How the Severity and Mechanism of Recurrent Laryngeal Nerve Dysfunction during Monitored Thyroidectomy Impact on Postoperative Voice

Abstract

Intraoperative neuromonitoring can qualify and quantify RLN function during thyroid surgery. This study investigated how the severity and mechanism of RLN dysfunction during monitored thyroid surgery affected postoperative voice. This retrospective study analyzed 1021 patients that received standardized monitored thyroidectomy. Patients had post-dissection RLN(R2) signal <50%, 50–90% and >90% decrease from pre-dissection RLN(R1) signal were classified into Group A-no/mild, B-moderate, and C-severe RLN dysfunction, respectively. Demographic characteristics, RLN injury mechanisms(mechanical/thermal) and voice analysis parameters were recorded. More patients in the group with higher severity of RLN dysfunction had malignant pathology results (A/B/C = 35%/48%/55%, p = 0.017), received neck dissection (A/B/C = 17%/31%/55%, p < 0.001), had thermal injury (p = 0.006), and had asymmetric vocal fold motion in long-term postoperative periods (A/B/C = 0%/8%/62%, p < 0.001). In postoperative periods, Group C patients had significantly worse voice outcomes in several voice parameters in comparison to Group A/B. Thermal injury was associated with larger voice impairments compared to mechanical injury. This report is the first to discuss the severity and mechanism of RLN dysfunction and postoperative voice in patients who received monitored thyroidectomy. To optimize voice and swallowing outcomes after thyroidectomy, avoiding thermal injury is mandatory, and mechanical injury must be identified early to avoid a more severe dysfunction.

Effects of Intraoperative Neural Tunnel in Protecting Recurrent Laryngeal Nerve: Experiences in Open, Trans Breast, and Transoral Endoscopic Thyroidectomy

“…In the present study, intermittently IONM was performed with the standard four-step procedure. All electromyography (EMG) amplitudes (V1–R1–R2–V2) were obtained and recorded during vagus nerve stimulation before thyroid dissection (V1) and after thyroidectomy (V2), and RLN stimulation at initial identification (R1) and after dissection (R2) ( 11 ).…”

Improving Voice Outcomes After Thyroid Surgery – Review of Safety Parameters for Using Energy-Based Devices Near the Recurrent Laryngeal Nerve

“…Compared to the non-EBD group, the EBD group had a significantly higher rate of hoarseness. However, the rate of severe hoarseness was significantly higher in the non-EBD group (1,8,9).…”

“…Avoiding iatrogenic RLN injury is essential for voice and swallowing outcomes after thyroid surgery. Impaired RLN function and vocal fold movement are problematic complications that may lead to medicolegal litigation after thyroid surgery in the quality-of-life era (8,9,42,43).…”

Necessity of Routinely Testing the Proximal and Distal Ends of Exposed Recurrent Laryngeal Nerve During Monitored Thyroidectomy

“…From the results of this study, it can be found that permanent VC palsy rarely occurred in nerve injuries caused by traction or dissecting trauma, but there was a high rate of permanent VC palsy (40%, 2/5) in thermal injuries. The voice outcome and VC mobility prognosis are worse in patients with thermal RLN injuries than in those with mechanical RLN injuries ( 30 , 31 ). Therefore, the use of EBDs or electrocauterization near the RLN should pay special attention to the safety distance.…”