Application Of Intraoperative Neuromonitoring Research Articles

The INMSG Survey on the Loss of Signal Management on the First Side During Planned Bilateral Thyroid Surgery.

The aim of this study is to describe the management and associated follow-up strategies adopted by thyroid surgeons with different surgical volumes when loss of signal (LOS) occurred on the first side of planned bilateral thyroid surgery, and to further define the consensus on intraoperative neuromonitoring (IONM) applications. The International Neural Monitoring Study Group (INMSG) web-based survey was sent to 950 thyroid surgeons worldwide. The survey included information on the participants, IONM team/equipment/procedure, intraoperative/postoperative management of LOS, and management of LOS on the first side of thyroidectomy for benign and malignant disease. Out of 950, 318 (33.5%) respondents completed the survey. Subgroup analyses were performed based on thyroid surgery volume: <50 cases/year (n = 108, 34%); 50 to 100 cases/year (n = 69, 22%); and >100 cases/year (n = 141, 44.3%). High-volume surgeons were significantly (P < .05) more likely to perform the standard procedures (L1-V1-R1-S1-S2-R2-V2-L2), to differentiate true/false LOS, and to verify the LOS lesion/injury type. When LOS occurs, most surgeons arrange otolaryngologists or speech consultation. When first-side LOS occurs, not all respondents decided to perform stage contralateral surgery, especially for malignant patients with severe disease (eg, extrathyroid invasion and poorly differentiated thyroid cancer). Respondents felt that IONM was optimized when conducted under a collaborative team-based approach, and completed IONM standard procedures and management algorithm for LOS, especially those with high volume. In cases of first-site LOS, surgeons can determine the optimal management of disease-related, patient-related, and surgical factors. Surgeons need additional education on LOS management standards and guidelines to master their decision-making process involving the application of IONM.

신세포암종의 경부 림프절 전이 절제술 중 미주신경에 대한 수술 중 신경모니터링 증례 보고

Intraoperative neuromonitoring (IONM) of recurrent laryngeal nerve has been widely applied worldwide. However, IONM of vagus nerve during lateral neck surgery has been rarely reported. In this case report, we introduce the application of IONM of vagus nerve during dissection of a metastatic lymph node of renal cell carcinoma of left level IV located deep to the vagus nerve.

Does neuromonitoring affect voice quality in patients subjected to a complete thyroidectomy ?

Voice dysfunction is the most common complication of thyroid surgery. The use of intraoperative neuromonitoring (IONM) is to protect the recurrent laryngeal nerves, the damage of which causes voice dysfunction. The aim of the study was to evaluate voice quality in patients who underwent complete thyroidectomy operated on with the application of IONM as well as a group of patients operated on with only macroscopic nerve visualization. In the analysis, clinical voice assessment was performed with particular focus on voice efficiency using the Voice Handicap Index (VHI), Vocal Tract Discomfort (VTD) and GRBAS scale. The study group consisted of 205 patients operated on with IONM. The control group consisted of 162 patients subjected to surgery only with macroscopic visualization of recurrent laryngeal nerves, without IONM. During the follow-up period from 2 to 10 years after surgery, checkups were performed. Each patient who came for a checkup was subjected to perceptual voice evaluation with the use of the GRBAS scale, indirect laryngoscopy procedure and voice selfevaluation with two questionnaires (VHI and VTD). The frequency of vocal fold palsy did not differ significantly statistically in the study group and the control group. Both in the study group and in the control group, patients with vocal fold paralysis had statistically significantly higher results in the VHI and VTD questionnaires as well as in the GRBAS study. Patients with recurrent laryngeal nerve injury show significant differences in the scope of voice handicap, both in the voice quality assessment with the use of the GRBAS scale, and self-evaluation questionnaires: VHI and VTD. All voice disorders evaluated with self-assessment are medium voice disability.

