Anatomy of Neck Dissections


1. Arranged as a ring around the base of the head submental, submaxillary, parotid, retroauricular, occipital
- these descend into vertical chains
--> superficial = external and anterior jugular; ie superficial cervical and anterior cervical chains respectively.
- deeper chains lie along the trachea (paratracheal) and behind the pharynx (retropharyngeal).
All these --> deep cervical nodes, around the internal jugular vein.
--> these end in terminating nodes of all head neck lymph, and give rise to teh right and left jugular lymphatic trunks --> us. to thoracic duct on left or right lymphatic trunk on right.

Hence the deep cervical nodes must be removed in head and neck dissections.


2. What are the lymph node groups in neck dissection

6 levels and increasing toward the chest

II,III,IV associated with IJV which is medical to posterior border of SCM and lateral to the sternohyoid

 

 

level I – submental and submandibular

submental nodes (in submental triangle)

submandibular nodes (in submandibular triangle)

includes submandibular gland

from contralateral anterior belly of digastric to ipsilateral posterior belly of digastric

level II – upper jugular

around upper third of internal jugular vein

from level of carotid bifurcation or hyoid to base of skull

lateral boundary posterior border of sternocleidomastoid

medial border lateral border of sternohyoid and stylohyoid

level III – middle jugular

around middle third of jugular

upper level carotid bifurcation or hyoid

lower level junction omohyoid with IJV or cricothyroid

lateral boundary posterior border of sternocleidomastoid

medial boundary lateral border of sternohyoid

level IV – lower jugular

around lower jugular

upper border junction omohyoid with IJV or cricothyroid

lower border clavicle

lateral border posterior border of sternocleidomastoid

medial border lateral border of sternohyoid

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level V – posterior triangle

Superior: union of two muscles at occipital bone

Medical: posterior border of sternocleidomastoid

Lateral: anterior border of trapezius

Inferior: clavicle

nodes along spinal accessory nerve

nodes along transverse cervical artery

supraclavicular nodes, including the infraclavicular Virchow’s node

level VI – anterior triangle

midline from hyoid superiorly to sternal notch inferiorly

lateral boundary is medial border of carotid sheath

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3.  What are the types of neck dissection

 

radical neck dissection

all nodes I – V

accessory nerve, IJV and sternocleidomastoid sacrificed

modified radical neck dissection

levels I – V

one or more of accessory nerve, IJV and sternocleidomastoid preserved

selective neck dissection

en-bloc removal of one or more lymph node groups at risk for early lymph node metastases

supraomohyoid selective neck dissection

levels I – III

for ca of oral tongue or floor of mouth

± contralateral side

add IV for tongue ca

lateral selective neck dissection

levels II – IV

for ca pharynx, hypopharynx and larynx

usually bilateral

posterolateral selective neck dissection

levels II – V

for cutaneous malignancies and soft-tissue sarcomas

Anterior selective neck dissection

level VI


Terminology

Comprehensive

· The comprehensive neck dissection removes all nodal tissue in the lateral neck:Levels I-V. They are subclassified into rad and mod rad. Generally indicated for the clinically positive neck N+.

·  Radical – removal of lymph nodes and sternocleidomastoid muscle,

internal jugular vein, spinal accessory nerve, and submandibular salivary gland.

· Modified radical: Preserving any one of

— Type 1: Accessory nerve

— Type II: XI and SCM

— Type III: XI, SCM and IJV: generally used only for metastatic differentiated thyroid carcinoma.

Extended radical: Resecting any of:

— Skin, external carotid

— XII

— Digastric

Selective

·  Used for SCC of the upper aerodigestive tract with clinically negative disease (N0), where there is at least a 15% to 20% risk of occult metastatic disease.

·  Based on metastasizes in a predictable and sequential pattern.

·  SLND spares all nonlymphatic tissue, including XI, SCM and IJV.

·  Does not removal all the lymphatic tissue on the involved side of the neck as does a comprehensive neck dissection.

·  SLND may be used for clinically evident nodal metastases confined to the first-echelon nodes (usually N1) when the primary is being treated by surgery. Post op RT is then required.


4.  What are the likely primary sites for lymph node metastases for the

different levels

level I

            lip, oral cavity, skin

level II

            oral cavity, oropharynx, nasopharynx, hypopharynx, larynx

level III

            oral cavity, oropharynx, hypopharynx, larynx, thyroid

level IV

            oropharynx, hypopharynx, larynx, cervical oesophagus, thyroid

level V

            accessory nerve chain – nasopharynx, scalp

supraclavicular – breast, lung, GIT

occipital – scalp

 

lip I

oral cavity I, II, III

oropharynx II, III, IV

nasopharynx II, V

hypopharynx II, III, IV

larynx II, III, IV

thyroid III, IV, VI

cervical oesophagus IV

breast, lung, GIT V

5. Skin Incisions
Raise skin flaps. Must consider flap viability, access and safe return of skin cover for carotids etc.
Consider also radiotherapy effect on wound healing.
Blood supply runs caudad from lower border of mandible and craniad from line of clavicle
--> hence theoretically transverse mid-cervical incision is the safest approach but other options common
- best policy is to avoid a three point junction.
Excellent exposure from a 'lateral apron flap' from tip of mastoid vertically to down along border of trapezius, curving forward to 2cm above clavicle then ending anterior down SCM; good blood supply
Elevate platysma with flap; augments blood supply


