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Increased prediction of right nonrecurrent laryngeal nerve in thyroid surgery using preoperative computed tomography with intraoperative neuromonitoring identification.

Gao EL, Zou X, Zhou YH, Xie DH, Lan J, Guan HG - World J Surg Oncol (2014)

Bottom Line: All patients were successfully detected at an early stage of operation using intraoperative neuromonitoring (IONM).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.

View Article: PubMed Central - PubMed

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.

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.

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Three types of nonrecurrent laryngeal nerve (NRLN) as described in the literature and based primarily on the course the nerve travels.
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Fig1: Three types of nonrecurrent laryngeal nerve (NRLN) as described in the literature and based primarily on the course the nerve travels.

Mentions: To determine whether NRLN could be identified preoperatively, CT scanning images were reviewed retrospectively by the expert radiologist (Dr. Xie) in this study. An arteria lusoria was identified on CT scans as a tubular structure that arose from the dorsal side of the aortic arch. It passed through the midline behind the trachea and esophagus, entered the right base of the neck and proceeded as a right subclavian artery that joined the right common carotid artery. Based on the positional relationship between the NRLN and thyroid artery observed by the surgeons intraoperatively, the NRLN was classified into three types (FigureĀ 1), as described by Toniato et al.[4].Figure 1


Increased prediction of right nonrecurrent laryngeal nerve in thyroid surgery using preoperative computed tomography with intraoperative neuromonitoring identification.

Gao EL, Zou X, Zhou YH, Xie DH, Lan J, Guan HG - World J Surg Oncol (2014)

Three types of nonrecurrent laryngeal nerve (NRLN) as described in the literature and based primarily on the course the nerve travels.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4150955&req=5

Fig1: Three types of nonrecurrent laryngeal nerve (NRLN) as described in the literature and based primarily on the course the nerve travels.
Mentions: To determine whether NRLN could be identified preoperatively, CT scanning images were reviewed retrospectively by the expert radiologist (Dr. Xie) in this study. An arteria lusoria was identified on CT scans as a tubular structure that arose from the dorsal side of the aortic arch. It passed through the midline behind the trachea and esophagus, entered the right base of the neck and proceeded as a right subclavian artery that joined the right common carotid artery. Based on the positional relationship between the NRLN and thyroid artery observed by the surgeons intraoperatively, the NRLN was classified into three types (FigureĀ 1), as described by Toniato et al.[4].Figure 1

Bottom Line: All patients were successfully detected at an early stage of operation using intraoperative neuromonitoring (IONM).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.

View Article: PubMed Central - PubMed

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.

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.

Show MeSH
Related in: MedlinePlus