Natural orifice surgery on the thyroid gland using totally transoral video-assisted thyroidectomy: report of the first experimental results for a new surgical method: are we going in the right direction?

Abstract

Dear Editor: Minimally invasive video-assisted thyroidectomy (MIVAT) [1], the most widespread minimally invasive technique, has been called into question by Benhidjeb et al. [2] because it is somewhat limited by the small size of the specimen removable through its 15-mm cervical incision. We were animated to comment on this first report of natural orifice surgery (NOS) applied in thyroid surgery. The authors report the first two totally scarless subtotal thyroidectomies performed on cadavers. This was a feasibility study, and the operation consisted of a transoral access with insertion of one 5-mm trocar and two 3-mm trocars into the oral cavity. Operative space was maintained by carbon dioxide (CO2) insufflation, and hemostasis was achieved using bipolar scissors. The thyroid gland was resected from the cranial to the caudal area and removed through the 5-mm midline mucosa incision. Furthermore, in the words of the authors, the retrothyroidal area is prepared and the laryngeal nerve visualized only ‘‘if necessary,’’ and finally, ‘‘if the gland is too large, the midline incision may be extended.’’ We do not disclaim the feasibility and reproducibility of their new endoscopic approach to the thyroid gland. The transoral video-assisted thyroidectomy (TOVAT) approach seems to respect surgical planes and to achieve an excellent cosmetic result, certainly better than other recently proposed endoscopic techniques such as chest, breast, and axillary approaches [3–5]. However, we have major concerns about the widespread applicability of this approach for live patients, and finally about its safety, for the following reasons: 1. With the cadavers, did the authors study the postoperative effects of CO2 after the operation? It is well known that CO2 insufflation, due to the absence of a virtual cavity in the neck, may lead to a troublesome postoperative emphysema, in addition to metabolic problems due to hypercarbia [6]. With MIVAT, we early abandoned the CO2 insufflation, shifting to an external retraction method with the aim of avoiding any complication due to gas insufflation and therefore any discharge delay. 2. Did the authors consider that multiple painful sutures in the mouth mucosa, even if invisible to others, may represent an important obstacle to oral intake after the operation? How many days should the patients fast and therefore remain in the hospital? This would mean a prolonged hospital stay, with neglect also of risks for infection and possible trauma to sublingual salivary glands. 3. Furthermore, the authors declare that they have retrieved the specimen from the 5-mm incision in the oral cavity, but they failed to report the size of the removed glands. Probably, a very normal gland can pass through such a narrow space, but it is difficult to understand how a nodule 2–3 cm or even larger can be retrieved without enlarging the mucosa wound. Consequently, with incisions larger than 5 mm, trauma to the oral cavity will be increased, taking us back to point 2. 4. A major concern is about laryngeal nerve dissection. Proper identification of the nerve would be the first target to achieve by a safe technique with both traditional and minimally invasive procedures. With MIVAT and other endoscopic techniques [7, 8], visualization of the nerve and parathyroids is enhanced by optical magnification and represents a fundamental P. Miccoli G. Materazzi (&) P. Berti Department of Surgery, University of Pisa, Pisa, Italy e-mail: gmaterazzi@yahoo.com