Intraoperative nerve monitoring reduces recurrent laryngeal nerve injury in geriatric patients undergoing thyroid surgery

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.

Recurrent laryngeal never monitoring versus non-monitoring in parathyroid surgery

Background

Although intraoperative neural monitoring (IONM) is well established in thyroid surgery, it is less commonly analyzed in parathyroid operations. This study presents the results of IONM for primary and secondary hyperparathyroidism surgery.

Methods

We retrospectively assessed 270 patients with primary hyperparathyroidism (PHPT), 53 patients with secondary hyperparathyroidism (SHPT), and 300 patients with thyroid cancer from June 2010 to June 2022 in one hospital in China. The follow-up was 12 months. Demographic, electromyography data from IONM, laboratory, and clinical information were collected. Laryngoscopy was collected from 109 patients with PHPT in whom IONM was not used. All groups were assessed by Pearson's chi-square test and Fisher's exact probability method to verify the relationship between parathyroid size and location, duration of surgery, preoperative concordant localization, laryngeal pain, IONM outcomes, cure rate, and RLN injury. Visual analog scale (VAS) assessed laryngeal pain. RLN outcomes were measured according to nerves at risk (NAR).

Results

The study comprehended 918 NAR, that is 272, 105, 109, and 432 NAR for PHPT, SHPT with IONM, PHPT without IONM, and thyroid surgery control group, respectively. IONM successfully prevented RLN injury (P<0.001, P=0.012): Fifteen (5.51%) RLNs experienced altered nerve EMG profiles during surgery, and five (1.84%) experienced transient RLN injury in PHPT patients. Five (4.76%) RLNs were found to have altered EMG profiles during surgery, and one (0.95%) RLN had a transient RLN injury in SHPT patients. There was no permanent nerve injury (0.00%) in this series. There was no association between location, gland size, preoperative concordant localization, cure rate, duration of surgery, and IONM (P >0.05). Duration of surgery was associated with postoperative pharyngeal discomfort (P=0.026, P=0.024). Transient RLN injury was significantly lower in patients with PHPT who underwent IONM than in those who did not. Intraoperative neuromonitoring played an effective role in protecting the recurrent laryngeal nerve (P=0.035). Compared with parathyroidectomy, thyroidectomy had a higher rate of RLN injury (5.32%, P<0.001).

Conclusion

IONM for SHPT and PHPT offers rapid anatomical gland identification and RLN functional results for effective RLN protection and reduced RLN damage rates.

[Safe thyroidectomy for thyroid and parathyroid diseases]

OBJECTIVE

To offer the ways for safe thyroidectomy aimed at prevention of damage of recurrent laryngeal nerve in patients with thyroid and parathyroid diseases.

MATERIAL AND METHODS

We analyzed postoperative outcomes after thyroidectomy in 342 patients aged 20-80 years. Topography of recurrent laryngeal nerves was studied on 20 laryngeal-tracheal complexes of deceased patients. Technique of visualization of various segments of recurrent laryngeal nerve was worked out.

RESULTS AND DISCUSSION

Thyroidectomy was performed in 342 patients with thyroid and parathyroid diseases. Thyroidectomy was performed in accordance with recommendations described by F.W. Lahey, W.B. Hoover (1938) and H. Malcolm, M.D. Wheeler (1998). Location of recurrent laryngeal nerve varied in patients with nodular, retrosternal goiter and parathyroid gland adenoma. Comparison of intraoperative and morphological data on recurrent laryngeal nerve visualization showed possible risks of its damage during manipulations on thyroid gland, esophagus and trachea. Our study confirmed the need for visualization and mobilization of recurrent laryngeal nerve in all procedures on thyroid and parathyroid glands. Introduction of the described technique of thyroidectomy and training sessions for recurrent laryngeal nerve mobilization on laryngeal-tracheal complexes reduced postoperative incidence of phonation disorders from 21.6% to 0.98%.

CONCLUSION

Thyroidectomy may be a safe procedure if surgeons are familiar with the details of surgical technique and prevent damage to adjacent structures.

Artificial intelligence-augmented, label-free molecular imaging method for tissue identification, cancer diagnosis, and cancer margin detection

Label-free high-resolution molecular and cellular imaging strategies for intraoperative use are much needed, but not yet available. To fill this void, we developed an artificial intelligence-augmented molecular vibrational imaging method that integrates label-free and subcellular-resolution coherent anti-stokes Raman scattering (CARS) imaging with real-time quantitative image analysis via deep learning (artificial intelligence-augmented CARS or iCARS). The aim of this study was to evaluate the capability of the iCARS system to identify and differentiate the parathyroid gland and recurrent laryngeal nerve (RLN) from surrounding tissues and detect cancer margins. This goal was successfully met.

Methodological Quality of Systematic Reviews of Intraoperative Neuromonitoring in Thyroidectomy: A Systematic Review

Importance

Systematic reviews and meta-analyses are considered the best evidence for clinical decision making. Many reviews of intraoperative neuromonitoring (IONM) in thyroidectomy have conflicting results, owing in large part to methodological quality.

