Multimodal Intraoperative Neurophysiological Monitoring Research Articles

Multimodal intraoperative neurophysiological monitoring may better predict postoperative distal upper extremities’ complex-functional outcome than spinal and muscular motor evoked potentials alone in high-cervical intramedullary spinal cord tumor surgery

ObjectiveD-wave can safely monitor the corticospinal-tract (CST)-function regarding gross-motor outcome of lower extremities, but it is still unknown whether i)D-wave can also safely monitor the gross-motor outcome of distal upper extremities in those patients undergoing high-cervical intramedullary-spinal-cord-tumor (IMSCT)-resection (enabling epidural D-wave-placement below C5) and ii)multimodal IONM can also predict fine-motor/complex hand function. MethodsWe prospectively assessed 20 patients undergoing IMSCT-surgery above the C4/5-level with multimodal IONM (D-wave/mMEPs/EMG/SSEPs). Detailed gross-/fine-motor and complex hand function was assessed pre- and postoperatively and during long-term follow-up (mean:29.5 ± 18.8 months) and correlated with IONM-findings. ResultsD-wave monitoring was without intraoperative critical changes in all patients and none had any permanent postoperative gross-motor deficits. However, D-wave did not allow to predict the occurrence of mild permanent postoperative deficits affecting fine-motor function which was the case in 8% for distal upper extremities. The complex distal upper extremities’ function assessed by Nine-Hole-Peg-Test (reflecting the complex motor/sensory interaction for hand-usability) was permanently deteriorated in 15% postoperatively and only the combination of D-wave/mMEPs/EMG/SSEPs was able to provide a viable predictive power (specificity:79%/sensitivity:43%). ConclusionsIn high-cervical IMSCT-surgery, unimpaired D-wave reliably predicts preserved gross-motor function, but fails to sufficiently cover distal upper extremities’ fine-motor/complex function. SignificanceOur study underlines the importance of multimodal IONM for fine-motor/complex hand function.

Application of multimodal intraoperative neurophysiological monitoring technology in neurofibromatosis type 1 related peripheral nerve tumor surgery

To summarize application effect and clinical experience of multimodal intraoperative neurophysiological monitoring (IONM) technology in the surgery of neurofibromatosis type 1 (NF1) related peripheral nerve tumors. A retrospective study was conducted on NF1 patients, who admitted between January 2019 and December 2023 and treated with peripheral nerve tumor resection surgery assisted by multimodal IONM technology. There were 49 males and 45 females. The age ranged from 5 to 78 years, with an average of 33.7 years. Tumor morphological classification included 71 cases of nodular type, 13 cases of diffuse type, and 10 cases of mixed type. Target tumors were distributed in craniofacial region (47 cases), neck (11 cases), trunk (12 cases), and limbs (24 cases). Preoperatively, 44 cases had no obvious neurological symptoms, while the remaining patients had neurological symptoms, including 15 cases of visual impairment, 5 cases of hearing impairment, 16 cases of somatic movement disorders, and 31 cases of somatic sensory disorders, of which 7 cases had more than one symptom. IONM plans were selected based on the relevant nerves and adjacent important structures of the target tumor, including visual evoked potential (17 cases), somatosensory evoked potential (44 cases), motor evoked potential (88 cases), and electromyogram (94 cases). All surgeries were successfully completed. Ninety-three patients underwent total/near total resection and 1 patient underwent palliative resection. Pathological examination showed 80 cases of neurofibroma and 14 cases of malignant peripheral nerve sheath tumors. Complications included 2 cases of hematoma and 3 cases of incision infection. All patients were followed up 3-61 months (median, 15 months). During follow-up, no significant changes in neurological symptoms or tumor recurrence were found. Among the patients with preoperative visual impairment, there were 14 cases with no improvement in symptoms and 1 with improvement after surgery. Among the patients with somatic movement disorders, there were 11 cases with no improvement in symptoms, 3 cases with improvement, 2 cases with aggravation, 4 newly onset cases, and 1 case with significant impact on daily life after surgery. Among the patients with somatic sensory disorders, there were 17 cases with no improvement in symptoms, 14 cases with improvement, and 13 newly onset cases. The patients with hearing impairment showed improvement after surgery. The clinical manifestations of NF1 related peripheral nerve tumors are complex. Multimodal IONM technology can provide real-time detection of nerve provocation and damage. Surgical treatment with multimodal IONM technology is safe and can reduce complications.

