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78
J. X. Wu and R. Raghunathan
• The anatomical compartments of the cervical lymph nodes are categorized into
six levels [6–8].
• Neck dissections can be divided into central versus lateral [6–8]:
– Central neck dissection (CND) removes lymph nodes from level VI and may
be unilateral or bilateral.
– Lateral neck dissections (LND) remove lymph nodes from levels II to V, and
are further categorized by which structures are spared.
Radical neck dissection removes all nodal tissue from levels I to V and
sacrices non-lymphatic structures including the sternocleidomastoid
muscle, spinal accessory nerve, and internal jugular vein.
Modied radical neck dissection removes all nodal tissue from entire
compartments (usually levels II-IV and often V for thyroid cancer) but
preserves one or more of the above structures. A more limited compartmental dissection is sometimes called a selective neck dissection.
• Neck dissections performed for clinically or radiographically evident disease are
referred to as therapeutic. Neck dissections done in the absence of evident disease are considered prophylactic.
• The 2009 American Thyroid Association (ATA) guidelines note that residual
malignant nodal disease constitutes the most common site of thyroid cancer persistence and recurrence, making “adequate surgery. .. the most important variable inuencing prognosis.” [9].
Central Neck Dissection
Indications for Central Neck Dissection inThyroid Cancer
(Cf. Table10.1)
Table 10.1 Summary of indications for central neck dissection
Therapeutic central neck dissection Prophylactic central neck dissection
1. Proven or suspected central compartment
nodes
2. PTC
3. FTC
4. MTC
5. cN1a in resectable ATC with no distant
metastases, IF surgery
cN1a clinically positive disease in the central neck nodes, cN0 clinically node negative disease in
the central neck nodes, cN1b clinically node positive disease in the lateral neck nodes, CLND
central lymph node dissection, DTC differentiated thyroid cancer, PTC papillary thyroid cancer,
FTC follicular thyroid cancer, ATC anaplastic thyroid cancer
1. Evidence of lateral neck nodal
metastases in WDTC
2. cN0in MTC requires:
– Total thyroidectomy and
– Bilateral CLND
10 Central andLateral Neck Dissection: Techniques andPotential Complications
79
• Central neck dissection (CND) should be performed when patients with all
types of thyroid cancer have biopsy-proven OR strongly suspected central
compartment (level VI) nodal disease:
– On initial presentation, 20–30% of PTC patients have macroscopic cervical
nodal metastases seen on ultrasound [3, 9–11].
– Therapeutic CND to remove clinically positive nodes (cN1) should be per-
formed at the time of thyroidectomy [1, 8] to minimize the risk of recurrent or
persistent disease and the risks involved with reoperation [1, 8, 12, 13].
• Routine prophylactic central neck dissection (pCND) should NOT be per-
formed for WDTC:
– Studies note up to 90% of PTC patients have microscopically positive nodal
metastases (<10mm in diameter) on pathological evaluation with immuno-
histochemistry [3, 9–11].
– Randomized clinical trials show no survival benet of pCND [14].
– Recent guidelines strongly recommend against pCND in clinically node-
negative PTC [1].
– For FTC, pCND for microscopic nodal disease or occult metastases should
not be performed, since FTC metastasizes hematogenously and has a very
low rate of lymph node metastases (<5%) [1].
• Prophylactic central neck dissection can be considered when WDTC patients
have lateral neck nodal disease but no evidence of disease in the central
compartment [1, 15, 16].
• Routine prophylactic central neck dissection should be performed in
patients with MTC:
– MTC has a high rate of multifocal disease and locoregional lymph node
involvement which may not be evident on preoperative ultrasound [17].
– Total thyroidectomy with concurrent routine bilateral pCND is the recommended
standard of care, even without sonographic evidence of nodal involvement [17].
– pCND can be omitted in small intrathyroidal MTCs with low preoperative
calcitonin (<20pg/mL) [17].
– Clinical evidence of nodal involvement in the central neck requires bilateral
CND and prophylactic lateral neck dissection ipsilateral to the positive central
nodes [1, 17].
Operative Considerations
Anatomy
• The neck nodes are divided into six levels (I–VI) and six sublevels (A or B)
(Table10.2 Levels of the neck; Fig.10.1 Levels of the neck) [6–8].
