Continuous Intraoperative Nerve Monitoring Research Articles

Modification of the Surgical Strategy for the Dissection of the Recurrent Laryngeal Nerve Using Continuous Intraoperative Nerve Monitoring.

The aim of this study was to describe first experiences and changes in management using continuous intraoperative neuromonitoring (C-IONM) in thyroid and parathyroid surgery. Retrospective analysis of patients who underwent surgery with C-IONM since 2012. Surgical maneuvers were modified when electrophysiologic events occurred. Patients with persistent loss of signal (LOS) underwent postoperative laryngoscopy. One hundred and one patients (of 1586 neck surgeries) were included and 19 had events: In 13 these were temporary (resolved before end of surgery) and led to intraoperative modifications in surgical approach; in all cases traction was released, and in 8, recurrent laryngeal nerve (RLN) approach was changed [superior approach (2), inferior approach (2), both (4)]. Six patients had persistent LOS (5.9%, present at end of procedure), with RLN palsy (RLNP) on postoperative day 1: In three, LOS occurred at electrode placement on the vagus nerve, leading to distal placement of the electrode allowing ipsilateral dissection under continuous monitoring; all three had complete recovery at 6months. In the three other patients, LOS occurred on the RLN: one probable thermal, one traction lesion and one accidental section of the anterior RLN branch. The RLN recovered within 6months in two patients, and in the third, RLNP persisted after 6months (1/101=1%). C-IONM provides real-time evaluation of the RLN function, allowing for adaptation of surgical maneuvers to prevent RLNP. It seems particularly useful in difficult cases like redo neck surgery, invasive thyroid cancer and intrathoracic or large goiter. Care should be given at electrode placement on the vagus nerve.

Tiroidektomi esnasında rekürren laringeal sinirin yaralanma mekanizmaları ve devamlı intraoperatif sinir monitorizasyonunun cerrahi strateji üzerine etkisi

Objective: To evaluate the mechanisms of recurrent laryngeal nerve (RLN) injury during thyroidectomy and the impact of continuous intraoperative nerve monitoring (C-IONM) on surgical strategy. Material and Methods: The data of 364 consecutive patients who underwent total or hemithyroidectomy between June 2014 and January 2016 were evaluated prospectively. All patients underwent thyroidectomy by using C-IONM. The mechanisms of RLN injury and the outcomes of the patients with combined events (CE) and loss of signal (LOS) were evaluated. Results: Combined events (CE) occurred in 6 (1.6%) of these 364 patients. The reduced electromyographic (EMG) amplitude and prolonged latency recovered in all patients intraoperatively by the reversal of the medial traction maneuver. Loss of signal (LOS) occurred in 7(1.9%) patients. The mechanisms of LOS was ligation of the anterior branch of the nerve in 1 (14.3%) patient and traction in 4(57%) patients. The probable mechanism of LOS was traction or transection in 2 (28.6%) patients in whom LOS occurred during the dissection of the intrathoracic portion of large substernal goiter. Of these 7 patients, LOS recovered intraoperatively after 20 minutes of waiting in 1(14.3%) patient. In the remaining 6 (85.7%) patients, unilateral vocal cord paralysis (VCP) was verified on the postoperative laryngoscopic examination. The overall temporary and permanent unilateral VCP rates were 1.6% (n=6) and 0.8% (n=3), respectively in these 364 patients. No bilateral VCP was recorded. Continuous intraoperative nerve monitoring (C-IONM) prevented bilateral VCP in 1 (0.3%) patient. Conclusion: The major advantage of C-IONM is to alert the surgeon for imminent RLN injury. Combined event (CE) is a pathognomonic sign of impending nerve injury that may progress to LOS. This situation enables the surgeon to adverse (reverse) the surgical maneuver before permanent damage to the nerve sets in. Continuous intraoperative nerve monitoring (C-IONM) can also immediately spot RLN injury during thyroidectomy. This property of C-IONM gives the surgeon the opportunity for an early corrective action to release the affected nerve promptly. In case of permanent LOS, staged thyroidectomy could be planned to prevent bilateral VCP.

