Current Indications for combined surgical approaches to RG
Several goiter-related and patient-related factors must be considered in
the surgical plan. The former are usually evaluated by neck and chest
imaging, and as already mentioned patients are deemed at high risk for
an extra-cervical approach when: RG extends below the aortic arch, it
has multiple or separate mediastinal compartments, it has an “iceberg”
or conical shape (i.e. , it extends to both sides of the thorax or
it has a diameter that is larger than the upper thoracic
inlet)3,21,38,61. Some authors believe that in
presence of possible malignancy, sternotomy may be favored, but there is
no consensus on this point62. In extreme cases, RG may
be strictly adherent to the pericardium63, or it can
even invade it: in these exceedingly rare cases of intrapericardial RG,
sternotomy and the availability of a cardiopulmonary bypass are
essential64. Instead, patient-related features that
may favor an extracervical approach include a history of previous
thyroid or thoracic surgery, previous irradiation in the neck or chest
areas, preoperative dysfunction of the vocal cords, coagulopathies, or
platelet disorders (e.g. , Bernard-Soulier
syndrome)2,21,65.
The most important study that has corroborated these factors was
published in 2019: in a cohort of 237 RGs where 29 (12.2%) required
sternotomy, on multivariate logistic regression analysis, extension
below the aortic arch (OR 10.84), an iceberg shape (OR 59.30), and
previous neck surgery (OR 4.83) were all significantly associated with
an extra-cervical approach66. For the sake of
completeness, another group has suggested the presence of an
inflammatory component in the excised RG as a predictor for sternotomy
(only on univariate analysis and in a small series)67,
while in another series of 109 RGs, only the part extending beyond the
sternal notch into the mediastinum would predict sternotomy (univariate
only, odds ratio 3.43, confidence interval 1.65-6.41), with a
sensitivity of 94% and specificity of 86.5% when it is more than 5
cm68. Unmeasurable aspects such as the surgeon’s
expertise do however exist since there are case series where RG cases
below the aortic arch or in the posterior mediastinum were reported to
be completely excised through a purely transcervical
approach69.
Complete sternotomy is the gold standard access for RG but less
extensive approaches have been devised, namely partial or split
sternotomy70, manubriotomy71,
anterolateral or posterolateral thoracotomy, the hemi-clamshell approach
(partial median sternotomy plus an anterolateral
thoracotomy)72, and they are all technically described
in the work of Uludag et al39. Endoscopic-assisted
approaches are another option but in the last years, video-assisted
mediastinoscopy has lost its interest in favor of thoracoscopic
approaches3,73. For example, the subxiphoid
thoracoscopic approach is a novel alternative proposed by a Chinese
group for median RGs74. Robotic-assisted procedures
are being also actively explored but they are always combined with a
transcervical incision75–77.
Interestingly, in the 2016 American Thyroid Association (ATA) Statement
on Remote-Access Thyroid Surgery (RATS), the substernal extension was
considered a contraindication, but the latest papers seem to overcome
this limit. A RATS by an axillo-thoracic endoscopic approach has been
applied on very selected patients with RG78. The
excellent view of the surgical field provided by high-definition cameras
is obviously very helpful in the identification of critical
neurovascular structures (RLN and phrenic nerves, etc.) but, at present,
all these approaches remain preliminary and a formal comparison with
standard techniques is lacking. Finally and in very rare cases, a
straightforward indication for combined approaches to RG is given by a
coexisting thoracic condition: for instance, a minimally invasive
transcervical and robotic transthoracic approach has been described for
RG and concurrent thymoma79, or RG excision and aortic
valve replacement were performed through a mini-J
sternotomy80.