Overview
Definition:
Lateral neck dissection, specifically targeting levels II through V, is a surgical procedure aimed at removing lymph nodes in the lateral compartments of the neck
This is primarily performed for the management of squamous cell carcinomas of the oral cavity, oropharynx, larynx, hypopharynx, and salivary glands, as well as metastatic disease from other primary sites to the neck.
Epidemiology:
Cervical lymph node metastasis is the most common route of spread for head and neck cancers, with up to 40-50% of patients presenting with clinically involved lymph nodes
The prevalence of involvement in specific levels varies with the primary tumor site
Lateral neck dissections (levels II-V) are indicated in a significant proportion of these cases.
Clinical Significance:
Accurate and oncologically sound neck dissection is paramount in the management of head and neck malignancies
It is crucial for staging, controlling locoregional disease, improving survival, and facilitating adjuvant therapy planning
Understanding the anatomical boundaries and nodal stations of levels II-V is critical for preventing recurrence and minimizing morbidity.
Indications
Surgical Indications:
Elective neck dissection for clinically node-negative (cN0) patients with high-risk primary tumors (e.g., T3-T4 oral cavity, advanced oropharyngeal cancers)
therapeutic neck dissection for clinically node-positive (cN+) patients with squamous cell carcinoma or other malignancies involving the neck
management of occult primary with clinically positive neck nodes
recurrence in the neck after previous treatment.
Relative Indications:
Metastatic disease from unknown primary tumor in the neck
certain thyroid cancers with nodal metastasis
metastatic melanoma to the neck.
Contraindications:
Distant metastasis
unresectable locally advanced disease involving critical structures (e.g., carotid artery encasement)
patient refusal or significant comorbidities precluding surgery.
Anatomic Considerations
Level Ii:
Upper jugular chain, deep to sternocleidomastoid, anterior to spinal accessory nerve
includes nodes along the internal jugular vein from the skull base to the hyoid bone.
Level Iii:
Middle jugular chain, deep to sternocleidomastoid, inferior to hyoid bone, superior to cricothyroid membrane
nodes along the internal jugular vein from the hyoid bone to the cricothyroid membrane.
Level Iv:
Lower jugular chain, deep to sternocleidomastoid, inferior to cricothyroid membrane, superior to clavicle
nodes along the internal jugular vein from the cricothyroid membrane to the clavicle.
Level V:
Posterior triangle nodes, located posterior to sternocleidomastoid and inferior to the occipital nodes
includes nodes along the transverse cervical artery and the supraclavicular nodes.
Critical Structures:
Internal jugular vein, carotid arteries, vagus nerve, spinal accessory nerve (CN XI), phrenic nerve, brachial plexus, thoracic duct (left side), omohyoid muscle, sternocleidomastoid muscle, scalene muscles.
Preoperative Preparation
History And Physical:
Thorough head and neck examination, including assessment for occult primary
detailed history of symptoms, prior treatments, and comorbidities.
Imaging:
CT or MRI of the neck with contrast to assess nodal size, extracapsular extension, and involvement of vascular structures
PET-CT for distant metastasis screening and nodal staging.
Laboratory Investigations:
Complete blood count, coagulation profile, electrolytes, renal function tests, liver function tests, ECG, chest X-ray as per standard surgical protocols.
Informed Consent:
Detailed discussion with the patient and family regarding the procedure, risks (nerve injury, bleeding, infection, lymphedema, shoulder dysfunction), benefits, alternatives, and expected outcomes.
Anesthesia Considerations:
Airway assessment, positioning, intubation strategy, monitoring of vital signs, and management of potential complications.
Surgical Technique
Incision:
Typically a modified Schobel incision, bilateral Y-shaped, or curvilinear incision
The incision is planned to provide adequate exposure and aesthetic outcome.