Continuous intraoperative vagus nerve stimulation for monitoring of recurrent laryngeal nerve during minimally invasive esophagectomy.

For squamous cell carcinoma of the esophagus, extended mediastinal lymphadenectomy especially around the bilateral recurrent laryngeal nerves (RLN) is associated with high risk of nerve injury. This does not only result in hoarseness of voice, increase the chance of pulmonary complications, but would also affect the quality of life of patients in the long term. Methods to improve safety of lymphadenectomy are desirable. Continuous intraoperative nerve monitoring (CIONM) based on a system using vagus nerve stimulation was tested. In thyroidectomy, this system has been shown to be useful. Our patient cohort was unselected, with the intent to perform bilateral RLN dissection undergoing video-assisted thoracoscopic (VATS) esophagectomy. Intermittent nerve stimulation for mapping and CIONM were employed to monitor left RLN nodal dissection, while only intermittent stimulation was used for the right RLN. CIONM has the potential to aid RLN dissection. The learning curves for the placement technique of CIONM, the threshold level and the interpretation of myographic amplitude and latency have been overcome. With the availability of nerve mapping and CIONM, more aggressive and thorough nodal dissection may be possible with less fear of RLN injury.

Left recurrent laryngeal nerve dissection. Both CIONM & Ball-tip Monopolar Stimulator Probe were used for recurrent laryngeal nerve dissection. CIONM, continuous intraoperative nerve monitoring

Left recurrent laryngeal nerve dissection. Both CIONM & Ball-tip Monopolar Stimulator Probe were used for recurrent laryngeal nerve dissection. CIONM, continuous intraoperative nerve monitoring

Continuous Intraoperative Nerve Monitoring during Thyroid Surgery: Realistic Utility

Continuous Intraoperative Nerve Monitoring during Thyroid Surgery: Realistic Utility

Intraoperative nerve monitoring during thyroid surgery.

Laryngeal nerve injury, resulting in speech and swallowing dysfunction, is a feared complication of thyroid operations. Routine visualization of the recurrent laryngeal nerve (RLN) has decreased the likelihood of nerve injury, and intraoperative nerve monitoring has been applied in the hope of further enhancing safety. There is conflicting evidence about the value of nerve monitoring during thyroid operations, despite ample research. The data favor nerve monitoring in certain situations, such as neck re-explorations, contralateral RLN injury, extensive or challenging dissections, invasive tumors or large goiters, and nonrecurrent or branching recurrent laryngeal nerves. Continuous intraoperative nerve monitoring may reduce the chances of excessive traction, which is the most common mechanism of injury. Nerve monitoring may also identify and protect the external branches of the superior laryngeal nerve. Surgeons should routinely identify recurrent laryngeal nerves during thyroid operations, and intraoperative nerve monitoring might be a useful adjunct to prevent injury. As a result of the relatively low probability of permanent recurrent laryngeal nerve injury, it is difficult to establish the absolute value of nerve monitoring. Further research may focus on continuous nerve monitoring and intraoperative monitoring of the external branches of the superior laryngeal nerves.

The role of continuous intraoperative neuromonitoring followed by facial nerve stimulation during parotidectomy

Abstract BACKGROUND. Intraoperative neural monitoring (IONM) has begun to be studied in detail by surgeons around the world since several decades ago from the need to verify functional integrity of the neural elements. Parotid gland surgery requires a thorough knowledge of the anatomy of this region by ENT surgeons. Also, the surgeons performing parotid surgery need to have important strategies of management which include: handiness to identify facial nerve, dissection nerve branches and application of neuromonitoring in order to preserve nerve functions. OBJECTIVE. This study has analysed the usefulness of intraoperative continuous monitoring in superficial or in total parotidectomy. It identifies the facial nerve and reduces the risk of postoperative facial palsy. We have been using intraoperative continuous monitoring - evoked facial nerve electromyograms (EMG). MATERIAL AND METHODS. Continuous intraoperative facial nerve monitoring was prospectively achieved in the case of three patients diagnosed with benign tumors, on which parotidectomy with the preservation of the nerve was carried out in order to highlight the value and efficacy of this method. RESULTS. In our country, continuous intraoperative facial nerve monitoring performance is still not a common practice in ENT Departments. It revealed postoperatively that the incidence of temporary or permanent facial palsy was 0% and the minimal stimulation was obtained at levels equal to 0,5 mA, which implies integral functioning of the facial nerve. CONCLUSION. In parotid surgery, facial nerve IONM represents the gold standard in recognition of real-time electrophysiological signals, electromyography waves and auditory signals to enable the correct approach wherever possible, avoiding extensive nerve damage. It is known the importance of continuous IONM in postoperative prognosis of the neural function and intraoperative decision making regarding the technical surgery.

