title: Increased prediction of right nonrecurrent laryngeal nerve in thyroid surgery using preoperative computed tomography with intraoperative neuromonitoring identification.
abstract: BACKGROUND
  A nonrecurrent laryngeal nerve (NRLN) is a rare but potentially serious anatomical variant. Although the incidence is reported to be 0.3% to 1.3%, it carries a much higher risk of palsy during thyroid surgery. The objective of this study is to investigate the usefulness of computed tomography (CT) for preoperative identification and intraoperative neuromonitoring identification (IONM) of NRLN in thyroid cancer patients.
  
  
  METHODS
  The preoperative neck CT scans from 1,574 patients who needed thyroid surgery were examined. Absence of the brachiocephalic artery (BCA) and the presence of arteria lusoria were defined as positive with NRLN. Systematic intraoperative neuromonitoring (IONM) was also carried out for these 1,574 patients to localize and identify NRLN. A negative electromyography (EMG) response from lower vagal stimulation but a positive EMG response from the upper position indicated the occurrence of an NRLN.
  
  
  RESULTS
  Nine NRLN (0.57%) were intraoperatively identified out of the 1,574 patients, and no patient with a NRLN showed preoperative clinical symptoms related to NRLN. Prior to the operation, surgeons identified only seven suspected NRLN cases based on identification of arteria lusoria. But a review of CT scans revealed that all cases could be identified by vascular anomalies. All patients were successfully detected at an early stage of operation using intraoperative neuromonitoring (IONM). Postoperative vocal cord function was normal in all patients.
  
  
  CONCLUSIONS
  CT of the neck is a reliable method for predicting NRLN before thyroid cancer surgery. However, some image features can be easily missed. Neurophysiology helps the surgeon to identify the NRLNs more precisely. Combining the two evaluation methods may decrease the incidence of nerve palsy, especially in cases of NRLN. Considering that CT is expensive, requires an X-ray, and achieves less information than ultrasound (US) concerning thyroid nodules, we suggest that applying US and IONM is more reasonable.
authors.forename: Er-li
authors.initials: EL
authors.lastname: Gao
authors.forename: Xian
authors.initials: X
authors.lastname: Zou
authors.forename: Ye-hui
authors.initials: YH
authors.lastname: Zhou
authors.forename: Dao-hai
authors.initials: DH
authors.lastname: Xie
authors.affiliation: Department of General Surgery, The First Affiliated Hospital of Soochow University, No, 188 Shizi Street, Suzhou 215006, Jiangsu, People's Republic of China. 21474646@qq.com.
authors.forename: Jin
authors.initials: J
authors.lastname: Lan
authors.forename: Hong-geng
authors.initials: HG
authors.lastname: Guan
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007431:Intraoperative Complications / Q000517:prevention & control*; D064795:Intraoperative Neurophysiological Monitoring / Q000379:methods*; D061224:Laryngeal Nerve Injuries / Q000517:prevention & control*; D007823:Laryngeal Nerves / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D011300:Preoperative Care; D011379:Prognosis; D012189:Retrospective Studies; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging* / Q000601:surgery; D013965:Thyroidectomy; D014057:Tomography, X-Ray Computed / Q000379:methods*; D055815:Young Adult