Nerve Integrity Monitoring Research Articles

Facial Nerve Injury after Extracapsular Dissection for Benign Parotid Tumors with and without Intraoperative Monitoring: A Retrospective Study of a Single Center.

Facial nerve injury (FNI) is the most common complication of parotid surgery and manifests as FN paralysis. The use of intraoperative facial nerve monitoring (IFNM) is becoming an established intraoperative aid for surgeons, assisting in the identification of the location and dissection of the facial nerve trunk or branches. The postoperative outcomes of parotid surgery with and without monitoring have been addressed in only a limited number of studies. The objective of this study is to evaluate the incidence of postoperative paralysis in patients undergoing extracapsular dissection (ED) for benign parotid tumors concerning the use or non-use of IFNM. The retrospective study was conducted at the Maxillo-Facial Department of the Magna Graecia University of Catanzaro. The patients were divided into two groups: Group 1 consisted of patients who underwent surgery without IFNM (1 January 2015 to 31 December 2018); Group 2, on the other hand, consisted of patients who underwent surgery with IFNM (1 January 2019 to 31 December 2022). Group 2 employed the Nerve Integrity Monitor (Medtronic's NIM®). To classify the FN function, we employed the modified House-Brackmann classification system. To evaluate the dependence between the "use of IFNM" and "postoperative paralysis", a descriptive analysis was conducted, including applying the Chi-squared test and calculating the Pearson correlation. Subsequently, a binary logistic regression model was applied to further evaluate the correlation between the latter. The level of statistical significance was set at p < 0.05. A total of 276 patients were included in the study: 120 subjects were assigned to Group 1 (43.5%, comprising 60 men and 60 women) and 156 subjects were assigned to Group 2 (56.5%, comprising 93 men and 63 women). In 91.7% of the cases (n. 253, precisely 105 in Group 1 and 148 in Group 2), no FNI occurred. In 8.33% of the cases (n. 23, specifically 15 in Group 1 and 8 in Group 2), postoperative paralysis was observed. Of these subjects, only two in Group 1 had permanent paralysis (8.69%); therefore, 91.31% had transient paralysis. As a result, 91.31% of the subjects exhibited transient paralysis. In the case of FNI, 78% of the cases involved the marginal mandibular branch (n. 18), 13% involved the temporo-zygomatic branch (n. 3), and 7% involved more than one branch (n = 2). The results of the multivariable binary logistic regression analysis demonstrated that the use of IFNM was a statistically significant influencing factor, with an estimated reduction in postoperative paralysis of approximately 62% (OR 0.378; 95% CI: 0.155-0.92). In Group 2, the occurrence of transient complications was significantly reduced (OR 0.387; 95% CI: 0.149-1.002 with p < 0.05). The use of IFNM in the ED for benign parotid tumors significantly reduces the rate of FNI and, consequently, postoperative FN paralysis. On the other hand, the use of monitoring systems must not replace the experience and anatomical knowledge of the surgeon.

Robot-assisted cervical esophagectomy with simultaneous transhiatal abdominal procedure for thoracic esophageal carcinoma

BackgroundMinimally invasive robot-assisted cervical esophagectomy has been sporadically reported as a novel thoracic esophagectomy technique for patients with thoracic esophageal carcinoma. Most reports indicate that the abdominal component of robot-assisted cervical esophagectomy is performed sequentially after the cervical phase. However, if the cervical and abdominal phases are performed simultaneously using a nerve integrity monitoring system with no administration of muscle relaxants, there are two major advantages: a reduced risk of recurrent nerve palsy and a shorter operative time. We herein report our experience performing novel robot-assisted transcervical esophagectomy with a simultaneous transhiatal abdominal approach using a nerve integrity monitoring system.MethodsThirty cases of robot-assisted cervical esophagectomy performed from 2023 to April 2024 were reviewed. The operative and short-term surgical outcomes of this procedure were compared with those of robot-assisted cervical esophagectomy using a sequential abdominal approach, and the feasibility and efficacy of the simultaneous procedure were analyzed.ResultsAll patients successfully underwent robot-assisted cervical esophagectomy with no intraoperative adverse events. There were no differences in the patients’ demographic or operative data between the two groups. There was no difference in the mean operation time for the cervical procedure (p = 0.23). However, there was a significant difference in the total time for the whole procedure (sequential group: 453.8 ± 26.8 min, simultaneous group: 291.2 ± 36.1 min; p < 0.01). There were no differences in postoperative surgical complications between the groups. There was also no difference in the total number of surgically harvested mediastinal lymph nodes (p = 0.33).ConclusionsRobot-assisted transcervical esophagectomy, a new technique for thoracic esophageal cancer, was safe and feasible under intraoperative management using nerve integrity monitoring without muscle relaxants. This procedure facilitates intraoperative monitoring of recurrent laryngeal nerve activity, significantly shortening the total operative time.

