Electrophysiological Neuromonitoring Research Articles

Large Pontine Cavernoma Operated by Anterior Petrosal Approach-Two-Dimensional Operative Video.

Brainstem cavernoma is a challenging neurosurgical pathology and microsurgery remains the only treatment option. Although the decision-making between interventional and conservative approach to this disease may be complex, malformations presenting multiple bleedings are usually good candidates for surgery. 1 On the other hand, microsurgical resection of cavernomas can offer an effective resolution with acceptable morbidity. In this video, we present a case of pontine cavernoma with multiple hemorrhages in a young patient. The anatomical characteristic of the lesion defines the best suitable craniotomy for surgery. In this case, an anterior petrosal approach 2 3 4 was used to access the peritrigeminal area and safely perform the resection. Anatomical considerations are described on this skull base approach along with the rationale and benefits of this exposure. Electrophysiological neuromonitoring is essential for this kind of procedure and preoperative tractography also enabled the best understanding of the disease. Finally, we also discuss alternative managements and potential complications. 5 With the patient's consent, we also show the excellent clinical evolution after few weeks of recovery and the restoration of the corticospinal tract, previously displaced by the cavernoma, to its original position.

Risk for Additional Infarction in Emergency Carotid Artery Endarterectomy in Thrombectomy Acute Stroke Patients.

Purpose: Thromboembolic occlusion of the middle cerebral artery with tandem occlusion of the internal carotid artery is a life-threatening condition with unfavorable neurological outcome. We perform emergency carotid endarterectomy in the same anesthesia session as thrombectomy in our angiography suite whenever needed despite the absence of electrophysiological neuromonitoring. Methods: We evaluated 47 thrombectomy patients with emergency CEA in our clinic between June 2013 and November 2020. To determine whether there were additional infarctions due to the surgical procedure, we assessed the initial diagnostic CT imaging for previously infarcted areas, cerebral perfusion, and vascular anatomy, including collateralization in the Circle of Willis (CoW). We then analyzed follow-up imaging with respect to new infarctions that could not be explained by the initial stroke. Results: 5 of 47 (11%) patients had a complete CoW. There was contralateral internal carotid artery (ICA) stenosis or occlusion in 18/47 (38%) patients. Surgical procedure was eversion CEA in 34 (72%) and with a patch graft CEA in 13 (28%) cases. Shunts were used during surgery in 17/47 (36%) patients. Two patients suffered from an additional infarction in a new territory, however this was not caused by the surgical procedure but due to embolism during endovascular thrombectomy. In 1 of these 2 patients a hemodynamic border zone infarction was also observed, which could have developed during thrombectomy as well as during surgery, although this could not be attributed with absolute certainty to the surgery. The final infarction size was significantly larger in patients with contralateral ICA stenosis or occlusion (P = .038). Neither CoW anatomy nor the absence of a shunt during surgery could be identified as risk factors for additional infarction. Conclusion: Emergency surgery in the angiography suite without neuromonitoring was not associated with an increased additional stroke rate in our patient cohort.

Brainstem Pilocytic Astrocytoma, a Surgical Disease: 2-Dimensional Operative Video.

Brainstem pilocytic astrocytomas are benign lesions that frequently develop in the medulla with an often exophytic component.1-3 These lesions develop in children and young adults and are revealed by lower cranial nerves dysfunction and long tracts involvement. Medulla pilocytic astrocytomas have a better overall prognosis than pontine and midbrain lesions, particularly after surgical resection, which can be curative, allowing the control of the disease and avoiding adjuvant treatments in young patients.2-5 The transcondylar approach with mobilization of the vertebral artery offers the necessary ventral exposure for the resection of such medulla oblongata lesions.6 After exposure, the initial step of resection starts with the cerebellopontine angle occupying exophytic portion after identification of cerebrovascular landmarks. Ultrasonic aspiration on a low setting allows to progressively debulk the tumor and identify the normal medulla tissue while closely following the electrophysiological neuromonitoring. Preservation of the small medulla perforators is the key for successful resection, including minimal use of bipolar coagulation in the vicinity of brainstem tissue. We demonstrate these principles through the case of a 33-year-old woman presenting with a large left medulla oblongata exophytic tumor, with an MRI presentation consistent with pilocytic astrocytoma. The patient consented to the procedure and publication of her images.

