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
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Occult or micrometastases are not detectable on physical examination or radiographic imaging.
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SNDs are used for pathologic staging of the clinically negative neck.
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Pathologic findings guide decision making for adjuvant therapy.
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Learn both clinical and radiographic borders for the levels of the neck.
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Understand the lymphatic drainage patterns and lymph node groups at risk for occult metastasis according to site and stage of the primary cancer.
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Be familiar with the surgical anatomy of the neck.
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SNDs are also used for N1 and limited N2 cancers.
Preoperative Period
History
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Complete patient history with attention to symptoms of the primary cancer
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No specific symptoms for occult lymph nodes
Physical Examination
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Complete examination of the head and neck to assess the extent of primary cancer
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Accuracy of neck examination is dependent on patient habitus.
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Assess location and mobility of palpable neck nodes.
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Rule out synchronous second primary cancer.
Imaging
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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
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Radiographic criteria for suspicious lymph nodes: size, shape, irregular enhancement, groups of lymph nodes
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Imaging not sensitive or specific enough to detect lymph node metastasis less than 1 cm
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Ultrasound-guided fine-needle aspiration biopsy of suspicious lymph nodes if results will impact the treatment plan
Indications for Selective Neck Dissection
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Clinically N0 neck and risk of occult metastases greater than 15% to 20%
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Transcervical approach to the primary cancer
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Access the neck for vascular anastomosis/free flap reconstruction
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Clinically N1 neck with metastases in the first echelon level
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Low-volume clinical N2 neck without fixation of surrounding soft tissue invasion
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Limited neck metastasis following radiation or chemoradiation
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Indications for specific levels by primary site:
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Ia: Cancer of the lower lip, anterior tongue, and anterior mandibular alveolar ridge
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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.
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III: Oral cavity, nasopharynx, oropharynx, hypopharynx, and larynx
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IV: Larynx, hypopharynx, thyroid, and cervical esophagus
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V: Nasopharynx, oropharynx, skin of the posterior scalp and neck
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VI: Thyroid, glottis/subglottis, hypopharynx, and cervical esophagus
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Contraindications
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Poor surgical candidate
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Nonsurgical treatment of primary cancer
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Unresectable primary cancer
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Fixed cervical lymph adenopathy
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Distant metastases
Preoperative Preparation
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Appropriate assessment of surgical risk from medical standpoint
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Plan for reconstruction of primary site defect if applicable.
Operative Period
Anesthesia
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General endotracheal anesthesia
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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.
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Communicate during the case when anticipated significant blood loss and any change in the patient’s condition is encountered.
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Presurgical discussion with anesthesia team about duration of procedure, anticipated blood loss, nerve monitoring, and other intraoperative concerns
Positioning
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Turn table 90 to 180 degrees to facilitate surgeon and assistant’s access to the head and neck, especially with bilateral neck dissections.
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Patient position—Supine with head turned away from side of surgery
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Shoulder roll—Moderate shoulder roll for neck extension; avoid hyperextension to prevent postoperative neck pain
Perioperative Antibiotic Prophylaxis
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Guided by surgical approach to the primary cancer
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Not required for isolated neck dissection
Monitoring
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Not routinely used for isolated neck dissection
Instruments and Equipment to Have Available
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Standard neck dissection set
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Vascular suture for inadvertent internal jugular venotomy or other bleeding
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Nerve hooks and/or loops
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Headlight and loupes
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Bipolar, monopolar, and harmonic scalpel
Key Anatomic Landmarks
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External during surgical marking
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Osseous: Lower border and angle of mandible, mastoid tip, clavicle, and hyoid bone
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Non-osseous: sternocleidomastoid (SCM) muscle, external jugular vein, and carotid sheath
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Superficial and deep layers of the deep cervical fascia—SND removes the lymphoareolar tissue between these two layers
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Erb’s point—Landmark for location of spinal accessory nerve at posterior border of SCM
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Cervical plexus—Motor and sensory branches
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Phrenic nerve
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SCM, anterior and posterior belly of digastric, sternohyoid, and omohyoid muscles
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Level I—Facial artery and vein, marginal mandibular nerve, lingual and hypoglossal nerves
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Spinal accessory nerve
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Carotid artery, jugular vein, vagus nerve
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Thoracic duct—Location, tributaries, and course
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Cervical sympathetic trunk—Ascending preganglionic sympathetic fibers; deep and medial to the carotid artery with multiple ganglia. Injury results in ipsilateral Horner’s syndrome.
Surgical Landmarks for the Levels of the Neck
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Ia: Submental lymph nodes—Triangle overlying the anterior belly of digastric muscles, from the mandible to the hyoid
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Ib: Submandibular lymph nodes—Triangle bounded by mandible, anterior belly of digastric muscle and stylohyoid muscle, along with the posterior belly of the digastric muscle; includes the submandibular gland, the preglandular, prevascular, retrovascular, retroglandular, intracapsular, and deep submandibular lymph node groups
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IIa/IIb: Upper jugular lymph nodes—Area from the skull base to the hyoid bone, bounded anteriorly by the lateral border stylohyoid muscle; extends to the posterior border of the sternocleidomastoid muscle. A vertical plane formed by CN XI divides IIa from IIb.