559. SURGICAL PROCEDURE AND CLINICAL OUTCOME OF TRANSMEDIASTINAL ESOPHAGECTOMY FOR ESOPHAGEAL CANCER

Abstract Background We started performing esophagectomy by a laparoscopic transhiatal approach in 2009, and 577 patients had undergone to date. Furthermore, we started performing single-port mediastinoscopic cervical approach in 2014, and developed a technique for total mediastinal lymph node dissection (390 patients). Methods The upper and middle mediastinal lymph node dissection including lymph nodes along the left recurrent laryngeal nerve, using a left cervical approach, was performed with a single-port mediastinoscopic technique. This approach with pneumomediastinum by AirSeal System improved the visibility and handling in the deep mediastinum around the aortic arch. We recently performed intraoperative monitoring of the recurrent laryngeal nerve using Nerve Integrity Monitor system. For dissection of upper and middle mediastinal lymph nodes, the left recurrent laryngeal nerve was sometimes compressed by the shaft of the sealing device or the retractor. We used continuous monitoring with the Automatic Periodic Stimulation electrode for the left recurrent laryngeal nerve, and immediately recognized dangerous procedures. Frequency of recurrent laryngeal nerve palsy was dramatically reduced to half by the introduction of Nerve Integrity Monitor system. Furthermore, to understand the anatomy of bilateral bronchial arteries, we performed 3-dimensional computed tomography angiography preoperatively, which was crucial to avoid intraoperative bleeding. Results The outcome of patients performed transmediastinal radical esophagectomy was compared with those performed the right thoracotomy by using propensity score matching. The operative time, the operative bleeding, and postoperative respiratory complications were significantly decreased by transmediastinal radical esophagectomy. Conclusion Our surgical procedure resulted in a good surgical view, safe en-bloc mediastinal lymph node dissection, and the decrease of postoperative respiratory complications. https://intconferenceservices-my.sharepoint.com/:v:/g/personal/barbarav_icsevents_com/ER9oAGbon3xJvdMGlJ2EUbIBgaq_8XDlKNA-wzVH3-7Hcg?nav=eyJyZWZlcnJhbEluZm8iOnsicmVmZXJyYWxBcHAiOiJPbmVEcml2ZUZvckJ1c2luZXNzIiwicmVmZXJyYWxBcHBQbGF0Zm9ybSI6IldlYiIsInJlZmVycmFsTW9kZSI6InZpZXciLCJyZWZlcnJhbFZpZXciOiJNeUZpbGVzTGlua0NvcHkifX0&amp;e=KbAfDr

Intraoperative cortical stimulation mapping with laryngeal electromyography for the localization of human laryngeal motor cortex.

The objectives of this study were to describe the authors' clinical methodology and outcomes for mapping the laryngeal motor cortex (LMC) and define localization of the LMC in a cohort of neurosurgical patients undergoing intraoperative brain mapping. Because of mapping variability across patients, the authors aimed to define the probabilistic distribution of cortical sites that evoke laryngeal movement, as well as adjacent cortical somatotopic representations for the face (mouth), tongue, and hand. Thirty-six patients underwent left (n = 18) or right (n = 18) craniotomy with asleep motor mapping. For each patient, electromyography (EMG) electrodes were placed in the face, tongue, and hand; a nerve integrity monitor (NIM) endotracheal tube with surface electrodes detected EMG activity from the bilateral vocal folds. After dense cortical stimulation was delivered throughout the sensorimotor cortex, motor responses were then mapped onto a three-dimensional reconstruction of the patient's cortical surfaces for location characterization of the evoked responses. Finally, stimulation sites were transformed into a two-dimensional coordinate system for probabilistic mapping of the stimulation site relative to the central sulcus and sylvian fissure. The authors found that the LMC was predominantly localized to a mid precentral gyrus region, dorsal to face representation and surrounding a transverse sulcus ventral to the hand knob. In 14 of 36 patients, the authors identified additional laryngeal responses located ventral to all orofacial representations, providing evidence for dual LMC representations. The authors determined the probabilistic distribution of the LMC. Cortical stimulation mapping with an NIM endotracheal tube is an easy and effective method for mapping the LMC and is simply integrated into the current neuromonitoring methods for brain mapping.