Intraoperative Neurophysiological Monitoring in Tethered Cord Syndrome Surgery: Predictive Values and Clinical Outcome.

"Tethered cord syndrome" (TCS) refers to a congenital abnormality associated with neurological signs and symptoms. The aim of surgery is to prevent or arrest their progression. This study reports a retrospective case series of tethered cord syndrome surgeries, supported by intraoperative neurophysiological monitoring. The case series comprises 50 surgeries for tethered cord syndrome in which multimodal intraoperative neurophysiological monitoring was performed using motor evoked potentials (transcranial motor evoked potentials [TcMEPs]), tibial nerve somatosensory evoked potentials (TNSEPs), and pudendal-anal reflex (PAR). The intraoperative neurophysiological monitoring results are reported and correlated with clinical outcomes. Sensitivity, specificity, and negative predictive value were high for TcMEPs and TNSEPs, while PAR exhibited low sensitivity and positive predictive value but high specificity and negative predictive value. Fisher's exact test revealed a significant correlation between changes in TcMEPs, TNSEPs, and clinical outcome ( P < 0.000 and P = 0.049 respectively), but no correlation was detected between PAR and urinary/anal function ( P = 0.497). While TcMEPs and TNSEPs were found to be reliable intraoperative neurophysiological monitoring parameters during tethered cord syndrome surgery, PAR had low sensitivity and positive predictive value probably because the reflex is not directly related to bladder function and because its multisynaptic pathway may be sensitive to anesthetics. New onset muscle weakness and sensory deficits were related to postoperative changes in TcMEPs and TNSEPs, whereas changes in PAR did not predict bladder/urinary impairment. Urinary deficits may be predicted and prevented with other neurophysiological techniques, such as the bladder-anal reflex.

Multimodal intraoperative neurophysiological monitoring with special emphasis on facial MEPs for facial nerve preservation in vestibular schwannoma surgeries: Surgical nuances and outcome predictability

Objectives: The objective of this study was to evaluate the utility of facial motor-evoked potentials (FMEPs) as a significant part of multimodal intraoperative neurophysiological monitoring (IONM) for preserving facial nerve (FN) function in vestibular schwannoma surgery guiding the resection, and predicting outcome. Materials and Methods: This prospective observational study included 35 cases of vestibular schwannomas operated under multimodal IONM using free-running electromyography (EMG), triggered EMG (with both monopolar probe and suction stimulator), FMEPs, electroencephalography and its spectral derivatives and train-of-four testing. Direct stimulation using a monopolar probe helped in the identification of FN and guiding tumour resection. The suction stimulator probe was used for quasi-continuous stimulus delivery and FN mapping. FMEPs helped in the assessment of the integrity of FN. Results: In 14 cases, there was a single instance, and in 11 cases, there was more than one instance of a significant drop in FMEPs. Sixteen cases had &gt;50% fall in FMEPs during surgery. In 28 cases, the proximal stimulation threshold for FN was ≤0.1 mA at the end of the tumour resection. At the end of the first week following surgery, only 42.9% of the cases had good functional preservation (House–Brackmann [HB] Grade I or II) of FN, which increased to 78.8% at the end of one year. The remaining 21.2% had HB Grade III weakness. Percentage drop in FMEP amplitude and final FMEP amplitude correlated significantly (P &lt; 0.01) with the post-operative HB Grade at 1st week, 3, 6 and 12 months following surgery. Conclusion: FMEPs, as a significant component of multimodal IONM, provide a real-time assessment of FN function during surgery, facilitate safe maximal resection, predict immediate post-operative FN outcomes, and improve long-term FN function by minimising the cumulative insult inflicted on the FN during surgery.

Multimodal Intraoperative Neurophysiological Monitoring in Cranial and Spinal Tumour Surgeries: A Descriptive Observational Study.