80
Table 10.2 Levels of the neck
Level Sub- level Anatomic boundaries Nodal contents
I A A: platysma
B IB: Submandibular triangle nodes
II A A: SMG
B IIB: Upper jugular nodes, posterior to
III A: lateral border SHM
IV A: lateral border of SHM
V A A: SCM
B VB: Posterior triangle nodes below the cricoid
VI S: hyoid bone
A anterior border, P posterior border, S superior border, I inferior border, L lateral borders, SMG
submandibular gland, SCM sternocleidomastoid, SHM sternohyoid muscle, IJV internal jugular
vein, CB carotid bifurcation
P: posterior border of SMG
S: mylohyoid muscle and
mandible
I: inferior border of hyoid
P: posterior border of SCM
S: skull base
I: CB (surgical) or hyoid
(clinical)
P: posterior border of SCM
S: inferior limit of level II
I: cricoid or junction of
omohyoid and IJV
P: SCM
S: inferior limit of level III
I: clavicle
P: trapezius
S: skull base
I: clavicle
I: innominate artery
L: medial border of carotid
arteries
IA: Submental triangle nodes
IIA: Upper jugular nodes, anterior to accessory
nerve
accessory nerve
Middle jugular lymph nodes located between
cricoid cartilage and hyoid bone
Lower jugular nodes located from clavicle to
cricoid cartilage
VA: Posterior triangle nodes above cricoid
cartilage
cartilage
Central compartment nodes: pretracheal,
paratracheal, and prelaryngeal nodes
J. X. Wu and R. Raghunathan
• The central compartment is delimited superiorly by the hyoid bone, laterally by
the carotid arteries, anteriorly by the supercial layer of the deep cervical fascia,
posteriorly by the deep layer of the cervical fascia and inferiorly by the innominate artery (Fig.10.2. Anatomy of the central neck compartment) [6–8].
• CND for thyroid cancer usually only extends superiorly to the cricoid
cartilage,
• The inferior border of the central compartment, the innominate artery includes
the anterior mediastinal nodes, which are also referred to as level 7 nodes.
• Thyroid carcinoma most commonly spreads to prelaryngeal (Delphian), pretracheal, and paratracheal nodes in the central compartment (Fig.10.2 Anatomy of
the central neck compartment) [6–8].
• Important structures include (Fig. 10.2 Anatomy of the central neck
compartment):
10 Central andLateral Neck Dissection: Techniques andPotential Complications
Fig. 10.1 Levels of the
neck; Bruinsma M,
BFA, 2023
81
– Nerves: the external branch of the superior laryngeal nerve and the recurrent
laryngeal nerve, both of which come from the vagus nerve.
Recurrent laryngeal nerve courses around the arch of the aorta on the left
and around the subclavian artery on the right.
– Vasculature: the superior thyroid artery, a branch of the external carotid, and
the inferior thyroid artery, which is a branch of the thyrocervical trunk, and
the superior, middle, and inferior thyroid veins, which drain into the internal
jugular vein (IJV).
Equipment for Central Neck Dissection [1, 12, 13]
• Ultrasound in the operating room after induction of anesthesia to localize
small nodes.
• Standard instrument tray for thyroid operations.
• Prepare 5-0 prolene suture if there is a risk of injury to jugular vein.
• [Optional] Nerve stimulation and monitoring system.
82
Fig. 10.2 Anatomy of central neck compartment; Bruinsma M, BFA, 2023
J. X. Wu and R. Raghunathan
Technique: How toPerform aCentral Neck Dissection
[1, 8, 12, 13]
Pre-Operative Maneuvers
• Position patient supine with arms tucked bilaterally.
• Extend neck using shoulder roll.
• Raise head of bed by 20–30° (decreases venous pressure).
• [Optional] Set up nerve monitoring system.
Incision
• Note anatomic landmarks: sternal notch, cricoid cartilage.
• Incision should be placed in a curvilinear fashion, within a skin crease when possible, approximately one nger breadth below cricoid cartilage.
– In general, incisions placed higher provide better exposure than lower
incisions.
