane can be established with a Freer, Lempert, or similar elevator on both the lateral and medial cortices of the mandible, recognizing that the mylohyoid muscle inserts on the medial cortex of the anterior two-thirds of the mandibular arch, and must be detached to gain access to the submucosa of the oral cavity. For oral cavity tumors near the midline, the submental triangle is stripped of its fat and nodal tissues, along with the submandibular triangle contents, accomplishing a Level I nodal dissection. Most surgeons likewise strip the adjacent Level II nodes from the jugulodigastric region even if no nodes suspicious for tumor are present which not only aids in eventual tumor staging and post-operative treatment, but allows simple circumferential exposure to branches of the external carotid artery and jugular vein for recipient vessel access. Additional nodal dissection is completed as indicated.

After removal of the relevant cervical lymphatic structures, associated fat and the submandibular gland(s), the surgeon is in close proximity underneath any oral or oropharyngeal neoplasm, and only needs to identify the hypoglossal and lingual nerves and external carotid system before proceeding to en bloc resection of the tumor via a combination transoral and the transcervical access.

If a bony resection is necessary, the degloving approach still frequently suffices, with exposure of the entire mandibular body and most of the ascending rami, and obviates a lip/chin split (Fig. 16). To accomplish such, the periosteum over the lateral cortex of the mandible is elevated, and, if necessary the mental nerve is divided as it exits the mental foramen on the ipsilateral side, allowing the surgeon to place one-inch Penrose drains from the neck incision through the oral cavity and out the mouth. Upward traction then can readily distract the lip and chin soft tissues superiorly, while downward traction on the mandible with a bone hook will deliver the mandible, FOM and tongue into the neck dissection field. Prior to the bony resection, the anticipated bony defect is marked, and an appropriately tailored titanium locking 2.0 or 2.4 bridging plate is bent to conform to the contours of the anticipated proximal and distal bony segments. It is most convenient to utilize a pre-

Figure 16 Lateral facial degloving for T3 of tonsil, soft palate and adjacent tongue; note intact lip and chin yet a mandibulotomy with a lateral rotation and superior retraction of the ipsilateral body and ramus; note vascular tapes around internal and external carotid arteries in the posterior field of dissection.

Figure 16 Lateral facial degloving for T3 of tonsil, soft palate and adjacent tongue; note intact lip and chin yet a mandibulotomy with a lateral rotation and superior retraction of the ipsilateral body and ramus; note vascular tapes around internal and external carotid arteries in the posterior field of dissection.

fabricated angulated bridging plate if the ascending ramus of the mandible is part of the proximal segment, placing four, rather than the minimum of three bi-cortical screws, in that segment as the ramus is much thinner than the body of the mandible. To maximize stability, the plate is positioned along the posterior border of the ramus, its thickest segment.

Some patients with relatively circumscribed intraoral lesions can have an extirpation without the necessity of a tracheostomy even if the mandibular contour has been disrupted (but intra-operatively reconstituted with a bridging plate). However, in most cases in which a mandibulotomy is performed or when there has been extensive mobilization of the tongue, peri-operative use of a tracheostomy is prudent, particularly when the anterior tongue attachments are separated from the mandible (base of tongue migrates posteriorly).

Midface Degloving Approach

For tumors of the hard palate mucosa that invade bone and require a wide area of bone resection, another type of "degloving," a "midfacial degloving,'' is an excellent way to approach the tumor, and is preferred to a lateral rhinotomy with a lip split and cheek rotation unless there is tumor spread posteriorly through the pterygoid plates and/or into the parapharyngeal space (3,12,31). Such a "degloving" involves retracting the upper lips laterally and superiorly, typically with Goulet retractors, and is performing what is essentially a bilateral Caldwell-Luc access (extended across the midline, through the pyriform apertures and the base of the septum; Fig. 17). First, the mucosa is elevated over the anterior faces of the maxillary sinuses, extending superiorly to the levels of the infraorbital nerves. The anterior face of one or both

Figure 17 Well differentiated carcinoma of posterior hard palate and adjacent soft palate, eroding through hard palatal bone to floor of maxillary sinus, excised via unilateral midfacial degloving and transoral routes.

maxillary sinuses can be removed, depending on tumor location. Such allows the surgeon access to the floor(s) of the maxillary sinus(es) and adjacent nasal cavity(s), and, in most cases, a clear margin above any palatal tumor. Indeed, removal of the entire hard and soft palates can be accomplished through this straightforward midfacial degloving approach, although the reconstruction of such a defect is a significant challenge and involves placement of the initial stage of osseointegrated implants in the same surgical sitting that clear tumor margins are confirmed by frozen-section study.

If the anterior or premaxillary region does not require resection, it is helpful to leave this area intact, including the periosteum, and perform a combined transoral/ transfacial (lateral rhinotomy or sublabial incision) or transoral/endoscopic approach.