Adaptation of Continuous Intraoperative Vagus Nerve Stimulation for Monitoring of Recurrent Laryngeal Nerve During Minimally Invasive Esophagectomy.

Esophagectomy has risk of recurrent laryngeal nerve (RLN) injury. Conventional nerve monitoring has been used to help identify and protect the RLN. A new concept of continuous intraoperative nerve monitoring (CIONM) by stimulation of the ipsilateral vagus nerve has been used in thyroidectomy. The current report describes adapting the CIONM method for use in video-assisted thoracoscopic (VATS) esophagectomy. The nerve monitor employed is NIM 3.0 with automatic periodic stimulation (Medtronics Inc., USA). Patient is intubated with NIM contact-reinforced EMG endotracheal tube (Medtronics Inc., USA). The operation starts with a left lower neck incision, and the stimulating electrode is secured around the left vagus nerve. The patient is then turned to the left lateral position for VATS esophagectomy. CIONM of the left RLN is achieved by regular stimulation of the left vagus nerve, and intact nerve conduction is detected by the electromyography (EMG) of the left vocalis muscle. The alarm is set to activate when EMG amplitude reduces by 50% or latency prolongs by 10%. Initial experience of ten cases showed that a mean time of 35 min was required to complete the electrode insertion in the neck. There was one event in which there was more than 50% reduction of EMG amplitude that persisted but the patient had no vocal cord paralysis after operation. In another patient, the EMG reduced by 75% and persisted. The patient had temporary vocal cord paralysis. CIONM is feasible during VATS esophagectomy and can alert the surgeon of imminent injury to the RLNs, thereby preventing permanent injury.

Dynamics of loss and recovery of the nerve monitoring signal during thyroidectomy predict early postoperative vocal fold function.

The characteristics of segmental type 1 and global type 2 injuries to the recurrent laryngeal nerve (RLN) and the extent and dynamics of nerve recovery are poorly understood. This investigation of 785 patients who underwent thyroidectomy under continuous intraoperative nerve monitoring aimed at exploring the dynamics of loss and recovery of the nerve monitoring signal and its relationship to early postoperative vocal fold palsy. Persistent complete loss of signal and signal recovery <50% identified all (based on 12 and 4 patients with type 1 injuries) or most (based on 9 of 12 and 4 of 6 patients with global type 2 injuries) early unilateral vocal fold palsies. Signal recovery ≥50% (based on 7 patients) always signified normal vocal fold function. These data, including the observation that global type 2 injuries may entail less severe nerve injury, require validation in independent series before being adopted more widely. © 2015 Wiley Periodicals, Inc. Head Neck 38: E1144-E1151, 2016.

Preoperative percutaneous nerve mapping of the mandibular marginal branch of the facial nerve.

In this study, we introduce a reliable method for mapping the location of the mandibular marginal branch of the facial nerve. The utility of preoperative percutaneous mandibular marginal branch mapping and continuous intraoperative nerve monitoring during operation with a submandibular approach is reported. The mapping technique was performed in 40 patients. Electromyography surface electrodes were placed on the orbicularis oris muscles. A modified bipolar probe with an adjustable distance between the 2 tips was used to apply surface stimulation at a frequency of 1 Hz to 2 Hz. The stimulating current most frequently used was 5.0 mA to 5.5 mA. By moving the electrode at right angles across the suspected path of the nerve around the marginal border of the mandible, 4 to 5 points were marked and connected, where the orbicularis oris contracted and the action potential was evoked. After general anesthesia, the mapping path was verified using needle electrodes with different needle-to-nerve distances. The nerve could be mapped preoperatively in all patients and were protected in 39 patients. The thresholds of the needle electrode on the mapping path were at or below 0.5 mA, verifying the accuracy of mapping. Preoperative percutaneous nerve mapping was a precise method of identifying the location of the nerve and could protect the nerve from accidental injury.

