Dionigi, Gianlorenzo1, Yub, Kim Hoon2, Wu, Che-Wei3, Lavazza, Matteo1, Chiang, Feng-Yu3
1 1st Division of General Surgery, Research Center for Endocrine Surgery, Department of Surgical Sciences and Human Morphology, University of Insubria (Varese-Como)
2 Department of Surgery, Division of Breast and Endocrine Surgery, Minimally Invasive Surgery and Robotic Surgery Center, Korea University, Anam Hospital, Seoul, Korea
3 Department of Otolaryngology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung City,Taiwan
Bsckground: Vagus nerve (VN) stimulation is mandatory in standardized intraoperative nerve monitoring (IONM) in thyroid surgery. This study evaluated prospectively the diameter of the VN.
Methods: 100 consecutive patients underwent thyroidectomy, providing 191 intraoperative VN measurement. The tips of a caliper were adjusted to fit laterally the VN to be measured. 70 VN underwent electrode placement for continuous IONM (CIONM). VN measurement was performed before (V1) and after thyroid resection (V2) to document changes in the size.
Results: 36% VN measured less than 2 mm diameter, 64% more than 2 mm. Correlation tests did not demonstrate significant relationships between VN diameter and gender, age, weight, side, thyroid pathology, VN distribution within the carotid sheath, recurrent laryngeal nerve (RLN) anatomy and neurophysiologic data. We observed increase in VN diameter between V1 and V2. Temporary RLN palsy rate was 4.7%.
Discussion & Conclusion: The study describes precise VN measurement. The information is useful for appropriate CIONM electrode selection to overcome electrode VN compression. VN size increased between V1 and V2, probably due to edema. Therefore, important feature of a CIONM electrode design is that they have to adapt over the time of the surgical procedure.