Between August 2011 and December 2011, 50 patients underwent thyroidectomy at Korea University, Anam Hospital in Seoul, Korea. IONM was performed with the NIM response 3.0 system.
Forty-two total thyroidectomies and eight lobectomies were performed with IONM and 92 EBSLNs were evaluated. Type I EBSLN was observed in 15 of the 92 nerves (16.3 % ), type IIa EBSLN was noted in 52 (56.5 % ) and type IIb EBSLN was noted in 25 (27.2 % ). Patients with types IIa and IIb were at higher risk of injuries and these types were more frequently observed (83.7 % ) compared with previous Western studies. We found that 35.9 % of distal insertion sites of EBSLNs were located within 1 cm of the center of the cricoid cartilage.
Surgeons should pay close attention to preserving the EBSLN during thyroidectomy in Korean patients because their EBSLNs are more frequently located beneath the superior thyroid vessels.