Intracapsular Enucleation of Brachial Plexus Schwannoma With Intraoperative Neuromonitoring: A Case Series Study and a Review of Literature.

Brachial plexus schwannoma (BPS) is a rare clinical entity that poses a significant challenge for head and neck surgeons due to its neuroanatomical complexity and potential severe complications, such as major motor or sensory neurological deficits or pain of the corresponding upper extremity. This article summarizes our experience in its diagnosis and intracapsular enucleation with intraoperative neuromonitoring (INM). A retrospective review of BPS cases treated at our tertiary medical institution was conducted between April 2020 and May 2023. The clinical and demographic data were retrieved from case notes. Totally, 3 cases were included. All 3 patients were male, aged 43 to 54 years (median age = 52). The presenting symptom was a palpable supraclavicular mass in all these cases (2 on the left side and 1 on the right side). Neuromonitoring was performed with a 4-channel nerve integrity monitor, with the electrodes placed in the upper arm and forearm muscles, as demonstrated in the literature. After exposing the mass and identifying its origin from the brachial plexus, a unipolar stimulating probe was used to stimulate the tumor surface or the nerves with a 1.0-mA current, and a longitudinal incision into the tumor capsule was made along a carefully mapped line with no INM response. Then the mass was carefully exposed and meticulously dissected from its capsule to achieve an intact enucleation. Immediate postoperative neurological deficit was documented in Case 1 as a mild grasping weakness. The recovery of the other 2 patients was uneventful. The follow-up duration was 7 to 38 months (median = 8 months). The minor motor deficit of Case 1 recovered completely 1 month after surgery. No recurrence of BPS was observed. Intracapsular enucleation with INM could result in complete removal of BPS and minimal postoperative neurological deficit, whose recovery was quick and satisfactory.

The Importance of Mapping Vagus and Laryngeal Nerves Monitoring During Thyroid Surgery.

To determine the location of thyroid-related nerves by nerve monitoring and demonstrate the usefulness of Nerve Integrity Monitor in thyroid surgery. Descriptive study. Department of General Surgery, University of Health Sciences, Istanbul Training and Research Hospital, Turkey, from February 2017 to January 2020. Patients, who underwent thyroid surgery, were evaluated for age, gender, preoperative diagnosis, type of surgery, histopathological result, postoperative hoarseness, and postoperative vocal cord examinations. The vagus nerve, recurrent laryngeal nerve (RLN), and superior laryngeal nerve (SLN) were mapped by nerve monitoring. A total of 328 patients were included in this study. On both sides, the vagus nerve was most often located in the posterior of the internal carotid artery and internal jugular vein and less frequently anterior to this vein. A total of 303 right RLNs and 305 left RLNs were verified. The SLN was visualised or motor activity was verified by nerve monitoring on the right side in 181 patients and on the left side in 179 patients. The SLN's location was classified most frequently as type I and least frequently as type IIb on the right and left sides. The reported variations, the experience of the surgeon, and these anatomical markers cannot be adequate in preventing nerve injuries. Furthermore, the variations can be identified more clearly peroperatively with the use of nerve monitoring. Laryngeal nerves, Nerve mapping, Nerve monitoring, Nervus vagus, Thyroid surgery, Zuckerkandl tubercles.

The impact of intraoperative "Nerve Monitoring" in a tertiary referral center for thyroid and parathyroid surgery.

