Thyroid

evolution of endoscopic thyroidectomy | IJGM

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introduction

Thyroid surgery, including thyroidectomy, is a potential field for minimally invasive surgery using a vestibular incision to facilitate endoscopic and robotic transoral approaches.1–3 Early approaches used rigid endoscopes or linear robotic platforms that require a large workspace. Hybrid NOTES or laparoscopically assisted procedures have also been used for thyroidectomy using a vestibular approach.4,5 Although these approaches are less invasive, they have been associated with complications with a proportion requiring conversion to open surgery. The new approach of pure flexible endoscopic thyroidectomy has been studied in porcine models and shows the potential advantages over hybrid NOTES or laparoscopic instrument-assisted rigid endoscopic operations.6 Here we summarize established endoscopic thyroidectomy techniques, highlight the pros and cons of the various popular endoscopic approaches available for thyroid resection, and discuss how flexible endoscopic thyroidectomy compares to well-established laparoscopic and robotic thyroidectomy techniques.

Laparoscopically assisted thyroidectomy

Endoscopic surgery theoretically allows surgeons to perform remote thyroidectomy without leaving a visible scar on the neck and a number of remote access approaches have been developed for thyroid surgery over the past 2 decades. Most still result in a visible scar somewhere on the body. For example, Angkoon et al and others have reported a NOTES hybrid thyroidectomy using a vestibular approach.4,5,7,8 The evolution of the technique began with a sublingual transoral approach which involved piercing through the floor of the mouth. Due to severe tissue damage and high risk of complications, the technique was modified to use the oral vestibular approach (laparoscopically assisted/NOTES hybrid) which uses vestibular incisions anterior to the mandible between the mental muscles. The laparoscopic-assisted vestibular approach is currently used in a variety of centers and requires three ports and a large operating field (Figure 1A).7,8 However, even with the large working space, it can be difficult to reach all parts of the thyroid gland and 5-10% of procedures must be converted to open surgery. With this approach, precise dissection is a challenge and only thyroid specimens smaller than 2–3 cm can be removed via the intraoral midline incision. Specimens that are larger or of such a hard consistency must be fragmented in order to be removed through the midline incision. Such manipulation of the tumor can also cause rupture of the capsule which increases the risk of spillage of the tumor into the operative field.

Figure 1 (A) Diagram of laparoscopically assisted surgery with three ports and a large operating field. (B) Schematic of a pure flexible endoscopic thyroidectomy.

Robotic thyroidectomy

Transoral robotic thyroidectomy has been the introduction of robotic technology in thyroidectomy and the combination with the transoral vestibular approach has provided new solutions.9 Elizabeth et al reported transoral thyroidectomy using a flexible robotic system and noted no major limitations to its use.ten However, they found that side ports would still be needed for the introduction of instruments. The technique embodies minimally invasive principles including limited tissue dissection and retraction, tight access to the thyroid gland, natural orifice surgery, and produces no visible skin scarring. These improvements have solved many of the limitations of current robotic technology. However, there are still hurdles to overcome for transoral robotic thyroidectomy. As with any robotic surgery, the surgeon cannot directly receive real-time tactile feedback as is the case with laparoscopic instruments. Additionally, robotic thyroidectomies require additional time for robot docking and currently require relatively longer operation time compared to the transoral endoscopic vestibular approach. Additionally, while conventional laparoscopic instruments are readily available in most hospital settings these days, access to robotic systems remains limited. Robotic surgery is also still relatively more expensive than laparoscopically assisted thyroidectomy. Nevertheless, with the increasing number of companies investing and competing in the production and development of robotic surgical systems, these financial barriers may diminish over time in the future.

Flexible endoscopic thyroidectomy

Liu et al proposed a new flexible endoscopic thyroidectomy technique based on their success with flexible endoscopy for pure NOTES. They reported a pilot study in the porcine model to assess the feasibility of flexible endoscopic transoral thyroidectomy.6 Using a transoral incision, a subcutaneous tunnel was produced from the mouth to the thyroid gland to perform a partial thyroidectomy. Flexible endoscopic thyroidectomy includes the following steps: (1) locate the thyroid site using ultrasound, (2) make a 15 mm midline vestibular incision, (2) make a tunnel using forceps through the mandible (3) insertion of a single flexible endoscope channel through the tunnel to access the thyroid gland, (4) dissection of the thyroid gland using a hook and insulated tip knives , and (5) complete resection of the gland using a snare and remove the specimen with endoscopic assistance. The procedure was successfully performed in six pigs, with an average procedure time of 35 min; none of the pigs showed any adverse events. Experience has shown that endoscopic thyroidectomy can be performed using a single operating channel, obviating the need for hybrid NOTES or laparoscopic instrument-assisted rigid endoscopes (Figure 1B). With flexible endoscopy, it has proven possible to reach all parts of the thyroid gland. The gland has been partially resected, among the skills necessary for a successful total thyroidectomy in man include the reliable identification and preservation of the recurrent laryngeal nerve and parathyroid glands as well as the identification and ligation of thyroid vessels upper and lower. However, the current pilot study has a limitation, as the anatomy of the pig’s thyroid gland is slightly different from that of humans. Translation of these techniques to humans will require modification and practice, but this first step showing safe and rapid thyroid resection in humans should be achievable. However, by flexible endoscopic techniques, we can perform all kinds of procedures and if performed in humans, the parathyroid gland and the recurrent laryngeal nerve can be detected and protected in the same way as by a rigid endoscope (assisted by laparoscopy). There are several methods used by the surgeon for sample retraction and these can also be used with a flexible endoscope. In this current study, only the neck was used for retraction because it was the normal glandular tissue. For cancerous lesions, a basket/bag can be used which can completely cover the cancerous tissue and not let the cancer cell spread. Further development of a flexible endoscopic thyroidectomy approach should aim not only for larger-scale preclinical studies, but also for conducting randomized controlled trials comparing this new modality to well-established laparoscopic and robotic thyroidectomy techniques.

Conclusion and future prospects

Flexible endoscopes provide much-needed freedom for tissue access, manipulation, traction, resection and suturing.9,ten Flexible endoscopic thyroidectomies are likely to be a relatively safe and feasible technique and have potential advantages over laparoscopic or hybrid techniques, including requiring limited working space, little tissue damage, less procedure time, and rapid recovery. . However, more research, especially using newly developed tools to further improve this technique, and large-scale practice are needed to make it more accessible to patients around the world. Clinical application of the technique will require cooperation between gastroenterologists and ENT/cosmetic surgeons to leverage the gastroenterologist’s skills in flexible endoscopy and the surgeon’s practical knowledge and experience in thyroidectomy. Acquiring the skills learned from the endoscopist may eventually enable ENT surgeons to perform these types of surgeries either independently or as combined GI-ENT procedures.

Funding

This study was financially supported by grants from Henan General Charity Federation Hepatobiliary Foundation (No: GDXZ2019006) and Henan General Charity Federation Hepatobiliary Foundation (No: GDXZ2022003).

Disclosure

The authors report no conflict of interest in this work.

The references

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