Lingual Release Approach

The lingual release approach can be considered an "internal degloving'' approach to the more posteriolateral aspect of the oral cavity, tonsillar fossa, and oropharynx, hypopharynx and base of tongue. Described by Bradley and Stell (32) and popularized by Stanley (33), this access is achieved via a combination of transcervical and intraoral incisions. The external cervical incision consists of a broad apron flap placed in a skin crease approximately two fingerbreadths below the mandible and extending from mastoid to mastoid. The skin flap is elevated as for a degloving approach with the elevation of the submandibular fascia to protect the marginal mandibular branch of the facial nerve (Hayes Martin maneuver). This elevation is carried across the midline to expose the inferior border of the mandible from angle to angle. The periosteum of the mandible is then encised along the lower boarder of the mandible allowing elevation on the lingual surface of the bone from angle to angle.

The intraoral incision is then made through a transoral approach. If the mandible is edentulous the incision is placed on the superior aspect of the alveolar ridge from retromolar trigone to retromolar trigone and carried into the oropharynx as needed. If the patient has dentition the mucosa of the lingual surface of the mandible can be elevated from the dental ligament at the base of the teeth or an incision can be placed 2-mm below the base of the teeth. The periosteum on the lingual surface of the mandible is then elevated to the lower border of the mandible which will include elevation of the insertion of the mylohyoid muscle from it's insertion along a ridge of bone.

At this juncture of the exposure the periosteal pocket developed intraorally is connected with the elevation started extraorally to completely free the lingual mandibular periosteum. The only remaining attachment will be that of glossal muscles to the midline genial tubercle which must be released either sharply or with elec-trocautery. The entire oral tongue/FOM/mandibular mucoal-periosteum complex is then passed into the neck wound by placing a suture in the tip of the tongue and pulling it medial to the mandible into the neck (pull-through technique).

The neck skin flap and mandible are then retracted superiorly while the oral cavity contents including the FOM, submandibular ducts, sublingual tissues, lingual and hypoglossal nerves and oral tongue are pulled inferiorly as a unit (Figs. 12 and 13). If the tumor to be excised involves the oropharynx, hypopharynx, or base of tongue, the mucosal incisions may be extended posteriorly to improve the exposure. Unlike the mandibular swing approach, with the lingual release method, the further posteriorly the exposure, the better the visualization in these areas. Obviously, a mandibulotomy is avoided as well. If necessary, a composite resection can be combined with this approach which is then more like the traditional degloving operations (Fig. 16).

Once the resection is performed and any needed reconstruction completed the intraoral mucosal incision must be carefully repaired via a transoral approach. This is very straight forward in the edentulous patient with simple repair of the alveolar ridge mucosa. In the dentulous patient it is useful to support the repair with mattress sutures passed around teeth rather than relying on mucosal sutures placed at the tooth root level. Resuspension of the oral cavity structures relies primarily on the mucosal repair. Reattachment of the lingual muscles to the mandible anteriorly is accomplished by placing a 2.0-suture through the muscle attachments from the genial tubercle to the intact periosteum of the mandible in the midline. This successfully resuspends the hyoid bone and supralaryngeal structures.

The lingual release approach has largely replaced the lip split/mandibulotomy approach to the posterior oral cavity and pharynx in many instances. A violation of the mandible is avoided, the lip and chin scar becomes unnecessary and posterior exposure is superior. However, performing the intraoral incisions and closure can be quite difficult in the dentulous patient with trismus and another approach should be considered.

Transhyoid Approach

Although this text is on oral cavity reconstruction more posterior and larger tumors of the oral cavity can invade the oropharynx, particularly from a mid third of tongue, retromolar trigone or tonsillar primary. Though rarely employed as a sole approach, a transhyoid exposure of the base of the tongue and inferior tonsillar region may serve as an adjunct to one of the previously mentioned accesses (1-3,34). Such is most commonly utilized in conjunction with a lower facial "degloving" and/or transoral approach. After careful identification and preservation of the hypoglossal and superior laryngeal nerves, some surgeons excise the entire hyoid bone by cutting it free of the strap and tongue base muscles, whereas others, such as the authors, merely cut along the superior surface of the hyoid, thus releasing the base of tongue, digastric and mylo-hyoid muscles and allowing the hyoid to drop inferiorly in the neck. The vallecula and lateral oropharyngeal mucosa are within 5 mm of the hyoid bone in most patients, so entering these regions is quickly and easily accomplished by pulling the base of tongue anteriorly into the wound and somewhat superiorly with a wide, double-pronged hook. Next, by retracting inferiorly on the hyoid, the surgeon, with the help of headlight illumination, can view the entire base of tongue, inferior tonsil, and soft palatal regions, and thereby can control the inferior aspects of an oral tumor resection. After tumor resection and reconstruction of the defect, it is prudent to resuspend the hyoid, and hence laryngotracheal complex, to the mandible, using permanent sutures around the hyoid at each lesser cornu, stabilized to small drill holes in the inferior borders of the mandible in the region of the mandibular angles, or to a similarly located bridging plate used to reconstruct a mandibular defect. If free-tissue transfer is used, confirm that there does not exist any compression by these permanent sutures on the flap or pedicle prior to closing the wound.

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