Early Prediction of Impending Recurrent Laryngeal Nerve Injury during Neck Surgery by Continuous Intraoperative Vagus Nerve Monitoring

Early Prediction of Impending Recurrent Laryngeal Nerve Injury during Neck Surgery by Continuous Intraoperative Vagus Nerve Monitoring

The Current State of Recurrent Laryngeal Nerve Monitoring for Thyroid Surgery

There is an increasing interest in intraoperative nerve monitoring (IONM), and numerous institutions have begun to perform monitored thyroidectomies. Attitudes have changed with the introduction of non-invasive devices, the publication of trials and guidelines defining standards, structured courses and descriptions of legal implications. The use of IONM helps to identify the nerve and give an objective evaluation of its function during the dissection. Recently, continuous IONM was introduced; it is a promising tool for early recognition of recurrent laryngeal nerve stress. This paper describes current issues in IONM.

Continuous intraoperative vagus nerve stimulation for identification of imminent recurrent laryngeal nerve injury

Conventional intraoperative nerve monitoring, predicated on intermittent stimulation, can predict recurrent laryngeal nerve (RLN) palsy only after the damage has been done. Fifty-two patients (52 nerves at risk) who underwent continuous intraoperative nerve monitoring (CIONM) for thyroid surgery via vagus nerve stimulation had their electromyographic (EMG) tracings recorded and correlated with surgical maneuvers and postoperative RLN function. There was 1 imminent loss of signal (LOS) with intraoperative signal recovery and there were 4 losses of signal with corresponding unilateral transient RLN palsy. When EMG amplitude decreased >50% and EMG latency increased >10%, LOS and postoperative RLN palsy were noted in 4 of 8 patients (50%) who had multiple combined events. In 9 of 13 patients (70%) who developed adverse EMG changes, modification of the causative surgical maneuver resulted in recovery of those EMG changes and aversion of impending RLN palsy. CIONM reliably signaled impending nerve injury, enabling immediate corrective action.

Intraoperative recurrent laryngeal nerve monitoring: a useful method for patients with esophageal cancer

It is well accepted that recurrent laryngeal nerve paralysis is a severe complication of esophagectomy or lymphadenectomy performed adjacent to the recurrent laryngeal nerves. Herein, determination of the effectiveness of implementing continuous recurrent laryngeal nerve monitoring to reduce the incidence of recurrent laryngeal nerve paralysis after esophagectomy was sought. A total of 115 patients diagnosed with esophageal cancer were enrolled in the thoracic section of the Tangdu Hospital of the Fourth Military Medical University from April 2008 to April 2009. Clinical parameters of patients, the morbidity, and the mortality following esophageal resection were recorded and compared. After the surgery, a 2-year follow up was completed. It was found that recurrent laryngeal nerve paralysis and postoperative pneumonia were more frequently diagnosed in the patients that did not receive continuous recurrent laryngeal nerve monitoring (6/61 vs. 0/54). Furthermore, positive mediastinal lymph nodes (P = 0.015), total mediastinal lymph nodes (P < 0.001), positive total lymph nodes (P = 0.027), and total lymph nodes (P < 0.001) were more often surgically removed in the patients with continuous recurrent laryngeal nerve monitoring. These patients also had a higher 2-year survival rate (P = 0.038) after surgery. It was concluded that continuous intraoperative recurrent laryngeal nerve monitoring is technically safe and effectively identifies the recurrent laryngeal nerves. This may be a helpful method for decreasing the incidence of recurrent laryngeal nerve paralysis and postoperative pneumonia, and for improving the efficiency of lymphadenectomy.

