Role Of Intraoperative Neurophysiological Monitoring Research Articles

Role of intraoperative neurophysiological monitoring during spinal deformity surgery

Role of intraoperative neurophysiological monitoring during spinal deformity surgery

Posterior fossa tumor resection in children: a case report and the role of intraoperative neurophysiologic monitoring

Introduction/Background: Surgery plays a crucial role in the surgical management of posterior fossa tumors in children, but maximizing the resection while preserving function remains challenging. Along with other tools available to the surgeon, intraoperative neuromonitoring aims at improving safety during these complex interventions. This case report highlights the role of real-time intraoperative neuromonitoring during surgery and its impact on the surgeon's decision-making process. Case report: We present the case of a 10-year-old boy with a fourth ventricle medulloblastoma, who underwent microneurosurgical resection under intraoperative neuromonitoring. The use of neurophysiological monitoring yielded relevant information during the tumor dissection of the floor of the fourth ventricle, the most crucial step of surgery, thus helping the surgeon to change tactics to minimize long-term neurological deficits. Conclusion: In combination with meticulous microneurosurgery techniques, modern anesthetic regimens, and ultrasonic aspiration, intraoperative neuromonitoring adds up to the surgeon's armamentarium for increasing safety and improving outcomes following surgery for pediatric patients bearing posterior fossa tumors.

Role of Intraoperative Neurophysiological Monitoring in Preventing Stroke After Cardiac Surgery

BackgroundPerioperative stroke after cardiac surgical procedures carries significant morbidity. Dual intraoperative neurophysiological monitoring with electroencephalography (EEG) and somatosensory-evoked potentials detects cerebral hypoperfusion and predicts postoperative stroke in noncardiac procedures. We further evaluated preoperative risk factors and intraoperative neuromonitoring ability to predict postoperative stroke after cardiac operations. MethodsAll patients who underwent cardiac operations with intraoperative neurophysiological monitoring from 2009 to 2020 at a single academic medical center were retrospectively analyzed. Patients with circulatory arrest were excluded. Risks factors analyzed were sex, age, tobacco use, hypertension, diabetes mellitus, dyslipidemia, atrial fibrillation, prior cerebrovascular accident, cerebrovascular disease, antiplatelet/anticoagulant use, abnormal somatosensory-evoked potentials and EEG baselines, and significant somatosensory-evoked potentials and EEG change as well as their permanence. Patients were divided into 2 groups by 30-day postoperative stroke occurrence. Univariate and multivariate logistical regressions were used for postoperative stroke significant predictors, and Kaplan-Meier curves estimated survival. ResultsThe study included 620 patients (67.6% men), mean age 65.1 ± 14.1 years, with stroke in 5.32%. In univariate analysis, diabetes (odds ratio [OR], 2.62) and permanence of EEG change (OR, 5.35) were each associated with increased postoperative stroke odds. In multivariate analysis, diabetes (OR, 2.64) and permanent EEG change (OR, 4.22) were independently significantly associated with postoperative stroke. Overall survival was significantly better for patients with no intraoperative neurophysiological monitoring changes (P < .005). ConclusionsPermanent EEG change and diabetes were significant postoperative stroke predictors in cardiac operations. Furthermore, overall survival out to 10 years postoperatively was significantly higher in the group without intraoperative neurophysiological monitoring changes, emphasizing its important predictive role.

Predicting transient ischemic attack after carotid endarterectomy: The role of intraoperative neurophysiological monitoring

ObjectiveTransient ischemic attacks (TIA) after carotid endarterectomy (CEA) are not well-studied. We aimed to investigate the characteristics and the predictive role of intraoperative neurophysiological monitoring (IONM) in TIA post-CEA. MethodsPatients who underwent CEA utilizing IONM from 2009-2020 were included. Analyses included TIA incidence, sensitivity, specificity, and predictive values of IONM, risk factor regression analyses, and mortality Kaplan Meier plots. ResultsOut of 2232 patients, 46 experienced TIA, 14 of which were within 24 hours of CEA (p < 0.01). Nine of these patients displayed significant IONM changes during CEA. The odds of TIA increased with somatosensory evoked potential (SSEP) changes (Odds Ratio (OR): 2.48 95% Confidence Interval (CI): 1.14–5.4), electroencephalogram (EEG) changes (OR: 2.65 95% CI: 1.22–5.77), and combined SSEP/EEG changes (OR: 2.98 95% CI: 1.17–7.55). Patients with TIA were less likely to be alive after an average of 4.3 years (OR: 0.5 95% CI: 0.26–0.96). ConclusionsThe odds a patient will have TIA post-CEA are greater in patients with IONM changes. This risk is inversely related to the time post-CEA. SignificanceChanges in IONM during CEA predict postoperative TIA. Post-CEA TIA may increase long-term mortality, thus further research is needed to better elucidate clinical implications of postoperative TIA.

