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45 Isthmusectomy andSubtotal Thyroidectomy
https://t.me/med1917
Fig. 45.2 The isthmus is exposed by elevating the strap muscles away from the thyroid capsule
471
Fig. 45.3 Inferior thyroid veins are divided
Fig. 45.4 Anterior trachea is exposed
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K. Black and J. Hubbard
along this line (Fig.45.5). The author’s practice is to use an
energy device but could also be done by use of clamps and
transxion sutures.
The now free edge of isthmus is lifted and separated it
from the trachea, until the isthmus is fully mobilised
(Fig. 45.6). The recurrent laryngeal nerve should not be
within the operative eld, but care should be taken to avoid
excessive lateral dissection. Again, ensuring there is an
adequate margin around the lesion, the contralateral side of
the thyroid isthmus is divided (Figs.45.7 and 45.8).
The specimen is removed and sent for histopathological
assessment (Figs. 45.9 and 45.10). Additional pretracheal
tissue can be dissected and excised, if wanting lymph node
sampling in the setting of malignancy (Fig.45.11).
45.4.3 Subtotal Thyroidectomy
Following initial incision and exposure as above, the plane
between the thyroid and the strap muscles is developed until
a retractor can be positioned for the assistant to retract the
muscles laterally, while the surgeon applies nger traction to
pull the thyroid medially. A combination of blunt and sharp
dissection is used to continue capsular dissection of the thyroid around the lateral surface of the gland. If middle thyroid
veins are encountered, these are ligated and divided with use
of energy device or ligaclips.
Once there is adequate exposure, the superior pole can be
gently pushed laterally to allow dissection of the tissue plane
medially between the cricothyroid and superior thyroid ves-
Fig. 45.5 The thyroid is divided, ensuring adequate margin around the lesion
Fig. 45.6 The free edge of isthmus is lifted and separated from the trachea
45 Isthmusectomy andSubtotal Thyroidectomy
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Fig. 45.7 The lateral boundary of excision is dened, ensuring adequate margin beyond the lesion
473
Fig. 45.8 The remaining side of isthmus is divided
Fig. 45.9 The specimen has been removed
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Fig. 45.10 The surgical eld after removal, demonstrating exposed anterior surface of trachea, with the divided thyroid edges laterally
K. Black and J. Hubbard
Fig. 45.11 Pretracheal tissue can also be excised depending on the indication
sels (bloodless plane of Reeve’s). Further dissection about
the superior pole vessels is done so that they are fully exposed
more medial aspect of the line of dissection to be visualised
and dened.
to allow to safe division. This is done using an energy device
or ligaclips, or combination of both until the superior pole is
adequately mobilised. The superior pole vessels should be
divided close to their point of entry into the gland, and care
using energy device (or cut between artery clips and then
tied) leaving the thyroid remnant posteriorly and therefore
not exposing or damaging the recurrent laryngeal nerve.
should be taken to avoid the external branch of the superior
laryngeal nerve if visible. Any remaining lower pole vessels
can then also be ligated.
ing thyroid tissue is required. The procedure is then repeated
on the contralateral side.
At this point, the limit of dissection is dened to determine the amount of thyroid tissue that will remain. It should
be a safe distance from the likely path of the recurrent
45.4.4 Closure
laryngeal nerve. And if possible, the parathyroid glands
should be identied and considered when deciding the line
of dissection. The thyroid isthmus is divided to allow the
A drain is used depending on surgeon preference. The wound
is closed in layers with interrupted Vicryl sutures to reap-
The thyroid lobe is then divided along the dened line
Attention to ensure adequate haemostasis of the remain-
45 Isthmusectomy andSubtotal Thyroidectomy
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475
proximate strap muscles, followed by the platysma. Then
continuous subcuticular monocryl sutures are used to close
skin.
45.4.5 Post-operative Care
Following the procedure, the patient should be nursed head
up. They should be observed for a short time in the recovery
area then admitted to a surgical ward. A drain would typically be removed day one post-operatively and the patient
discharged home. In the case of isthmusectomy, they could
be discharged home on the day of surgery if well.