Risk Factors for Iatrogenic Vocal Fold Palsy during Thyroid Surgery: A Single Institutional Experience Over 10 Years

Background and Objectives Recurrent laryngeal nerve (RLN) palsy is a critical complication of thyroid surgery. The aim of this study was to investigate the incidence of iatrogenic temporary or permanent RLN palsy and to determine the surgeon’s experience factor for iatrogenic RLN palsy.Subjects and Method We retrospectively reviewed 3404 patients, who underwent thyroidectomy between 2010 and 2019, to identify the surgeon’s experience factor for iatrogenic RLN palsy. Information about patient demographics, surgeon factor, whether or not intraoperative neuromonitoring (IONM) were used, and the postoperative status of RLN were collected. The incidence of RLN injury was analyzed according to the surgeon experience, surgery for thyroid cancer, effect of IONM and the extent of surgery.Results A total of 4479 RLNs were at risk in 3094 thyroidectomies in this study. There were 34 (1.10%) postoperative vocal cord palsy (VCP) cases after thyroidectomy. All patients with RLN palsy showed a unilateral type. VCP was temporary in 26 (0.84%) cases and permanent in 8 (0.26%) cases. Using the nerve at risk (NAR) method, we found that there were 34 NAR palsy out of the total (4479) NAR (0.76%), 26 NAR temporary palsy (0.58%), and 8 NAR permanent palsy (0.18%). The mean recovery time after temporary VCP ranged between 2-180 days (50.6 days in average). The incidence of permanent RLN injury was higher in surgery conducted by less experienced surgeon (1.71% in less experienced vs. 0.05% in experienced surgeon, odds ratio 35.991, &lt;i&gt;p&lt;/i&gt;&lt;0.001). Application of IONM had no impact on incidence of iatrogenic RLN injury.Conclusion The present study demonstrated that less experienced surgeon is associated with an increased risk of iatrogenic permanent RLN palsy after thyroidectomy.

Intraoperative nerve monitoring in surgery for thyroid cancer

: Surgery for thyroid cancer is multifaceted, especially as it relates to the management of the recurrent laryngeal nerve (RLN). Treatment of recurrent thyroid cancer may require reoperation and entail dissection through scar tissue and distorted anatomy. Intraoperative neuromonitoring (IONM) is a helpful tool in such cases and many other settings. Careful preoperative evaluation is imperative for assessing risk of RLN invasion and has important bearing on patient counseling and informed consent. Whereas anatomic identification of the RLN remains key, IONM adds a functional level of neural assessment. Understanding the dynamics of loss of signal (LOS) is important for determining surgical strategy, especially as it relates to staging of bilateral surgery and avoidance of bilateral vocal cord paralysis (VCP). Neuromonitoring information incorporated with knowledge of preoperative vocal cord function, patient-specific disease information, and surgical findings informs intraoperative decision-making as it relates to management of the invaded RLN. Additionally, IONM plays an important role in mapping and identification of RLN in the settings of revision surgery complicated by scar tissue and distorted anatomy. Optimized application of IONM requires knowledge of appropriate set-up and technique so that errors associated with equipment problems can be avoided. IONM guided decision-making allows a surgeon to optimize both functional and oncologic benefit.

Application of an Intraoperative Neuromonitoring System Using a Surface Pressure Sensor in Parotid Surgery: A Rabbit Model Study.

ObjectivesFacial nerve monitoring (FNM) can be used to identify the facial nerve, to obtain information regarding its course, and to evaluate its status during parotidectomy. However, there has been disagreement regarding the efficacy of FNM in reducing the incidence of facial nerve palsy during parotid surgery. Therefore, instead of using electromyography (EMG) to identify the location and state of the facial nerve, we applied an intraoperative neuromonitoring (IONM) system using a surface pressure sensor to detect facial muscle twitching. The objective of this study was to investigate the feasibility of using the IONM system with a surface pressure sensor to detect facial muscle twitching during parotidectomy.MethodsWe evaluated the stimulus thresholds for the detection of muscle twitching in the orbicularis oris and orbicularis oculi, as well as the amplitude and latency of EMG and the surface pressure sensor in 13 facial nerves of seven rabbits, using the same stimulus intensity.ResultsThe surface pressure sensor detected muscle twitching in the orbicularis oris and orbicularis oculi in response to a stimulation of 0.1 mA in all 13 facial nerves. The stimulus threshold did not differ between the surface pressure sensor and EMG.ConclusionThe application of IONM using a surface pressure sensor during parotidectomy is noninvasive, reliable, and feasible. Therefore, the IONM system with a surface pressure sensor to measure facial muscle twitching may be an alternative to EMG for verifying the status of the facial nerve.

