The surgical management of neck metastases from head and neck cancer consists primarily of neck dissection. An awareness of both the cervical anatomy and natural history of squamous cell carcinoma of the upper aerodigestive tract is necessary to understand the role of neck dissection and to appreciate when it may be appropriate to modify the standard radical neck dissection. The use of imaging to augment palpation of the neck has resulted in greater accuracy in identifying neck metastases and has further clarified the role of modified neck dissections. Depending on the site and size of the primary tumor, radiation therapy, modified neck dissection, or selective neck dissection are all appropriate options for the elective treatment of the neck when there is a high risk of occult metastasis. Therapeutic neck dissection alone is adequate for early-stage neck disease, but must be combined with irradiation for more advanced stages. Regional control of tumor metastases is highly dependent on the stage of neck disease and the presence of extranodal cancer spread.
Radical neck dissection, first described by Crile in 1906 , is the standard against which all surgical approaches to neck metastases is compared. Consideration was subsequently given to more conservative surgical techniques, but they did not gain widespread acceptance and were condemned by Martin et al in the 1950s .
Surgical management of the neck has continued to evolve toward more conservative approaches, however. Even selective neck dissection techniques are now widely accepted. Current controversies center around the appropriate use of modified and selective neck dissections, indications for elective neck treatment, and selection of the best therapeutic modality for elective neck treatment. This article will address these as well as other surgical considerations, and will review the surgical techniques currently available for neck treatment.
A neck dissection is, in fact, an anatomic dissection of the neck. Therefore, a clear grasp of the anatomy of the cervical lymph node groups and cervical aponeurotic system is essential for proper understanding of neck dissection.
Cervical Lymph Node Groups
There are approximately 150 to 350 lymph nodes above the clavicles. Since the lymphatic system is embryologically related to the venous system, the lymph nodes are closely related to veins. The cervical lymph nodes have commonly been divided into surgical levels to facilitate discussions of patterns of metastases and types of neck dissection (Figures 1 and 2).
The submandibular and submental nodes constitute the level I group. The submental lymph nodes are located in the midline within the triangle defined by the anterior bellies of the digastric muscles and the hyoid bone. The submandibular nodes are situated within a triangle bounded by the anterior and posterior bellies of the digastric muscle and the mandibular body. These nodes are in close relationship to the submandibular gland and the posterior facial vein. Notably, the gland itself does not include any lymph nodes.
The internal jugular vein lymph nodes are limited anteriorly by the lateral margin of the sternohyoid muscle and posteriorly by the posterior border of the sternocleidomastoid muscle, and are subdivided into three groups. The level II group, or upper internal jugular nodes, extend from the skull base superiorly to the hyoid bone or carotid bifurcation inferiorly. These nodes , also commonly referred to as jugulodigastric nodes, are closely related to the superior portion of the spinal accessory nerve as well. The middle jugular group (level III group) continues inferiorly to the omohyoid muscle. The lower jugular group (level IV) nodes extend from the omohyoid muscle to the level of the clavicle.
The level V group, or posterior triangle lymph nodes, are bounded by the posterior edge of the sternocleidomastoid muscle, anterior border of the trapezius muscle, and clavicle. Superiorly, these nodes closely approximate the spinal accessory nerve, and are often referred to as the spinal accessory chain. The nodes that are located near the confluence of the posterior triangle and upper jugular groups are sometimes termed junctional nodes. The supraclavicular nodes are part of the posterior triangle group.
The anterior compartment group (level VI) is bounded superiorly by the hyoid bone, inferiorly by the sternum, and laterally by the common carotid arteries. Included in this group are the paratracheal, pretracheal, precricoid (Delphian), and tracheoesophageal groove nodes.
Additional groups that are sometimes dissected outside the normally described boundaries of the neck include the facial, parotid, preauricular, retroauricular, suboccipital, and retropharyngeal nodes.
Cervical Aponeurotic System
The cervical aponeurotic system divides the neck into compartments, including the lateral and paravisceral spaces, that are removed with a neck dissection (Figure 3). The superficial cervical fascia is a thin layer that invests the platysma muscle. The deep cervical fascia is subdivided into three layers: investing (superficial), pretracheal (middle), and prevertebral (deep).
The investing layer completely encircles the neck, splitting to enclose the sternocleidomastoid, omohyoid, and trapezius muscles. Superiorly, the investing fascia splits to enclose the subman- dibular and parotid glands, and attaches to the lower border of the mandible. The pretracheal layer encompasses the trachea, thyroid gland, and esophagus.