Final histology results should be reviewed when available
to assess whether any further completion surgery should be
considered. Approximately 4–6weeks post-operatively, the
patient should have a blood test to check their thyroid function and consider whether thyroxine supplementation is
required; however, this should be less commonly required
following isthmusectomy.
References
1. Li Y, Li Y, Zhou X.Total thyroidectomy vs bilateral subtotal thyroidectomy for bilateral multinodular nontoxic goiter: a metaanalysis. ORL J Otorhinolaryngol Relat Spec. 2006;78:167–75.
2. Ku CF, Lo CY, Chan WF, etal. Total thyroidectomy replaces subtotal thyroidectomy as the preferred surgical treatment for graves’
disease. ANZ J Surg. 2005;75:528–31.
3. Tekin K, Yilmaz S, Yalcin N.What would be left behind if subtotal
thyroidectomy were preferred instead of total thyroidectomy? Am
J Surg. 2010;199:765–9.
4. Skilbeck C, Leslie A, Simo R.Thyroid isthmusectomy: a critical
appraisal. J Laryngol Otol. 2007;121:986–9.
5. Perros P, Colley S, Boelaert K, et al. British thyroid associated
guidelines for the management of thyroid cancer. Clin Endocrinol.
2014;81:1–122.
6. Palit TK, Miller CC, Miltenburg DM.The efcacy of thyroidectomy
for Graves’s disease: a meta-analysis. J Surg Res. 2000;90:161–5.
7. Maser C, Donovan P, Udelsman R. Thyroid Isthmusectomy: a
rarely used but simple, safe and efcacious operation. J Am Coll
Surg. 2007;204:512–4.
8. Perez-Ruiz L, Ros-Lopez S, Gudelis M, etal. Isthmectomy: a conservative operation for solitary nodule of the thyroid isthmus. Acta
Chor Belg. 2008;108:699–701.
9. Goldfarb M, Rodgers S, Lew JI.Appropriate surgical procedure for
dominant thyroid nodules of the isthmus 1cm or larger. Arch Surg.
2012;147:881–4.
10. Nixon IJ, Palmer FL, Whitcher MM, et al. Thyroid isthmusectomy for well-differentiated thyroid cancer. Ann Surg Oncol.
2011;18:767–70.
11. Wang J, Sun H, Gao L, etal. Evaluation of thyroid isthmusectomy as a potential treatment for papillary thyroid carcinoma
limited to the isthmus: a clinical study of 73 patients. Head Neck.
2016;38:1510–4.
12. Park H, Harries V, McGill MR, et al. Isthmusectomy in selected
patients with well-differentiated thyroid carcinoma. Head Neck.
2019;1-7:43.
13. Karatzas T, Charitoudis G, Vasileiadis D, etal. Surgical treatment
for dominant malignant nodules of the isthmus of the thyroid gland:
a case control study. Int J Surg Lond Engl. 2015;18:64–8.
14. Lee YS, Jeong JJ, Nam KH, etal. Papillary carcinoma located
in the thyroid isthmus. World J Surg. 2010;34:36–9.
15. Lei J, Zhu J, Li Z, etal. Surgical procedures for papillary thyroid
carcinoma located in the thyroid isthmus: an intention-to-treat analysis. Onco Targets Ther. 2016;9:5209–16.
16. Song CM, Lee DW, Ji YB, etal. Frequency and pattern of central
lymph node metastasis in papillary carcinoma of the thyroid isthmus. Head Neck. 2016;38:E412–6.
17. Vasileiadis I, Boutzios G, Karalaki M, etal. Papillary thyroid carcinoma of the isthmus: total thyroidectomy or isthmusectomy? Am J
Surg. 2018;216:135–9.
18. Haughan BR, Alexander EK, Bible KC, etal. Management guidelines for adult patients with thyroid nodules and differentiated
thyroid cancer: the American Thyroid Associated Guidelines Task
Force on Thyroid Nodules and Differentiated Thyroid Cancer.