Review of the Role of Intraoperative Neurophysiological Monitoring in Spinal Surgery With a Focus on the True and False Positives and a Clinical Correlation.

Spinal surgery is a technically challenging endeavor with potentially devastating complications. Intraoperative neurophysiological monitoring (IONM) is a method of preventing and identifying damage to the spinal cord. The aim of our study was to examine the clinical utility of IONM in spinal surgeries performed at our institution and what effect, if any, subsequent interventions had on postoperative patient outcomes. This is a retrospective cohort study of 169 patients who underwent spinal surgery with IONM at 2 institutions between 2013 and 2018. Signal changes detected were recorded as well as the surgeon's response to these changes. Neurological status was recorded using a standard neurological examination and characterized as per the McCormick Neurological Scale. Patients were followed up for 12 months after surgery. A total of 169 spinal surgery cases with concurrent use of spinal cord monitoring were carried out in our institution between 2013 and 2018. The youngest patient was 14 years old, and the oldest was 92 years old (mean, 51.9 ± 19.6 years). There were 100 female patients and 69 male patients. Most patients (n = 124) had no signal changes. Signal changes were observed in 26.6% of the cases (n = 45). Most of these signal changes were rectified through repositioning of the patient (n = 24). The other 21 patients saw no improvement in their signals before the end of their procedures; however, these 21 patients had no postoperative deficits (grade I). This brought the false positive rate to 38% (21/55); the false negative rate was 1.8% (3/169). This study showed similar outcomes in patients whether IONM signals were recovered or not. The false positive and false negative rates were high. Our study helps to raise awareness about IONM's strengths and weaknesses to inform future clinical practice. We recommend prioritizing clinical judgment in spinal surgery cases and using IONM with caution.

SY5.3. IONM in spine deformity surgery

In this symposium, Dr Sandip Chatterjee discusses on the role of intraoperative neurophysiological monitoring (IONM) in spinal deformity surgery.

Role of Intraoperative Neurophysiologic Monitoring in Internal Carotid Artery Injury During Endoscopic Endonasal Skull Base Surgery

In the present study, we investigated the role of intraoperative neuromonitoring (IONM) in internal carotid artery (ICA) injury during endoscopic endonasal skull base surgery (EESBS). The study group included all 13 patients who had experienced an ICA injury during EESBS with IONM from 2004 to 2017. The medical records were reviewed for the perioperative data. The IONM reports were reviewed to evaluate the baseline somatosensory evoked potentials (SSEP), electroencephalography (EEG), and brainstem auditory evoked potentials (BAEP) and their significant changes related to ICA injury and/or the subsequent surgical/endovascular interventions. All 13 patients had undergone SSEP and 7 patients had BAEP monitoring during surgery. EEG was added during emergent angiography following the surgery for 5 patients. Two patients showed significant SSEP changes, and one showed significant SSEP and EEG changes, indicating cerebral hypoperfusion. Of these 3 patients, patient 1 had experienced irreversible SSEP loss with postoperative stroke. Patients 2 and 3 had SSEP and/or EEG changes that had recovered to baseline after interventions without postoperative deficits. Despite ICA injury, 10 patients showed no significant SSEP and/or EEG changes, and all 7 patients with BAEP monitoring showed no significant BAEP changes, indicating adequate cerebral and brainstem perfusion, respectively. The injured ICA was sacrificed in 4 patients, of whom 3 showed stable SSEP and 1 had experienced irreversible SSEP loss. IONM correlated with the postoperative neurologic examination findings in all cases, adequately predicting the neurologic outcomes after ICA injury. SSEP and EEG monitoring can accurately detect cerebral hypoperfusion and provide real-time feedback during surgery. SSEP and EEG changes predicted forneurologic outcomes and guide surgical decisions regarding the preservation or sacrifice of the ICA. Comprehensive multimodality monitoring according to the surgical risks can serve to detect and guide the management of ICA injury in EESBS.

