چکیده (انگلیسی):

y Background: Preservation of the external branch of the superior laryngeal nerve
(EBSLN) during thyroidectomy is important because its injury may lead to frequent occurrence
of vocal fatigue and the inability to perform superenergetic phonation. Most studies on the
anatomy of EBSLN have been performed in Western countries and, thus, have some limitations
in their application to Koreans. We explored the anatomy of EBSLNs using intraoperative neuromonitoring
(IONM) in Korean adults.
Methods: 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.
Results: 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.
Conclusion: 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.