[Transoral endoscopic thyroidectomy. Part 1: rationale and anatomical studies].

BACKGROUND: Surgical access trauma in thyroidectomy has been minimized by the adoption of minimally invasive techniques. Extracervical approaches moved the incision lines outside of the visible neck region. However, because of the extensive dissection they no longer comply with the term minimally invasive. Therefore, our goal was to reduce the access trauma and establish a non-traumatic approach according to surgical planes for endoscopic minimally invasive thyroidectomy: the transoral approach.
MATERIAL AND METHODS: In a preclinical investigation anatomical dissection was performed on three human cadavers to visualize anatomical relationships and identify safe zones of access to the anterior neck and the submandibular regions. The investigation focused on relevant vascular and neural structures in the floor of mouth. Endoscopic minimally invasive thyroidectomy was additionally performed in five specimens with anatomical dissections for the evaluation of collateral damage.
RESULTS: For a safe approach the optic trocar can be placed sublingually in the midline as there are no relevant vascular or neural structures on the way to the thyroid region. The working trocars can be placed bilaterally in the oral vestibule behind the canine teeth. In this way access and dissection plane are placed directly in an avascular subplatysmal area and the pretracheal working space can be reached easily, safe and fast.
CONCLUSIONS: Minimum impact and a gentle dissection according to anatomical planes are the rational for the transoral route to the thyroid gland. Thus based on anatomical dissections the foundations of a novel procedure in the context of natural orifice surgery (NOS) could be established.