Surgical Approaches to the Oropharynx

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

2. 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

3. 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

4. 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

5. 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

6. 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

7. 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

8. 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

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

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

11. 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

12. 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

13. 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

14. 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

15. 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

16. 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

17. 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

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

19. 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

20. 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

21. 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

22. 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

23. Mandibular resection • Marginal • 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

24. 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

25. 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

26. 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

27. 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

28. 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

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

30. 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