Thyroid. 2016;26:1–133.
19. Hubbard JGH, Inabnet WB, Lo CY.Endocrine surgery: principles
and practice. Springer; 2009.
Total Thyroidectomy withLevel VI
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andVII Neck Dissection
ChristopherFundakowski, IainJ.Nixon, DiptiKamani,
andGregoryW.Randolph
46
46.1 Introduction
The thyroid gland lies within the central neck. It has a rich
blood and lymphatic supply derived from its surrounding
anatomical region and is surrounded by critical anatomical
structures including the carotid arteries, recurrent laryngeal
nerve (RLN) and the external branch of the superior laryngeal nerve (EBSLN), as well as the laryngotracheal complex
and oesophagus. As such, surgeons involved in the management of thyroid cancer should understand the indications for
surgical intervention, the techniques required to achieve safe
and effective surgery and the outcomes of procedures that
involve removal of the thyroid gland and its surrounding
lymphatics without damage to these critical structures.
Total thyroidectomy with level VI and VII neck dissection
involves excision of the thyroid gland and all nodal tissue
from the central compartment of the neck, from the hyoid
bone superiorly to the innominate artery inferiorly, between
the common carotid arteries laterally and from the infrahyoid
strap muscles ventrally to the prevertebral fascia dorsally.
During the procedure, structures within the operative eld
are at risk, but protection of the recurrent laryngeal nerves
C. Fundakowski
Department of Otolaryngology-Head and Neck Surgery, Thomas
Jefferson University, Philadelphia, PA, USA
e-mail: christopher.fundakowski@tuhs.temple.edu
I. J. Nixon
Department of Otolaryngology-Head and Neck Surgery, NHS
Lothian, University of Edinburgh, Edinburgh, Scotland, UK
e-mail: Iain.Nixon@nhslothian.scot.nhs.uk
D. Kamani
Division of Thyroid and Parathyroid Surgery, Department of
Otolaryngology, Massachusetts Eye and Ear, Harvard Medical
School, Boston, MA, USA
e-mail: dipti_kamani@meei.harvard.edu
G. W. Randolph (*)
Department of Otolaryngology Head and Neck Surgery, Harvard
Medical School, Boston, MA, USA
e-mail: gregory_randolph@meei.harvard.edu
and parathyroid glands is of particular importance in order to
avoid long-term complications from surgery.
The aim of this chapter is to review the indications for this
procedure and the surgical technique involved, as well as the
outcomes that can be expected.
46.2 Indications
The presence of malignant thyroid disease metastatic to nodes
in the central compartment is an indication for therapeutic
nodal surgery [1]. The aim of the procedure in this setting is
to remove all macroscopic evidence of malignancy from the
central compartment. This procedure may also be combined
with a lateral neck dissection if metastatic nodes are identied
in the lateral compartment. Indeed, most authors would recommend ‘elective’ central neck dissection if there is lateral
neck disease but no evidence of central neck disease, as the
central neck is considered the rst echelon of nodal spread. In
proven medullary thyroid cancer without evidence of metastatic spread, it is accepted that there is a high risk of occult
metastatic nodes in the central compartment, and to overlook
such nodes may prevent denitive cure [2]. For these reasons,
‘elective’ central neck dissection is recommended, and this
should be considered an indication.
In contrast, the position for differentiated thyroid cancer is
more controversial. Follicular cancers do not commonly
metastasise to nodes, so such elective dissection of the central
neck is not routinely recommended. Papillary cancers, however, have high rates of metastasis, and elective dissection of
the central compartment identies metastatic spread in up to
40% of cases, but when such small-volume metastatic deposits are observed rather than removed, they rarely manifest as
progressive clinical disease during follow-up. This contrast
between high rates of occult metastasis, low rates of clinically
signicant progressive disease and a recognition of the higher
rates of morbidity associated with more aggressive surgery
have resulted in signicant controversy over the role of ‘elec-
© Springer Nature Switzerland AG 2024
R. Simo et al. (eds.), Atlas of Head and Neck Surgery, Springer Surgery Atlas Series,
https://doi.org/10.1007/978-3-031-36593-5_46
477
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C. Fundakowski et al.
tive’ central neck dissection in papillary thyroid cancers.
