BACKGROUNDWith 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.

METHODSFifteen 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.

RESULTSThree 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).

CONCLUSIONThe transoral procedure is progressive and innovative which not only gives the best cosmetic result and minimal access trauma but also provides a craniocaudal view.