Intraoperative neurophysiological monitoring (IONM) involves monitoring the functional integrity of critical brain regions and pathways as well as identifying and preserving functionally viable neural tissues (mapping) during surgery using electrophysiological techniques. Multimodality combines various neurophysiological techniques to optimise diagnostic effectiveness and to improve the outcomes of the surgeries. The present study is a case series with comprehensive and illustrative descriptions of the neurophysiological changes in five neuromonitored cases of cranial and spinal cord tumour surgeries conducted with a multimodal approach. The cases were monitored with somatosensory evoked potentials (SSEP), transcranial motor evoked potentials (TcMEP), and both free run and triggered electromyography (fEMG and tEMG). No false negative outcomes were identified in the cases studied as there was an association of absence of change in SSEP and TcMEP both, with no neurological deficit postoperatively.Two cases were identified as having true positive neuromonitoring alerts.No false positive alerts were found in any case. Multimodal monitoring using SSEP, TcMEP, and EMG (fEMG and tEMG) in cranial and spinal tumour surgeries can improve performance with fewer false-negative and false-positive results. Neuromonitoring approaches used in combination can provide reliable information regarding postoperative neurological outcomes.

Spinal intradural extramedullary tumors: microscopic keyhole resection with the focus on intraoperative neurophysiological monitoring and long-term outcome

ObjectiveSpinal schwannomas (SS) and spinal meningiomas (SM) account for most intradural extramedullary (IDEM) tumors. These tumors are usually benign lesions, which generally respond favorably to surgical excision. Few studies up to now tried to determine the long-term outcome after minimally invasive surgery (MIS) with multimodal intraoperative neurophysiological monitoring (IONM) for IDEM tumors. The aim of this study was to present one of the largest case series with special regard to IONM findings and long-term outcome after MIS-keyhole surgery with a tubular retractor system.MethodsBetween January 2013 and August 2018, 87 patients with IDEM tumors who underwent tumor removal surgery via MIS-keyhole approach under multimodal IONM were retrospectively reviewed. The neurological status was assessed using a modified McCormick grading scale pre- and postoperatively. Multimodal IONM consisted of motor evoked potentials (MEP), somatosensory evoked potentials (SEP), and electromyography (EMG). Both short-term and long-term clinical evaluations as well as patients’ medical files were retrospectively analyzed.ResultsSurgeries were performed for resection of SS in 49 patients and SM in 38 patients. Tumor locations were cervical in 16.1%, thoracic in 48.3%, thoracolumbar in 4.6%, lumbar 31%. Critical IONM changes were detected in 9 operations (10.3%) in which there were 2 SEPs, 5 MEPs, and 2 EMG events. Three IONM changes (2 MEPs, 1 EMG) were turned out to be transient change in nature since they were resolved in a short time when immediate corrective actions were initiated. Six patients with permanent IONM changes (2SEPs, 3MEPs, 1EMG event), all deficits had resolved during hospitalization or on short -term follow-up evaluation. Sensitivity, specificity, and positive and negative predicted values of IONM were 100, 96, 67, and 100%, respectively. Gross total resection rate was 100%, and a stable or improved McCormick grade exhibited in all patients. No tumor recurrence and no spinal instability were found in the long-term follow-up evaluation (mean 5.2 ± 2.9 years postoperatively). Overall, 94% of patients were either satisfied or very satisfied with their operation, and 93% patients reported excellent or good general clinical outcome according to Odom’s criteria.ConclusionMIS-keyhole surgery with multimodal IONM for IDEM tumors enables a high level of satisfaction and a satisfying long-term clinical and surgical outcome.

Intraoperative Neurophysiological Monitoring in Syringomyelia Surgery: A Multimodal Approach.