International guidelines at one point supported the practice in
almost all cases, but they now advocate a more selective
approach, reserving elective neck surgery for T3 or T4
tumours (extrathyroidal extension and larger tumours), which
are at higher risk of metastatic spread [1, 3].
Contemporary management of the clinically node- negative
neck requires an appreciation of the biology of the disease, the
requirements of the patient and the outcomes of the operating
surgeon. An anxious patient with high-volume primary disease,
particularly in the setting of proven extrathyroidal extension,
who is managed in a high-volume setting with a low incidence
of iatrogenic complications, is probably best served with elective central neck dissection. In contrast, the lower-risk patient
managed in a low-volume centre with resultant higher rates of
complications is probably best served with a more conservative
approach to treatment. By understanding this balance between
risk of both disease and surgery versus the potential for harm,
one can see that higher-risk patients should be considered for
referral to high-volume surgeons in order to optimise overall
outcome in these potentially complex cases.
46.3 Surgical Technique
46.3.1 Thyroidectomy
Choice of incision for thyroidectomy with level VI/VII dissection is typically similar to that of standard thyroidectomy.
The extent of superior/inferior subplatysmal aps is at the
discretion of the surgeon; they generally extend from the thyroid notch to the sternal notch. Next, the infrahyoid midline
raphe is identied and split vertically from the level of the
hyoid to the sternal notch to allow for maximum lateral
retraction of the strap muscles and improve visualisation.
When assessing the planes between the sternohyoid and
sternothyroid muscles, as well as between the sternothyroid
and thyroid gland, one must assess for the presence of extrathyroidal extension. Some focal adherence in these planes is
likely to be encountered from previous ne needle aspiration
(FNA), though signicant adherence of the otherwise typical
areolar planes in this region should be met with suspicion.
When in doubt, a cuff of the adherent sternothyroid (and sternohyoid if necessary) should be resected in continuity with the
thyroid gland to serve as a ventral margin. In rare cases with
extensive soft-tissue invasion, where both layers of infrahyoid
strap muscles require resection bilaterally, one may consider
placement of an acellular dermal graft or a locoregional softtissue ap (particularly if overlying skin is involved) to minimise adherence of the laryngotrachea to the overlying skin.
Once the strap muscles have been retracted laterally and
considered free of tumour, attention is directed towards the
thyroid gland. There are well-described approaches to the
thyroid and the recurrent laryngeal nerve (RLN) from vari-
ous directions: medial, inferior, superior and lateral
(Fig.46.1) [4, 5]. It is of utmost importance for the surgeon
to be familiar and facile with more than one approach to the
RLN, as occasionally the anatomy may be distorted by scar
tissue or invasive disease that prevents the routine plan of
dissection. Similarly, the identication and preservation of
parathyroid glands to minimise post-operative hypocalcaemia is of critical importance while dissecting in the paratracheal region during thyroid surgery.
As the superior pole vessels are addressed and the thyroid
gland is mobilised off of the lateral aspect of the larynx, the
cricothyroid and cricopharyngeus muscles and the EBSLN
are seen. If the cricothyroid muscle is invaded and requires
resection, it is important to be aware of the post-operative
impact on phonation and deglutition. Dorsal invasion of the
cricopharyngeus and pharyngeal constrictor is best
approached after identifying and following the RLN cranially, given the relative proximity of these structures.
When mobilizing the thyroid gland off of the ventral trachea
towards the ligament of Berry, one needs to assess for potential
invasion into the perichondrium and/or underlying cartilage.