The prevertebral layer covers the prevertebral, scalene, levator scapulae, splenius, and semispinalis capitis muscles, and constitutes the floor of the lateral neck. The phrenic nerve, brachial plexus, sympathetic trunk, and dorsal scapular nerve all lie deep to the prevertebral fascia.
The carotid sheath consists of all three layers of deep cervical fascia and contains the carotid artery and vagus nerve. The jugular vein is located within an extension of the carotid sheath as well.
Critical to an understanding of modified and selective neck dissections is the concept that the lymph nodes lie within the lateral and paravisceral spaces, not within the fascial wrappings of the muscles or the carotid artery. The lymph nodes may, however, be in very close association with these fascial layers. The spinal accessory nerve must be uniquely considered in neck dissection, as it actually travels through the lateral space of the neck just deep to the investing fascia and superficial to the prevertebral fascia.
Squamous cell carcinoma of the upper aerodigestive tract is the most common tumor to metastasize to the cervical nodes. Less commonly, neck dissection is performed for malignant neoplasms of the thyroid gland, parotid gland, or skin. Distant metastases from below the clavicle occur, but neck dissection is generally of no benefit in the management of these neoplasms.
Once a metastasis reaches a lymph node, tumor growth results in an indurated and more rounded node. Increasing size of the lymph node is directly associated with increased risk of tumor invasion through the capsule, and eventually, fixation to adjacent structures.
The risk of cervical metastases from different primary sites and stages has been estimated by examining the percentage of patients with similar stage tumors who present with clinically positive node , the distribution of pathologically positive nodes in an electively dissected, clinically negative neck, and failure rates in untreated necks. In this fashion, the relative risk of cervical metastases may be approximated for specific sites. For example, the glottis has a low risk of metastasizing to the neck(< 20%), whereas the nasopharynx has a high risk (> 30%). Finally, lesions such as early supraglottic laryngeal tumors are considered to be of intermediate risk (20% to 30%) .
In many cases, these fairly consistent patterns of metastases allow for the application of selective removal of nodal groups for specified lesions. There are, however, situations in which the normal pattern of nodal metastases do not hold. For example, the right and left sides of the cervical lymphatic system normally do not shunt. However, previous neck surgery, prior irradiation, or multiple positive nodes obstructing the lymphatic system may alter the patterns of cervical metastases such that shunting across the submental region occurs, or unusual nodal groups are involved for a given primary. Furthermore, recurrent lesions are associated with a higher risk of cervical metastasis.
1. Crile G: Excision of cancer of the head and neck with special reference to the plan of dissection based upon one hundred thirty-two operations. JAMA 47:1780-1786, 1906.
2. Martin HE, De Valle B, Ehrlich H, et al: Neck dissection. Cancer 4:441-449, 1951.
3. Lindberg RD: Distribution of cervical lymph node metastases from squamous cell carcinoma of upper respiratory and digestive tracts. Cancer 29:1446-1449, 1972.
4. Mendenhall WM, Million RR: Elective neck irradiation for squamous cell carcinoma of the head and neck: Analysis of time-dose factors and causes of failure. Int J Radiat Oncol Biol Phys 12:741-746, 1986.
5. Stevens MH, Harnsberger HR, Mancuso AA, et al: Computed tomography of cervical lymph nodes. Arch Otolaryngol Head Neck Surg 111:735-739, 1985.
6. van den Brekel MW, Castelijns JA, Croll GA, et al: Magnetic resonance imaging vs palpation of cervical lymph node metastasis. Arch Otolaryngol Head Neck Surg 117:663-673, 1991.
7. Hughes CJ, Gallo O, Spiro RH, et al: Management of occult neck metastases in oral cavity squamous ca. Am J Surg 166:380-383, 1993.
8. Jesse RH, Barkley HT, Lindberg RD, et al: Cancer of the oral cavity: Is elective neck dissection beneficial? Am J Surg 120:505-508, 1970.
9. Mendenhall WM, Million RR, Cassisi NJ: Elective neck irradiation in squamous cell ca of the head and neck. Head Neck 3:15-20, 1980.
10. Friedman M, Mafee MF, Pacella BL: Rationale for elective neck dissection in 1990. Laryngoscope 100:54-59, 1990.
11. Weiss MH, Harrison LB, Isaacs RS: Use of decision analysis in planning a management strategy for the stage N0 neck. Arch Otolaryngol Head Neck Surg 120:699-702, 1994.
12. Byers RM: Modified neck dissection: A study of 967 cases from 1970 to 1980. Am J Surg 150:414-421, 1985.
13. Medina JE: A rational classification of neck dissections. Otolaryngol Head Neck Surg 100:169-176, 1989.
14. Molinari R, Chiesa F, Cantu G, et al: Retrospective comparison of conservative and radical neck dissection in laryngeal cancer. Ann Otol 89:578-581, 1980.