Syringomyelia can be associated with multiple etiologies. The treatment of the underlying causes is first-line therapy; however, a direct approach to the syrinx is accepted as rescue treatment. Any direct intervention on the syrinx requires a myelotomy, posing a significant risk of iatrogenic spinal cord (SC) injury. Intraoperative neurophysiological monitoring (IONM) is crucial to detect and prevent surgically induced damage in neural SC pathways. We retrospectively reviewed the perioperative and intraoperative neurophysiological data and perioperative neurological examinations in ten cases of syringomyelia surgery. All the monitored modalities remained stable throughout the surgery in six cases, correlating with no new postoperative neurological deficits. In two patients, significant transitory attenuation, or loss of motor evoked potentials (MEPs), were observed and recovered after a corrective surgical maneuver, with no new postoperative deficits. In two cases, a significant MEP decrement was noted, which lasted until the end of the surgery and was associated with postoperative weakness. A transitory train of neurotonic electromyography (EMG) discharges was reported in one case. The surgical plan was adjusted, and the patient showed no postoperative deficits. The dorsal nerve roots were stimulated and identified in the seven cases where the myelotomy was performed via the dorsal root entry zone. Dorsal column mapping guided the myelotomy entry zone in four of the cases. In conclusion, multimodal IONM is feasible and reliable and may help prevent iatrogenic SC injury during syringomyelia surgery.

Changes in motor evoked potentials after erector spinae block in scoliosis surgery-when to take pre-incision baseline recordings?

Multimodal intraoperative neurophysiological monitoring (IONM) is highly valuable in scoliosis surgeries for monitoring spinal cord function, particularly during instrumentation. Accurate timing of baseline recordings of TcMEP and SSEP is crucial, as any changes observed during surgery and instrumentation are compared to these baseline recordings. However, the impact of ultrasound-guided erector spinae block (USG-ESPB) on SSEP and TcMEP is not well-studied in scoliosis surgery. In this report, we present two cases of scoliosis surgery where bilateral two-level USG-ESPB using different concentrations of ropivacaine (0.375% and 0.2%) resulted in a transient and significant deterioration of TcMEP, occurring 3 minutes after the block and lasting for 20 minutes. Remarkably, SSEPs remained unchanged during this period. These findings suggest that USG-ESPB may produce TcMEP changes, highlighting the importance of carefully considering the timing of baseline TcMEP acquisition in scoliosis surgery.

Impact of multimodal intraoperative neurophysiological monitoring of the spinal cord during spine and spinal cord surgeries

BackgroundThere is growing evidence of the valuable role of multimodal intraoperative neurophysiological monitoring (IONM) during spine and spinal cord surgeries, as it provides an opportunity to recognize functional changes of the neural elements, usually in the reversible stage, during complex surgical manipulations. Therefore, it may reduce the risk of postoperative neurological dysfunction and improve functional outcomes. The aim of the current study was to evaluate the efficacy of multimodal IONM for preventing and predicting iatrogenic neurological dysfunction during spinal cord and spine surgeries.ResultsSignificant alerts had occurred in 9 out of 24 patients; however, all the changes were reversible and did not contribute to postoperative clinical deterioration. Only one case got worsened in the early postoperative follow-up period, with stable intraoperative monitoring.ConclusionIntraoperative monitoring is a valuable tool in spine and spinal cord surgeries. Combined transcranial motor-evoked potential (TcMEP), somatosensory-evoked potential (SSEP), and spontaneous electromyography (EMG) monitoring may prevent permanent motor deficit and enhance the postoperative outcomes.

CLINICAL SIGNIFICANCE OF INTRAOPERATIVE NEUROPHYSIOLOGICAL MONITORING DURING SCOLIOSIS SURGERY: A LITERATURE REVIEW

Mechanical damage to nerve fibers during scoliosis correction can result in severe neurological disorders. It has been demonstrated that intraoperative neurophysiological monitoring during spinal surgery reduces the risk of motor deficits or paraplegia. Despite significant advances in the technique and application of IONM (intraoperative neurophysiological monitoring), data reporting the impact of implementing intraoperative neurophysiological monitoring on scoliosis surgery intervention remains very limited. Therefore, this review aims to investigate the correlation between the application of IONM and the risk of neurologic deficits in scoliosis patients undergoing surgery. The database sourced from PubMed (Jan 2010 to Jan 2022) was used to identify all studies evaluating the effectiveness and impact of intraoperative neurophysiological monitoring during scoliosis surgery and reducing the risk of postoperative complications. This systematic review included five studies. Multimodal IONM, with its high sensitivity and specificity, provides an objective benchmark that surgeons can implement to review surgical strategies to reduce the risk of permanent neurologic deficits. Multimodal IONM can be considered the gold standard of IONM in scoliosis surgery to prevent neurological damage and provide a more satisfactory result of surgical intervention.

