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Contribution of intraoperative neural monitoring to preservation of the external branch of the superior laryngeal nerve: a randomized prospective clinical trial

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Abstract

Purpose

The purpose of this study was to evaluate the effect of intraoperative neuromonitoring (IONM) on the injury rate of the external branch of the superior laryngeal nerve (EBSLN) during thyroidectomy.

Methods

A total of 133 consenting patients (98 female, 35 male; mean age, 45.6 ± 11.7 years) undergoing thyroidectomy were randomly assigned to 2 groups. In group 1 (n = 65 patients, 105 nerves), superior thyroid pole dissection was performed with no attempt to identify the EBSLN; in group 2 (n = 68 patients, 106 nerves), IONM was used to identify the EBSLN during surgery. EBSLN function was evaluated by intraoperative electromyography of the cricothyroid muscle. The EBSLN Voice Impairment Index-5 (VII-5) was conducted preoperatively and at 1, 3, and 6 months postoperatively. The primary outcome was the prevalence of EBSLN injury. The secondary outcomes were the identification rate of the EBSLN using IONM and changes in postoperative voice performance.

Results

EBSLN injury was detected in eight (12.3%) patients and nine (8.6%) nerves in group 1 and in one (1.5%) patient and one (0.9%) nerve in group 2 (patients, p = 0.015; nerves, p = 0.010). IONM contributed significantly to visual (p < 0.001) and functional (p < 0.001) nerve identification in group 2. The VII-5 indicated more voice changes in group 1 than 2 at 1, 3, and 6 months postoperatively (p = 0.012, p = 0.015, and p = 0.02, respectively).

Conclusion

IONM contributes to visual and functional identification of the EBSLN and decreases the rate of EBSLN injury during superior pole dissection. Routine use of IONM to identify the EBSLN will minimize the risk of injury during thyroidectomy.

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Authors’ contributions

Study conception and design: Mehmet Uludag, Nurcihan Aygun. Acquisition of data: Nurcihan Aygun, Kinyas Kartal, Bülent Çitgez, Evren Besler, Gürkan Yetkin, Cemal Kaya, Hamdi Ozsahin, Mehmet Mihmanli. Analysis and interpretation data: Mehmet Uludag, Nurcihan Aygun, Adnan Isgor. Drafting of manuscript: Mehmet Uludag, Nurcihan Aygun, Kinyas Kartal. Critical revision of manuscript: Mehmet Uludag, Adnan Isgor.

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Authors and Affiliations

  1. General Surgery, Sisli Hamidiye Etfal Training and Research Hospital, Istanbul, Turkey

    Mehmet Uludag, Nurcihan Aygun, Kinyas Kartal, Bulent Citgez, Evren Besler, Gurkan Yetkin, Cemal Kaya, Hamdi Ozsahin & Mehmet Mihmanli

  2. General Surgery, Bahcesehir University Medical Faculty, Istanbul, Turkey

    Adnan Isgor

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  1. Mehmet Uludag
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Correspondence to Mehmet Uludag.

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All authors have agreed to the manuscript’s content. All authors warrant that the submitted article is original and has not been submitted to another journal for publication, published elsewhere, or if published in whole or in part. All permissions were granted for publication in Langenbeck’s Archives of Surgery.

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The authors declare that they have no conflict of interest.

Ethical approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. This article does not contain any studies with animals performed by any of the authors. This prospective study was approved by the institutional review board of Sisli Hamidiye Etfal Training and Research Hospital.

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Informed consent was obtained from all individual participants included in the study.

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Uludag, M., Aygun, N., Kartal, K. et al. Contribution of intraoperative neural monitoring to preservation of the external branch of the superior laryngeal nerve: a randomized prospective clinical trial. Langenbecks Arch Surg 402, 965–976 (2017). https://doi.org/10.1007/s00423-016-1544-7

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