Endoscopic-Assisted Resection of Anterior Foramen Magnum Meningiomas through a Midline Suboccipital Subtonsillar Approach.

Objective This study was aimed to demonstrate the resection of anterior foramen magnum meningiomas through an endoscopic-assisted posterior midline suboccipital subtonsillar approach. Design This study was designed with illustration of the surgical steps and safety of this approach. Setting Evidence of cerebrospinal fluid (CSF) cleft between the tumor and brainstem on MRI was studied ( Fig. 1A and B ). Preoperative tracheotomy was considered in cases of preoperative dysphagia to prevent any further neurological deterioration due to the bilateral access through the lower cranial nerves corridors. Semisitting position with extensive electrophysiological neuromonitoring and transesophageal echocardiogram was adopted. A standard midline incision with bilateral suboccipital craniotomy and C1-laminotomy was performed ( Fig. 2A ). After partial resection and elevation of the tonsils, tumor was debulked unilaterally around the lower cranial nerves and the vertebral artery, devascularized from the clival dura and then dissected from the brainstem ( Fig. 2B, C ). Endoscopic-assisted removal of its anterior portion followed. The same procedure was repeated from the opposite site for the contralateral portion, before approaching the purely anterior part with endoscope assistance ( Fig. 2D ). Participants Four consecutive patients were included in the study. Main Outcome Measures Grade of tumor resection and outcome (mRS) were primary measurement of this study. Results Clinical outcome and grade of resection are comparable to other series of patient treated with other foramen magnum approaches ( Fig. 1C and D ). Conclusion Anterior foramen magnum meningiomas can be safely removed through this relatively faster midline suboccipital approach with bilateral exposure of lower cranial nerves (CNs) and vertebral arteries and lower approach-related morbidity (no condyle drilling). The surgical corridor is created by the tumor during debulking reducing need for brain retraction and the removal of the anterior dural attachment coagulated under the microscope is verified and completed endoscopically with pituitary curettes (Simpson's grade II) ( Fig. 1C and D ). The link to the video can be found at: https://youtu.be/9eACAJVwQBs .

Using Heart Rate Variability Monitoring for Dexmedetomidine Dosing in Neurointensive Care Patients

Aim: to validate the use of heart rate variability monitoring during dexmedetomidine administration in patients with brain injury of various etiologies.Material and methods. The study included 25 patients (14 male, 11 female, mean age 58.2±1.81 years) 20 and more days after traumatic brain injury (TBI) (n=9; 36%), acute stroke (n=4; 16%), anoxic brain injury (n=6; 24%), subarachnoid hemorrhage (SAH) (n=6; 24%). Dexmedetomidine was prescribed because of sympathetic hyperactivity as diagnosed by heart rate variability (HRV). The following indices were measured: SI (stress index, in normalized units [nu]), SDNN (standard deviation of all normal sinus RR intervals over 24 h, in ms), RMSSD (root-mean-square of successive normal sinus RR interval difference, in ms), pNN 50% (the percentage of successive normal sinus RR intervals >50 ms), TP (total power of the frequency spectrum, in ms2). HRV parameters were determined prior to dexmedetomidine infusion (baseline), on days 1–3, 4–5, 9–10, 15–20 of drug administration. Sympathetic hyperactivity was diagnosed by determining following values: SDNN < 13.31 ms, RMSSD < 5.78 ms, pNN 50% < 0.110%, SI > 900 nu, and TP < 200 ms2. Normal reference ranges for HRV parameters were as follows: SDNN (13.31–41.4 ms), RMSSD (5.78–42.3 ms), pNN5 0% (0.110–8.1%), SI (80–900 nu), and TP (200–2000 ms2).Results. The starting dose of dexmedetomidine for sympathetic hyperactivity was 0.12–0.24 µg/kg/hr (mean dose 0.16±0.01; total 200 µg/day). According to digital HRV data, the effective dose ED50 of dexmedetomidine was 0.26±0.03 µg/kg/hour (353.8±35.1 µg total per day) that was achieved on day 9–10 of drug administration.Conclusion. Electrophysiological neuromonitoring of the autonomic nervous system function increases the efficacy of dexmedetomidine administration in patients with brain injury of various etiologies.