Feasibility of multimodal intraoperative neurophysiological monitoring for extramedullary spinal cord tumor surgery in elderly patients

Background/purposeExtramedullary spinal cord tumors (EMSCTs) are mostly benign tumors which are increasingly diagnosed and operatively treated in the elderly. While there are hints that multimodal intraoperative neurophysiological monitoring (IONM) could be influenced by age and age-related comorbidities, no study has ever systematically evaluated its feasibility and value for EMSCT surgery in elderly patients.MethodsWe retrospectively evaluated all patients with microsurgical EMSCT resection under continuous multimodal IONM with SSEPs, MEPs and electromyography between 2016 and 2020. Epidemiological, clinical, imaging and operative/IONM records as well as detailed individual outcomes were analyzed and compared for the cohort < / ≥ 65 years.ResultsMean age was 45 years in cohort < 65 years (n = 109) and 76 years in cohort ≥ 65 years (n = 64), while baseline/operative characteristics did not significantly differ. Mean baseline SSEPs’ latencies (left–right average) were significantly higher in the cohort ≥ 65 years for both median (20.9 ms vs. 22.1 ms; p < 0.01) and tibial nerve (42.9 ms vs. 46.1 ms; p < 0.01) without significant differences for SSEPs’ amplitudes. Stimulation intensity to elicit intraoperative MEPs was significantly higher in the cohort ≥ 65 years (surrogate-marker: left–right-averaged quotient ID1-muscle/abductor-hallucis-muscle; 1.6 vs. 2.1; p < 0.001). Intraoperatively, SSEP and MEP monitoring were feasible in 99%/100% and 99%/98% for the cohort < / ≥ 65 years without significant differences in rates for significant IONM changes during surgery or postoperatively new sensorimotor deficits. Sensitivity of IONM was 29%/43%, specificity 99%/98%, positive and negative predictive values 67%/75% and 95%/93% for the cohort < / ≥ 65 years. Overall, age was no risk factor for IONM feasibility or rate of significant IONM changes.DiscussionMultimodal IONM is feasible/reliable for EMSCT surgery in elderly patients. An age-related prolongation of SSEPs’ latencies and demand for higher stimulation intensities for MEPs’ elicitation has to be considered.

Pediatric Intraoperative Neurophysiological Monitoring and Long-Term Outcomes in a Developing Country.

Pediatric intraoperative neurophysiological monitoring (IONM) has been shown to be effective in preventing and reversing postoperative neurological deficits in developed countries. There are currently no published studies from developing countries that describe neurophysiological findings and postoperative outcomes. Our study aims to address these gaps in children undergoing neurosurgical procedures in a single center. We conducted a retrospective study of case series of children who underwent IONM (2014-2020) in the State of Mexico, Mexico. Sociodemographic characteristics, IONM modalities, changes during procedures, and short-term and long-term postoperative results were recorded. Descriptive statistics were used. We included 35 patients (≤18 years of age), 57% (20/35) boys. A relative increase of up to 5 times in the use of IONM is observed from 2014 (5.7%) to 2020 (25.7%) in our center. The most frequent preoperative pathologies were located at the infratentorial cranium (40%), followed by the spine and spinal cord (37.1%). The IONM modalities were as follows: free-running EMG 94.3%, transcranial electrical stimulation motor-evoked potentials 91.4%, somatosensory-evoked potentials 85.7%, triggered EMG 28.6%, EEG 25.7%, and visual-evoked potentials 5.7%. Only in 8.3%, we did not obtain sufficient evoked potential baseline signals. At 24 hours postoperatively true negatives were 100%. Long-term follow-up was completed in 22/35 (63%) at 3 months, 12/35 (34.2%) at 6 months, and 5/35 (14.3%) at 12 months with progressive motor and sensory improvement. Pediatric multimodal IONM in neurosurgeries from a single center in a developing country is mainly used in pathologies of the posterior fossa, spine, and spinal cord, with true negatives in 100% of those monitored, preventing and avoiding postoperative sequelae.

