Recurrent laryngeal nerve injury with incomplete loss of electromyography signal during monitored thyroidectomy—evaluation and outcome

Che Wei Wu, Min Hao, Mengzi Tian, Gianlorenzo Dionigi, Ralph P. Tufano, Hoon Yub Kim, Kwang-Yoon Jung, Xiaoli Liu, Hui Sun, I. Cheng Lu, Pi Ying Chang, Feng Yu Chiang

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Purpose: During monitored thyroidectomy, a partially or completely disrupted point of nerve conduction on the exposed recurrent laryngeal nerve (RLN) indicates true electrophysiologic nerve injury. Complete loss of signal (LOS; absolute threshold value <100 μV) at the end of operation often indicates a postoperative vocal cord (VC) palsy. However, the evaluation for the injured RLN with incomplete LOS and its functional outcome has not been well described. Methods: Three hundred twenty-three patients with 522 RLNs at risk who underwent standardized monitored thyroidectomy were enrolled. The RLN was routinely stimulated at the most proximal (R2p signal) and distal (R2d signal) ends of exposure after thyroid resection to determine if there was an injured point on the RLN. Pre- and postoperative VC function was routinely examined. Results: Twenty-nine RLNs (5.6 %) were detected with an injury point. Five nerves had complete LOS and other 24 nerves had incomplete LOS where the R2p/R2d reduction (% of amplitude reduction compared with proximal to distal RLN stimulation) ranged from 22 to 79 %. Postoperative temporary VC palsy was noted in those five RLNs with complete LOS (final vagal signal, V2 < 100 μV) and four RLNs with incomplete LOS (R2p/R2d reduction 62–79 %; V2 181–490 μV). In the remaining 20 nerves with R2p/R2d reduction ≤53 % (V2 373–1623 μV), all showed normal VC mobility. Overall, false negative results were found in two RLNs (0.4 %) featuring unchanged V2 and R2p/R2d but developed VC palsy. Conclusions: Testing and comparing the R2p/R2d signal is a simple and useful procedure to evaluate RLN injury after its dissection and predict functional outcome. When the relative threshold value R2p/R2d reduction reaches over 60 %, surgeon should consider the possibility of postoperative VC palsy.

Original languageEnglish
Pages (from-to)691-699
Number of pages9
JournalLangenbeck's Archives of Surgery
Volume402
Issue number4
DOIs
Publication statusPublished - 2017 Jun 1

Fingerprint

Recurrent Laryngeal Nerve Injuries
Recurrent Laryngeal Nerve
Electromyography
Vocal Cord Paralysis
Vocal Cords
Thyroidectomy
Neural Conduction
Wounds and Injuries
Dissection
Thyroid Gland

Keywords

  • Electromyography
  • Intraoperative neuromonitoring
  • Loss of signal
  • Recurrent laryngeal nerve
  • Thyroid surgery

ASJC Scopus subject areas

  • Surgery

Cite this

Recurrent laryngeal nerve injury with incomplete loss of electromyography signal during monitored thyroidectomy—evaluation and outcome. / Wu, Che Wei; Hao, Min; Tian, Mengzi; Dionigi, Gianlorenzo; Tufano, Ralph P.; Kim, Hoon Yub; Jung, Kwang-Yoon; Liu, Xiaoli; Sun, Hui; Lu, I. Cheng; Chang, Pi Ying; Chiang, Feng Yu.

In: Langenbeck's Archives of Surgery, Vol. 402, No. 4, 01.06.2017, p. 691-699.