Dissection Strategy:
The dissection commences with identifying the superior extent (skull base/digastric muscle), inferior extent (clavicle), anterior extent (carotid sheath/sternohyoid muscle), and posterior extent (trapezius muscle/scalenes)
The sternocleidomastoid muscle is often divided or retracted to expose the lymph node-bearing tissue.
Lymph Node Removal:
Systematic en bloc removal of lymph nodes and associated fatty tissue from levels II, III, IV, and V, preserving critical neurovascular structures
Careful attention is paid to ligation of lymphatic channels
Marginal mandibulectomy or other oncologic resections may be performed concurrently if indicated.
Special Nerve Management:
Identification and preservation of the spinal accessory nerve (CN XI) is crucial, especially in levels II and V
Injury can lead to shoulder weakness and pain
Consideration for nerve monitoring or rerouting may be necessary.
Reconstruction:
Depending on the extent of resection, reconstruction may involve primary closure, local flaps, regional flaps (e.g., Pectoralis major flap), or free flaps to restore form and function
Placement of drains is routine.
Postoperative Care
Monitoring:
Close monitoring of vital signs, fluid balance, wound status, and airway patency
Assessment for signs of hematoma, seroma, infection, or flap compromise.
Pain Management:
Adequate analgesia, often with patient-controlled analgesia (PCA) or multimodal pain regimens.
Drainage Management:
Regular monitoring and management of surgical drains
removal when output is minimal.
Nutritional Support:
Initiation of diet as tolerated, often starting with clear liquids
Nutritional support may be required via nasogastric tube or parenteral nutrition if oral intake is compromised.
Mobilization And Rehabilitation:
Early mobilization to prevent deep vein thrombosis and pneumonia
Physiotherapy for shoulder exercises is essential if the spinal accessory nerve is at risk or sacrificed.
Complications
Early Complications:
Hematoma or seroma formation
wound infection or dehiscence
chyle leak (especially from thoracic duct injury on the left)
phrenic nerve injury leading to diaphragm paralysis
carotid artery injury
nerve injury (CN XI, superior laryngeal nerve).
Late Complications:
Chronic shoulder dysfunction and pain (with CN XI injury)
persistent lymphedema of the neck
fistula formation
pharyngeal or esophageal stenosis
cosmetic deformity
tumor recurrence.
Prevention Strategies:
Meticulous surgical technique
meticulous ligation of lymphatic channels
careful identification and preservation of critical nerves and vessels
appropriate wound closure and drainage
postoperative physiotherapy.
Prognosis
Factors Affecting Prognosis:
Stage of the primary tumor and nodal disease (number of positive nodes, extracapsular extension)
presence of distant metastasis
completeness of surgical resection
patient's overall health and adherence to adjuvant therapy.
Outcomes:
Successful lateral neck dissection significantly improves locoregional control rates and survival for head and neck cancer patients
For cN0 patients, elective dissection has a lower recurrence rate than observation
For cN+ patients, therapeutic dissection is associated with improved survival compared to no treatment.
Follow Up:
Regular clinical examination of the neck and primary site
surveillance imaging as per oncologic guidelines
prompt management of any signs of recurrence or complications
Adjuvant radiotherapy or chemotherapy may be indicated based on histopathological findings.
Key Points
Exam Focus:
Accurate anatomical delineation of levels II-V
critical structures at risk in each level
indications for elective vs
therapeutic neck dissection
management of the spinal accessory nerve
common complications and their management
role of neck dissection in staging and treatment planning.
Clinical Pearls:
Always identify the carotid sheath and sternocleidomastoid muscle boundaries early in dissection
If the spinal accessory nerve is sacrificed, intensive physiotherapy is crucial for functional recovery
Consider sentinel lymph node biopsy in select early oral cancers to avoid formal dissection.
Common Mistakes:
Inadequate dissection of nodal levels, particularly superiorly towards the skull base (level II) or inferiorly towards the supraclavicular region (level V)
injury to the spinal accessory nerve due to poor visualization or aggressive dissection
failure to identify and manage chyle leak
incomplete oncologic resection.