Intraoperative Posterior Cricoarytenoid Muscle Electromyography May Predict Vocal Cord Function Prognosis after Loss of Signal during Thyroidectomy

ABSTRACT

Purpose

Intraoperative posterior cricoarytenoid muscle (PCAM) electromyography (EMG) may be useful for predicting postoperative vocal cord function (VCF) and prognosis of vocal cord palsy (VCP) in patients with intraoperative loss of signal (LOS).

Materials and Methods

Thirty out of 395 patients having LOS detected by intraoperative neural monitoring (IONM), were applied intraoperative PCAM EMG.

Results

VCP was present in all Type 1 injury RLNs (16) (100%) and in 8 (57%) of 14 RLNs with Type 2 injury (p = 0.005). 14 out of 30 LOS patients (47%) had positive PCAM EMG amplitudes. The sensitivity, specificity, positive and negative predictive values and accuracy rates for predicting postoperative VCP via PCAM EMG, were calculated as 66.7%, 100%,100%, 42.86% and 73.33%. The negative PCAM EMG was related to VCP in both Type 1 and Type 2 LOS. VCP recovery time of Type 1 LOS patients was significantly longer than that of Type 2 LOS patients (p = 0.009). In Type 2 LOS, VCP recovery time was significantly longer in negative PCAM EMG patients compared to positive PCAM EMG patients (p = 0.046).

Conclusion

Negative PCAM EMG is associated with the postoperative VCP. Type 1 injury results in VCP regardless of PCAM EMG results, and VCF recovers after a longer period compared to Type 2 LOS.

In Type 2 LOS, positive PCAM EMG may result in VCP by 40%. However, the presence of negative PCAM EMG is related to the postoperative VCP in all patients and the recovery time is longer compared to positive PCAM EMG patients.

KEYWORDS:

• Thyroidectomy
• posterior cricoarytenoid muscle electromyography
• loss of signal
• vocal cord paralysis
• recurrent laryngeal nerve
• intraoperative neuromonitorisation

Disclosure statement

No potential conflict of interest was reported by the author(s).

Ethical approval

This research study was conducted retrospectively from data obtained for clinical purposes. The Ethics Committee of Sisli Hamidiye Etfal Research and Training Hospital approved this study Informed consent was obtained from all individual participants included in the study.

Consent to participate

Conception and design: Nurcihan Aygun, Mehmet Uludag; Analysis and interpretation of data: Nurcihan Aygun, Mehmet Uludag; Drafting of the manuscript: Nurcihan Aygun, Mehmet Uludag; Revising: Adnan Isgor, Mehmet Uludag; Final approval of the version: Nurcihan Aygun, Adnan Isgor, Mehmet Uludag

Authorship

This study was presented as an oral presentation at 16th Panhellenic Congress of Endocrine Surgery with Turkish Participation on 22-24 November of 2019, in Athens, Greece.