Interdisciplinary Laparoscopic Implantation of Neuromodulation Leads to the Sacral Plexus for Therapy of Chronic Pelvic Pain and Neurogenic Bladder Dysfunctions

The aim of this study was to report on the use of laparoscopic implantation of leads on the branches of the sacral plexus for neuromodulation in the treatment of chronic pelvic pain (CPP) in a multidisciplinary setting with the help of electrophysiological neuromonitoring. Between 2012 and 2019, six female patients complaining of chronic pain and bladder and bowel dysfunctions underwent laparoscopic exposure and nerve identification with the help of electrophysiological neuromonitoring. A lead was placed laparoscopically in direct contact with the affected nerve. Pain intensity (numerous ranking scale [NRS]), generic health status (EQ-5D-5L), Becks Depressions Inventory (BDI-V), Pain Catastrophizing Scale (PCS), and Client Satisfaction Questionnaire (CSQ-8) were assessed pre-/postoperatively as well as three and six months after surgery. Statistical analysis was performed using Mann-Whitney U and Wilcoxon rank-sum test. The median age was 36.5 years. NRS improved from a median of 9.5 preoperatively to 3.0 (p < 0.001) at six-month follow-up. Median EQ-5D-5L index value before treatment was 0.18, indicating a notably lowered quality of life and increased up to 0.83 after six months (p < 0.001). Preoperative median BDI-V scores indicated a major depressive mood and improved from a median of 46.0 to 12.0 after six months (p = 0.007). Preoperative PCS was elevated with a median score of 41.0 and decreased to 4.0 after six months (p < 0.001). CSQ showed that patients were satisfied with the treatment. This unique method is an alternative and effective treatment option for CPP even years after primary endometriosis surgery.

Anesthesia Management for Electrophysiological Neuromonitoring in a Patient of a Spinal Tumor Excision at Lumbar Level: A Case Report

Anesthesia Management for Electrophysiological Neuromonitoring in a Patient of a Spinal Tumor Excision at Lumbar Level: A Case Report

P17-F Intraoperative electrophysiological neuro-monitoring in neurosurgery: Preliminary experience, pitfalls, theoretical and practical limitations

P17-F Intraoperative electrophysiological neuro-monitoring in neurosurgery: Preliminary experience, pitfalls, theoretical and practical limitations

Diagnostic and therapeutic values of intraoperative electrophysiological neuromonitoring during resection of intradural extramedullary spinal tumors: a single-center retrospective cohort and meta-analysis.

With the advent of intraoperative electrophysiological neuromonitoring (IONM), surgical outcomes of various neurosurgical pathologies, such as brain tumors and spinal deformities, have improved. However, its diagnostic and therapeutic value in resecting intradural extramedullary (ID-EM) spinal tumors has not been well documented in the literature. The objective of this study was to summarize the clinical results of IONM in patients with ID-EM spinal tumors. A retrospective patient database review identified 103 patients with ID-EM spinal tumors who underwent tumor resection with IONM (motor evoked potentials, somatosensory evoked potentials, and free-running electromyography) from January 2010 to December 2015. Patients were classified as those without any new neurological deficits at the 6-month follow-up (group A; n = 86) and those with new deficits (group B; n = 17). Baseline characteristics, clinical outcomes, and IONM findings were collected and statistically analyzed. In addition, a meta-analysis in compliance with the PRISMA guidelines was performed to estimate the overall pooled diagnostic accuracy of IONM in ID-EM spinal tumor resection. No intergroup differences were discovered between the groups regarding baseline characteristics and operative data. In multivariate analysis, significant IONM changes (p < 0.001) and tumor location (thoracic vs others, p = 0.018) were associated with new neurological deficits at the 6-month follow-up. In predicting these changes, IONM yielded a sensitivity of 82.4% (14/17), specificity of 90.7% (78/86), positive predictive value (PPV) of 63.6% (14/22), negative predictive value (NPV) of 96.3% (78/81), and area under the curve (AUC) of 0.893. The diagnostic value slightly decreased in patients with schwannomas (AUC = 0.875) and thoracic tumors (AUC = 0.842). Among 81 patients who did not demonstrate significant IONM changes at the end of surgery, 19 patients (23.5%) exhibited temporary intraoperative exacerbation of IONM signals, which were recovered by interruption of surgical maneuvers; none of these patients developed new neurological deficits postoperatively. Including the present study, 5 articles encompassing 323 patients were eligible for this meta-analysis, and the overall pooled diagnostic value of IONM was a sensitivity of 77.9%, a specificity of 91.1%, PPV of 56.7%, and NPV of 95.7%. IONM for the resection of ID-EM spinal tumors is a reasonable modality to predict new postoperative neurological deficits at the 6-month follow-up. Future prospective studies are warranted to further elucidate its diagnostic and therapeutic utility.