Multimodality Intraoperative Neurophysiological Monitoring (IONM) During Shoulder Surgeries

ABSTRACT Introduction: The purpose of this study is to identify the advancing role of Intraoperative Neurophysiological Monitoring (IONM) in detecting and preventing nerve injuries during shoulder surgery procedures. Methods: We performed a retrospective analysis of IONM data from ten shoulder procedures. The patients consisted of nine females and one male with ages ranging from 67 to 81 years (median: 74 years). IONM modalities utilized were bilateral Somatosensory Evoked Potentials (SSEP), Transcranial Motor Evoked Potentials (TCeMEP), ipsilateral Electromyogram (EMG) from upper extremity muscles and Train of four (TOF) recordings. Results: A decrease in signals was noted in three patients (30%). Only upper SSEP amplitude decreased in one patient; both upper extremity SSEP and TCeMEP decreased in two patients. Only one patient had poor baseline radial nerve SSEP that improved during the surgery. We performed spontaneous EMG (s-EMG) in all ten patients and successfully recorded triggered (t-EMG) in seven patients (71.4%). In one patient, SSEP and TCeMEP did not improve, and the patient woke up with deficits. Conclusions: In this small series, we were able to identify real-time impending nerve injury. The use of IONM alerted and may have prevented intraoperative nerve injury in 30% of the patients in this series. In one patient, SSEP and TCeMEP did not recover even after the intervention due to severe blood loss. The patient woke up with sensory and motor deficits. The utilization of multimodality IONM can be helpful due to signal changes, therefore minimizing the frequency of nerve injury and deficits.

Modern Views on the Role of Intraoperative Neurophysiological Monitoring in Brain Tumour Surgery

The article defines the role of intraoperative neurophysiological monitoring (IONM) in neurosurgery, provides a brief historical background, as well as describes the main methods of IONM — somatosensory and motor evoked potentials. The authors describe electrical stimulation of the cerebral cortex and subcortical structures under general anaesthesia and in the conscious state. IONM is an integral part of neurosurgery, with its importance growing in orthopaedics and cavity surgery, where there is a risk of damaging nerve structures.

Intraoperative neurophysiological monitoring in paediatric Chiari surgery-help or hindrance?

The role of intraoperative neurophysiological monitoring (IONM) during surgery for Chiari I malformation has not been fully elucidated. Questions remain regarding its utility as an adjunct to foramen magnum decompression surgery, specifically, does IONM improve the safety profile of foramen magnum decompression surgery and can IONM parameters help in intraoperative surgical decision-making. This study aimed to describe a single institution experience of IOM during paediatric Chiari I surgery. The methodology comprised a retrospective review of prospectively collected electronic neurosurgical departmental operative database. Inclusion criteria were children under 16years of age who had undergone foramen magnum decompression for Chiari I malformation with IONM. In addition to basic demographic data, details pertaining to presenting features and post-operative outcomes were obtained. These included primary symptoms of Chiari I malformation and indications for surgery. MRI findings, including the presence of syringomyelia on pre-and post-operative imaging, were reviewed. Details of the surgical technique for each patient were recorded. Only patients with either serial brainstem auditory evoked potential (BAEP) and/or upper limb somatosensory evoked potential (SSEP) recordings were included. Two time points were used for the purposes of analysing IONM data; initial baseline before skin incision and final at the time of skin closure. Thirty-seven children underwent foramen magnum decompression (FMD) with IONM. Mean age was 10.5years (range 1-16years) with a male:female ratio 13:24. The commonest clinical features on presentation included headaches (15) and scoliosis (13). Twenty-four patients had evidence of associated syringomyelia (24/37 = 64.9%). A reduction in the SSEP latency was observed in all patients. SSEP amplitude was more variable, with a decrease seen in 18 patients and an increase observed in 12 patients. BAEP recordings decreased in 13 patients and increased in 4 patients. There were no adverse neurological events following surgery; the primary symptom was resolved or improved in all patients at 3-month follow-up. Resolution or improvement in syringomyelia was observed in 19/24 cases. Our data shows that FMD for Chiari malformation (CM) is associated with changes in SSEPs and BAEPs. However, we did not identify a definite link between clinical outcomes and IONM, nor did syrinx outcome correlate with IONM. There may be a role for IONM in CM surgery but more robust data with better-defined parameters are required to further understand the impact of IONM in CM surgery.