Intraoperative neurophysiological monitoring in surgery of lumbar spinal stenosis

Background. Lumbar spinal stenosis is a pathological constriction of the central spinal canal, lateral pocket or intervertebral foramen. The complication rate of lumbar spinal stenosis surgery ranges from 10 to 24 %. In order to reduce the number of intraoperative and early postoperative complications accompanied by the development of neurological deficit, various techniques of intraoperative neurophysiological monitoring are used.Aim. Study of informativity of the use of intraoperative neurophysiological monitoring during surgical treatment of degenerative lumbar spinal stenosis based on the experience of the neurosurgical department of the Republican Clinical Hospital (Yoshkar‑Ola, Mari El Republic).Materials and methods. Thus, 69 decompressive‑stabilizing surgical interventions for degenerative lumbar spinal stenosis at the L3–L5 level, performed with intraoperative neurophysiological monitoring (free‑run electromyography, transcranial motor evoked potentials, somatosensory evoked potentials, triggered electromyography were included in the retrospective study).Results. During intraoperative neurophysiological monitoring transcranial motor evoked potentials from the legs was registered in all cases. Normal somatosensory evoked potentials were recorded in most cases, in 12 cases (17.4 %) baseline somatosensory evoked potentials were not registered due to preoperative neurological deficits and the presence of concomitant somatic pathology. 308 inserted pedicular screws were examined using the triggered electromyography. Muscle responses were registered in 31 (45 %) operations, 45 (14 %) screws. True negatives were registered with 29 (64.4 %), true positives were registered with 12 (26.7 %), and false positives were registered with 4 (8.9 %) screws. In the postoperative period no increase in motor and sensory neurological deficits was observed in all patients; no neurological signs of screw malpositioning were revealed.Conclusion. The use of multimodal intraoperative neurophysiological monitoring during surgical treatment of lumbar spinal stenosis reduces the risk of postoperative neurological complications.

The effect of intraoperative neurophysiological monitoring on neurological outcomes after spinal tumors operations: A single institution experience

We aim to report our study about using multimodality intraoperative neurophysiological monitoring (IONM) in intradural spinal tumor surgery. This cohort present a retrospective review of the patient who underwent intraspinal tumors surgery at Vajira Center of Excellence in Neurosurgery; between 2005 and 2020. Transcranial motor evoked potentials, somatosensory evoked potentials, and free run electromyography were used for IONM with alarm criteria. Patient record were reviews with preoperative and postoperative neurological outcome measurements; Frankel Grading, McCormick Score, American Spinal Injury Association (ASIA) Grading, Karnofsky Performance Status (KPS) Scale and The Japanese Orthopedic Association (JOA) Score at 1, 6, 12, 24 months after operation. Overall, 104 patients were operated. 77.4 % operations were used IONM. 70.2 % of tumor located at intradural extramedullary (IDEM) space and 16.7 % located at intramedullary space. There were demonstrating statistically significant (p-value < 0.050) improvement between preoperative and postoperative neurological outcome in all follow up time in IONM group. The sensitivity and specificity of alarm IONM to predict early worsening postoperative neurological outcome were 66.7 % and 88.7 %, respectively. IDEM spinal cord tumor surgery are associated with good neurological outcome (OR 0.187 [95 % CI 0.05–0.71]; p-value 0.014). Used of IONM in intradural spinal tumor surgery statistically significant improved postoperative neurological outcome and decrease postoperative neurological deficit. IONM has ability to detect postoperative neurological deficit and poor outcome with fair sensitivity and high specificity. Especially, using of IONM in IDEM have preferable postoperative neurological outcomes.

The role of multi-modal intra-operative neurophysiological monitoring in corrective surgeries for thoracic tuberculosis with kyphosis.

