Intra-operative monitoring as an adjuvant to standard vagus nerve stimulation implantation

PURPOSE

The treatment of refractory epilepsy by vagus nerve stimulation (VNS) is a well-established therapy. Complications following VNS insertion may be procedure-related or stimulation-related. Herein, we describe our technique of intra-operative neuro-monitoring (IONM) in an attempt to diminish these adverse events.

METHODS

This retrospective study describes 66 consecutive patients between the ages of 3 and 12 years who had undergone primary VNS implantation. The study population consisted of two cohorts, one in which the VNS device was implanted according to the standard described technique and a second group in which IONM was used as an adjuvant during the VNS device placement. Prior to VNS insertion, a Pediatric Voice Handicap Index (PVHI) was performed to assess voice-related quality of life, and this was repeated at 3 months following VNS insertion.

RESULTS

Sixty-six patients underwent the VNS implantation. Forty-three patients had a "standard" VNS insertion technique performed, whereas 23 had IONM performed during the VNS implantation. There were significant changes in the PVHI scores across both cohorts at 3-month follow-up. There were no statistically significant differences in PVHI scores between the monitored group and non-monitored group at 3-month follow up.

CONCLUSIONS

IONM can be used during VNS insertions to ensure correct placement of the leads on CNX. IONM may minimise vocal cord stimulation by placing the lead coils on the area of nerve eliciting the least amount of vocal cord EMG response. IONM however does not appear to improve voice outcomes at early follow up.

Comparison of Monopolar and Bipolar Stimulator Probes for Intraoperative Nerve Mapping During Thyroidectomy: A Prospective Study

OBJECTIVES/HYPOTHESIS

During intraoperative neuromonitoring in thyroid surgery, two different kinds of stimulator probes, monopolar and bipolar, are commonly used to stimulate the laryngeal nerves. We explore the unique characteristics of both of these probes as they relate to intraoperative laryngeal nerve mapping.

METHODS

Twenty-one patients undergoing neuromonitored thyroidectomy by a single surgeon were enrolled. Electromyography (EMG) amplitude and latency measurements were prospectively recorded concurrently from 1 mA stimulation of vagus nerve (VN) and inferior/superior recurrent laryngeal nerve before (with and without fascia) and after thyroid resection using bipolar and monopolar stimulator probes.

RESULTS

Significantly higher amplitudes were obtained with monopolar stimulator probes as compared to bipolar probes, in several stimulation scenarios such as at right VN pre-resection (carotid sheath intact), right VN pre-resection (carotid sheath dissected), right VN post-resection and left VN (carotid sheath dissected). No significant differences were found between amplitudes and latency values in all other stimulation scenarios.

CONCLUSIONS

According to this study, both probes are reliable and safe for neural mapping. The kind of probe used during neural monitoring is based on surgical situations and surgeon preference.

LEVEL OF EVIDENCE

Level 3 (According to Oxford Centre for Evidence-Based Medicine 2011 Levels of Evidence) Laryngoscope, 2021.

Intraoperative Nerve Monitoring for Tarsal Tunnel Decompression: A Surgical Technique to Improve Outcomes

The aim of the current study was to evaluate the effectiveness of intraoperative neuromonitoring (INM) as an adjunct in performing tarsal tunnel decompression surgery. We reviewed 38 patients who met inclusion criteria. INM was used to measure the voltage of the abductor hallucis and digiti quinti muscles both before and after decompression. Observed changes intraoperatively were acute and within minutes of the decompression performed by the surgeon. Patient outcomes were ascertained from clinical findings and classified as excellent, fair, or poor. Patient outcomes and the voltage change were measured and assessed for association, and statistically significant differences were found between outcome groups. Of the 38 patients, 29 (76%) had excellent outcomes, with a mean change in microvolts of 2088.28 ± 1172.44 (684%) (p = .0004) and 2173.24 ± 1228.39 (742%) (p = .0014) for abductor hallucis and abductor digiti quinti, respectively. The study supports INM as a useful adjunct in performing tarsal tunnel decompression.

Litigation in thyroid surgery in England

Thyroid surgery has the potential for significant life-changing postoperative complications. Since 1995, the NHS Litigation Authority has handled litigation claims in England. This article reviews all thyroid surgery litigation claims between 1995 and 2012 and looks at potential strategies to minimize future claims.