19. Intraoperative neurophysiological monitoring of spinal dural arteriovenous fistula

The surgical management during ligation of a spinal dural arteriovenous fistula (SDAVF) is usually based on fluorescenceangiography, intraoperative Doppler ultrasound, and intraoperative digital subtractionangiography. We investigated the potential role of intraoperative neurophysiologic monitoring (IONM) during surgical management of SDAVF. A 45 years-old woman with a history of bilateral dysesthesia in the lower limbs showed on MR myelopathy at dorsal level likely due to SDAVF. A surgical approach was planned and IONM was required. IONM included transcranial electrical stimulation Motor Evoked Potentials (tceMEPs) recorded from AH and TA bilaterally and ADM on the left arm, Somatosensory Evoked Potentials (SEP) for stimulation of left and right Posterior Tibial and left Median Nerves, continuous electroencephalogram for checking any changes due to anesthesia. The surgeon clamps for four times on vessels belonging fistula then takes into account neurophysiological changes before proceeding to the final ligation. We observed no significant SEP changes during surgery, and only transient disappearance of tceMEPs after the fourth clamp. IONM allowed a real-time functional evaluation of piramidal tract before and after microsurgical occlusion of the fistula. IONM can integrate other imaging modalities during SDAVF.

43. Intraoperative neurophysiological monitoring in spine surgery: A significant tool for neuronal protection and functional restoration

Although there is recent evidence for the role of intraoperative neurophysiological monitoring (IONM) in spine surgery, there are no uniform opinions on the optimal combination of the different tools. We analyzed the impact of the multimodal IONM (mIONM) on the preservation of neuronal structures and on functional restoration in a prospective series of our patients who underwent spine surgery. The mIONM approach in spine surgery involves the evaluation of somatosensory evoked potentials (SEPs) and motor evoked potentials (MEPs) with electrical transcranial stimulation, including the use of a multipulse technique with multiple myomeric registration of responses from limbs, and a single-pulse technique with D-wave registration through epi- and intradural recording, and free running and evoked electromyography. We observed an improvement of neurological status in 50% of the patients. The D-wave registration was the most useful intraoperative tool, especially when MEP and SEP responses were absent or poorly recordable. Our preliminary data confirm that mIONM plays a fundamental role in the identification and functional preservation of the spinal cord and nerve roots. It is highly sensitive and specific for detecting and avoiding neurological injury during spine surgery and represents a helpful tool for achieving optimal postoperative functional outcome.

Intraoperative neurophysiological monitoring in spinal deformity surgery

The role of intraoperative neurophysiological monitoring (IOM) during spinal deformity surgery is to continuously evaluate the integrity of the nervous system, providing the surgeon with an early warning in the event of an adverse change and the opportunity to take corrective action in order to avoid neurological injuries. Strong evidence supports the association between multimodal IOM and a significantly reduced risk of iatrogenic injury to the nervous system and in recent years this has become the gold standard of care in most spinal deformity centres. In this chapter, we provide an overview of the development of IOM and its role in major spinal surgery describing its efficacy, limitations and the importance of effective communication in the event of an adverse neurophysiological change. We also provide a summary of the basic neurophysiological principles and techniques, with clinical examples illustrating true-positive and false-positive events.

Outcome of L5 radiculopathy after reduction and instrumented transforaminal lumbar interbody fusion of high-grade L5-S1 isthmic spondylolisthesis and the role of intraoperative neurophysiological monitoring.