Identication and management of both tracheal and oesophageal invasion is of considerable importance, given its association with worsened locoregional control. Tracheal invasion is
fairly common, being noted in approximately one third of cases
of locally invasive, differentiated thyroid carcinoma. Ideally,
preoperative imaging and endoscopy would identify full-thickness intraluminal tracheal invasion, and appropriate resection
and reconstruction should be planned preoperatively. Supercial
tracheal invasion may occasionally be removed sharply with
acceptable margins without entering the airway. More extensive
involvement requires more aggressive resection and may result
in a through-and-through tracheal defect. In such a scenario,
options may include a window resection with myofascial and/or
cartilaginous reconstruction, or segmental resection with primary anastomosis, based on the extent of trachea resected.
If there is concern preoperatively for oesophageal invasion,
oesophagoscopy should be performed to assess for intraluminal extension. For supercial oesophageal invasion, placement
of an oesophageal dilator may assist with the determination of
tissue planes, subsequent dissection and preservation of inner
mucosa. When outer oesophageal musculature is resected, the
area may be bolstered with regional myofascial ap or acellular dermal graft. In instances of full- thickness oesophageal
invasion, the reconstruction will be based on the extent of the
initial resection. Primary inverted closure may be performed
for focal defects, though overzealous primary closure may
result in iatrogenic stenosis and subsequent dysphagia.
Extensive full-thickness oesophageal defects commonly
require either regional or free tissue transfer reconstruction.
Local invasion of the RLN is also fairly common, being
encountered in approximately 33–61% of locally invasive differentiated thyroid carcinoma [6]. This nding in isolation is
not noted to impact overall survival, but it may be associated
ab
yroid pole
46 Total Thyroidectomy withLevel VI andVII Neck Dissection
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Fig. 46.1 Various approaches
to the recurrent laryngeal
nerve (RLN). (a) Inferior; (b)
superior; (c) lateral
c
479
RLN
Ligament
of berry
Reflected
superior
th
RLN
Thyrothymic
horn
with worsened disease-free survival and higher locoregional
recurrence rates (though to a lesser extent than tracheal and
oesophageal invasion). The International Neural Monitoring
Study Group (INMSG) guidelines assist with intraoperative
decision-making and optimal management of RLN invasion.
Preoperative glottic function, intraoperative anatomic
ndings and intraoperative real-time electrophysiologic
information are all utilised to determine optimal management of the RLN.Approximately 45% of patients with RLN
invasion found at surgery may still have normal preoperative
vocal fold mobility [7].
RLNs with invasion of the epineurium (Type A invasion)
can typically have this layer shaved off the nerve, with functional recovery exceeding 80% [8]. Deeper invasion (Type B
invasion) will likely alter the appearance of the nerve intraoperatively; dissection without leaving macroscopic tumour is
rarely possible. INMSG guidelines recommend attempting to
preserve RLNs that have maintained some degree of glottic
function on preoperative examination. The decision for
aggressive oncologic resection at the expense of impact on
voice may be appropriate in scenarios where available adju-
RLN Ligament
vant treatment options are less effective (higher-grade malignancy, medullary thyroid carcinoma, anaplastic carcinoma,
iodine-refractory disease). A preoperative discussion with the
patient that claries this trade-off and the potential for biologic cure is essential. In cases of known preoperative vocal
fold paresis, intraoperatively assess RLN stimulation proximally; a positive response indicates that the RLN should be
preserved when possible. Preservation of the RLN in this case
may prevent further vocal fold atrophy; sacrice may result in
worsening of voice, dysphagia and/or aspiration [9].
Occasionally, an intraoperative loss of signal (LOS) of the
RLN may occur during dissection. An initial EMG amplitude
of 500μV or greater serves as an optimal normative baseline,
with LOS dened as an amplitude <100μV.If the amplitude
does not recover to 50% of initial baseline (>250μV) within
20min of injury, there is an 80% risk of vocal fold paralysis,
with recovery time varying between 27days for type II-global
injuries and 62days for type I-segmental injuries.
Routine placement of a drain for patients undergoing thyroidectomy (with or without central neck dissection) is not
recommended.
of berry
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Middle
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C. Fundakowski et al.
