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.