To evaluate the incidence and course of iatrogenic L5 radiculopathy after reduction and instrumented fusion of high-grade L5-S1 isthmic spondylolisthesis and the role of intraoperative neurophysiological monitoring (IONM). Consecutive patients treated for high-grade spondylolisthesis with IONM from 2005 to 2013 were screened for eligibility. Prospectively collected clinical and surgical data as well as radiographic outcomes were analyzed retrospectively. Patients completed the multidimensional Core Outcome Measures Index (COMI) before and at 3, 12, and 24months after surgery. Seventeen patients were included, with a mean age of 26.3 (±9.5) years. Mean preoperative L5-S1 slip was 72% (±21%) and was reduced to 19% (±13%) postoperatively. Mean loss of reduction at last follow-up [mean 19months (±14, range 3-48months)] was 3% (±4.3%). Rate of new L5 radiculopathy with motor deficit (L5MD) after surgery was 29% (five patients). Four patients fully recovered after 3months, one patient was lost to neurologic follow-up. IONM sensitivity and specificity for postoperative L5MD was 20 and 100%, respectively. COMI, back pain and leg pain scores showed significant (p<0.001) improvements at 3months postoperatively, which were retained up to 24months postoperatively. Transient L5 radiculopathy after reduction and instrumented fusion of high-grade spondylolisthesis is frequent. With IONM the risk of irreversible L5 radiculopathy is minimal. If IONM signal changes recover, full clinical recovery is expected within 3months. Overall, patient-reported outcome of reduction and instrumented fusion of high-grade spondylolisthesis showed clinically important improvement.

Intraoperative Neurophysiological Monitoring in Spine Surgery: A Significant Tool for Neuronal Protection and Functional Restoration.

Although there is recent evidence for the role of intraoperative neurophysiological monitoring (IONM) in spine surgery, there are no uniform opinions on the optimal combination of the different tools. At our institution, multimodal IONM (mIONM) approach in spine surgery involves the evaluation of somatosensory evoked potentials (SEPs) and motor evoked potentials (MEPs) with electrical transcranial stimulation, including the use of a multipulse technique with multiple myomeric registration of responses from limbs, and a single-pulse technique with D-wave registration through epi- and intradural recording, and free running and evoked electromyography (frEMG and eEMG) with bilateral recording from segmental target muscles. We analyzed the impact of the mIONM on the preservation of neuronal structures and on functional restoration in a prospective series of patients who underwent spine surgery. We observed an improvement of neurological status in 50 % of the patients. The D-wave registration was the most useful intraoperative tool, especially when MEP and SEP responses were absent or poorly recordable. Our preliminary data confirm that mIONM plays a fundamental role in the identification and functional preservation of the spinal cord and nerve roots. It is highly sensitive and specific for detecting and avoiding neurological injury during spine surgery and represents a helpful tool for achieving optimal postoperative functional outcome.

Role of Intraoperative Neurophysiologic Monitoring in the Resection of Thalamic Astrocytomas

The thalamus is a deep-seated and crucial structure for the sensorimotor system. It has been long considered a surgically inaccessible area because of the morbidity associated with surgical resections. Astrocytomas of the thalamus are usually treated with bioptic procedures followed by adjuvant treatments. Intraoperative neurophysiologic monitoring (IONM) allows safe and satisfactory resections of lobar gliomas, but few data are available for thalamic lesions. The aim of this study was to review the outcome of a small series of patients with thalamic astrocytomas that were treated with surgical resection with the aid of IONM. Surgical resection with IONM was performed in 5 patients with thalamic astrocytomas (1 grade I, 1 grade II, 2 grade III, 1 grade IV). Two astrocytomas were in the dominant hemisphere. Preoperative and postoperative neuropsychological assessments were performed in 3 patients. IONM was tailored to the individual patient and consisted of transcranial motor evoked potential monitoring, cortical motor evoked potential monitoring, somatosensory evoked potential monitoring, direct electrical stimulation, electroencephalography, and electrocorticography. None of the patients experienced permanent motor deficits; 2 patients had a transient hemiparesis requiring rehabilitation; 1 patient had a transient aphasia, and 1 patient had permanent aphasia. None of the patients had intraoperative seizures, but 1 patient experienced postoperative transient status epilepticus. The extent of resection on postoperative volumetric magnetic resonance imaging was >70% in all cases. Surgical resection of thalamic astrocytomas appeared to be effective and relatively safe when guided by IONM. Larger series of patients are required to confirm these preliminary data.