The most fearsome complication in thyroid surgery is the temporary or definitive recurrent laryngeal nerve (RLN) injury. The aim of our study was to evaluate the impact of intraoperative neuromonitoring (IONM) on postoperative outcomes after thyroid and parathyroid surgery. From October 2014 to February 2016, a total of 80 consecutive patients, with high risk of RLN injuries, underwent thyroid and parathyroid surgery. They were divided in two groups (IONM group and control group), depending on whether neuromonitoring was used or not. We used the Nerve Integrity Monitoring System (NIM)-Response 3.0® (Medtronic Xomed®). The operation time (p = 0.014). and the length of hospital stay (LOS) (p = 0.14) were shorter in the IONM group. Overall mean follow-up was 96.7 ± 14.3 months. The rate of transient RLN palsy was 2.6% in IONM group and 2.5% in the control group (p = not significant). Only one case of definitive RLN injury was reported in control group. No differences were reported between the two groups in terms of temporary or definitive RLN injury. Routine use of IOMN increases the surgery cost, but overall, it leads to long-term cost savings thanks to the reduction of both operating times (106.3 ± 38.7 vs 128.1 ± 39.3, p: 0.01) and LOS (3.2 ± 1.5 vs 3.7 ± 1.5 days, p = 0.14). Anatomical visualization of RLN remains the gold standard in thyroid and parathyroid surgery. Nevertheless, IONM is proved to be a valid help without the ambition to replace surgeon's experience.

Association between Intraoperative Nerve Monitoring and the Duration of Thyroid Surgery

Background: Recurrent laryngeal nerve (RLN) injury is one of the serious complications of thyroid surgeries, which has been a topic of medicolegal concern. Although the course of the nerve can vary between patients, RLN visualization has been the gold standard method for identifying the nerve intraoperatively. However, over recent years, intraoperative nerve monitoring (IONM) has gained more acceptance and has been standardized and utilized, in addition to visual nerve identification, in many thyroids and parathyroid surgery centers. In this study, we aim to determine the association between the use of nerve integrity monitoring systems and the duration of thyroid surgery. Materials and Methods: This is a retrospective chart review, conducted at hospital in Jeddah, Saudi Arabia. We included all patients who underwent thyroid surgery during the period between 2014 and 2019, with no exclusion criteria. We studied variables including duration of surgery, preoperative assessment, diagnosis, surgical procedure, use of IONM, and comorbidities. Results: A total of 236 patients were included, of which 69 (29.2%) cases used IONM. The mean duration of all surgeries was 179.95 ± 96.9 min, whereas the mean duration of surgeries using IONM only was 214.39 min, compared to 165.72 min of surgeries without IONM, which reveals a statistically significant association between the use of nerve monitoring and an increase in the duration of surgery (P ≤0.002). Conclusion: IONM utilization in thyroid surgeries was associated with a longer duration of surgery. However, more studies are required to support this result.

Comparative Effectiveness of Recurrent Laryngeal Nerve Monitoring Techniques in Pediatric Surgery.

The recurrent laryngeal nerve (RLN) is at risk during pediatric cervical, thoracic, and cardiac surgery. We aim to determine the feasibility and effectiveness of RLN monitoring techniques in all pediatric patients. Retrospective case series. Retrospective review of patients/procedures with RLN(s) at risk and RLN monitoring at Boston Children's Hospital July 2019-October 2020. pre/postoperative vocal fold mobility by awake flexible fiberoptic laryngoscopy (FFL). One hundred one patients (median [interquartile range, IQR] age 14.6 months [4.6-49.7 months], weight 10 kg [5.2-16.2 kg]) underwent 122 procedures with RLN(s) at risk. RLN monitoring attempted 111 cases, successful 96 (84%). Surgical indications: esophageal atresia/tracheoesophageal fistula, and tracheobronchomalacia. Sixty-two (56%) procedures in reoperative field. Median follow-up 112 days (IQR 41-230). Pre/postoperative FFL performed 84 procedures (69%), 19 new postoperative RLN injuries (16%), median age 12 months, reoperative fields 11 (18%). Prass probes: 34 cases (28 successful, 82%), 6 injuries (18%), age 12.2 (5.8-23.6) months. Dragonfly electrodes: 45 cases (37 successful, 82%), 8 injuries (18%), age 7.5 (3.8-19) months. Nerve integrity monitoring (NIM) integrated electrode endotracheal tube: 33 cases (33 successful, 100%), 5 injuries (15%), age 90 (58.8-136.7) months. Automatic periodic stimulation (APS): 16 cases, 13 successful (81%), four injuries (25%), age 7.2 (5.3-20.6) months. NIM RLN monitoring is significantly more successful than Prass, Dragonfly (95%CI -0.3 to 0.02, P=.02; and 95%CI 0.05-0.31, P=.008). Rates of injury are not different between types of RLN monitoring (P=.94), with APS use (P=.47), or with monitoring success (95%CI -0.36 to 0.09, P=.28). RLN monitoring is feasible in pediatric patients of all ages. Although NIM type RLN monitoring success is superior, all forms offer similar rates of nerve protection. 3 Laryngoscope, 132:889-894, 2022.