Objective

To assess the methodological quality and the causes of heterogeneous results of systematic reviews that compare routine IONM vs visual identification of the recurrent laryngeal nerve (RLN) in patients undergoing thyroidectomy.

Data Sources

A systematic search was performed of MEDLINE (PubMed), Embase, the Cochrane Library, LILACS (Literatura Latino Americana e do Caribe em Ciências da Saúde), Web of Science, and Google from January 1, 1968, through June 30, 2018. Data were analyzed from July 17 to November 30, 2018.

Study Selection

Studies that mentioned performance of a systematic review/meta-analysis during the search period.

Data Extraction and Synthesis

Data including study characteristics, type of patients, numbers of nerves at risk, and temporary and definitive RLN paralysis by group were extracted. Data about methodological characteristics, type of statistical analysis and summary estimator, endorsement of systematic review/meta-analysis guidelines, heterogeneity, publication bias, funding, conflict of interest, and statistical analysis were also recorded. The methodological quality was measured with the AMSTAR2 (A Measurement Tool to Assess Systematic Reviews) tool by 2 independent evaluators.

Main Outcomes and Measures

Methodological quality.

Results

The search identified 13 systematic reviews that included patients who underwent open or minimally invasive thyroidectomy, second operations, and a mixture of low- and high-risk procedures. The mean compliance with the AMSTAR2 overall criteria was 53% (range, 11%-83%); with critical criteria, 71% (range, 50%-94%). The percentage of nerves at risk from RCTs was 4.8%. The mean (SD) crude rate of definitive RLN paralysis was 0.81% (0.22%; median, 0.75% [range, 0.53%-1.30%]) in the monitoring group and 1.14% (0.56%; median, 0.96% [range, 0.57%-2.56%]) in the control group.

Conclusions and Relevance

A substantial number of systematic reviews of IONM in thyroidectomy have conflicting results, but their mean methodological quality is critically low. Design of a systematic review should comply with methodological standards and recommendations to offer relevant and practical information for decision making.

[Sequential method for determining the maximum dose of mivacurium continuously infused for intraoperative neuromonitoring in thyroid surgery]

OBJECTIVE

To determine the maximum dose of continuously infused mivacurium for intraoperative neuromonitoring and observe its adverse effects in thyroid surgery.

METHODS

Twenty-eight patients undergoing thyroid surgery with intraoperative neuromonitoring received continuous infusion of mivacurium at the initial rate of 5.43 μg?kg^-1?min^-1, and the infusion rate for the next patient was adjusted based on the response of the previous patient according to the results of neurological monitoring. The depth of anesthesia was maintained with sevoflurane and remifentanil during the surgery. The LD50 and 95% CI of mivacurium were calculated using Brownlee's up-and-down sequential method.

RESULTS

The LD50 of continuously infused mivacurium was 8.94 μg?kg^-1?min^-1 (95% CI: 8.89- 8.99 μg?kg^-1?min^-1) during thyroid surgery, which did not affect neurological function monitoring. Transient chest skin redness occurred after induction in 9 patients (32.1%). None of the patients experienced intubation difficulties or showed intraoperative body motions during the surgery.

CONCLUSIONS

In patients undergoing thyroid surgery under anesthesia maintained by inhalation and intravenous infusion, the LD50 of mivacurium was 8.94 μg?kg^-1?min^-1 (95% CI: 8.89-8.99 μg?kg^-1?min^-1) for continuous infusion, which does not cause serious adverse effects during the operation.

Protective Effects of Intraoperative Nerve Monitoring (IONM) for Recurrent Laryngeal Nerve Injury in Thyroidectomy: Meta-analysis

Recurrent laryngeal nerve (RLN) injury is an intractable complication of thyroidectomy. Intraoperative nerve monitoring (IONM) was designed to prevent RLN injury. However, the results concerning the protective effect of IONM on RLN injury are still controversial. We searched all eligible databases from 1980 to 2017. Meta-analysis was performed to evaluate the effect of IONM on RLN injury. Sensitivity analysis was also conducted to check the stability of our results. There were 34 studies included in the analysis. Overall analysis found a significant decrease in total injury (RR = 0.68, 95%CI: 0.55 to 0.83), transient injury (RR = 0.71, 95%CI: 0.57 to 0.88), and permanent injury (RD = −0.0026, 95%CI: −0.0039 to −0.0012) with IONM. Subgroup analysis found IONM played a preventive role of total, transient and permanent injury in patients undergoing bilateral thyroidectomy. IONM also reduced the incidence of total and transient injury for malignancy cases. Operations with IONM were associated with fewer total and transient RLN injuries in operation volume < 300 NARs per year and fewer total and permanent RLN injuries in operation volume ≥ 300 NARs per year. The application of IONM could reduce the RLN injury of thyroidectomy. Particularly, we recommend routine IONM for use in bilateral operations and malignancy operations.