89. Recovery of evoked potentials in spine surgery

The role of intraoperative neurophysiologic monitoring (IOM) in detection and prevention of an jatrogenic injury has been well documented. Only few studies, however, has been focused on recovery of evoked potentials. Aim of this study is to describe the rate of reappearance of basally unexcitable muscle-motor evoked potentials (m-MEPs) and somatosensory evoked potentials (SEPs) in a large cohort of spinal surgeries. Data on 720 spinal surgeries are shown. Transcranially elicited lower limbs m-MEPs and tibial nerve SEPs were intraoperative recorded according to standard protocols. Reasons for surgey included cervical/thoracic myelopathy (300 pts, 41.7%), spinal cord tumors (190, 26.4%), lumbar stabilization (109 pts, 15.1%), scoliosis correction (83, 11.5%), trauma (32, 4.4%) and spinal vascular malformations (6 pts, 0.8%). Overall no intraoperative changes were observed in 648 surgeries (90%), 54 (7.5%) transient or persistent deterioration of evoked potentiantials and 18 (2.5%) recovery of basally unexcitable SEPs or MEPs (9 myelopathies, 4 spinal cord tumors, 2 metastasis, 3 trauma). The large majority of these “positive” modifications (17/18, 94.4%) consisted in reappearance of MEPs. Surgical decompression of spinal cord may lead to an acute improving of spinal motoneuron functionality. IOM can provide useful information even in patient with basally absent m-MEPs.

Subpial Spinal Lipoma: Surgery with Intraoperative Monitoring of Neural Function and Review of Literature

Intradural spinal lipomas not associated with congenital dysraphism and malformations, are rare and benign slow growing tumors, representing about 1% of all spinal tumors. We report two cases both of a 59 years-old women complaining of gait difficulties, progressive para-paresis and long history of back pain with a magnetic resonance imaging suggestive for a subpial spinal lipoma with compression of posterior aspect of spinal cord from T1 to T3 and cono-cauda. The aim of this paper is to illustrate the technique of resection of this type of lesions and to emphasize the role of intraoperative neurophysiological monitoring in order to perform a safer surgery and to objectively establish its end with an extensive review of the literature focused on this aspect.

P07.02 * THE ROLE OF INTRAOPERATIVE NEUROPHYSIOLOGICAL MONITORING IN SURGERY OF INTRADURAL EXTRAMEDULLARY SPINAL CORD TUMORS

INTRODUCTION: Surgery of intradural extramedullary spinal cord tumors (IESCT) carries the risk of new neurological deficits in the post-operative period. Intraoperative neurophysiological monitoring (IONM) represents the most effective technique able to improve clinical and functional outcomes, which are obtained through identification and real-time intraoperative monitoring of spinal cord, giving informations about neurological conduction of both, spinal cord long pathways and cauda equina radices. The most widely used and reliable techniques are somatosensory evoked potentials (SEPs), motor evoked potentials (MEPs) and D-wave registration. Although in the literature there are recent evidences of the IONM usefulness, there are not uniform opinions about the different techniques employed, and, their use in IESCT. In the present study we describe the results in our 2-year experience at the Neurosurgery of the University of Messina Hospital. MATERIALS AND METHODS: Our protocol includes evaluation of SEPs from posterior tibial nerve stimulation, MEPs obtained with elevate voltage electrical transcranial stimulation (through multiple myomeric registration of motor evoked responses from inferior limbs), D-Wave registration (through epi- and intradural registration after single pulse electrical transcranial stimulation) in spinal tumor surgery. RESULTS: We did not recorded any intraoperative complication by the use of our IONM protocol. In all patients IONM was useful for correct neurological and functional identification of spinal cord. We observed an optimal correlation between neurological examination on admission and responses from IONM of inferior limbs SEPs and MEPs. In fifty percent of patients, the D-wave registration was the most useful intraoperative tool, due to the lack of motor and somatosensory evoked responses. We matched all pre and post-operative neurological and neurophysiological data, along with tumors' features (localization, dimensions and histology) in order to quantify the impact of IONM on outcome. In our series, none of the patients presented with neurological worsening in the post-operative period. Conversely, surgical treatment of IESCT lead to a significant improvement of neurological status of our patients. CONCLUSIONS: Our preliminary data, although based on a limited series of patients evaluated at a single institution, confirm the role of IONM as an essential tool in operative work-up of all spine surgeries, including IESCT, to achieve an optimal post-operative functional outcome. This study gives further evidences about relevance, impact and usefulness of IONM in IESCT surgery.

P491: Reversible intraoperative neurophysiologic monitoring changes associated with surgical retraction

P491: Reversible intraoperative neurophysiologic monitoring changes associated with surgical retraction