A new technique useful for lumbosacral percutaneous pedicle screw placement without fluoroscopy or computer-aided navigation systems

BackgroundPercutaneous pedicle screw (PPS) placements in the lumbosacral spine generally rely on fluoroscopy at the expense of radiation exposure. Our accumulated experience in open PS placements without fluoroscopic guidance realized a consistent shift toward PPS insertion with newly developed devices, which require neither fluoroscopy nor navigation. We wish to report our new technique and evaluations of its accuracy. MethodsOur equipment consisted of a pedicle targeting tool to identify and escort the cannulated awl to the correct starting point for cortical bone perforation and a cannulated awl-probe system with a guidewire to maintain the optimal position throughout the subsequent surgical steps. The surgeon could advance the blunt-tipped probe searching for the cancellous bone track using tactile feedback as experienced in open techniques. A 2-year period of transition from a free-hand (1169 screws in 286 patients) to the new PPS technique (1933 screws in 413 patients) allowed accuracy comparison between the two procedures using postoperative CT scans. ResultsCompared with the open-group, the PPS-group showed a lower rate of fully contained intrapedicular PS placements at L1 through S1, as a whole (90.7% vs 85.4%), but not at L4 through S1 (89.9% vs 90.2%). Less-accurate PPS placements at upper than lower lumbar spines in part reflect intended pedicle perforations laterally as a trade-off for avoiding facet violation immediately above the most cephalad screw. The PPS-group also had a higher incidence of PS-related transient nerve root complications (0% vs 1.7%). These values for the PPS-group, however, fell within those previously reported for free-hand or fluoroscopy techniques. ConclusionsOur new PPS technique, although useful for eliminating the potential risk of repeated radiation exposure, fell short of reaching the accuracy of the free-hand technique. Nerve integrity monitoring with PS stimulation, which we currently use, will help further improve the technical precision. Study designOriginal Article. The study was approved by our institutional review boad (2,019,231).

Use of GlideScope in Patients Undergoing NIM Thyroidectomy.

Thyroidectomy and parathyroidectomy using the nerve integrity monitor (NIM) require proper placement of the endotracheal tube with electrodes aligned correctly within the larynx. The purpose of this study is to determine the percentage of patients who require positional adjustments of the endotracheal tube prior to beginning surgery and to understand the value of using the GlideScope to assure proper NIM tube placement within the larynx. This prospective study examines operative data from 297 patients who underwent NIM thyroidectomy and parathyroidectomy. After routine orotracheal intubation by an anesthesiologist and positioning of the patient for surgery, a GlideScope was used to check the position of the tube in 2 planes: depth of tube placement and rotation of the tube within the larynx assuring proper placement of the electromyogram electrodes within the glottis. Tube adjustment was required for 66.5% of patients. In 48.1% of cases, tube retraction or advancement to a proper depth was needed. Tube rotation was required for 30.1% of patients, and 11.8% of patients required both adjustment of tube depth and tube rotation to properly align electrodes. After the anesthesiologist places the NIM endotracheal tube, and the patient is positioned for surgery, additional tube adjustment is often needed prior to the start of surgery. The GlideScope is readily available in the operating suite, its use adds little time to the procedure, and assures proper NIM tube placement. The use of the GlideScope is recommended.

Surgeon-performed ultrasound analysis of the status of the vocal cords of post-thyroidectomy patients with intraoperative neuromonitoring in a tertiary referral center

Objectives: Recurrent laryngeal nerve (RLN) palsy constitutes one of the dreaded complications of thyroid surgery. Sequelae of RLN injury may affect quality of life and can sometimes be life threatening. Pre-, intra-, and post- operative monitoring of the RLN is desirable for safe thyroid surgery. Surgeon-performed transcutaneous laryngeal ultrasound (TLUS) may become a substitute for laryngoscopy in the evaluation of vocal cords after thyroidectomy and may be used for prognostic correlation of intraoperative neurophysiologic monitoring (IONM). In this study, a retrospective cohort of patients who underwent thyroidectomy with monitoring of the RLN by intermittent IONM (I-IONM) was subjected to post-operative ultrasound assessment of vocal cords for the evaluation of RLN integrity. Material and Methods: This was a prospective study of a retrospective cohort in a tertiary care endocrine surgery unit. Fifty-six patients who underwent thyroidectomy with RLN monitoring from March 2017 to March 2019 were analyzed. Patients were analyzed during follow-up either when they arrived at the endocrine surgery outpatient department or through a telephone call. All patients underwent pre-operative laryngoscopy, intraoperative monitoring with I-IONM and Nerve Integrity Monitor 3.0 monitor, and post-operative TLUS evaluation of vocal cords. Results: Of the 56 patients evaluated in this study, 112 vocal cords and 102 nerves at risk were analyzed. The incidence of vocal palsy was 7.84%. The sensitivity of ultrasonography for vocal cord analysis was 85%, specificity was 95.23%, positive predictive value was 85%, and negative predictive value was 95.23% in that series. The vocal cord visualization rate was 93.5%. Conclusion: Surgeon-performed ultrasound may be used to assess RLN integrity in post-thyroidectomy patients to enhance post-operative care.

