Transoral Thyroidectomy

History of Transoral Thyroidectomy

Since Kocher introduced the modern era of thyroid surgery well over a century ago, the surgical approach has remained virtually unchanged: a lower midneck transverse incision. With improved instrumentation, lighting, and safer operating conditions over the decades, the size of the incision has decreased, but a resultant scar persisted in the anterior neck as a conspicuous hallmark of the surgery. However, there has been recent interest in the development of remote access approaches to the thyroid with the primary goal of avoiding a visible postoperative scar. Although the value of avoiding a visible thyroidectomy scar has been fiercely contested by various experts over the years, there is a growing body of evidence (to be discussed later) that suggests a visible scar may have a significant quality-of-life effect on a patient. This patient-centered perspective, combined with a focus on nonmalignant disease in predominantly a young, female population, has motivated both patients and surgeons to explore alternative approaches to the thyroid (See Chapter 31 , Principles in Thyroid Surgery and Chapter 32 , Robotic and Extracervical Approaches to the Thyroid and Parathyroid Glands).

Since 1997, there have been approximately 20 different thyroidectomy techniques proposed as minimally invasive alternatives to the conventional transcervical approach. Most of the novel thyroidectomy approaches effectively move the incision to a concealed area of the chest, axilla, or hairline. A minimally invasive procedure should strive to minimize tissue dissection, be safe, respect surgical planes, minimize surgical trauma, and avoid scarring. With these criteria in mind, it is clear that many of these procedures are actually more invasive than the transcervical approach. These alternative approaches have engendered much controversy because they necessitate a compromise between minimal tissue dissection, a visible cervical scar (the status quo), and extensive tissue dissection with a remote, imperceptible scar. The challenge to minimize tissue dissection while still achieving an optimal, scarless cosmetic result has led to the evolution of transoral thyroidectomy.

Natural orifice transluminal endoscopic surgery (NOTES) has garnered increasing enthusiasm in various surgical fields over the past decade. By accessing surgical targets deep in the abdomen and pelvis using transoral, transvaginal, or transanal endoluminal approaches, tissue dissection can be minimized; this can result in a favorable risk profile and improved recovery. Within the field of head and neck surgery specifically, there have been advances in transoral surgery for pathologies in the oropharynx and laryngopharynx that have been made possible by technologic innovations in robotic and laser microsurgery. In the context of remote access thyroid surgery, a transoral approach offers several key advantages that make it particularly attractive; the advantages include the following: reduced tissue dissection to reach the central neck; a midline approach, which affords equal exposure to both sides of the neck; and anatomy that is more familiar to the head and neck surgeon (in contrast to the chest and axillary approaches).

In 2007, Witzel et al. published the first report demonstrating the feasibility of a transoral approach to the thyroid in two human cadavers and 10 porcine models through a single, sublingual incision. With the proof of concept established, there were further preclinical experiments establishing the potential of the transoral route.

The first clinical use of transoral endoscopic thyroidectomy was reported in 2011 by Wilhelm et al. In this series of eight patients, three patients required conversion to an open approach, and one patient had a permanent recurrent laryngeal nerve (RLN) injury. Nakajo et al. next described their transoral video-assisted approach in eight patients with a premandibular (rather than sublingual) incision and the use of Kirschner wires to elevate the anterior neck skin flap. All patients experienced anterior chin sensory disorders for more than 6 months, which demonstrated one of the risks inherent in this technique. In 2011, Richmon et al. modified the transoral endoscopic approach by introducing the da Vinci robotic system (Intuitive Surgical, Inc., Sunnyvale, CA). Advantages of the robotic over endoscopic technology include the following: a high-resolution, three-dimensional image; wristed and tremor free instrumentation; and precise robotic motion scaling, which allows for superb tissue visualization and handling. The initial approach included a single midline sublingual port for the camera and two lateral vestibular ports for the effector arms. Although feasible, the camera position through the floor of mouth resulted in restricted motion with collisions against the nose and maxilla. The technique was modified by moving the camera port anterior to the mandible such that all three ports were transvestibular; this allowed for unrestricted translation of the camera. The transvestibular approach was subsequently described via a purely endoscopic approach as well. This approach would subsequently become the accepted standard for transoral endoscopic and robotic thyroidectomy. Notable preclinical developments in transoral thyroidectomy can be found in Table 33.1 .

