Is intraoperative nerve monitoring useful for surgical training in thyroid surgery?

Frequency of side effects experienced in two different NIM-EMG tubes used in thyroid and parathyroid surgery; a prospective observational study

BACKGROUND

In this study, we observed the frequency of side effects encountered when the neural integrity monitor electromyogram endotracheal tube (NIM-EMG-ETT) was used in thyroidectomy and parathyroidectomy surgeries.

METHODS

After obtaining hospital ethics committee approval, 239 cases affiliated with the American Society of Anesthesiologists (ASA II-IV) who used NIM EMG tubes in thyroid and parathyroid surgery were included in the prospective observational study. Tube and patient-related complications encountered with two different NIM EMG-ETT (silicone and polyvinyl chloride-PVC) were recorded.

RESULTS

The average age of the patients is 49.50 ± 13.44 years, the average BMI is 28.25 ± 4.91 kg/m2, the median surgery time is 115 (32-475) minutes, 75.7% are women, 97.5% are ASA II. Additional diseases other than thyroid and parathyroid problems were present in 77.3%. Thyroidectomy was performed in 73.2% of the patients. In our study, only 0.8% of patients with transient recurrent laryngeal nerve RLN paralysis were observed in thyroid and parathyroid surgeries performed using NIM-EMG tubes, 3 patient already had nerve involvement in the preoperative period. The most common complication was loss of stimulation response related to tubes and patient-related ventilation failure. There was no difference between the complications of silicone and PVC tubes except for irregular EMG response.

CONCLUSIONS

There was no significant difference in side effects other than irregular EMG response in the two different tubes we used in our study. It was observed that prolonging the surgical time increased the risk of irregular EMG response. It should not be forgotten that no matter which NIM-EMG tube is used, additional risks are encountered during the intubation and extubation process. In order to avoid negative consequences, it is necessary to follow the usage rules recommended by the manufacturer when using NIM-EMG tubes.

Does the Use of Intraoperative Neuromonitoring during Thyroid and Parathyroid Surgery Reduce the Incidence of Recurrent Laryngeal Nerve Injuries? A Systematic Review and Meta-Analysis

Injury to the recurrent laryngeal nerve (RLN) can be a devastating complication of thyroid and parathyroid surgery. Intraoperative neuromonitoring (IONM) has been proposed as a method to reduce the number of RLN injuries but the data are inconsistent. We performed a meta-analysis to critically assess the data. After applying inclusion and exclusion criteria, 60 studies, including five randomized trials and eight non-randomized prospective trials, were included. A meta-analysis of all studies demonstrated an odds ratio (OR) of 0.66 (95% CI [0.56, 0.79], p < 0.00001) favoring IONM compared to the visual identification of the RLN in limiting permanent RLN injuries. A meta-analysis of studies employing contemporaneous controls and routine postoperative laryngoscopy to diagnose RLN injuries (considered to be the most reliable design) demonstrated an OR of 0.69 (95% CI [0.56, 0.84], p = 0.0003), favoring IONM. Strong consideration should be given to employing IONM when performing thyroid and parathyroid surgery.

The role of intraoperative neuromonitoring in thyroid surgery training

Aim: Intraoperative nerve monitoring (IONM) during thyroid surgery has been widely accepted as an additive improvement to the gold standard of visually identifying the RLN. This study aims to evaluate the role of IONM application in thyroid surgery education during general surgery residency. Materials and Methods: Patients who underwent total thyroidectomy between January 2012 and December 2019 were included in the study. The patients were divided into 2 groups according to the use of IONM (Group 1: With IONM, Group 2: Without IONM). These groups were also divided into subgroups as assistants and experts among themselves. Results: This study involved 256 patients. There were 116 patients in group 1, and 140 patients in group 2. Histologic analysis results revealed that IONM was used more frequently in patients with a malignancy (p=0.015). The median operative time was significantly longer when IONM was used, with an operative time of 130 minutes for group 1 and 120 minutes for group 2 (p=0.015). When Group 1B and Group 2B were compared among themselves, the median operation time in Group 1B was 130 minutes, and the median operation time in Group 2B was 125 minutes (p=0.026). In the comparison between Groups 1B and 2B, it was detected that the rate of use of IONM was higher in malignancies (p=0.025). Conclusion: According to our results, the use of IONM did not reduce the incidence of RLN paralysis in thyroidectomy performed by specialists and residents.

Anatomical and functional identification of the external branch of the superior laryngeal nerve: classification based on morphology and electrophysiological monitoring

BACKGROUND

Motor function of the external branch of superior laryngeal nerve (EBSLN) is vital for voice quality. We studied the rate of EBSLN identification and integrity in the era of intraoperative neuromonitoring (IONM).

METHODS

Anatomic and functional identification of 515 EBSLNs-at-risk was performed under the guidance of IONM that motor integrity was electrophysiologically checked. The functional integrity was assessed with crico-thyroid muscle (CTM) twitches and/or recordable waveform amplitude. We tried to establish the systematic classification of EBSLN identification and integrity.

RESULTS

Visual, electrophysiological and total identification rates were 64.3%, 31.6% and 95.9%, respectively. We could identify 4.1% of EBSLNs neither anatomically nor electrophysiologically. We recorded CTM twitches alone or both CTM twitches and wave amplitude in 203(39.4%) and 291(56.5%) branches respectively. Identification features of EBSLNs were systematically classified under three main types: Visualized-monitored (1), non-visualized-monitored (2), unidentified (3), and electrophysiological integrity of EBSLNs under two subtypes: CTM twitches alone (a) and CTM twitches and wave amplitude (b).

CONCLUSION

Dedicated thyroid surgeon could visually identify EBSLNs. IONM contribution significantly increases the identification rate. Systematic classification of identification and electrophysiological integrity of EBSLNs may increase comprehensive knowledge about its motor function that is crucial for complication-free thyroidectomy.