Feasibility of Continuous Intraoperative Neural Monitoring During Transoral Endoscopic Thyroidectomy Vestibular Approach in a Porcine Model.

Background: Experimental study to evaluate feasibility of continuous intraoperative neural monitoring (C-IONM) in transoral endoscopic thyroidectomy vestibular approach (TOETVA). Methods: Duroc-Landrace pigs were orally intubated with electromyogram endotracheal tube. Automatic periodic stimulation (APS) electrode was allocated in the operative field through the 5-mm ports. APS was then repose on vagal nerve (VN) with different approaches: (1) median, that is, between sternothyroid and thyroid gland; and (2) lateral, that is, between sternocleidomastoid and sternothyroid. VN was stimulated proximally and distally to the APS location to verify whether the dissection and/or placement determined VN injury. Video presentation is offered. Results: Assembled APS accessory was feasible in large-brained animals. The two basic options for VN approaches were tested. Baseline obtained had amplitude values >1000 µV, bilaterally. Conclusions: C-IONM was feasible in TOETVA in porcine models, but simplification of electrode design and application is needed.

Intraoperative Neural Monitoring in Endoscopic Thyroidectomy Via Bilateral Areola Approach.

OBJECTIVE: The aim of this report was dual: (a) to describe the step by step standardized intraoperative neural monitoring (IONM) procedure for recurrent laryngeal nerve (RLN) and external branch of the superior laryngeal nerve focusing on percutaneous IONM method, and (b) evaluation and outcomes of intermittent IONM in 237 endoscopic thyroidectomy via bilateral areolar approach cases. MATERIALS AND METHODS: A 10-mm curved incision is made along the margin of the right areola at the 2 to 4 o'clock position for the 30-degree endoscope. Bilaterally 5-mm incisions are required on the edges of the areola at the 11 to 12 o'clock positions as accessory operating ports. Ball-tip, monopolar, single-use, standard stimulating probe with a 10-cm handle and 9-cm shaft is adopted percutaneously for IONM. As reference, on the dominant thyroid lesion side, a 0.5-cm circle is drawn with the center at the intersection of a line 2-cm lateral to the anterior median line and a line 2-cm above the line connecting the bilateral clavicular heads. After ensuring with ultrasonography that no vessels are within the puncture passage, the skin is pierced with an 18-G syringe needle. After withdrawing the needle, the probe is carefully inserted through the tract. IONM is performed according to standards of equipment set up, anesthesia, tube positioning verification tests, and electromyography determinations. RESULTS: A total of 277 nerves at risk were favorably monitored with percutaneous probe stimulation. RLN, vagus nerve, and external branch of the superior laryngeal nerve were successfully determined. There were no instances of IONM malfunction, equipment displacement, or interference with the other endoscopic instruments. IONM probe insertion incision determined no scarring or morbidity in the neck. The incidence of RLN monolateral temporary palsy was 6%. CONCLUSIONS: Standardized monitoring in endoscopic thyroidectomy via bilateral areolar approach is feasible. IONM was implemented by means of percutaneous stimulating probe.