Initial experience with transoral robotic thyroidectomy (TORT) was fraught with an unacceptable rate of mental nerve injury. This was due to the placement of the lateral trocars low in the vestibule and close to the mental nerve foramen, which resulted in excessive tension on the nerve with instrument movement. This setback was overcome in Anuwong’s landmark publication of his initial 60 patients of transoral endoscopic thyroidectomy by vestibular approach (TOETVA); the patients had excellent surgical outcomes. There were no mental nerve injuries as the lateral port sites were moved closer to the commissure and away from the mental nerve foramen. Since this publication and the dissemination of this technique through conferences and cadaveric courses, there are currently more than 50 centers, in 13 countries worldwide, that perform transoral thyroidectomy. Enthusiasm for this technique continues to expand, and the rapidly growing body of evidence further supports the safety and feasibility of this procedure.

Better Cosmetic RESULTS are a Natural Outcome of Process Improvement

Thyroid surgery has evolved in various facets over the years. Examples of process improvements that have become common include the avoidance of surgical drains, use of intraoperative nerve monitoring (IONM), and outpatient thyroid surgery. Each of these changes has been passionately debated by the experts; however, over time, these and other improvements have become well-accepted among most high-volume thyroid surgeons. The excellent safety profile and low morbidity of thyroid surgery is the product of continuous improvements made over more than a century.

The midline cervical incision represents possibly the final, and likely most contentious, area of potential improvement. Despite myriad approaches developed to either reduce the size of the scar or move the incision away from the middle of the neck, none of these have become widespread in North America or Europe. Almost all Western world surgeons and patients continue with the Kocher incision (popularized more than 100 years ago), even though some patients find it undesirable and even though repeated attempts have been made to improve cosmesis.

Remote-Access Thyroid Surgery is more Popular in Asia Than in the Western World?

Much of the evolution and dissemination of remote access thyroid surgery has occurred in Asia. Patient selection and operative indications likely play a role in the more tempered adoption of remote access approaches in the United States (US). Historically, an elevated body mass index (BMI) was a contraindication for remote access surgery. Many Western patients have a different body habitus; series of remote access patients from the US demonstrate a higher BMI on average than most series from Asia. Authors have suggested that this factor may contribute to the novel complications that were noted with remote access thyroid surgery in the US. Furthermore, the size of thyroid tumors was found to be larger in US series than in those from Asia. Nodules or tumors larger than 3 cm have traditionally been contraindicated for remote access thyroidectomy. Because Western patients have a higher BMI and have larger tumors than their Asian counterparts, they are less likely to be considered as candidates for most remote access approaches.

More nuanced explanations likely exist and may contribute to the discrepancy between the remote access thyroidectomy experience in Asia and the Western world. Some authors have alluded to the fact that there is less interest in avoiding a cervical incision in Western populations. Unfortunately, there is little evidence to support such conclusions as will be discussed later. The cost of robotic remote access approaches has been found to be higher than open controls, but this decreases as operative times decrease. There is also the role of compensation; in societies where robotic remote access approaches reimburse at a higher rate than open thyroidectomy, these approaches are more common. On the other hand, in a fee-for-service system, prevalent in the US, there is a financial disincentive for surgeons to perform cases that take longer; this is especially the case if there is a learning curve associated with proficiency. Perhaps all of these and/or other explanations are valid, but it is clear that remote access thyroid surgery has lagged in adoption in the Western world despite a recognized demand among some patients and despite an excellent safety profile among patients in Asia.

Why Offer Remote Access Thyroid Surgery at All?

If patients are less likely to be candidates for remote access approaches in the Western world, and if the procedures are costlier and may have additional risks, why should it be offered to patients at all?

There is a growing body of research evaluating the effect of a cervical incision on quality of life demonstrating that a scar may appear to negatively affect some patients in both Asia and North America. Reports from one South Korean series suggest that the characteristics of the scar are not as important as the presence of the scar itself. In other words, no matter how well an incision heals, having a cervical incision is detrimental to the overall quality of life at least during the initial period after surgery. The authors reported that a well-healed cervical incision affected the health care-related quality of life at a level similar to the effect of psoriasis, vitiligo, or severe atopic dermatitis. Another series from the Midwestern US suggests that approximately 20% of patients are self-conscious about a cervical incision more than 1 year after thyroid surgery; however, a majority are satisfied with their scar. The authors noted that more than 10% of patients were considering additional intervention to correct a thyroid scar. This subset of patients affected negatively by a cervical incision was further characterized in a large quality-of-life series focused specifically on thyroid cancer survivors. In their research, Goldfarb and colleagues suggest that young patients especially are more likely to suffer a worse quality of life owing to a cervical incision. The authors hypothesize that this may be related to stigma or a negative body image; this may be seen with some pediatric cancers.