Research output: Contribution to journalArticle

Wu, Che Wei ; Hao, Min ; Tian, Mengzi ; Dionigi, Gianlorenzo ; Tufano, Ralph P. ; Kim, Hoon Yub ; Jung, Kwang-Yoon ; Liu, Xiaoli ; Sun, Hui ; Lu, I. Cheng ; Chang, Pi Ying ; Chiang, Feng Yu. / Recurrent laryngeal nerve injury with incomplete loss of electromyography signal during monitored thyroidectomy—evaluation and outcome. In: Langenbeck's Archives of Surgery. 2017 ; Vol. 402, No. 4. pp. 691-699.
@article{1d34e169b18c4b278fc6c394e9ef9778,
title = "Recurrent laryngeal nerve injury with incomplete loss of electromyography signal during monitored thyroidectomy—evaluation and outcome",
abstract = "Purpose: During monitored thyroidectomy, a partially or completely disrupted point of nerve conduction on the exposed recurrent laryngeal nerve (RLN) indicates true electrophysiologic nerve injury. Complete loss of signal (LOS; absolute threshold value <100 μV) at the end of operation often indicates a postoperative vocal cord (VC) palsy. However, the evaluation for the injured RLN with incomplete LOS and its functional outcome has not been well described. Methods: Three hundred twenty-three patients with 522 RLNs at risk who underwent standardized monitored thyroidectomy were enrolled. The RLN was routinely stimulated at the most proximal (R2p signal) and distal (R2d signal) ends of exposure after thyroid resection to determine if there was an injured point on the RLN. Pre- and postoperative VC function was routinely examined. Results: Twenty-nine RLNs (5.6 {\%}) were detected with an injury point. Five nerves had complete LOS and other 24 nerves had incomplete LOS where the R2p/R2d reduction ({\%} of amplitude reduction compared with proximal to distal RLN stimulation) ranged from 22 to 79 {\%}. Postoperative temporary VC palsy was noted in those five RLNs with complete LOS (final vagal signal, V2 < 100 μV) and four RLNs with incomplete LOS (R2p/R2d reduction 62–79 {\%}; V2 181–490 μV). In the remaining 20 nerves with R2p/R2d reduction ≤53 {\%} (V2 373–1623 μV), all showed normal VC mobility. Overall, false negative results were found in two RLNs (0.4 {\%}) featuring unchanged V2 and R2p/R2d but developed VC palsy. Conclusions: Testing and comparing the R2p/R2d signal is a simple and useful procedure to evaluate RLN injury after its dissection and predict functional outcome. When the relative threshold value R2p/R2d reduction reaches over 60 {\%}, surgeon should consider the possibility of postoperative VC palsy.",
keywords = "Electromyography, Intraoperative neuromonitoring, Loss of signal, Recurrent laryngeal nerve, Thyroid surgery",
author = "Wu, {Che Wei} and Min Hao and Mengzi Tian and Gianlorenzo Dionigi and Tufano, {Ralph P.} and Kim, {Hoon Yub} and Kwang-Yoon Jung and Xiaoli Liu and Hui Sun and Lu, {I. Cheng} and Chang, {Pi Ying} and Chiang, {Feng Yu}",
year = "2017",
month = "6",
day = "1",
doi = "10.1007/s00423-016-1381-8",
language = "English",
volume = "402",
pages = "691--699",
journal = "Langenbeck's Archives of Surgery",
issn = "1435-2443",
publisher = "Springer Verlag",
number = "4",

}

TY - JOUR

T1 - Recurrent laryngeal nerve injury with incomplete loss of electromyography signal during monitored thyroidectomy—evaluation and outcome

AU - Wu, Che Wei

AU - Hao, Min

AU - Tian, Mengzi

AU - Dionigi, Gianlorenzo

AU - Tufano, Ralph P.

