Complications of transoral endoscopic thyroidectomy vestibular approach (TOETVA)

The thyroidectomy is the most frequently executed procedure in head and neck surgery. Since its first description by Kocher, the transverse cervical incision has been the main access to the thyroid site, as it provides broad exposure of the central neck compartment. Despite the meticulous suture of the incision, the development of a scar with variable dimensions is unavoidable and, hence, some patients might not agree to the approach, due to this consequence. The transoral endoscopic thyroidectomy vestibular access (TOETVA) gains importance as an alternative to the traditional surgery, since it avoids the formation of visible scars. The objective of this study is to develop a systematic review on the currently available literature to evaluate possible complications related to the TOETVA. The systematic review was based on the databases of Medline, Cochrane library, Embase and Scielo/Lilacs, resulting in the selection of six studies, which were compared in regard of the type of study duration of the study and identified complications. Our study showed that TOETVA is related to complications similar to the ones identified in the conventional approach, such as hematoma, seroma, recurrent laryngeal nerve injury, hypoparathyroidism, surgical site infection. The TOETVA was associated to a higher risk of thermic injury of the skin and mentual nerve paresthesia. Moreover, it was possible to conclude that TOETVA is a safe procedure for well selected patients, with favorable conditions and concerned about the aesthetic outcome. The risk of complications of the procedure should always be explained to those patients.


INTRODUCTION
T hyroid gland surgery is the most common surgical procedure performed on the head and neck area 1,2 . Currently, the most widely used technique for thyroidectomy is similar to that described by Kocher in the late 1880s, with minor modifications [2][3] . Since its description, the transverse cervical incision constitutes the main access to the thyroid site in interventions on the thyroid and parathyroid glands due to the wide, central neck region exposure 3 . Despite the meticulous closure of the incision, scarring of varying degrees is inevitable, and certain patients may disagree with such an approach 3 . The increasing incidence of thyroid diseases, as well as younger patients at the time of diagnosis, the predominance of female patients, and society's emphasis on the physical appearance of the human being, generated great search for the development of aesthetically favorable, alternative approaches 3 .
Endoscopic neck surgery was first described by Gagner in 1996, with the minimally invasive techniques of thyroidectomy surgery developed over the past two decades, which spares the cervical region from a scar 4 . Such techniques include endoscopic or robotic incisions: mammary, axillary-mammary, axillary, and retroauricular 5 . However, all the techniques previously described lead to visible scars, sometimes larger or more prominent than those generated by the conventional Complications of transoral endoscopic thyroidectomy vestibular approach (TOETVA) described: the sublingual technique, related to severe tissue injury and a high rate of complications, and the transoral endoscopic thyroidectomy vestibular approach (TOETVA), which appears to be safer than the first one 6,7 .
The TOETVA access is in the vestibular area of the lower lip, through which the thyroid can be accessed

Ethical aspects
This study was not submitted to the Ethics Council of the Institution involved because it is a systematic review, studying only already published articles.

Search strategy, inclusion and exclusion criteria
To conduct the systematic review, we searched the main databases Medline, Cochrane Library, Embase, SciElo, and Lilacs (Latin American and Caribbean Health Sciences). The search considered articles in Portuguese and English, published between 2015 and 2020, with a broad search strategy to avoid publication bias. We used combinations between the terms "thyroidectomy", "toetva", "transoral endoscopic vestibular approach thyroidectomy" and "complications".
We excluded articles in languages other than those mentioned above, or those that could not be fully recovered. we also excluded papers that did not contain sufficient data to evaluate the variables under study.
We included studies on complications related to conventional thyroidectomy and transoral endoscopic thyroidectomy vestibular approach (TOETVA). We excluded articles that did not cover the subject. We used systematic review articles to discuss the results, not as part of them.

Data analysis
We used The Microsoft Excel software (Microsoft Corp., Redmond, WA) to tabulate data, including type of study, country of origin, time taken to obtain the sample, type of operation performed, complication rates, and the association of the surgical approach with complications.

RESULTS
We found 38 studies in the literature, of which we excluded 15 articles that did not study humans.
From the remainder, we excluded those that did not appraise TOETVA and its complications, those that were  Case series Uni / multinodular Goiter (10) not written in Portuguese or English, those that did not contain sufficient data, and systematic reviews, as shown in the flowchart of Figure 1. Thus, based on these criteria, we included six articles in the review, with results described in Tables 1 and 2