Decreasing the prospect of upper extremity neuropraxia during robotic assisted laparoscopic prostatectomy: a novel technique.

Risk of intraoperative neuropathic injury in minimally invasive surgery has been established as a leading complication. Continuous intraoperative neuromonitoring (IONM), such as upper extremity somatosensory evoked potentials (ueSSEPs), to decrease peripheral nerve injury due to positional stress has been described. Robotic-assisted laparoscopic prostatectomy (RALP) requires steep Trendelenberg, which may predispose patients to upper extremity neuropraxia. Subdermal stimulating electrodes were placed on the patients' bilateral wrists over the ulnar nerve and the nerve was stimulated. Realtime waveforms were compared to baseline data to prevent and detect injury to the ulnar nerve. Established intervention criteria, indicating risk for neuropathic damage necessitating intraoperative patient repositioning, was a 50% loss in amplitude or a 10% increase in latency. One hundred and forty three patients received RALP with IONM. 17 of 143 patients (11.8%) met ueSSEP intervention criteria. Only weight was significantly different between the two groups (p = 0.04). Mean reduction in amplitude was 79.9% (SE 4.1). Average amplitude loss duration was 22min (SE 4.0). Weight and BMI were correlated to the degree of amplitude reduction (p = 0.03 and < 0.01), while operative time and DM approached significance (p = 0.09 and p = 0.14). This is the first study to use IONM to reduce the risk of nerve injury during genitourinary surgery. Realtime nerve monitoring using ueSSEP allowed for upper extremity intraoperative monitoring and repositioning. This may decrease the risk of upper extremity neuropraxia due to malpositioning during RALP. Weight and BMI were identified as risk factors for possible nerve injury. Further data collection and analysis to preoperatively stratify patients for application of IONM during RALP is currently ongoing.

The application of intraoperative neuromonitoring in lateral neck dissections for thyroid cancers

Neck dissections play an essential role in the management of thyroid cancer, it involves resection of the metastatic lymph nodes from levels II to V and often relating to important anatomical structures such as the motor branch of the vagus nerve (VN), spinal accessory nerve (SAN), hypoglossal nerve (HN), mandibular marginal nerve (MMN), phrenic nerve (PN) and brachial plexus (BP). Intraoperative neuromonitoring (IONM) of these motor nerves is relatively rare, however, it offers a potential way of protecting nerve integrity and reducing surgical risks in difficult cases. This review article will introduce the recent progress of IONM of six vulnerable motor nerves in lateral neck dissections (LNDs) for thyroid cancers.

Development of a Novel Intraoperative Neuromonitoring System Using a Surface Pressure Sensor to Detect Muscle Movement: A Rabbit Model Study.

ObjectivesFalse-negative or false-positive responses in intraoperative neuromonitoring (IONM) using electromyography (EMG) in thyroid surgery pose a challenge. Therefore, we developed a novel IONM system that uses a surface pressure sensor instead of EMG to detect muscle twitching. This study aimed to investigate the feasibility and safety of a new IONM system using a piezo-electric surface pressure sensor in an experimental animal model.MethodsWe developed the surface pressure sensor by modifying a commercial piezo-electric sensor. We evaluated the stimulus thresholds to detect muscle movement, as well as the amplitude and latency of the EMG and surface pressure sensor in six sciatic nerves of three rabbits, according to the stimulus intensity.ResultsThe surface pressure sensor detected the muscle movements in response to a 0.1 mA stimulation of all six sciatic nerves. There were no differences in the thresholds of stimulus intensity between the surface pressure sensor and EMG recordings to detect muscle movements.ConclusionIt is possible to measure the change in surface pressure by using a piezo-electric surface pressure sensor instead of EMG to detect muscle movement induced by nerve stimulation. The application of IONM using a piezo-electric surface pressure sensor during surgery is noninvasive, safe, and feasible. Measuring muscle twitching to identify the state of the nerves using the novel IONM system can be an alternative to recording of EMG responses.