ESTIMATING THE EFFECTIVENESS OF SURGICAL TREATMENT OF CHILDREN WITH THRYOID NEOPLASMS

Aim. To estimate the effectiveness of the developed design of perioperative examination of patients and surgery of children and adolescents with thyroid neoplasms.Materials and methods. The data of surgical treatment and perioperative control of 70 patients’ condition from 2012 to July 2017 were presented. The features of perioperative control included prevention of postoperative hypoparathrosis, use of ACR TI-RADS system to interpret the thyroid ultrasound findings as the first line diagnosis of a malignant neoplasm and intraoperative electrophysiological neuromonitoring of the laryngeal nerves. The follow-up was 1 to 56 months. The quality of life was estimated using a questionnaire.Results. The basic risk factors of an intraoperative injury to the recurrent laryngeal nerve, postoperative hypocalcemia and hypoparathyrosis were found during the study. The disease duration and aggressive course and a number of surgeries in a patient significantly decrease their life quality (p&lt;0.05).Conclusions. Comparison of quality of life indicators before and after a surgery and popula tion indicators of healthy adolescents revealed the advantage of using the developed scheme of perioperative control of surgical treatment of thyroid neoplasms in children and adolescents.

T142. Intraoperative electrophysiological neuro-monitoring in neurosurgery: Preliminary experience, pitfalls, theoretical and practical limitations

Introduction Intraoperative neuro-monitoring is one of the minimally invasive neurosurgery techniques to reduce the risk of intraoperative damage to the nervous system, thereby reducing the risk of postoperative neurological deficits. Neuro-monitoring consists on the intraoperative recording of the activity of the nervous system. Several recordings technics can be made: somatosensitive evoked potentials (SEP), motor evoked potentials (MEP), EMG, electrocorticography, auditory evoked potentials (AEP), and brainstem evoked potentials, the study of the D wave. Methods We report our preliminary experience and discuss the value of these recordings technics in neurosurgery. Results The series include thirty-six cases: twenty cases of awake surgery for low-grade glioma in or near the eloquent areas, four scoliosis, two spina bifida, two traumatic cervical spines, two cases of cervical disc herniation, one lumbar neuroma, one case of facial hemi-spasm, one case of acoustic neuroma, two spinal cord tumors and one rolandic cavernoma. Conclusion Our department will continue to develop these technics in order to make our neurosurgical procedures more safe and we will insist on the multidisciplinary nature of these procedures.

Electrophysiological neuromonitoring of the laryngeal nerves in thyroid and parathyroid surgery: A review.

Recurrent laryngeal nerve (RLN) injury is one of the most common complications of thyroid surgery. Injury to the external branch of the superior laryngeal nerve is less obvious and affects the voice variably; however, it can be of great significance to professional voice users. Recent literature has led to an increase in the use of neuromonitoring as an adjunct to visual nerve identification during thyroid surgery. In our review of the literature, we discuss the application, efficacy and safety of neuromonitoring in thyroid surgery. Although intraoperative neuromonitoring (IONM) contributes to the prevention of laryngeal nerves injury, there was no significant difference in the incidence of RLN injury in thyroid surgery when IONM was used compared with visual identification alone. IONM use is recommended in high risk patients; however, there are no clear identification criteria for what constitutes "high risk". There is no clear evidence that IONM decreases the risk of laryngeal nerve injury in thyroid surgery. However, continuous IONM provides a promising tool that can prevent imminent nerve traction injury by detecting decreased amplitude combined with increased latency.