The aim of this study was to assess the performance and utility of motor evoked potentials (MEP) and somatosensory evoked potentials (SSEP) during corrective surgery for thoracic tuberculosis with kyphosis (TTK). 68 patients (mean age 31.7 ± 20.3 years) who underwent corrective surgery for TTK from 2012 to 2019 were included in this retrospective study. Patients were neurologicaly evaluated before and after surgery with systematic neurologic examinations. Intraoperative neurophysiological monitoring (IONM) with SSEP and MEP was carried out. A receiver operating characteristic (ROC) curve and area under ROC curve (AUC) were used to identify the diagnostic accuracy of potential recovery. IONM alerting occurred in 12 surgeries (12/68, 17.6%), of which 6 were SSEP alerting, 2 MEP alerting, and 4 combinations of both SSEP and MEP. Among the 12 cases where there was IONM alerting, 3 (25%) had postoperative neurological deficits(PND), whereas one patient had PND without IONM alerting. IONM sensitivity and specificity were 0.75 (95% CI 0.22-0.99) and 0.86 (95% CI 0.74-0.93) respectively. Positive predictive value (PPV) and negative predictive value (NPV) were 0.25 and 0.98 respectively. The AUC of evoked potential recovery in diagnosing PND was 0.884. Our study showed that multi-modal IONM with SSEP and MEP can effectively indicate a potential neural injury and predict PND during TTK corrective surgery. Level IV, Therapeutic Study.

Carotid Endarterectomy Surgeries: A Multimodality Intraoperative Neurophysiological Monitoring Approach.

Patients with untreated carotid artery stenosis remain at high risk for stroke. Carotid endarterectomy (CEA) is a surgical procedure for the treatment of symptomatic and severe asymptomatic carotid stenosis. A small percentage of patients who do not have good collateral circulation are at high risk of cerebral ischemia during the cross-clamping of the carotid artery. Aspects of CEA, such as cross-clamping and routine shunting, can also carry the risk of perioperative stroke through dislodgement of emboli causing thrombosis, therefore, selective shunting is highly recommended during the CEA procedure. A multimodality approach of intraoperative neurophysiological monitoring (IONM) techniques such as somatosensory evoked potential (SSEP) and electroencephalography (EEG) can be used to monitor cerebral perfusion throughout the duration of the surgery and to predict the need for a selective shunt after cross-clamping. Additional use of transcranial Doppler (TCD) in the multimodality approach can aid in visualizing the cerebral blood flow and detecting any microemboli that may also cause a stroke. A multimodality IONM approach has been reported as more sensitive and specific for predicting and minimizing any postoperative neurological deficits.

Advances in Intraoperative Neurophysiological Monitoring Techniques in Transnasal Endoscopic Skull Base Surgery

Transnasal endoscopic skull base surgery has been increasing in volume in recent years and its indications are constantly expanding. The potential occurrence of intraoperative and postoperative neurovascular complications deserves special attention from neurosurgeons. Multimodal intraoperative neurophysiological monitoring technology allows neurosurgeons to monitor cerebral perfusion and the functional status of the associated cranial nerves in real time, thereby enabling surgeons to make prompt adjustments in surgical procedures and strategies and reduce the risks of postoperative neurological complications in patients. Based on available literature, we reviewed how appropriate monitoring strategies were optimized for different key components of transnasal endoscopic skull base procedures, intending to provide reference for clinicians.

Surgery for intramedullary spinal cord ependymomas in the neuromonitoring era: results from a consecutive series of 100 patients.

The established treatment of intramedullary spinal cord ependymomas (ISCEs) is resection. Surgical series reporting treatment results often lack homogeneity, as these are collected over long time spans and their analysis is plagued by surgical learning curves and inconsistent use of intraoperative neurophysiological monitoring (IONM). The authors report the oncological and functional long-term outcomes in a modern series of 100 consecutive ISCEs that were resected between 2000 and 2015 by a surgically experienced team that consistently utilized IONM. In this retrospective study, the authors tailored surgical strategy and multimodal IONM, including somatosensory evoked potentials, muscle motor evoked potentials (mMEPs), and D-waves, with the aim of gross-total resection (GTR). Preservation of the D-wave was the primary objective, and preservation of mMEPs was the second functional objective. Functional status was evaluated using the modified McCormick Scale (MMS) preoperatively, postoperatively, and at follow-up. Preoperatively, 89 patients were functionally independent (MMS grade I or II). A GTR was achieved in 89 patients, 10 patients had a stable residual, and 1 patient underwent reoperation for tumor progression. At a mean follow-up of 65.4 months, 82 patients were functionally independent, and 11 lost their functional independence after surgery (MMS grades III-V). Muscle MEP loss predicted short-term postoperative worsening (p < 0.0001) only, while the strongest predictors of a good functional long-term outcome were lower preoperative MMS grades (p < 0.0001) and D-wave preservation. D-wave monitorability was 67%; it was higher with lower preoperative MMS grades and predicted a better recovery (p = 0.01). In this large series of ISCEs, a high rate of GTR and long-term favorable functional outcome were achieved. Short- and long-term functional outcomes were best reflected by mMEPs and D-wave monitoring, respectively.