Continuous Intraoperative Facial Nerve Monitoring in Predicting Postoperative Injury During Parotidectomy

Continuous Intraoperative Facial Nerve Monitoring in Predicting Postoperative Injury During Parotidectomy

Continuous Intraoperative Facial Nerve Monitoring in Predicting Postoperative Injury During Parotidectomy

To assess whether the use of continuous intraoperative facial nerve monitoring correlates to postoperative facial nerve injury during parotidectomy. A retrospective analysis. Forty-five consecutive parotidectomies were performed using an electromyograph (EMG)-based intraoperative facial nerve monitor. Of those, 37 had complete data for analysis. Intraoperative findings and final interpretation of the EMGs were analyzed by a senior neurologist and neurophysiologist. All patients were analyzed, including those with preoperative weakness and facial nerve sacrifice. The overall incidence of facial paralysis (House-Brackmann scale > 1) was 43% for temporary and 22% for permanent deficits. This includes an 11% incidence of preoperative weakness and 14% with intraoperative sacrifice. An abnormal EMG occurred in only 16% of cases and was not significantly associated with permanent or temporary facial nerve paralysis (chi, P < 1.0; Fisher's exact P < .68). Of the eight patients with permanent paralysis, only two had abnormalities on the facial nerve monitor. Also, only one of five patients with intraoperative sacrifice of the facial nerve had an abnormal EMG. Factors significantly associated with the incidence of facial paralysis include malignancy, advanced age, extent of parotidectomy, and dissection beyond the parotid gland (chi and Fisher's, P < .05). The results suggest that abnormalities on the intraoperative continuous facial nerve monitor during parotidectomy do not predict facial nerve injury. The incidence of permanent and temporary facial nerve paralysis compare favorably with the literature given that this study includes patients with revision surgery, intraoperative sacrifice, and preoperative paralysis. Standard of care implications will be discussed.

Prospective analysis of the efficacy of continuous intraoperative nerve monitoring during thyroidectomy, parathyroidectomy, and parotidectomy

Objective: Continuous intraoperative electromyographic monitoring was prospectively performed in all parotidectomies, thyroidectomies, and parathyroidectomies over approximatelsy 5 years to assess the efficacy of this technology. Study Design and Setting: Continuous intraoperative nerve monitoring with perioperative nerve assessment was performed. The postresection minimal stimulation level of the nerves was determined to evaluate if this level would predict nerve function postoperatively. Results: Forty-four parotidectomies and 70 thyroid/parathyroid operations were performed with 140 nerves at risk (44 facial, 96 recurrent laryngeal). The incidence of temporary facial paralysis was 15.9% (7 of 44) and the incidence of permanent paralysis was 0%. The incidence of temporary recurrent laryngeal nerve paralysis in terms of nerves at risk was 1.0% (1 of 96), and the incidence of permanent recurrent laryngeal nerve paralysis was 0%. All patients with normally functioning facial and recurrent laryngeal nerves postoperatively had minimal stimulation levels less than or equal to 0.4 mA. Conclusion: Continuous intraoperative nerve monitoring was associated with extremely low rates of temporary and permanent nerve paralysis in our series of 140 nerves at risk as compared to the rates documented in the literature. (Otolaryngol Head Neck Surg 2001;124:537-43.)

Improved Preservation of Facial Nerve Function in the Infratemporal Approach to the Skull Base

Although the infratemporal approach described by Fisch provides excellent exposure of the jugular foramen, intrapetrous carotid artery, and lateral skull base, the anterior displacement of the seventh cranial nerve often results in temporary facial paralysis. The use of a modified technique for facial nerve mobilization resulted in significant improvement of both early and final facial function. Since that earlier report, continuous intraoperative electrical facial nerve monitoring has been used during the infratemporal approach in 20 additional cases. Immediate postoperative facial function was normal in 93% of the monitored cases and in 70% of the cases in the unmonitored group. More importantly, no patients in the monitored group developed grade V or VI weakness after surgery, whereas 48% of the unmonitored patients had grade V or VI weakness during the early postoperative period. This article will describe how intraoperative facial nerve monitoring is used during infratemporal surgery and will compare early facial function in 31 unmonitored patients with early facial function in 20 monitored procedures.