Laparoscopic Neuromapping in Pelvic Surgery

New developments in intraoperative electrophysiological neuromonitoring for conventional surgery are providing further insights into functional neuroanatomy and nerve-sparing in the minor pelvis. The aim of this study was to open up potential scopes of application in laparoscopy. Ten patients with different indications for surgery (presacral tumor excision, n = 2; resection rectopexy. n = 2; low anterior rectal resection, n = 2; proctocolectomy. n = 2; abdomino-perineal excision of the rectum, n = 2) were investigated prospectively. The pelvic autonomic nerves were bilaterally mapped by laparoscopic electric stimulation under simultaneous electromyography of the internal anal sphincter and manometry of the bladder. Stimulation results were compared to patients' anorectal and urogenital functional outcome. In all the operations laparoscopic neuromapping (LNM) was technically feasible. Laparoscopy enabled excellent visibility of pelvic neural structures for simple and differentiated electric stimulation. In all cases LNM resulted in significantly evoked electromyographic potentials and intravesical pressure rises. The technique facilitated electrophysiological determination of functional neuroanatomical topography in the minor pelvis. The stimulation results were suitable to confirm laparoscopic nerve-sparing and compatible with patients' anorectal and urogenital functional outcome. LNM is technically feasible and opens up a new dimension for verification of functional nerve integrity. Further developments and investigations are mandatory to evaluate its role for laparoscopic nerve-sparing procedures.

Protocol for electrophysiological monitoring of carotid endarterectomies

Abstract Near zero stroke rates can be achieved in carotid endarterectomy (CEA) surgery with selective shunting and electrophysiological neuromonitoring. though false negative rates as high as 40% have been reported. We sought to determine if improved training for interpretation of the monitoring signals can advance the efficacy of selective shunting with electrophysiological monitoring across multiple centers, and determine if other factors could contribute to the differences in reports. Processed and raw beta band (12.5–30 Hz) electroencephalogram (EEG) and median and tibial nerve somatosensory evoked potentials (SSEP) were monitored in 668 CEA cases at six surgical centers. A decrease in amplitude of 50% or more in any EEG or SSEP channel was the criteria for shunting or initiating a neuroprotective protocol. A reduction of 50% or greater in the beta band of the EEG or amplitude of the SSEP was observed in 150 cases. No patient showed signs of a cerebral infarct after surgery. Selective shunting based on EEG and SSEP monitoring can reduce CEA intraoperative stroke rate to a near zero level if trained personnel adopted standardized protocols. We also found that the rapid administration of a protective stroke protocol by attending anesthesiologists was an important aspect of this success rate.

Utility of neuronavigation and neuromonitoring in epilepsy surgery

The management of medically refractory epilepsy poses both a valuable therapeutic opportunity and a formidable technical challenge to epilepsy surgeons. Recent decades have produced significant advancements in the capabilities and availability of adjunctive tools in epilepsy surgery. In particular, image-based neuronavigation and electrophysiological neuromonitoring represent versatile and informative modalities that can assist a surgeon in performing safe and effective resections. In the present article the authors discuss these 2 subjects with reference to how they can be applied and what evidence supports their use. As technologies evolve with demonstrated and potential utility, it is important for all clinicians who deal with epilepsy to understand where neuronavigation and neuromonitoring stand in the present and what avenues for improvement exist for the future.