Predictors of functional outcome after spinal cord surgery: Relevance of intraoperative neurophysiological monitoring combined with preoperative neurophysiological and MRI assessments

ObjectivesTo assess the accuracy of intraoperative neurophysiological monitoring (IONM) in predicting immediate and 3-month postoperative neurological new deficit (or deterioration) in patients benefiting from spinal cord (SC) surgery; and to identify factors associated with a higher risk of postoperative clinical worsening. MethodsConsecutive patients who underwent SC surgery with IONM were included. Pre and postoperative clinical (modified McCormick scale), radiological (lesion-occupying area ratio), and electrophysiological features were collected. ResultsA total of 99 patients were included: 14 (14.1%) underwent extradural surgery, 50 (50.5%) intradural extramedullary surgery, and 35 (35.4%) intramedullary surgery. Cumulatively, multimodal IONM (motor and somatosensory evoked potentials, D-wave whenever possible) significantly predicted postoperative deficits (p<0.001), with a sensitivity, specificity, positive predictive value, and negative predictive value of 0.81, 0.93, 0.83, and 0.92, respectively. Sixty (60.6%) patients displayed no IONM change, whereas 39 (39.4%) displayed IONM worsening. In multivariate analysis, predictors for postoperative clinical worsening were: abnormal preoperative electrophysiological assessment (p=0.03), intramedullary tumor (p<0.001), lesion-occupying area ratio ≥0.7 (p<0.001), and IONM alterations (p<0.001). Three months after the surgical procedure, in patients presenting at least one of the risk factors described above, 45/81 (55.6%) and 19/81 (23.5%) were clinically and electrophysiologically improved, respectively; while 13/81 (16.0%) and 10/81 (12.3%) were clinically and electrophysiologically worsened. ConclusionMultimodal IONM is an essential tool to guide SC surgery, and enables the accurate prediction of postoperative neurological outcome. Specific attention should be given to patients presenting with preoperative electrophysiological abnormalities, large tumor volume, and intramedullary tumor location.

Evaluation of multimodal intraoperative neurophysiologic monitoring during supratentorial aneurysm surgery: a comparative study.

The objective of this study is to determine the role of multimodal intraoperative neurophysiologic monitoring (IONM) in the overall outcome of intracranial aneurysms surgery, and the risk factors associated with ischemic complications. We grouped 268 ruptured and unruptured intracranial aneurysms surgically treated at our institution into 2 cohorts, based on the use of IONM (180; 67.16%) or non-use of IONM (88; 32.84%). The IONM technique used was multimodal: electroencephalogram (EEG), somatosensory evoked potentials (SSEPs), transcranial (TES), and direct cortical (DCS) stimulation motor evoked potentials (MEPs). There was a significant difference, with a reduction in perioperative strokes (p = 0.011) and better motor surgery-related outcome in the IONM group (p = 0.016). Independent risk factors identified for surgery ischemic complications were temporary clipping time ≥ 6'05″ (odds ratio [OR]: 3.03; 95% CI: 1.068-8.601; p = 0.037), aneurysm size ≥ 7.5mm (OR: 2.65; 95% CI: 1.127-6.235; p = 0.026), and non-use of IONM (OR: 2.79; 95% CI: 1.171-6.636; p = 0.021). Conversely, aneurysm rupture was not detected as an independent risk factor (OR: 2.5; 95% CI: 0.55-4.55; p = 0.4). Longer temporary clipping time, larger aneurysm size, and the non-use of IONM could be considered as risk factors for ischemic complications during microsurgical clipping. A standardized designed protocol including multimodal IONM with DCS provides continuous information about blood supply and allows reduction of treatment-related morbidity. Multimodal IONM is a valuable technique in intracranial aneurysm surgery.