To better understand the demand for improved cosmesis in the US, Coorough and colleagues administered nearly 1000 questionnaires to healthy volunteers in the US; they asked for insight on open thyroidectomy versus transaxillary thyroidectomy. They found that more than 80% of respondents preferred to avoid a cervical incision, and a majority were willing to pay more to avoid an incision. Perhaps most importantly, a majority of patients were willing to accept a hypothetical increase in surgical risk to avoid a cervical incision. Finally, 20% of respondents were more likely to choose avoidance of a cervical incision even if it was less likely to cure their thyroid cancer. Although these responses came from nonpatients, the authors suggest that ethical dilemmas exist regarding autonomy in such situations. When it is clear that a patient may prefer to avoid a cervical incision even with increased risk and expense, should they have the option of selecting such a procedure?

Finally, Nellis and colleagues recently presented data regarding the effect of a cervical incision by asking 193 casual observers to compare patients with a cervical scar to controls without a scar. They found that patients with a cervical scar were perceived negatively in regard to overall attractiveness, attractiveness of the neck, and perceived quality of life. These same casual observers were, on average, willing to pay more than $10,000 to avoid a cervical incision.

There is sufficient evidence to demonstrate that some patients prefer to avoid a cervical incision, even in cases of cancer, even if the surgery is more expensive, and even if the complication rates may be higher. It is clear that, to some patients, a cervical incision is a cause of morbidity. Because most thyroid pathology is indolent, the onus is on the surgeon to minimize all morbidity as much as possible and engage with patients to develop an individualized treatment plan. Thus, minimizing the effect of a cervical incision becomes a priority for every thyroid surgeon.

TransOral Thyroid Surgery (TOTS) Versus Other Remote Access Approaches

It is beyond the scope of this chapter to address all the remote approaches to thyroid surgery, and some of these approaches are addressed elsewhere in this text (see Chapters 31 , Principles in Thyroid Surgery, and Chapter 32 , Robotic and Extra Cervical Approaches to the Thyroid and Parathyroid Glands). The bilateral axillo-breast approach (BABA), robot assisted transaxillary surgery (RATS), and retroauricular facelift approach (RFA) have all found success in some hands but are used in a very limited fashion in North America. Primary limitations that have been cited for each include difficulty visualizing the contralateral lobe (RFA), extensive dissection (BABA, RATS, RFA), unfamiliar angle of dissection (BABA, RATS), and increased operative times (BABA, RATS, RFA). None are truly “minimally invasive,” and none avoids a cutaneous incision. Additionally, the learning curve for these procedures is generally felt to be between 35 to 50 cases. In addition to the financial disincentive identified previously, it is difficult for practicing surgeons to dedicate 50 cases to mastery of a novel technique. For these and other reasons, none of these approaches have gained a significant following in the Western world.

Compared with each of the previously mentioned approaches, the potential technical advantages of TOTS are obvious. It is the only approach without any cutaneous incision, and therefore provides the best cosmetic outcome. It has the shortest dissection route of any of the other methods, and therefore may be expected to have a shorter operative time and less postoperative pain. The midline approach of TOTS allows equal visualization of both the right and left central necks, allowing total thyroidectomy to be completed without the need for repositioning or additional incisions. The superior to inferior angle of dissection is a vantage point that is familiar to most high-volume thyroid surgeons who may regularly find the RLN at the insertion (as for the superior approach to the RLN, see Chapter 36 , Surgical Anatomy and Monitoring of the Recurrent Laryngeal Nerve). Same day discharge is more common in the Western world and is more likely for TOTS compared with other remote access approaches.

In addition to the technical advantages of TOTS, there are patient selection advantages as well. The indications for the procedure are broader; body habitus has not affected outcomes in some US series, and patients with larger nodules (up to 6 cm with a thyroid lobe up to 10 cm in maximal dimension) remain potential candidates for the approach. Our own unpublished review of the last 300 cases of thyroid surgery by a single surgeon found that more than 50% of patients were candidates for TOTS. Finally, the learning curve for this approach has been anecdotally described as 7 to 10 cases and more recently has been defined as approximately 11 cases for a laparoscopic naïve surgeon in a North American population. For all of these reasons, TOTS offers distinct patient and surgeon advantages over the other remote access approaches to the thyroid.

Compared with all other remote access approaches, it is apparent that TOTS has broader indications in a Western population, allows for faster discharge, has lower pain scores, bilateral central neck access, and a faster learning curve than other remote access approaches. TOTS also offers the best cosmetic outcome with no cutaneous incisions.