Role of intraoperative neuromonitoring of the recurrent laryngeal nerves during thyroid reoperations of recurrent goiter

We retrospectively analyzed the results of thyroid reoperation performed at the Department of Endocrine, General and Vascular Surgery of Medical University of Lodz in the period from January 2014 to June 2016. The study included 80 patients, who were divided into 2 groups: group A consisted of 27 patients, who had undergone surgery with the use of IONM, while group B included 53 patients, in whom RLN was identified visually. During statistical analysis we took into account the number of nerves at risk, not the number of patients. There were 47 nerves at risk In group A and 86 in group B. We analyzed whether application of IONM had any effect on the frequency of RLN palsy and procedure duration. The frequency of RLN palsy was 10.64% (5/47) in group A and 15.12% (13/86) in group B (no statistical significance, p=0,47). Mean operation time was shorter in group B 71.29 ± 17.125 minutes vs. 75.75 ± 17.94 minutes in group A (no statistical significance, p=0,377). Use of IONM did not significantly reduce the occurrence of RLN palsy and procedure duration.

Value of exposure of recurrent laryngeal nerve during high-risk thyroid operation

Objective To study the value of the technique of exposure of recurrent laryngeal nerve (RLN) in preventing RLN injury during high-risk thyroid operation.Methods Three hundred and twentyfive patients subject to high-risk thyroid operation were analyzed retrospectively.The patients were divided into exposure group and un-exposure group according to whether to expose the RLN during operation.RLN injury rate of the two groups was calculated according to the number of involved RLN during operation.The RLN injury rate was compared.The exposure group was divided into auxiliary exposure subgroup and routine exposure subgroup according to whether to use intraoperative neuromonitoring.The RLN injury rate and hospitalization expenses were compared between routine exposure subgroup and auxiliary exposure subgroup.Results The RLN palsy rate in exposure group and un-exposure group was 2.25％ (8/355) and 8.00％ (14/175) respectively,while the temporary RLN palsy rate was 1.97％ (7/355) and 5.14％ (9/175),and the permanent RLN palsy rate was 0.28％ (1/355) and 2.86％ (5/175) respectively.The differences were statistically significant (P ＜ 0.05).Temporary RLN palsy rate and permanent RLN palsy rate in auxiliary exposure subgroup were both lower than in routine exposure subgroup,but there was no significant difference (P ＞ 0.05).There was significant difference in hospitalization expenses between routine exposure subgroup and auxiliary exposure subgroup (P ＜ 0.05).Conclusion Exposure of RLN during high-risk thyroid operation can reduce the RLN injury rate,and application of intraoperative neuromonitoring can not decrease RLN injury rate further. Key words: Thyroid operation; Recurrent laryngeal nerve; Intraoperative neuromonitoring; Recurrent laryngeal nerve injury

Application of intraoperative neuromonitoring in neurosurgical procedures

Objective To explore the feasibility and validity of intraoperative neuromonitoring (IONM) in neurosurgical procedures.Methods 80 patients schedualed for neurosurgical treatment were randomly divided into a study group and a control group,40 for each group.The control group received intraoperative wake-up test,while the study group received IONM.The efficacy of the procedures was assessed postoperatively.Results After surgical treatment,the Karnofsky Performance Scale Index showed 26 patients (65％) scored 80 points or greater,12 (30％)scored,and 2 (5％) scored 50.The study group was superior to the control group in the improvement in postoperative neural function and quality of life (P＜0.05).Conclusions Intraoperative neuromonitoring can accurately detect peripheral nerve function during neurosurgical procedures,effectively locate functional cortex,reduce nerve injuries associated with the procedures,and improve the efficacy of neurosurgical treatment. Key words: Neural function; Neurosurgery procedures; Intraoperative monitoring

Vagus Nerve Neuromonitoring During Carotid Endarterectomy

To determine the causes and site(s) of nerve injury and to identify potential predictors of vocal fold paralysis (VFP) after carotid endarterectomy (CEA) by application of intraoperative neuromonitoring (IONM). A total of 68 CEA patients were enrolled in this study. A 3-step IONM procedure was designed to obtain vocal fold EMG data at V1 (just after identification of the vagus nerve [VN]), V2 (just before arteriotomy), and V3 (just before wound closure). We also performed IONM before/after hemostasis near the VN using bipolar forceps and before/after dissection of the VN. All patients underwent laryngoscopy to assess postoperative VFP. One patient showed loss of EMG signals between V2 and V3 and developed VFP that persisted for 11 months. The other 62 patients had no loss of EMG signals, but 2 patients had confirmed VFP for 1 month after CEA. There were no changes of EMG signal before and after VN dissection or hemostasis with bipolar forceps near the VN.