Continuous intraoperative neural monitoring in thyroid surgery: a Mexican experience

Intraoperative continuous neural monitoring (C-IONM) during thyroid surgery has been recognized as a useful tool to identify and confirm recurrent laryngeal nerve integrity. The aim of the present study is to analyze electromyographic features and thresholds for normal vocal fold function in our initial experience with C-IONM in thyroid surgery. C-IONM was utilized in 57 patients who underwent thyroid surgery between July 2012 and December 2015. EMG parameters were analyzed looking for potential predictors of postoperative vocal fold dismotility. There were 54 females (94.7%) and 3 males (5.3%) with a mean age of 46.7 ± 11.6 years. C-IONM was successfully registered in 89 of 107 nerves at risk (83.1%). Mean basal amplitude was 727.31 ± 471.25 μV and mean final amplitude was 650.27 ± 526.87 μV (P = 0.095, CI 95% 13.83-167.91). Mean basal latency was 5.23 ± 1.42 mS and mean final latency was 5.18 ± 1.50 mS (P = 0.594, CI 95% 0.39-0.24). Four patients had transient postoperative vocal fold paresis. None of these four patients had loss of signal (LOS), three had transient decrease in amplitude, and one had a normal registry throughout the operation. C-IONM is a useful tool to identify patients in whom intraoperative RLN is at risk during surgery. Final amplitude above 500 μV and no LOS is associated with RLN integrity and normal postoperative vocal fold function.

Intraoperative Neurophysiological Monitoring of the Laryngeal Nerves During Anterior Neck Surgery: A Review

Contributions to the literature on intraoperative neuro monitoring (IONM) during endocrine and head and neck surgery have increased over recent years. Organizational support for neural monitoring during surgery is becoming evident and is increasingly recognized as an adjunct to visual nerve identification. A comprehensive understanding of the role of IONM for prevention of nerve injuries is critical to maximize safety during surgery of the anterior compartment of the neck. This review will explore the potential advantages of IONM to improve the outcomes among patients undergoing anterior neck surgery.

Neuromonitoring of the laryngeal nerves in thyroid surgery: a critical appraisal of the literature

One of the most significant complication of thyroid surgery is injury of the recurrent laryngeal nerve. Injury of the external branch of the superior laryngeal nerve is a less obvious but occasionally significant problem. Recently, neuromonitoring during thyroidectomy has received considerable attention because of literature encouraging its use, but there is no consensus about its advantages and utility. A critical assessment of the literature on neuromonitoring was conducted in order to define its effectiveness, safety, cost-effectiveness and medical-legal impact. Available data does not show results superior to those obtained by traditional anatomical methods of nerve identification during thyroid surgery. Data about cost-effectiveness is scarce. The literature shows inconsistencies in methodology, patient selection and randomization in various published studies which may confound the conclusions of individual investigations. The current recommendation for use in "high risk" patients should be assessed because definition heterogeneity makes identification of these patients difficult. As routine use of neuromonitoring varies according to geography, its use should not be considered to be the standard of care.

Prospective study on loss of signal on the first side during neuromonitoring of the recurrent laryngeal nerve in total thyroidectomy

Background

Staged thyroidectomy has been recommended when loss of the signal from intraoperative nerve monitoring is observed after first-side dissection of the recurrent laryngeal nerve. There is no high-quality evidence supporting this recommendation. In addition, it is not clear whether signal loss predicts postoperative vocal cord paralysis.

Methods

This was a prospective observational study of consecutive adult patients undergoing neuromonitored total thyroidectomy for either malignancy or multinodular goitre. The prevalence of first-side loss of signal was recorded. Surgery was completed, and vagus and laryngeal nerves on the first side were rechecked at the end of the procedure.

Results

Two-hundred and ninety patients were included. Loss of signal on the first side was noted in 16 procedures (5·5 per cent). Thyroidectomy was completed and, at retesting, 15 of 16 initially silent nerves recovered an electromyographic signal with a mean(s.d.) amplitude of 132(26) mcV. Mean time to recovery was 20·2 (range 10–35) min. In no patient was the signal lost on the opposite side. Only three of 15 nerves with a recovered signal were associated with transient vocal cord dysfunction.

Conclusion

After loss of signal of the recurrent laryngeal nerve dissected initially, there was a 90 per cent chance of intraoperative signal recovery. In this setting, judicious bilateral thyroidectomy can be performed without risk of bilateral recurrent nerve paresis.