Historical Overview

Removal of cervical lymphadenopathy has long been recognized as an important component in the care of head and neck cancer, dating back to the early 19th century.¹ Although case reports and case series for removal of isolated cervical metastases were published by von Langenbeck, Billroth, and von Volkmann in the 1870s and 1880s, Kocher advocated for resection of lymphadenopathy with a margin of normal tissue in 1880.² The first radical neck dissection was described in 1888 by the Polish surgeon Jawdynski,² who performed the procedure on a patient who lived for 7 years postoperatively. However, Crile is credited with popularizing the procedure in 1906 with his report comparing the outcomes of 36 patients who had undergone radical neck dissections and 96 patients who had more selective neck dissections. Of the traceable patients who had radical en bloc neck dissections, 75% were alive at 3 years compared to 19% of those who had undergone more selective operations.³

Given the significant morbidity associated with sacrificing the spinal accessory nerve, the sternocleidomastoid muscle, and the internal jugular vein, surgeons increasingly looked to minimizing functional deficits while maintaining oncologic outcome. In 1926, Bartlett and Callander reported similar recurrence rates between radical neck dissection and more conservative neck dissections that spared nonlymphatic structures in the neck.⁴ However, the concept of nonradical neck dissections remained controversial, with Hayes Martin strongly endorsing routine radical neck dissections for cervical metastases.⁵ In his 1951 manuscript, Martin declared that techniques sparing the spinal accessory nerve “should be condemned unequivocally.”⁵ In 1963, Suarez described the first functional neck dissection based on cervical fascial compartments,⁶ which was later popularized by Bocca and Pignataro.⁷ Ballantyne furthered the concept of a modified radical neck dissection by advocating the removal of only those lymph node groups most likely to drain the site of the primary tumor.⁸ More conservative lymphadenectomy paralleled the development of adjuvant therapies. Published literature has demonstrated the effectiveness of selective neck dissection in the appropriate clinical settings.⁹

In 1955, George Crile, Jr, reported similar outcomes for patients with thyroid malignancy undergoing either radical or conservative neck dissections.¹⁰ He emphasized that radical procedures were unnecessary for thyroid cancers, which anatomically drain primarily to the central compartment first and only secondarily to the jugular chain.¹¹

Anatomy

The lymphatic drainage of the head and neck has been well demonstrated (Table 40-1), allowing surgeons to perform more conservative neck dissections to avoid morbidity while maintaining oncologic integrity. The thyroid gland drains primarily to the prelaryngeal, para- and pretracheal, and superior mediastinal lymph basins, which secondarily drain to the jugular lymphatic chain. These drainage patterns are so reliable that a prelaryngeal lymph node found anterior to the cricothyroid membrane is often referred to as the Delphian node. It is named for the Greek oracle, Delphi, because enlargement of this lymph node often heralds the presence of thyroid malignancy.

Table 40-1 Lymphatic Drainage Patterns by Anatomic Site^16,17

Cervical and superior mediastinal lymph nodes are divided into seven levels that are delineated by anatomic boundaries (Table 40-2; see also Chapter 39, Lateral Neck Dissection: Indications, Figure 39-1). Level I, which is rarely involved with thyroid malignancy, includes both submental (level IA) and submandibular (level IB) lymph node groups. Level IA, which comprises the submental triangle, lies between the anterior bellies of bilateral digastric muscles, superior to the hyoid. Level IB is situated posterior to the anterior belly of the digastrics muscle, superior to the posterior belly of the digastrics muscle, and anterior to the posterior border of the submandibular gland.

Table 40-2 Cervical Lymph Node Levels

Levels II, III, and IV represent the upper, middle, and lower thirds of the jugular chain. Level II is bounded by submandibular gland anteriorly, the posterior border of the sternocleidomastoid muscle posteriorly, the skull base superiorly and either the carotid bifurcation (surgical landmark) or hyoid (clinical landmark) inferiorly. The spinal accessory nerve divides this level into anterior (level IIA) and posterior (level IIB) compartments. Level III extends from the posterior border of the sternocleidomastoid muscle to the lateral limit of the sternohyoid muscle, and from the inferior limits of level II superiorly (i.e., hyoid bone) to the superior limit of level IV inferiorly, as marked by the junction of the omohyoid muscle with the internal jugular vein (surgical landmark) or the inferior border of the cricoid (clinical landmark). Level IV extends from the latter landmarks superiorly to the clavicle inferiorly. As with level III, this level extends from the posterior border of the sternocleidomastoid muscle to the lateral border of the sternohyoid.

Level V lies posterior to the posterior border of the sternocleidomastoid muscle, anterior to the anterior border of the trapezius muscle, and superior to the clavicle. The spinal accessory nerve (surgical landmark) and the inferior border of the cricoid (clinical landmark) divide this level into superior (level VA) and inferior (level VB) compartments.

Levels VI and VII constitute the central compartment, which is bounded on either side by the carotid sheath. Level VI extends from the hyoid superiorly to the suprasternal notch inferiorly. Level VII, often referred to as superior mediastinal lymph nodes, extends from the suprasternal notch superiorly to the innominate vein inferiorly.¹²

In addition to understanding cervical lymphatic anatomy, it is important to know the cervical fascial planes (Figure 40-1). The superficial cervical fascia contains subcutaneous fat and sheaths the platysma muscle. The deep cervical fascia has three layers: superficial, middle, and deep. The superficial layer of the deep cervical fascia invests the posterior belly of the omohyoid muscle and the sternocleidomastoid and trapezius muscles. The middle layer of the deep cervical fascia envelops the strap muscles (muscular subdivision) and the thyroid, larynx, trachea, and esophagus (visceral subdivision). The deep layer of the deep cervical fascia invests the deep paravertebral muscles of the neck. All three layers of the deep cervical fascia contribute to the carotid sheath.

Figure 40-1 Classification of cervical fascial planes.

(From Janfaza P, et al, editors: Surgical anatomy of the head and neck, Philadelphia, 2001, Lippincott Williams & Wilkins.)

Types of Neck Dissection

The classic or radical neck dissection description entails inclusion of the spinal accessory nerve, sternocleidomastoid muscle, and internal jugular vein with removal of levels I to V. Including an additional lymph node group or nonlymphatic structure in the resection constitutes an extended radical neck dissection. A modified radical neck dissection involves removing levels I to V while preserving one or more of the spinal accessory nerve, internal jugular vein, or sternocleidomastoid muscle (Table 40-3).

Table 40-3 Classification of Neck Dissections

A selective neck dissection preserves one or more lymph node levels. Specific subclassifications within this category include supraomohyoid (levels I-III), lateral (levels II-IV), posterolateral (levels II-V), and central compartment (levels VI and VII) neck dissections.