Transoral endoscopic thyroidectomy with central neck dissection: experimental studies on human cadavers.

BACKGROUND: With the development of natural orifice trans-luminal endoscopic surgery, studies on transoral video-assisted thyroidectomy in preclinical experiments (e.g., human anatomy and animal trials) were progressing gradually. From 2009 to 2011, embalmed human cadavers were dissected to define the anatomical location, surgical planes, and related neural and vascular structures to create a safe transoral access to the front cervical spaces. Recently, experimental transoral endoscopic thyroidectomy was performed to verify the feasibility of this approach on 15 fresh specimens. METHODS: Fifteen specimens were placed in the supine position with slight neck extension. Endoscopic incision was made on the midline between the Wharton's duct papillae and two other incisions were made on mandibular first premolar buccal mucosa. Sublingual combined bilateral vestibular tunnels were created from oral cavity to the cervical region. The neck subplatysmal working space was insufflated with CO2 at 6-8 mmHg. The bilateral thyroid lobes and central lymph nodes were dissected under craniocaudal view. RESULTS: Three incisions were made in the oral cavity without any incisions on the body surfaces. The distance from the oral cavity to front neck region was the shortest. Bilateral thyroid lobes and central neck region were fully resected via transoral approach. This approach provided a craniocaudal view, in which retrosternal thyroid gland and lymph nodes were easily accessible. The recurrent laryngeal nerve could be identified safely on the inferior cornu of the thyroid cartilage. The only structure at risk was the mental nerve. Camera motion was somewhat limited by the maxillary dentition. The volume of harvested thyroid nodule through sublingual tunnel in the fifteen human cadavers was (40 ± 15) cm(3). CONCLUSION: The transoral procedure is progressive and innovative which not only gives the best cosmetic result and minimal access trauma but also provides a craniocaudal view.

[Surgical anatomy of totally trans-oral video-assisted thyroidectomy].

OBJECTIVE: To define the anatomical approach, anatomical planes and related vessels and nerves to create a safe and reproducible combined sublingual and bi-vestibular access for trans-oral video-assisted thyroidectomy. METHODS: From November 2009 to May 2011, twenty-five embalmed human specimens were dissected for anatomical information of the cervical region, the mandible region and the supra-hyoid muscles. On twenty fresh frozen human specimens after an experimental trans-oral endoscopic thyroidectomy, the related vascular, neural structures and muscles were evaluated. RESULTS: The optical access port was placed in the midline sublingual. The geniohyoid muscle, mylohyoid muscle and the anterior belly of the digastric muscle were divided in the midline in order to reach the plane under the platysma muscle. The mucosa was sagittal incised bilaterally in the vestibular of oral cavity for working trocar, at the level of the first molar of the mandible. The working trocar reached directly the periosteum of the mandible, under the facial vessel and the marginal branch of facial nerve, and then passed below the platysma muscle into the infra-laryngeal working area. The distance from mental nerve to mandibular midline and between mental nerve and facial artery were (25.8 ± 0.9) mm and (29.4 ± 0.9) mm respectively. Anatomical dissections showed that after an experimental trans-oral combined sublingual and bi-vestibular access, all muscles of the floor of the oral cavity as well as the related vascular and neural structures are intact. The maximum nodule size of the resected specimens in the totally trans-oral approach was up to 50 mm. CONCLUSION: The combined sublingual and bi-vestibular access of trans-oral video-assisted thyroidectomy is safe and reproducible.