Does extensive dissection of recurrent laryngeal nerve during thyroid operation increase the risk of nerve injury? Evidence from the application of intraoperative neuromonitoring

Purpose Extensive dissection of recurrent laryngeal nerve (RLN) is inevitable in some complicated thyroid operations. The study aimed to determine whether extensive dissection of RLN increases the risk of nerve injury. Method Three hundred thirty-one patients (506 nerves at risk) who underwent thyroid operations with intraoperative neuromonitoring were included. The study chiefly focused on the 101 RLNs on which extensive nerve dissection from the thoracic inlet to the entry of larynx was performed and for which the nerve exposure was longer than 5 cm. Electromyographic (EMG) signals were obtained from the RLN and vagus nerve before and after complete RLN dissection, and these were defined as R 1, V 1 and R 2, V 2 signals, respectively. The RLN palsy rates and the change of EMG signals were evaluated and analyzed. Results Among 101 nerves with extensive dissection, 13 nerves were due to the operation for recurrent goiter; 41 nerves, for large goiter with substernal extension; and 47 nerves, for thyroid cancer with paratracheal nodal metastasis. No permanent palsy occurred, but 2 nerves experienced loss of EMG signal after complete RLN dissection from a large recurrent goiter and developed temporary palsy. The palsy rates were 2% (2/101) in the extensive dissection group and 2.5% (10/405) in the nonextensive dissection group ( P = .77). Among 99 nerves with normal vocal function after operation, none experienced weakened signal after complete RLN dissection, and the mean amplitudes of R 2 and V 2 signals were not significantly different from those of R 1 and V 1 signals (R 2 vs R 1; 1038 vs 1030 μV; P = .74; V 2 vs V 1; 824 vs 816 μV; P = .75). Conclusions The results of this study suggest that careful surgical dissection is well tolerated by the RLN.

Detecting and identifying nonrecurrent laryngeal nerve with the application of intraoperative neuromonitoring during thyroid and parathyroid operation

Purpose The nonrecurrent laryngeal nerve (NRLN) is a rare anatomical variant but associated with high risk of nerve injury during thyroid and parathyroid operations. Therefore, intraoperative detection and verification of NRLN are necessary. Method A total of 390 consecutive patients who underwent thyroid and parathyroid operations (310 RLNs dissected on the right side and 293 nerves on the left side) were enrolled. Electrically evoked electromyography was recorded from the vocalis muscles via an endotracheal tube with glottis surface recording electrodes. At an early stage of operation, vagal nerve was routinely stimulated at the level of inferior thyroid pole to ensure normal path of RLN. If there is a negative response from lower position but positive response from upper vagal stimulation, it indicates the occurrence of a NRLN, and we localize its separation point and path. Results Four right NRLNs (1.3%) without preoperative recognition were successfully detected at an early stage of operation. Three patients were operated on for thyroid disease, one for parathyroid adenoma and all were associated with right aberrant subclavian artery. All NRLNs were localized and identified precisely with intraoperative neuromonitoring. Functional integrity of all nerves was confirmed by the intraoperative neuromonitoring and postoperative laryngeal examination. Conclusions Vagal stimulation at the early stage of operation is a simple, useful, and reliable procedure to detect and identify the NRLN.

Intraoperative Neuromonitoring for Early Localization and Identification of Recurrent Laryngeal Nerve During Thyroid Surgery