15. Lingeman RE, Stephens R, Helmus C, et al: Neck dissection: Radical or conservative. Ann Otol 86:737-744, 1977.
16. Gavilan C, Gavilan J: Five-year results of functional neck dissection for cancer of the larynx. Arch Otolaryngol Head Neck Surg 115:1193-1196, 1989.
17. Bocca E, Pignataro O: A conservation technique in radical neck dissection. Ann Otol Rhinol Laryngol 76:975-987, 1967.
18. Wenig BL, Applebaum EL: The submandibular triangle in squamous cell ca of the larynx and hypopharynx. Laryngoscope 101:516, 1991.
19. Ballantyne AJ: Significance of retropharyngeal nodes in cancer of the head and neck. Am J Surg 108:500-504, 1964.
20. Hasegawa Y, Matsuura H: Retropharyngeal node dissection in cancer of the oropharynx and hypopharynx. Head Neck 16:173-180, 1994.
21. Parsons JT, Million RR, Cassisi NJ: The influence of excisional or incisional biopsy of metastatic neck nodes on the management of head and neck cancer. Int J Radiat Oncol Biol Phys 11:1447-1454, 1985.
22. Snow GB, Annyas AA, van Slooten EA, et al: Prognostic factors of neck node metastasis. Clin Otolaryngol 7:185-192, 1982.
23. Johnson JT, Barnes EL, Myers EN, et al: The extracapsular spread of tumor in cervical node metastasis. Arch Otolaryngol Head Neck Surg 107:725-729, 1981.
24. Hirabayashi H, Koshii K, Uno K, et al: Extracapsular spread of squamous cell carcinoma in neck lymph nodes: Prognostic factor of laryngeal cancer. Laryngoscope 101:502-506, 1991.
25. Ellis ER, Mendenhall WM, Rao PV, et al: Does node location affect the incidence of distant metastases in head and neck squamous cell ca? Int J Radiat Oncol Biol Phys 17:293-297, 1989.
26. Strong EW: Preoperative radiation and neck dissection. Surg Clin North Am 49:271-276, 1969.
27. Skolnik EM, Deutsch EC: Conservative neck dissection. Laryngoscope 95:561-565, 1985.
28. Jesse RM, Ballantyne AJ, Larson D: Radical or modified neck dissection: A therapeutic dilemma. Am J Surg 136:516-519, 1978.
29. Barkley HT, Fletcher GH, Jesse RH, et al: Management of cervical lymph node metastases in squamous cell carcinoma of the tonsillar fossa, base of tongue, supraglottic larynx, and hypopharynx. Am J Surg 124:462-467, 1972.
30. Mendenhall WM, Million RR, Cassisi NJ: Squamous cell carcinoma of the head and neck treated with radiation therapy: The role of neck dissection for clinically positive neck nodes. Int J Radiat Oncol Biol Phys 12:733-740, 1986.
31. Grandi C, Mingardo M, Guzzo M, et al: Salvage surgery of cervical recurrences after neck dissection or radiotherapy. Head Neck 15:292-295, 1993.
32. Hillerman BL, Kennedy TL: Carotid rupture and tissue coverage. Laryngoscope 92:985-988, 1982.
33. Biller HF, Urken M, Lawson W, et al: Carotid artery resection and bypass for neck carcinoma. Laryngoscope 98:181-183, 1988.
34. Brennan JA, Jafek BW: Elective carotid artery resection for advanced squamous cell ca of the neck. Laryngoscope 104:259-263, 1994.
35. Meleca RJ, Marks SC: Carotid artery resection for cancer of the head and neck. Arch Otolaryngol Head Neck Surg 120:974-978, 1994.
36. Patten C, Hillel AD: The 11th nerve syndrome: Accessory nerve palsy or adhesive capsulitis? Arch Otolaryngol Head Neck Surg 119:215-220, 1993.
37. Remmler D, Byers R, Scheetz J, et al: A prospective study of shoulder disability resulting from radical and modified neck dissections. Head Neck 8:280-286, 1986.
38. Cotter CS, Stringer SP, Landau S, et al: Patency of the internal jugular vein following modified radical neck dissection. Laryngoscope 104:841-845, 1994.
39. Lake GM, Dinardo LJ, Demeo JH: Performance of the internal jugular vein after functional neck dissection. Otolaryngol Head Neck Surg 111:201-204, 1994.
40. Docherty JG, Carter R, Sheldon CD, et al: Relative effect of surgery and radiotherapy on the internal jugular vein following functional neck dissection. Head Neck 15:553-556, 1993.