Endoscopy-assisted transoral resection of a parapharyngeal space schwannoma without mandibular dissection

Of the schwannomas that arise from the parapharyngeal space, those in the high cervical region are particularly invasive, requiring mandibular dissection. Because these tumors are benign, however, excessive surgical invasion and postoperative neurological complications should be avoided. Postoperative dropout symptoms may be avoided by intracapsular extraction, including nerve integrity monitoring (NIM) and narrow-band imaging (NBI). Video laryngoscopy surgery is reported to be useful for transoral resection of pharyngeal and laryngeal tumors. This report describes the transoral removal of a giant schwannoma located in the high cervical region from a 74-years-old man using a surgical support device without mandibular dissection.The tumor was located on the right lateral pharyngeal wall and extended from the upper oropharynx to the hypopharynx while compressing the epiglottis to the skull base. No separation was observed between the internal jugular vein and the internal carotid artery. The tumor was diagnosed as a schwannoma with no malignancy on the basis of the histology of a core needle biopsy (CNB), and was completely and safely removed endoscopically using NIM and NBI, with no need for an external incision or mandibular dissection. This case illustrates that even a huge sympathetic schwannoma located in the parapharyngeal space at a high cervical position can be excised transorally using video-laryngoscopic surgery (TOVS) without mandibular dissection.

Reducing the morbidity of parotidectomy for benign pathology.

Conservative surgical approaches, reconstructive techniques and technology are increasingly used in parotid surgery. The aim of this study was to determine the surgeon-modifiable factors which impact the rates of post-operative complications following parotidectomy for benign pathology. A retrospective cohort study of patients undergoing parotidectomy for benign pathology by or under the supervision of the senior author between 2006 and 2019 was performed. Clinicopathological variables, operative techniques and post-operative complications were recorded using standardized templates. Multivariable logistic regression models were used to obtain odds ratios (ORs) whilst adjusting for the effect of other clinically relevant covariates. In total, 357 parotidectomies were performed. Independent factors associated with post-operative facial paresis were re-operative surgery (OR 3.51, 95% CI 1.19-10.33, P = 0.023), nerve integrity monitoring (OR 0.50, 95% CI 0.26-0.99, P = 0.046) and operation type, with focused tumour dissection (FTD) having the lowest rate of paresis (OR 0.19, 95% CI 0.040-0.92, P = 0.038) compared to limited parotidectomy. Factors associated with reduced wound complications on adjusted analysis were dermofat grafting (OR 0.10, 95% CI 0.01-0.72, P = 0.023), lesion size (OR 0.68, 95% CI 0.50-0.92, P = 0.01) and FTD (OR 0.16, 95% CI 0.05-0.59, P = 0.005) compared to limited parotidectomy. FTD, nerve integrity monitoring and dermofat grafting are surgeon-modifiable variables associated with lower rates of post-operative complications following parotidectomy for benign pathology. However, the benefit of these operative techniques relies on their appropriate utilization by performing surgeons.

Contralateral Tongue Muscle Activation during Hypoglossal Nerve Stimulation.