Radical Neck Dissection

· Preparation

— Head drape

— Shoulder roll

— Neck extension

— Bipolar diathermy

— Nerve stimulator ü If modified radical or selective

— Patient N OT paralysed þ

· Incision Hockey along SCM to below platysma

· Flaps raised

— Subplatysmal plane

Superior to mandible

Anterior to mid line

Posterior to trapezius

· Posterior D

— Define anterior border of trapezius

— Divide accessory nerve

— Define superior border of clavicle

— Identify & divide inferior belly of omohyoid

— Identift & divide posterior ends of transverse Cx vessels

— Sweep contents lateral ® medial

— Expose Levator scapulae, Scalenus posterior, scalenus medius & scalenus anterior

— Identify & preserve phrenic & brachial plexus

· Ligation of IJV

— Lower end SCM divided

v ThyroCx trunk underlyingclavicular head

— Lat border sternohyoid defined & retracted medially

— Carotid sheath opened

— X identified & preserved

— IJV exposed, ligated & divided

— Thoracic duct identified ± ligated & divided

— Medial end transverse Cx vessels ligated & divided

· Reflection of SCM & posterior D contents

— Superior belly omohyoid defined ® hyoid

Anteromedial limit of dissection

— SCM, IJV & lymphatics dissected superiorly off X & carotid

— Phrenic nerve preserved

— Trunks of Cx plexus divided

— Upper end SCM divided

— Hypoglossal & descendens hypoglossi identified crossing carotid

— Posterior belly digastric defined

RMV divided

Tail of parotid divided

— IJV divided superiorly

Common Ops 4

· Anterior D

— Cx fascia along mandible incised

— Facial artery & retromandibular vein divided

— Tissue dissected off anterior belly digastric

— Upper end of omohyoid divided

— Submandibular gland dissected out from under mylohyoid

— Lingual nerve identified & preserved

Fibres to SM gland divided

— Hypoglossal nerve identified

— SM duct divided

— Facial artery divided deep, after X’s stylohyoid

· Closure

— Suction drains

— S/c 2-0 vicryl to platysma

— Staples to skin

 


What are the complications of neck dissection

wound air leaks

bleeding

chyle fistula

facial/cerebral oedema (synchronous bilateral IJV ligation)

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blindness

carotid artery rupture (exposed carotid or infection)

 


Factors important in prognosis of nodal disease

· Presence of pathologically enlarged nodes, size, number and location (level IV and V have worse prognosis), extra-capsular spread of malignancy, perivascular and perineural infiltration.


Risk factors for nodal metastasis

· Site of the primary: the more posteriorly located the greater the risk increasing from lip to tongue to base of tongue and highest in hypopharynx. The glottis has a low rate due to relative paucity of lymphatics

· Size of the primary (T stage)

· Exophytic

· Vascular or perineural invasion

· Differentiation depth of invasion

Primary site

Certain primary sites are classically involved first with specific levels by neck metastasis

Oral cavity I-III

Oropharynx II-IV

Hypopharynx II-IV

Larynx I-IV

Nasopharynx: II-V

Lower lip, base of tongue, soft palate, supraglottis have a high rate of bilateral mets

The incidence of level V mets is low in head and neck SCC


image

 

Staging

TNM

v For metastatic SCC

· N0 nil paplpable

· N1 Single ipsilateral LNM £3cm

· N2

— a Single ipsilateral LNM 3 - 6cm

— b Multiple ipsilateral £ 6cm

— c Bilateral £6cm

· N3 ³6cm

Prognosis

· Recurrrence predicted by:

— Number of LNM

— Extracapsular spread

Survival

· N0 80% 5yrs

· N+ 40& 5yrs

· Extracaps spread 20% 5yrs

Indications

Therapeutic

· For N+ neck

· Selection of op based on

— N status

— Fixation

— Situation of XI

— CT findings of relational anatomy and deep structures

Selective

· N1 disease as below:

Site of 1° Level of LNM Levels dissected

Oral I I -IV

Lip I I – III bilaterally

Laryngopharyngeal II II - IV

Comprehensive

· Generally procedure of choice for clinical metastatic neck disease

— Skin

— Salivary gland

— Thyroid

— Oropharyngeal

· Also for N+ neck with unknown primary

— 63% 5yrs, contralateral failure 16% McMahon ANZJS 2000

· Preserve XI, IJV, SCM if possible

— XI functionally most important

Adjuvant XRT

· Consider for N1

— Extracapsular spread

· Bilateral recommended for N2 and N3

Elective (or selective)

· N0 neck

SCC

Site of 1° T stage Levels dissected

Oral cavity 2-4 I - III

Oropharynx 1-4 II - IV

Thyroid

· MTC

— N0 Bilateral ‘central’: III, IV and upper mediastinal

— N+ Unilateral comprehensive, central on other side

Incisions

Selective

· Incision below mandible

· Incision over SCM to clavicle

Comprehensive

· Y shaped incision

· Horizontal component from Level I to Level V

— lowest point £ 1/2 way down SCM

· lazy-S on vertical limb to clavicle over SCM

· Trifurcation of incision should be posterior to carotid artery in case of breakdown

Operative

· See handout and Mastery I p373