Surgical Approaches to the Oropharynx Karen Stierman, M.D. Christopher Rassekh, M.D. January 13, 1999

Anatomy Connects the nasopharynx and oral cavity to the hypopharynx Extends from hard palate to hyoid Opens into oral cavity. Bounded by circumvallate papillae, ant. tonsillar pillar, and junction of the hard and soft palate Clinically significant: lateral and posterior walls, tonsil, base of tongue, soft palate

Anatomy(cont’d) Pharyngeal walls made up of mucosa, submucosa, pharyngobasilar fascia, constrictor m., buccopharyngeal fascia Lateral walls made up of ant. and post. tonsillar pillars, tonsillar fossa with the palatine tonsil, lateral phayngeal wall Soft palate made up of palatine aponeurosis, tensor and levator veli palatini, uvular m, palatoglossus, palatopharyngeus

Anatomy(cont’d) Base of tongue extends from the cirumvallate papillae to the pharyngo and glossoepiglottic folds. Lingual tonsils are on the superficial and lateral surfaces Irregular surfaces on tonsil and tongue base tissue make tumor identification difficult

Anatomy(cont’d) Sensory and motor innervation is mainly through the glossophayngeal and vagus nerves otalgia from tympanic and auricular branches The hypoglossal nerve is motor supply to base of tongue V2, V3 are motor and sensory supply to soft palate

Anatomy Blood supply from external carotid Lymphatic drainage mainly from levels I, II and III Tongue base, soft palate, posterior pharyngeal wall drain to both sides Posterior pharyngeal wall and tonsil drain to retropharyngeal nodes

Anatomy(cont’d) Retropharyngeal space - loose connective tissue between buccopharyngeal fascia and the prevertebral fascia. Extends from skull base to superior mediastinum Parapharyngeal space - Extends from skull base to hyoid. Contains prestyloid and poststyloid compartments

Surgical Considerations Cure unlikely - extension into poststyloid compartment, prevertebral fascia, or involvement of the carotid artery Resection of tumor with 1 - 2 cm of grossly normal tissue Frozen sections

Four main surgical approaches Transoral Transoral/Transcervical Transpharyngeal Transmandibular Choice depends on size and location of tumor and if neck dissection is planned

Preoperative assessment History and Physical CT, MRI Neck dissection versus XRT Selective: Zones I, II and III MRND or RND

Transoral Approach Lip splitting without mandibulotomy Oral Small(T1), superficial, or exophytic tumors of soft palate, posterior pharynx, ant. tonsillar pillar Evaluate for trismus, dentition, excess soft tissue, and mandible height. Initial incision posterior or inferior Orientation and margins important Posterior pharyngeal - no skin graft

Transoral/Transcervical approach Lingual-mandibular release Base of tongue lesions Incision through floor of mouth from tonsillar pillar to pillar Tongue and floor of mouth released and pulled below mandible into neck Risk damage to lingual arteries and nerve and CN 12

Transpharyngeal approach Suprahyoid pharyngotomy Used for small tumors of base of tongue and posterior pharyngeal walls Enter into pharynx through the vallecula and extend the incision along the thryoid ala Downfall is poor visualization of the superior margin of large tumors Provides excellent functional and cosmetic outcome

Pharyngeal Approach(cont’d) Lateral pharyngotomy small tumors of base of tongue and pharyngeal walls enter the pharynx posterior to the thyroid ala on the least diseased side if more superior exposure need, may extend the pharyngotomy across the vallecula and/or combine with a lateral mandibulotomy

Transmandibular Approaches Mandibulotomy versus mandibulectomy based on bone invasion Consider if patient has full set of teeth, limited mouth opening, or posterior location of tumor Most transmandibular approached require splitting of the lower lip

Mandibulotomy Includes lip splitting approach, midline labiomandibular glossotomy, and mandibular swing approach Should be made between the two mental foramen and through a tooth socket Vertical, stair-step, or arrowhead configuration Select reconstruction plate, adapt, and drill holes prior to mandibulotomy

Mandibulotomy (cont’d) After mandibulotomy, mandible retracted laterally and soft tissue incised Cuff of 1 cm of floor of mouth mucosa is left on the mandible for closure

Lip Splitting Use scalpel to mark vermillion border Vertical Modified zigzap stepped technique minimizes vermillion contracture and does not damage facial or mental nerves

Midline labiomandibular glossotomy Rarely used Useful for small, inferior, midline posterior pharyngeal wall tumors, small midline tongue based tumors, and inferior nasopharyngeal and clival tumors Lip, gingiva, mandible and anterior tongue are split in the midline. Incision may be carried through the base of tongue

Mandibular swing approach Provides exposure to the entire oropharyx Procedure of choice for en bloc resection Useful for tumors that involve multiple sites and/or the parapharyngeal space Neck dissection first if indicated Lip splitting and osteotomy next Full thickness cut in floor of mouth until anterior margin reached

Mandibular swing(cont’d) Mandible and tongue retracted and tumor excised Posterior exposure improved when mylohyoid m. divided and submandibular gland and its duct are retracted medially Closure may require a flap and mandible reapproximated and plated

Composite resection with mandibulectomy Consider if mandible is grossly involved with tumor and in cases where mandibular invasion cannot be ruled out. May need a tracheostomy Usually need a neck dissection or XRT Selective, MRND, RND

Mandibular resection Marginal Segmental portion of the mandible(alveolus and medial plate) resected used when tumor fixed to periosteum Segmental condyle to condyle continuity disrupted used for tumors with gross involvement of the mandible

Mandibular resection(cont’d) Once cancer has accessed the marrow, the surgeon must suspect invasion of the neurovascular bundle If inferior alveolar nerve sections are positive, the entire canal must be resected If marrow invasion is suspected, care must be taken to get at least 2 cm margins

Composite resection After neck dissection, the specimen is left attached superiorly at the periostium of the mandible The massester is then elevated from the angle of the mandible and the periostium incised Lip splitting or visor flap performed next

Composite resection(cont’d) Cheek flap developed Anterior mandible cut made with Gigli saw or a reciprocation saw Posterior mandibular cuts made through the ramus. If ramus involved, the coronoid and condyle are resected. Mandible is retracted laterally and tumor is excised

Visor flap The visor flap or degloving approach has the following risks: damaging both mental nerves and poor posterior exposure in large tumors An intraoral incision is made through the buccogingival sulcus to allow elevation of the cheek without a lip split The incision is usually extended into the contralateral gingivolabial sulcus

Reconstruction First, reapproximate the floor of mouth mucosa Reapproximate and plate the mandible if mandibulotomy In the case of a mandibulectomy, the mandible is reconstructed with free vascularized bone or a metal reconstruction plate covered with free vascularized or pedicled soft tissue

Reconstruction(cont’d) Close the lip in three layers: orbicularis muscle, mucosa, and skins Worst complication is nonunion and osteomyelytis

Summary Four main approaches: transoral, transoral/transcervical, transpharyngeal, and mandibular splitting approaches Preop assessment crucial History and physical Bone / Neck involvement Correct choice of approach ensures adequate tumor resection and saves the surgeon time and frustration