The effectiveness of upper airway stimulation via hypoglossal nerve stimulation for obstructive sleep apnea depends upon the pattern of tongue muscle activation produced. This study investigated the nature of contralateral tongue muscle activation by unilateral hypoglossal nerve stimulation using intraoperative nerve integrity monitoring in conjunction with electromyography and explored the relationship between contralateral tongue muscle activation and polysomnographic measures of obstructive sleep apnea severity. Prospective case series. Tertiary care medical center. Fifty-one patients underwent unilateral (right) hypoglossal nerve stimulator implantation for obstructive sleep apnea. Neurophysiological data included electromyographic responses in ipsilateral (right) and contralateral (left) genioglossus muscles in response to intraoperative bipolar probe stimulation (0.3 mA) of medial hypoglossal nerve branches. Clinical data included pre- and postoperative apnea-hypopnea indices and oxygen desaturation levels. A subset of patients (20/51, 39%) exhibited electromyographic responses in both the ipsilateral and contralateral genioglossus (bilateral), whereas the remaining patients (31/51, 61%) exhibited electromyographic responses only in the ipsilateral genioglossus (unilateral). The baseline characteristics of bilateral and unilateral responders were similar. Both groups exhibited significant and comparable improvements in apnea-hypopnea index and oxygen desaturations after hypoglossal nerve stimulation. Neither the amplitude nor the latency of contralateral genioglossus responses was predictive of clinical outcomes. A subset of patients undergoing unilateral hypoglossal nerve stimulation exhibits activation of contralateral genioglossus muscles. Patients with unilateral and bilateral genioglossus responses exhibit comparable, robust improvements in apnea-hypopnea index and oxygen desaturation levels.

Nerve Integrity Monitor Responses to Direct Facial Nerve Stimulation During Facial Nerve Decompression Surgery Can Predict Postoperative Outcomes.

To test whether the threshold of nerve integrity monitor (NIM) responses during facial nerve decompression surgery can predict the postoperative outcome. Retrospective study. University hospital. Twenty peripheral facial palsy patients who underwent transmastoid decompression surgery. During decompression surgery, thresholds of NIM responses were measured via direct facial nerve stimulation at three sites: the geniculate ganglion (GG), the second genu (2 G), and the stylomastoid foramen. Facial nerve function was evaluated before and 6 months after surgery using the Yanagihara grading score (maximum score = 40 points). Complete recovery was defined as an improvement of the grading score to ≥ 36 points without synkinesis. Variables including age, sex, disease (Bell's palsy or Ramsay Hunt syndrome), time after onset, Yanagihara grading score, and electroneurography before surgery, and the thresholds of NIM responses during surgery were compared in the complete and incomplete recovery groups. NIM responders were defined as those exhibiting a NIM response of < 1.5 mA at any site. Postoperative Yanagihara grading scores in NIM responders and NIM nonresponders were compared. No variables differed significantly in the complete and incomplete recovery groups before surgery. NIM response thresholds in the complete recovery group at the GG and the 2nd G were significantly lower than the corresponding thresholds in the incomplete recovery group. The postoperative Yanagihara grading scores of NIM responders were significantly better than those of NIM nonresponders. NIM responses to intraoperative direct facial nerve stimulation were useful for predicting outcomes after decompression surgery.

Neurophysiological monitoring of tongue muscle activation during hypoglossal nerve stimulation.

Upper airway stimulation for obstructive sleep apnea (OSA) via implantable hypoglossal nerve stimulation (HGNS) reduces airway obstruction by selectively stimulating nerve fibers that innervate muscles that produce tongue protrusion, while avoiding fibers that produce tongue retraction. This selective stimulation likely depends upon the location, intensity, and type of electrical stimulation delivered. This study investigates the impact of changing stimulation parameters on tongue muscle activation during HGNS using intraoperative nerve integrity monitoring in conjunction with electromyography (EMG). Prospective case series. Ten patients undergoing unilateral HGNS implantation for OSA in a university hospital setting were studied. Data included EMG responses in tongue muscles that produce protrusion (genioglossus), retraction (styloglossus/hyoglossus), and stiffening (transverse/vertical) in response to intraoperative bipolar probe electrical stimulation of lateral and medial branches of the hypoglossal nerve (HGN) and to implantable pulse generator (IPG) unipolar and bipolar settings after placement of the stimulation cuff. Stimulation of medial division HGN branches resulted in EMG responses in genioglossus muscles, but not in styloglossus/hyoglossus muscles, whereas stimulation of the lateral division HGN branches drove responses in styloglossus/hyoglossus muscles. Variable responses in transverse/vertical muscles were observed with stimulation of lateral and medial division branches. After electrode cuff placement, unipolar and bipolar HGN stimulation configurations of IPG resulted in unique patterns of muscle activation. The relative activation of extrinsic and intrinsic tongue musculature by HGNS is determined by stimulus location, intensity, and type. Intraoperative neurophysiological monitoring of tongue muscle activation enables proper electrode cuff placement and may provide essential data for stimulus optimization. 4 Laryngoscope, 130:1836-1843, 2020.

