Neck Dissection
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Direct answer
George Crile's 1906 radical neck dissection removed lymphatic levels I to V with the sternocleidomastoid, internal jugular vein and spinal accessory nerve; the modern era kept the oncological principle and shed the mutilation, giving the modified radical dissection preserving one or more of those three structures, and the selective dissections — supraomohyoid (I-III) for oral cavity, anterolateral (II-IV) for larynx, central compartment (VI) for thyroid — removing only the levels at risk. No decision matters more than node level mapping: levels dictate extent, and extranodal extension dictates adjuvant chemoradiotherapy.
What you must remember
- Robbins levels: Ia submental, Ib submandibular; II upper jugular (IIa/IIb around the spinal accessory), III mid, IV lower jugular, V posterior triangle (Va/Vb around the omohyoid), VI central compartment, VII superior mediastinal.
- Drainage by primary: oral cavity to I-III (lateral tongue may skip to III-IV); oropharynx, hypopharynx and larynx to II-IV; thyroid to VI; nasopharynx to V.
- Radical neck dissection (Crile): levels I-V plus SCM, IJV and accessory nerve — reserved for disease encasing structures.
- Modified radical (Bocca): all five levels cleared but preserving any combination of SCM, IJV and accessory nerve.
- Selective dissections: supraomohyoid (I-III, extended to IV for tongue) as the elective oral cavity operation; anterolateral (II-IV); posterolateral (II-V); central compartment (VI).
- Elective dissection when occult risk exceeds roughly 20 per cent — the clinical N0 oral cavity T2-plus case; sentinel node biopsy is emerging in selected centres.
- Complications: chyle leak from the left thoracic duct (milky drainage; medium-chain-fat diet, drainage, closure if persistent); accessory palsy with shoulder syndrome (pain, droop, abduction limited beyond 90 degrees) treated by physiotherapy; marginal mandibular, hypoglossal, vagus, phrenic and brachial plexus injury; haematoma; lymphoedema; bilateral IJV sacrifice staged weeks apart.
- Pathology drives adjuvants: pN2/N3, extranodal extension and positive margins trigger postoperative radiotherapy, with concurrent cisplatin for ENE or involved margins.
- The Hayes Martin manoeuvre — ligating the facial vessels to drop the marginal mandibular nerve away from the field — protects during level I clearance.
A worked therapeutic case
A 60-year-old with a cT2 N2b buccal mucosa carcinoma — multiple right level II-III nodes, largest 3.5 cm — is listed for composite resection and neck dissection. Plan the neck as an oncological exercise in itself. Incision: a hockey-stick or utility cervical incision with limbs placed to avoid skin necrosis. Dissection: subplatysmal flap, protect the marginal mandibular branch by the Hayes Martin manoeuvre, clear level I with the submandibular gland as part of the specimen, then II through IV along the IJV with the accessory nerve in view — a modified radical dissection preserves SCM, IJV and accessory when oncologically safe; convert to radical if tumour encases the IJV or infiltrates SCM. Watch the thoracic duct low on the left; test clear fluid for chyle if suspicion arises. Orient the specimen with sutures per level — the pathologist's map, since extranodal extension decides adjuvant therapy. Post-op: drains until output falls below about 25-30 mL per day, early shoulder physiotherapy, voice and shoulder function documented at discharge. Histology showed ENE in one node: postoperative chemoradiotherapy with cisplatin follows — the chain from operative finding to adjuvant prescription is the sequence the examiner wants narrated.
Where students slip
Level anatomy recited without boundaries collapses under one viva question: "what separates IIa from IIb?" (the spinal accessory nerve) or "what bounds level V?" (trapezius, SCM, clavicle, split into Va and Vb by the omohyoid). The second slip is terminology: calling a supraomohyoid dissection a "modified radical" — it is selective, because levels IV-V are not removed; the radical-modified-selective ladder is about extent and preservation, and mixing categories forfeits the question. The third is forgetting why the accessory nerve matters: listing "shoulder weakness" without the mechanism (trapezius denervation, scapular droop, painful adhesive capsulitis) is a complication list without a patient.
Frequently asked questions
What structures are sacrificed in a radical neck dissection?
Levels I-V with the sternocleidomastoid, internal jugular vein and spinal accessory nerve — the Crile operation, now reserved for extensive disease.
How does a modified radical dissection differ?
It clears the same five levels but preserves one or more of accessory nerve, IJV and SCM.
Which levels are removed in a supraomohyoid dissection and for which primary?
Levels I-III — the elective operation for oral cavity — extended to IV for lateral tongue tumours because of skip metastasis.
What is the shoulder syndrome after neck dissection?
Painful dysfunction from accessory nerve injury — trapezius paralysis, scapular droop, weak abduction beyond 90 degrees — prevented by nerve preservation, treated with physiotherapy.
How is a chyle leak recognised and managed?
Milky triglyceride-rich drain output from left thoracic duct injury; drainage, medium-chain triglyceride diet, and surgical closure if high output persists.
When is elective neck dissection indicated?
When occult metastasis risk exceeds roughly 20 per cent — a clinically N0 T2 oral cavity cancer — because waiting converts a selective operation into a therapeutic one.