46.3.2 Central Neck Dissection (Level VI/VII)
A rm knowledge of the central (level VI) and upper mediastinal (level VII) compartments is of utmost importance in
order to successfully extirpate regional metastasis.
46.3.2.1 Boundaries
Level VI nodes are conned by the following structures/
boundaries: the hyoid bone (cranial), the common carotid
artery (lateral), the sternal notch (caudal), the prevertebral
fascia (dorsal/posterior) and the undersurface of the sternothyroid muscles (ventral/anterior). Level VII is located inferior to the sternal notch and extends caudally to the
innominate artery and brachiocephalic vein. One must
remember that in level VII, the boundaries may be somewhat variable and arbitrary, given that the innominate artery
Fig. 46.2 Central neck compartments.
The four major regions that constitute
the most important node- bearing regions
within the central neck are the
prelaryngeal (Delphian) compartment
(a), the pretracheal compartment (b) and
the bilateral paratracheal compartments
(c, d)
Upper
may be positioned superior to the sternal notch in some
patients, and it is not present in the left side of the
compartment.
46.3.2.2 Dissection: Level VI
After the thyroidectomy is completed, there will be an excellent view of the proximal ventral trachea, cricoid cartilage
and the anterior lamina of the thyroid cartilage. A comprehensive level VI dissection can be compartmentalised into
prelaryngeal, pretracheal and paratracheal regions
(Fig.46.2). American Thyroid Association (ATA) consensus
indicates that central neck dissection (CND) includes tissue/
nodes from pretracheal, prelaryngeal and at least one paratracheal compartment. The majority of regional metastasis
from well-differentiated thyroid cancer usually resides
within one or more of these four locations [10].
a
cd
Lower
b
Right
46 Total Thyroidectomy withLevel VI andVII Neck Dissection
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481
The prelaryngeal dissection may frequently have been
accomplished while addressing the pyramidal lobe. This dissection extends from the previous position of the superior
thyroid isthmus cranially to the level of the thyroid notch.
Occasionally, lymph nodes may be present at the cricothyroid
membrane or may be intimately associated with the cricothyroid muscle fascia. One must be cognizant of the positioning
of the EBSLN overlying the cricothyroid muscle fascia when
addressing vessels that may bridge the space between the
superomedial upper pole of thyroid and the cricothyroid.
The pretracheal compartment dissection commences at the
previous location of the inferior thyroid isthmus and extends
caudally to the innominate artery. Several structures are positioned ventral to the trachea: the innominate artery, innominate vein, thymus and sternomanubrium. When dissecting in
this region, localizing the innominate artery to prevent inadvertent injury is of extreme importance. Similarly, dissecting
ventral to the trachea prevents injury to the RLNs, which are
located in the paratracheal compartments (especially the left
RLN, given its more medial position within the tracheoesoph-
ab
ageal groove). The rostral thymus is commonly in view during this dissection; it is unlikely to harbour metastatic nodes,
but it may well contain inferior parathyroid. Resection of the
thymus does not improve regional disease control or survival,
but increases the risk of postoperative hypocalcaemia.
Remaining ventral on the trachea will assist in prevention
of injury to the RLNs laterally. Transitioning from the pretracheal to paratracheal compartment without identication of
the RLN may result in injury, particularly on the left side.
The paratracheal compartments are bounded by the common
carotid (laterally), the trachea (medially), the innominate (caudally) and the cricoid cartilage (cranially). The anatomic course
of the RLN differs on the right and left sides, and the surgeon
must have an intimate understanding of the nerve trajectory,
which has a signicant impact on nodal yield and nerve preservation. Given the relationship of the RLN with the subclavian
artery, the course of the right RLN through the paratracheal
space begins comparatively more ventral caudally, traveling in
an oblique trajectory, as opposed to the left RLN, which essentially runs parallel to the tracheoesophageal groove (Fig.46.3).
Right
laryngeal
nerve
vagus
nerve
Fig. 46.3 Right (a) versus left (b) courses of the RLN
Left
laryngeal
nerve
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