AU - Kim, Hoon Yub

AU - Jung, Kwang-Yoon

AU - Liu, Xiaoli

AU - Sun, Hui

AU - Lu, I. Cheng

AU - Chang, Pi Ying

AU - Chiang, Feng Yu

PY - 2017/6/1

Y1 - 2017/6/1

N2 - Purpose: During monitored thyroidectomy, a partially or completely disrupted point of nerve conduction on the exposed recurrent laryngeal nerve (RLN) indicates true electrophysiologic nerve injury. Complete loss of signal (LOS; absolute threshold value <100 μV) at the end of operation often indicates a postoperative vocal cord (VC) palsy. However, the evaluation for the injured RLN with incomplete LOS and its functional outcome has not been well described. Methods: Three hundred twenty-three patients with 522 RLNs at risk who underwent standardized monitored thyroidectomy were enrolled. The RLN was routinely stimulated at the most proximal (R2p signal) and distal (R2d signal) ends of exposure after thyroid resection to determine if there was an injured point on the RLN. Pre- and postoperative VC function was routinely examined. Results: Twenty-nine RLNs (5.6 %) were detected with an injury point. Five nerves had complete LOS and other 24 nerves had incomplete LOS where the R2p/R2d reduction (% of amplitude reduction compared with proximal to distal RLN stimulation) ranged from 22 to 79 %. Postoperative temporary VC palsy was noted in those five RLNs with complete LOS (final vagal signal, V2 < 100 μV) and four RLNs with incomplete LOS (R2p/R2d reduction 62–79 %; V2 181–490 μV). In the remaining 20 nerves with R2p/R2d reduction ≤53 % (V2 373–1623 μV), all showed normal VC mobility. Overall, false negative results were found in two RLNs (0.4 %) featuring unchanged V2 and R2p/R2d but developed VC palsy. Conclusions: Testing and comparing the R2p/R2d signal is a simple and useful procedure to evaluate RLN injury after its dissection and predict functional outcome. When the relative threshold value R2p/R2d reduction reaches over 60 %, surgeon should consider the possibility of postoperative VC palsy.

AB - Purpose: During monitored thyroidectomy, a partially or completely disrupted point of nerve conduction on the exposed recurrent laryngeal nerve (RLN) indicates true electrophysiologic nerve injury. Complete loss of signal (LOS; absolute threshold value <100 μV) at the end of operation often indicates a postoperative vocal cord (VC) palsy. However, the evaluation for the injured RLN with incomplete LOS and its functional outcome has not been well described. Methods: Three hundred twenty-three patients with 522 RLNs at risk who underwent standardized monitored thyroidectomy were enrolled. The RLN was routinely stimulated at the most proximal (R2p signal) and distal (R2d signal) ends of exposure after thyroid resection to determine if there was an injured point on the RLN. Pre- and postoperative VC function was routinely examined. Results: Twenty-nine RLNs (5.6 %) were detected with an injury point. Five nerves had complete LOS and other 24 nerves had incomplete LOS where the R2p/R2d reduction (% of amplitude reduction compared with proximal to distal RLN stimulation) ranged from 22 to 79 %. Postoperative temporary VC palsy was noted in those five RLNs with complete LOS (final vagal signal, V2 < 100 μV) and four RLNs with incomplete LOS (R2p/R2d reduction 62–79 %; V2 181–490 μV). In the remaining 20 nerves with R2p/R2d reduction ≤53 % (V2 373–1623 μV), all showed normal VC mobility. Overall, false negative results were found in two RLNs (0.4 %) featuring unchanged V2 and R2p/R2d but developed VC palsy. Conclusions: Testing and comparing the R2p/R2d signal is a simple and useful procedure to evaluate RLN injury after its dissection and predict functional outcome. When the relative threshold value R2p/R2d reduction reaches over 60 %, surgeon should consider the possibility of postoperative VC palsy.

KW - Electromyography

KW - Intraoperative neuromonitoring

KW - Loss of signal

KW - Recurrent laryngeal nerve

KW - Thyroid surgery

UR - http://www.scopus.com/inward/record.url?scp=84958763968&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84958763968&partnerID=8YFLogxK

U2 - 10.1007/s00423-016-1381-8

DO - 10.1007/s00423-016-1381-8

M3 - Article

VL - 402

SP - 691

EP - 699

JO - Langenbeck's Archives of Surgery

JF - Langenbeck's Archives of Surgery

SN - 1435-2443

IS - 4

ER -