10 Central andLateral Neck Dissection: Techniques andPotential Complications
83
Exposure
• Raise subplatysmal aps superiorly to the thyroid notch and inferiorly to the
sternal notch.
• A vertical incision opens the median raphe between the sternohyoid and sternothyroid muscles from the thyroid to the sternal notch OR the sternohyoid, and the
sternothyroid muscles can be transected horizontally if needed.
• Proceed with usual steps of total thyroidectomy (see Chap. 9: Thyroidectomy:
Techniques, Adjuncts, and Potential Complications).
• Sometimes it is preferable to perform the central neck dissection prior to the division of Berry’s ligament, allowing the thyroid gland to be used as a handle.
Excision ofCentral Compartment Nodes
• Identication of the parathyroid glands, and optional marking with small vascular clips or a stitch away from their vascular supply, is crucial to preventing
inadvertent injury, particularly to the inferior glands during the thyroidectomy
and paratracheal dissection.
• Medial retraction of the trachea with the attached thyroid lobe or using a peanut
sponge and lateral retraction of the carotid artery will expose the paratracheal
compartment.
• Trace the length of the recurrent laryngeal nerve from its insertion into the cricopharyngeal joint proximally to where the nerve enters the thoracic inlet, crossing
underneath the innominate.
• The brofatty tissue is usually divided into two pieces over the recurrent laryngeal nerve, allowing the brofatty tissue between the carotid artery and trachea
to be excised with the nerve in full view.
• If the inferior parathyroid gland is devascularized during resection, it can be
morcellated and auto-transplanted, but this should be balanced against the risk of
auto-transplantation of thyroid cancer cells.
• On the right, nodes are distributed both anteriorly and posteriorly to the nerve,
while they are mostly anterior to the nerve on the left, rendering right-sided dissection more technically challenging.
Complex Situations [12, 13, 18, 19]
Tumor Stuck toNerve
• When central neck nodes exhibit extra-nodal extension, this can involve the
recurrent laryngeal nerve.
• If nerve monitoring was used and the recurrent laryngeal nerve/vagus nerve had
a positive signal prior to dissection, then every attempt should be made to leave
the nerve grossly intact.
84
J. X. Wu and R. Raghunathan
• If signal is lost during dissection but the nerve is grossly intact, consider a staged
procedure to allow time for the nerve to recover, to avoid bilateral recurrent
nerve injury.
• If the nerve is transected/sacriced, then one should proceed with contralateral
surgery because risk of bilateral nerve injury will not change with time.
• If preoperative laryngoscopy already demonstrated ipsilateral nerve paresis and
there is evidence of involvement of the recurrent laryngeal nerve, then the nerve
should be sacriced unilaterally for oncologic reasons.
• If a nerve is transected or sacriced, a nerve repair should be considered either
with the two ends of the recurrent nerve or with a graft from another nerve like
the ansa cervicalis.
Mediastinal Nodal Involvement
• Nodes that extend past the innominate are considered level VII lymph nodes.
• Preoperatively, a consult with thoracic surgery to consider potential need for
mediastinoscopy or median sternotomy should be obtained.
• Skin preparation and sterile drapes should extend to umbilicus.
• The level VI nodal packet should be kept intact when possible, to help retract the
level VII nodes cephalad.
• In certain circumstances, mediastinoscopy can reach involved nodes down to the
tracheal bifurcation, sparing the need for sternotomy.
Complications andManagement
Nerve Injury
• Recurrent laryngeal nerve injury paralyzes the vocal cord, causing hoarseness
and dysphagia with thin liquids (if vocal cords do not close, this increases the
risk of aspiration).
• Injury to the external branch of the superior laryngeal nerve impairs the modulation of voice volume, affecting projection and pitch [12, 13].
• Grossly intact nerves can recover with time, within a few days or up to 6months.
Vascular Injury
• Small injuries to the carotid artery or jugular vein can be repaired primarily with
ne non-absorbable monolament suture.
• If more than 50% of the circumference of the jugular vein is involved, the vein
can be resected and ligated.
• Uncontrolled small vessels can lead to a neck hematoma with risk of airway
compromise.
