Selective Neck Dissection

Introduction

Selective neck dissection (SND) is distinguished by the preservation of lymph node groups and nonlymphatic structures that are removed during radical neck dissection. SND is a generic term that applies to a group of procedures named according to the levels of the neck in which the lymph nodes are removed. SNDs evolved as surgeons developed an understanding of the predictable lymphatic drainage patterns in head and neck cancer and sought opportunities to optimize the patient’s postoperative function. The primary indication for SND is management of the clinically negative neck when the risk of occult metastases is greater than 15% to 20% and the primary tumor is treated surgically. Selective procedures are used for elective treatment of the neck in primary cancers of mucosal sites of the head and neck, malignancies of the thyroid, salivary glands, and skin.

Guidelines for naming neck dissections were developed by a committee with representatives from the American Head and Neck Society and the American Academy of Otolaryngology–Head and Neck Surgery. The committee also recommended the use of levels and sublevels designated by Roman numerals I–VII to describe the location of lymph nodes in the neck. The naming convention is accepted by surgeons worldwide and facilitates communication and reporting of results. This system names the procedure according to the levels/sublevels that are removed.

The most common SNDs are:

1.
SND I–III, known as supraomohyoid neck dissection, SND I–IV, or extended supraomohyoid, typically used for treatment of oral cavity cancer
2.
SND II–IV or lateral neck dissection for squamous cell carcinoma (SCC) of the oropharynx, hypopharynx, and larynx
3.
SND II–V or posterolateral neck dissection for cutaneous malignancies posterior to the coronal planes through the external auditory canal (EAC) (e.g., posterior pinna and scalp). The suboccipital and retroauricular lymph node groups are included in the dissection.
4.
SND VI or central compartment neck dissection, for thyroid cancer and cancers of the glottis and subglottis, piriform sinus, cervical esophagus, and trachea.

Key Operative Learning Points

Occult or micrometastases are not detectable on physical examination or radiographic imaging.
SNDs are used for pathologic staging of the clinically negative neck.
Pathologic findings guide decision making for adjuvant therapy.
Learn both clinical and radiographic borders for the levels of the neck.
Understand the lymphatic drainage patterns and lymph node groups at risk for occult metastasis according to site and stage of the primary cancer.
Be familiar with the surgical anatomy of the neck.
SNDs are also used for N1 and limited N2 cancers.

Preoperative Period

History

Complete patient history with attention to symptoms of the primary cancer
No specific symptoms for occult lymph nodes

Physical Examination

Complete examination of the head and neck to assess the extent of primary cancer
Accuracy of neck examination is dependent on patient habitus.
Assess location and mobility of palpable neck nodes.
Rule out synchronous second primary cancer.

Imaging

CT or MRI of the neck and primary cancer within 30 to 60 days prior to surgery to assess local extent of primary tumor and the status of cervical lymph nodes
Radiographic criteria for suspicious lymph nodes: size, shape, irregular enhancement, groups of lymph nodes
Imaging not sensitive or specific enough to detect lymph node metastasis less than 1 cm
Ultrasound-guided fine-needle aspiration biopsy of suspicious lymph nodes if results will impact the treatment plan

Indications for Selective Neck Dissection

Clinically N0 neck and risk of occult metastases greater than 15% to 20%
Transcervical approach to the primary cancer
Access the neck for vascular anastomosis/free flap reconstruction
Clinically N1 neck with metastases in the first echelon level
Low-volume clinical N2 neck without fixation of surrounding soft tissue invasion
Limited neck metastasis following radiation or chemoradiation
Indications for specific levels by primary site:
- Ia: Cancer of the lower lip, anterior tongue, and anterior mandibular alveolar ridge
- Ib: Oral cavity, anterior nasal cavity, skin of the midface, and submandibular gland
  
  IIa/IIb: Oral cavity, nasal cavity, nasopharynx, oropharynx, hypopharynx, and larynx. Level IIb has a very low (<5%) incidence of occult adenopathy and is usually not dissected in elective neck dissection. Removal of IIb is included when SND is performed for clinically positive neck metastasis.
- III: Oral cavity, nasopharynx, oropharynx, hypopharynx, and larynx
- IV: Larynx, hypopharynx, thyroid, and cervical esophagus
- V: Nasopharynx, oropharynx, skin of the posterior scalp and neck
- VI: Thyroid, glottis/subglottis, hypopharynx, and cervical esophagus

Contraindications

Poor surgical candidate
Nonsurgical treatment of primary cancer
Unresectable primary cancer
Fixed cervical lymph adenopathy
Distant metastases

Preoperative Preparation

Appropriate assessment of surgical risk from medical standpoint
Plan for reconstruction of primary site defect if applicable.

Operative Period

Anesthesia

General endotracheal anesthesia
Avoid muscle paralysis to assist with identification of important nerves. Once at-risk nerves are identified, the patient can be paralyzed at the surgeon’s discretion.
Communicate during the case when anticipated significant blood loss and any change in the patient’s condition is encountered.
Presurgical discussion with anesthesia team about duration of procedure, anticipated blood loss, nerve monitoring, and other intraoperative concerns

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