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III: Middle jugular lymph nodes—Inferior border of the hyoid bone to inferior border of cricoid cartilage, bounded anteriorly by the lateral border sternohyoid muscle; extends to the posterior border of the sternocleidomastoid muscle
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IV: Lower jugular lymph nodes—Lower border of the cricoid cartilage to the clavicle. Anterior extent is the lateral border of sternohyoid muscle; extends to the posterior border of sternocleidomastoid muscle
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Va/Vb: Posterior triangle lymph nodes—Superior border is intersection of sternocleidomastoid trapezius muscles, triangle formed by anterior border of trapezius, clavicle inferiorly, and posterior border of SCM. A horizontal plane extending from the inferior border of the cricoid cartilage divides level Va cranially from Vb caudally. Level Va includes the spinal accessory lymph node group, and Vb are the supraclavicular and transverse cervical lymph nodes.
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VI: Central compartment lymph nodes, including the prelaryngeal, pretracheal, and paratracheal lymph nodes. Surgical boundaries are the hyoid bone superiorly and medial border of carotid sheath bilaterally to the suprasternal notch inferiorly.
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Other lymph node groups: Groups of nodes located outside these levels are named by anatomic location:
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Superior mediastinum: Suprasternal notch to innominate arteries, lateral boundary-carotid sheath, includes the anterosuperior mediastinum, and tracheoesophageal grooves
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Retropharyngeal
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Periparotid
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Postauricular lymph nodes—on and behind the mastoid process
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Occipital lymph nodes
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Prerequisite Skills
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Basic surgical skills
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Familiar with the anatomy of the neck
Operative Risks
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Shoulder dysfunction, shoulder pain, capsulitis
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Chyle leak
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Infection
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Edema of the neck and face
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Sialocele
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Wound healing problems/flap necrosis in post radiation neck
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Hematoma
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Hypocalcemia for bilateral central compartment
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Nerve damage
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Vocal cord paralysis
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Skin and ear numbness
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Dysphagia
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Marginal mandibular nerve weakness/paralysis
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Dysarthria, tongue weakness, tongue numbness
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Horner’s syndrome
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Paralysis of the diaphragm
Surgical Technique
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Neck dissections are defined by the levels that are removed, and the surgical steps for each level are described individually here. The sequence of events for every neck dissection will be different, depending on surgeon preference, the location of palpable lymph nodes, and the plan for excision of the primary cancer. General principles for all neck dissections are to define the superficial borders of the dissection and work from the superficial to deep structures to ensure adequate exposure of critical structures.
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Planning the incision—Depends on levels being removed and surgeon’s preference. A transverse incision placed in a skin crease or standard utility incision affords good exposure for most SNDs.
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Incise the skin along the entire length of the planned incision. Identify the platysma prior to incising it, as the posterior border provides a reliable landmark for the external jugular vein and great auricular nerve.
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Incise platysma and elevate subplatysmal flaps. Keep the plane of dissection just deep to the platysma; this is an avascular plane that facilitates preservation of the external jugular vein, great auricular nerve, and the superficial layer of the deep cervical fascia (e.g., the fascia overlying the SCM). In areas where the platysma is dehiscent, flap elevation is continued in a subcutaneous plane of the dissection that is best defined by the surgeon.
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The extent of flap elevation depends on the levels of the neck that will be removed.
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Level I: Inferior border of the mandible. Staying in the avascular plane just deep to the platysma will minimize the risk of injury to the marginal mandibular nerve.
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Level II: Posterior belly of the digastric muscle
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Level III: Inferior belly of omohyoid muscle
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Level IV: Clavicle
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Level V: Anterior edge of the trapezius muscle and clavicle
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Level VI: Sternal notch, anterior border of SCM, hyoid bone
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Expose the most superficial boundaries of the neck dissection according to levels removed:
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Level Ia—Lateral border of contralateral anterior belly digastric, mentum, and hyoid
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Level Ib—Lower border of mandible, anterior and posterior digastric, facial artery and vein at their junction with the lower border of the mandible
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Levels II–III—Posterior belly of digastric, lateral border of sternohyoid, and SCM from behind the angle of the mandible to the posterior omohyoid muscle
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Levels II–IV—Posterior belly of the digastric, lateral border of sternohyoid, SCM from behind the angle of the mandible to the clavicle, and the clavicle anterior to the insertion of SCM
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Level V—Mastoid tip, anterior border of trapezius, clavicle, and posterior border SCM
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Level I Dissection
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Level Ia—Submental triangle: Dissect the fibrofatty tissue overlying the anterior bellies of the digastric muscles, from the mentum to the hyoid bone; includes lymphatic tissue between and deep to the anterior digastrics
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Complete dissection of level Ib includes the investing fascia of the submandibular gland and requires identification, dissection, and protection of the marginal mandibular nerve ( Fig. 64.1 ). The course of the nerve in relation to the inferior border of the mandible is variable, and identification is facilitated by opening the investing fascia in the vicinity of the angle of the mandible, where it exits the tail of the parotid. Once the nerve is skeletonized and placed above the inferior border of the mandible, the fascia of the gland is separated from the inferior border of the mandible, and the facial artery and vein are ligated. Level I contents are retracted inferiorly and posteriorly while dissecting the lymphatic tissue from the anterior belly of the digastric and mylohyoid to expose the lateral border of the mylohyoid. After ligating the blood supply to the mylohyoid, an angled retractor is used to retract the lateral border anteriorly to expose the lingual and hypoglossal nerves, submandibular ganglion, and duct and cross the hyoglossus muscle. The ganglion and the duct are ligated and transected while visualizing the lingual nerve and, once accomplished, will allow inferior retraction of the specimen and improved exposure of the hypoglossal nerve inferior and deep to the submandibular duct. Both the lingual and hypoglossal nerves are identified prior to ligating the submandibular duct as anteriorly as possible to ensure removal of the accessory gland tissue along the duct.