10 Central andLateral Neck Dissection: Techniques andPotential Complications
Hypocalcemia andHypoparathyroidism
• Injury to the parathyroid glands themselves, their vasculature, or inadvertent
removal of the glands with the specimen can compromise their function causing
transient or permanent hypoparathyroidism and hypocalcemia.
85
Lateral Neck Dissection
Indications forModied Radical Neck Dissection (MRND)
• Biopsy proven OR strongly suspected nodal involvement in the lateral neck.
– 20–30% of patients with WDTC have positive nodes in the lateral
neck [20].
– Both the National Cancer Care Network (NCCN) and American Thyroid
Association (ATA) guidelines recommend LND based on FNA conrmation
of nodal disease given the morbidity of the operation [1, 15].
– In select cases with strong clinical suspicion, conrmation of lateral neck
metastases with FNA biopsy is not necessary.
– If the FNA remains indeterminate, excisional biopsy of the suspected node(s)
with frozen section can be used to guide extent of surgery [12, 21].
– A delayed LND can also be performed with no added morbidity from reop-
eration, since the lateral neck compartment is not routinely entered as part of
surgery for DTC.
• Local recurrence of lateral neck nodal disease after previous surgery
for DTC.
– If the nodal recurrence is in a previously dissected compartment, subsequent
operation(s) should be a focused removal of the positive node and any adjacent nodes [1].
– Lateral neck compartments not previously dissected containing nodal metas-
tases should be formally excised.
– Ethanol ablation or active surveillance can be considered for patients who
have undergone multiple operations with high risk of morbidity with further
surgery [11, 22, 23].
• Medullary thyroid cancer with cN1a disease.
– Prophylactic LND in patients with MTC is controversial; recent guidelines
suggest considering it if basal calcitonin is greater than 200pg/mL and there
is no evidence of distant metastatic disease [17].
86
• Nodal disease in ATC.
– Compartment-oriented neck dissection should only be considered in select
patients with resectable disease with treatment response to targeted therapy [24].
– In general, ATC that is not limited to the thyroid is usually not amenable to
surgical intervention and patients should instead be considered for targeted
therapy, immunotherapy, chemotherapy, or clinical trials [24].
J. X. Wu and R. Raghunathan
Operative Considerations
Anatomy
• The extent of an LND for WDTC is controversial and depends on where the
nodal disease is located [12, 25].
• The ATA consensus statement recommends removal of nodal and brofatty tissue from levels IIA, III, IV, and VB (81), with the highest burden of disease
generally found in levels III (77%), IV (62%), and VB (40%) [16]; (Cf. Table10.2.
Levels of the Neck).
• Some surgeons perform a selective dissection that focuses on levels III, IV, and
the anterior portion of VB, pursuing further dissection in levels II and the remainder of V if positive nodal disease is conrmed in the adjacent compartment [25];
important anatomy of the lateral neck is depicted in Fig.10.1 Levels of the neck
and Fig.10.3 Anatomy of the lateral neck.
Equipment
• Same as Central Neck Dissection—Equipment.
• Optional—closed-suction drain left in situ to manage postoperative drainage
from the wound and to alert for chyle leak.
Technique
How to perform a modied radical neck dissection (MRND) [11, 12]:
Preoperative Maneuvers
• Similar to Central Neck Dissection—Technique: Preoperative Maneuvers.
• Remove hair with clippers or use paper tape to secure bouffant to patient skin.
• Skin preparation and draping should include the earlobe.
• Avoid paralysis to allow motor nerve monitoring during the procedure.
10 Central andLateral Neck Dissection: Techniques andPotential Complications
87
Fig. 10.3 Anatomy of the lateral neck; Bruinsma M, BFA, 2023
Incision
• Single-incision: a transverse cervical incision is placed in a skin crease, ideally
1–2 ngerbreadths below cricoid cartilage, gently curved upward toward the
mastoid process.
• OR
• Dual incision: midline transverse cervical incision is placed in a skin crease,
1–2cm below the cricoid cartilage AND a separate transverse skin incision in a
skin crease centered over level II of the neck.
Exposure
• Raise subplatysmal aps, taking care to avoid the marginal mandibular nerve
(branch of facial nerve) that courses within supercial cervical fascia overlying
submandibular gland.