RESECTION OF A BENIGN BRACHIAL PLEXUS NERVE SHEATH TUMOR USING INTRAOPERATIVE ELECTROPHYSIOLOGICAL MONITORING

Benign peripheral nerve sheath tumors arising from the brachial plexus are rare. Neurosurgeons often lack the clinical and surgical experience to optimize the management of these uncommon tumors. We filmed a video depicting the surgical resection of a benign peripheral nerve sheath tumor involving the brachial plexus. An illustrative case was used to demonstrate the proper management of a brachial plexus nerve sheath tumor including the important role of intraoperative electrophysiological neuromonitoring during tumor resection. Using an illustrative case, we describe a systematic approach in the evaluation and surgical management of patients with a brachial plexus nerve sheath tumor. The importance of taking a thorough clinical history, performing a thorough physical examination, applying high-resolution magnetic resonance imaging techniques to visualize the pathology, and using intraoperative electrophysiological neuromonitoring during surgical exposure and resection of the tumor are stressed. Combined with appropriate postoperative treatment, these techniques minimize the risks and increase the likelihood of achieving a good clinical outcome. Brachial plexus nerve sheath tumors are challenging mass lesions that should be evaluated and surgically resected by an experienced team of physicians to optimize clinical outcome.

The Advantages and Disadvantages of Nerve Monitoring During Thyroid Surgery in Childhood

Intraoperative damage of the recurrent laryngeal nerve (RLN) and the external branch of the superior laryngeal nerve (EBSLN) are common and cause complications in thyroid surgery. The method of intraoperative electrophysiological neuromonitoring (IONM) of the RLN and the EBSLN has been used in adults for several years. The question is whether IONM can be used in paediatric surgery for the identification and functional control of the RLN and the EBSLN, and what the advantages and disadvantages of using it are. Surgical treatment of benign (n = 9) and malign (n = 2) thyroid diseases was carried out in eleven children (median age: 13 years) with a total of 18 nerves at risk (NAR). The function of the vocal cord was monitored in all children before and after surgery. Intraoperative identification and functional control of RLN and EBSLN was performed using the Neurosign 100. All results before and after resection of the thyroid gland were documented. A clear and reliable identification of the RLN and the EBSLN was possible in all cases. All NAR showed a constant physiological nerve signal before and after surgical resection of the thyroid gland. However, in one young patient the postoperative examination of the vocal cord revealed a partial paralysis on the left side after thyroidectomy, despite the constant intraoperative signal of the RLN. After a period of six months, normal functioning had resumed. The IONM of both RLN and EBSLN in adult surgery could be used successfully in paediatric surgery. In this study a clear and positive identification of both nerves was possible in all patients. Therefore the IONM of the RLN and EBSLN could develop into a successful and easy method for the prevention of intraoperative nerve damage during thyroid surgery in childhood and young adolescence. Assuming that a constant IONM signal represents a normal vocal cord, our evaluation showed that there is a small percentage of false negative and positive results.

Functional Laryngeal Results after Thyroidectomy and Extensive Recurrent Laryngeal Nerve Dissection without Neuromonitoring

BACKGROUND: Permanent recurrent laryngeal nerve palsy (RLNP) is a major complication after thyroid surgery. Therefore methods are mandatory which reduce this complication. One strategy is the identification and dissection of the recurrent laryngeal nerve (RLN) in all patients as an inflexible rule. It is an ongoing discussion whether RLN neuromonitoring is helpful. METHODS: We prospectively investigated 624 surgical patients with 1076 nerves at risk (NAR) after hemithyroidectomy or total thyroidectomy because of a benign thyroid pathology (BT). In all patients, extensive nerve dissection was performed. Electrophysiological neuromonitoring was not used. All patients were investigated both pre- and postoperatively for regular laryngeal function, using indirect laryngoscopy and videostroboscopy. RESULTS: 2.4 % temporary and 0.3 % permanent RLNPs were documented respectively. CONCLUSIONS: Reviewing the literature, the total rates of (temporary and permanent) RLNPs are identical or lower in studies performing RLN dissection compared to those where no RLN dissection had been performed. Performing RLN dissection reduced the rate of permanent RLNPs. However, our results do not imply that neuromonitoring decreases the rate of permanent RLNP, since studies that included neuromonitoring did not reveal better data. Our observations also suggest that besides indirect laryngoscopy, videostroboscopy should be performed in all patients with no evidently normal bilateral laryngeal function and no normal voice quality. Failing this, the rate of false positive or negative identification of RLNP is likely to increase.