Axillary channel-assisted TOETVA: An effective way to prevent mental nerve from iatrogenic injury?

To evaluate the protective effect of axillary channel-assisted (ACA) transoral endoscopic thyroidectomy vestibular approach on mental nerve.

From August 2018 to December 2020, 126 cases of thyroid micro-carcinoma patients who underwent endoscopic thyroidectomy were recruited retrospectively. Of those, 74 cases were performed with ACA trans-oral endoscopic thyroidectomy vestibular approach (ACA_TOETVA) (V and A group), 52 cases received standard TOETVA (V group). On postoperative day 1 (POD1), nylon monofilament test and numbness visual analogue scale score were conducted to evaluate the severity of numbness within the mental area, facial expression was tested to determine the motor function of lower mandible and the thickness of cutaneous and subcutaneous layers was measured with ultrasound. The other observation parameters including the time for operation and intraoperative blood loss were carefully collected.

On POD1, nylon monofilament test showed that scores in the V and A group (2.9 ± 0.3) were significantly higher than V group (1.7 ± 0.5), P < 0.01, u = 254. The completion percentage of facial expression in the V and A group was 90.5% (67/74) and significantly higher than in V group (21.2%, 11/52), P < 0.01, χ² = 62.35. The thickness increment of cutaneous and subcutaneous layer was 2.2 ± 1.2 mm in the V and A group, which was significantly less than in the V group (4.0 ± 1.2 mm), P < 0.01, u = 605. Compared with V group, the operation time (113.4 ± 22.3 min vs. 127.7 ± 25.6 min, u = 1262) and intraoperative blood loss (43.5 ± 13.4 ml vs. 51.0 ± 14.1 ml, u = 1355) were also significantly less in the V and A group.

The ACA transoral endoscopic thyroidectomy possesses the protective effect on mental nerve and motor function of lower mandible and facilitates the operative procedures of TOETVA.