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Neck Metastases

Cernea CR, Dias FL, Fliss D, Lima RA, Myers EN, Wei WI (eds): Pearls and Pitfalls in Head and Neck Surgery. Basel, Karger, 2012, pp 38–39

DOI: 10.1159/000337961

2.2 N0 Neck in Oral Cancer: Elective Neck Dissection

Fernando L. Dias Roberto A. Lima

Head and Neck Surgery Department, Brazilian National Cancer Institute and Postgraduation School of Medicine, Catholic University of Rio de Janeiro, Rio de Janeiro, Brazil

P E A R L S

• Consider elective supraomohyoid neck dissection in early oral tongue and floor of mouth squamous cell carcinoma (SCC).

• Consider extending supraomohyoid neck dissection to level IV in SCC of the posterior 1/3 of the tongue.

• Identification of the posterior belly of the digastric muscle will ease the dissection of level IIa—b.

P I T F A L L S

• Avoid traction of nerve XI while dissecting level IIb.

• Avoid dissection of level II before identification of nerve XI.

Introduction

Lymph node metastasis (LNM) from oral cavity (OC) SCC occurs in a predictable and sequential fashion. For primary tumors of the OC the first echelon lymph node at highest risk for early dissemination includes levels I, II and III [1–5].

Poor salvage rates for regional recurrence ranging from 11 to 40%, despite the use of aggressive therapy, emphasize the role of elective treatment of the neck in OC SCC [6].

Practical Tips

Tumors more than 1 cm away from the midline present a low risk of bilateral/contralateral LNM (7%). Tumors crossing the midline by less than 1 cm have a risk increased to 16%, which reaches 46% in those patients where the crossing is more than 1 cm.

The depth of invasion and thickness, the characteristics of the tumor-normal tissue boundary (i.e., well-demarcated vs. diffuse invasion at the boundary), lymphatic or vascular space invasion, perineural invasion, and the degree of inflammatory (lymphoplasmacytic) response are considered predictive factors for LNM as well as its diameter and grade [6].

The incision is placed in an upper neck skin crease extending from the posterior border of the sternocleidomastoid muscle towards the hyoid bone up to the midline (at least two finger breadths below the angle of the mandible).

Nerves at risk during supraomohyoid neck dissection are marginal mandibular branch of the facial nerve (MBFN), lingual nerve, hypoglossal nerve, spinal accessory nerve, cutaneous and muscular branches of the cervical plexus, and great auricular nerve. They should be carefully identified and preserved [4, 7].

Start dissecting the anterior border of the sternomastoid muscle from its intersection with the omohyoid muscle (posterior belly) up to the mastoid tip. This maneuver will ease the identification of the posterior belly of the digastric muscle and, consequently, the dissection of the apex of the posterior triangle.

Nerve XI usually runs parallel and deep to the great auricular nerve. Avoid traction on nerve XI while dissecting level IIb.

There is a close relationship between the MBFN and the facial vessels. A surgical maneuver attributed to Hayes Martin, i.e. keeping the cranial stumps of facial vessels retracted upward during the dissection of the subman-dibular triangle, helps to protect the nerve. The use of nerve monitoring and magnification can be of help [7].

Only after the identification of the MBFN is exposure of the prevascular facial LN (level Ib) accomplished.

A brisk hemorrhage is expected during dissection along the lower border of the body of the mandible up to the attachment of the anterior belly of the digastric muscle [4].

Adequate exposure of the undersurface of the floor of the mouth is achieved with gentle traction of the submandibular gland downward and medial retraction of the lateral border of the mylohyoid muscle. Such exposure allows precise identification of the hypoglossal and lingual nerves as well as its secretomotor fibers to the submandibular gland and the Wharton's duct. Once the lingual nerve is clearly identified, the secretomotor fibers to the submandibular gland can be safely divided between clamps and ligated.

In N0 neck, levels IV and V LN are generally not at risk of harboring micrometastasis. The exception to this observation are SCC of the posterior 1/3 lateral border of the tongue in which level IV may be at risk of occult LNM [4, 5].

To facilitate accurate description of the excised LN, it is important to apply numerical tags to the LN depicting each level.

Conclusion

The limitations for the identification of occult cervical metastases and the negative impact of recurrent disease in the neck are important issues in the management of OC SCC [1–3]. Elective treatment of the neck must be strongly considered in OC, even in early stages when the primary tumor is located at the tongue and/or floor of the mouth.

References

1 Shah JP, Candela FC, Poddar AK: The patterns of cervical lymph node metastases from squamous carcinoma of the oral cavity. Cancer 1990;66:109–113.

2 Dias FL, Kligerman J, Matos de Sá G, et al: Elective neck dissection versus observation in stage I squamous cell carcinomas of the tongue and floor of the mouth. Otolaryngol Head Neck Surg 2001;125:23–29.

3 Laubenbacher C, Saumweber D, Wagner-Manslau C, et al: Comparison of fluorine-18-fluorodeoxyglucose PET, MRI and endoscopy for staging head and neck squamous carcinomas. J Nucl Med 1995;36:1747–1757.

4 Shah JP, Patel SG: Cervical lymph nodes; in Shah JP, Patel SG: (eds): Head and Neck Surgery and Oncology, ed 3. Edinburgh, Mosby, 2003, pp 353–394.

5 Dias FL, Lima RA, Kligerman J, et al: Relevance of skip metastases for squamous cell carcinoma of the oral tongue and floor of the mouth. Otolaryngol Head Neck Surg 2006;136:460–465.

6 Dias FL, Lima RA: Cancer of the floor of the mouth. Oper Tech Otolaryngol Head Neck Surg 2005;16:10–17.

7 Dias FL, Lima RA, Cernea CR: Management of tumors of the submandibular and sublingual glands; in Myers EN, Ferris RL (eds): Salivary Gland Disorders. Berlin, Springer, 2007, pp 339–376.

Prof. Fernando L. Dias, MD, FACS

Chief, Head and Neck

Surgery Department

Brazilian National Cancer Institute

Professor of Surgery

Post-Graduation School of Medicine

Av. Alexandre Ferreira, 190 Lagoa

Rio de Janeiro, SP 2270220 (Brazil)

E- Mail fdias@inca.gov.br