Early and definite identification of the recurrent laryngeal nerve (RLN) is an important step to avoid inadvertent nerve injury during complicated thyroid operations. This study aimed to determine the feasibility of routine use of intraoperative neuromonitoring (IONM) to localize and identify the RLN at an early stage of thyroid surgery. This prospective study enrolled 220 consecutive patients (333 RLNs at risk) who underwent thyroid operations with application of IONM. The RLN was localized and identified routinely with a nerve stimulator after opening the space between the thyroid and carotid sheath. The success rates of early RLN localization and identification were evaluated. The current for localization and the amplitude of evoked laryngeal electromyographic signals were also recorded and analyzed. All RLNs, including 87 (26%) nerves that were regarded as difficult to identify, were successfully localized and identified. The stimulation level for RLN localization was 2mA in 315 nerves (95%) and 3mA in the other 18 nerves (5%). The signal obtained from RLN localization (amplitude = 932 ±436μV) showed a clear and reliable laryngeal electromyographic response that was similar to that from direct vagus (amplitude=811±389μV) or RLN stimulation (amplitude=1132±472μV). The palsy rate was 0.6% and no permanent palsy occurred. RLN injury is rare if the nerve is definitely identified early in the thyroid operation. The conclusion of this study is that IONM is a reliable tool for early RLN localization and identification, even in complicated thyroid operations.

Intraoperative Electrophysiological Monitoring in Spine Surgery

Review of the literature with analysis of pooled data. To assess common intraoperative neuromonitoring (IOM) changes that occur during the course of spinal surgery, potential causes of change, and determine appropriate responses. Further, there will be discussion of appropriate application of IOM, and medical legal aspects. The structured literature review will answer the following questions: What are the various IOM methods currently available for spinal surgery? What are the sensitivities and specificities of each modality for neural element injury? How are the changes in each modality best interpreted? What is the appropriate response to indicated changes? Recommendations will be made as to the interpretation and appropriate response to IOM changes. Total number of abstracts identified and reviewed was 187. Full review was performed on 18 articles. The MEDLINE database was queried using the search terms IOM, spinal surgery, SSEP, wake-up test, MEP, spontaneous and triggered electromyography alone and in various combinations. Abstracts were identified and reviewed. Individual case reports were excluded. Detailed information and data from appropriate articles were assessed and compiled. Ability to achieve IOM baseline data varied from 70% to 98% for somatosensory-evoked potentials (SSEP) and 66% to 100% for motor-evoked potentials (MEP) in absence of neural axis abnormality. Multimodality intraoperative neuromonitoring (MIOM) provided false negatives in 0% to 0.79% of cases, whereas isolated SSEP monitoring alone provided false negative in 0.063% to 2.7% of cases. MIOM provided false positive warning in 0.6% to 1.38% of cases. As spine surgery, and patient comorbidity, becomes increasingly complex, IOM permits more aggressive deformity correction and tumor resection. Combination of SSEP and MEP monitoring provides assessment of entire spinal cord functionality in real time. Spontaneous and triggered electromyography add assessment of nerve roots. The wake-up test can continue to serve as a supplement when needed. MIOM may prove useful in preservation of neurologic function where an alteration of approach is possible. IOM is a valuable tool for optimization of outcome in complex spinal surgery.

The mechanism of recurrent laryngeal nerve injury during thyroid surgery—The application of intraoperative neuromonitoring

Identification of recurrent laryngeal nerve (RLN) has decreased the rates of permanent RLN palsy during thyroid operations; however, unexpected RLN palsy still occurs, even though the visual integrity was assured and most nerve injuries were not recognized intraoperatively. The aim of this study is to determine the causes of RLN palsy and to identify potentially reversible causes of RLN injury during the operation with the application of intraoperative neuromonitoring (IONM). One hundred and thirteen patients with 173 nerves at risk were enrolled in this study. All operations were performed by the same surgeon. The 4-step procedure of IONM was designed to obtain electromagnetic (EMG) signals from the vagus nerve and RLN before and after resection of thyroid lobe. Sixteen nerves had loss of EMG signals after thyroid dissection, and the causes of nerve injuries were well elucidated with the application of IONM. One nerve injury was caused by inadvertent transection, which led to permanent RLN palsy. Among the remaining 15 nerves, 1 injury was caused by a constricting band of connective tissue, which was detected precisely and released intraoperatively, 2 by inadvertent clamping of the nerve, and 12 by apparent overstretching at the region of Berry's ligament. (Five nerves regained signals before closing the wound, but 1 showed impaired cord movement. Another 7 nerves did not regain signals before closing the wound, and all developed temporary RLN palsy.) Our 4-step procedure of IONM is useful and helpful in elucidating the potential operative pitfalls during dissection near the RLN. Although the rates of RLN palsy were not decreased in this study, the use of neuromonitoring provided instructive information for future operations by ascertaining where and how the RLN has been injured.