The Dual-Path Nerve Integrity Monitor Method for Protection of the External Branch of the Superior Laryngeal Nerve During Thyroid Surgery

Abstract Introduction: This video illustrates a case report using our novel dual-path nerve integrity monitor (NIM) method for protection of the external branch of the superior laryngeal nerve (EBS...

Microsurgical Resection of a Ventral Pontine Cavernoma via Supratrigeminal Zone by Anterior Transpetrosal Approach: 2-Dimensional Operative Video.

Brainstem cavernomas with recurrent bleeding and gradual neurological deterioration should be considered an indication for surgical treatment. However, surgery is challenging for cavernous hemangiomas located in the ventral part of the pons. In such cases, safe surgical access to the brainstem is limited and obtaining a good surgical field, regardless of the approach selected, is often difficult. Here, we show a 73-year-old man with a history of 3 episodes of intracranial bleeding associated with a cavernous hemangioma located in the right ventral pons. The hemangioma was removed via the supratrigeminal zone of the brainstem using an anterior transpetrosal approach (ATPA). ATPA was first described in 1985 for upper petroclival lesions by Kawase T.1 This approach requires epidural subtemporal procedures to expose the petrous apex adequately. The petrous apex must be totally resected and the dura of the temporal lobe and posterior fossa is then cut to ligate the superior petrosal sinus and tentorium. In this procedure, the most important things are to preserve the internal carotid artery (C2 segment) and greater superficial petrosal nerve (GSPN). To identify the GSPN, facial nerve integrity monitor (Medtronic Inc, Dublin, Ireland) is very useful. In the extradural bone removal, Sonopet Ultrasonic Aspirator (Stryker Ltd, Portage, Michigan) is a very excellent surgical tool for avoiding the injury of the internal carotid artery. As demonstrated by Cavalcanti DD2, ATPA is particularly useful for accessing lesions located in the upper ventral pons via the supratrigeminal zone because it provides a wide and shallow surgical field above the trigeminal nerve without requiring retraction of the cerebellum. We received written informed consent from the patient for this publication.

Comparative Analysis of Phase Lag Entropy and Bispectral Index as Anesthetic Depth Indicators in Patients Undergoing Thyroid Surgery with Nerve Integrity Monitoring

BackgroundMost depth of anesthesia (DOA) monitors rely on the temporal characteristics of a single-channel electroencephalogram (EEG) and cannot provide spatial or connectivity information. Phase lag entropy (PLE) reflects DOA by calculating diverse connectivity from temporal patterns of phase relationships. The aim of this study was to compare the performance of PLE and bispectral index (BIS) monitors for assessing DOA during anesthesia induction, nerve integrity monitoring (NIM), and anesthesia emergence.MethodsThirty-five patients undergoing elective thyroid surgery with recurrent laryngeal nerve NIM received propofol and remifentanil via target-controlled infusion. After applying PLE and BIS monitors, propofol infusion was initiated at a calculated effect site concentration (Ce) of 2 µg/mL and then increased in 1-µg/mL Ce increments. After propofol Ce reached 5 μg/mL, a remifentanil infusion was begun, and anesthesia induction was considered complete. During NIM, PLE and BIS values were compared at a specific time points from platysma muscle exposure to subcutaneous tissue closure. PLE and BIS values were recorded continuously from preanesthetic state to full recovery of orientation; bias and limits of agreement between monitors were calculated.ResultsPLE and BIS values decreased progressively with increasing propofol Ce during anesthetic induction and increased by stages during emergence. The prediction probabilities of PLE and BIS for detecting propofol Ce changes were 0.750 and 0.756, respectively, during induction and 0.749 and 0.746, respectively, during emergence. No aberrant PLE or BIS values occurred during NIM. Correlation coefficients for BIS and PLE were 0.98 and 0.92 during induction and emergence, respectively. PLE values were significantly higher than BIS values at full recovery of orientation. Estimated bias between monitors was −4.16 ± 8.7, and 95% limits of agreement were −21.21 to 12.89.ConclusionPLE is a reasonable alternative to BIS for evaluating consciousness and DOA during general anesthesia and during NIM.Trial RegistrationClinical Research Information Service Identifier: KCT0003490