Intraoperative neurophysiological monitoring for intradural extramedullary tumors: Why not?

Diagnostic Accuracy of Somatosensory Evoked Potential and Transcranial Motor Evoked Potential in Detection of Neurological Injury in Intradural Extramedullary Spinal Cord Tumor Surgeries: A Short-Term Follow-Up Prospective Interventional Study Experience from Tertiary Care Center of India

Objective  Intraoperative neuromonitoring (IONM) is an acknowledged tool for real-time neuraxis assessment during surgery. Somatosensory evoked potential (SSEP) and transcranial motor evoked potential (MEP) are commonest deployed modalities of IONM. Role of SSEP and MEP in intradural extramedullary spinal cord tumor (IDEMSCT) surgery is not well established. The aim of this study was to evaluate sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of SSEP and transcranial MEP, in detection of intraoperative neurological injury in IDEMSCT patients as well as their postoperative limb-specific neurological improvement assessment at fixed intervals till 30 days. Materials and Methods  Symptomatic patients with IDEMSCTs were selected according to the inclusion criteria of study protocol. On modified McCormick (mMC) scale, their sensory-motor deficit was assessed both preoperatively and postoperatively. Surgery was done under SSEP and MEP (transcranial) monitoring using appropriate anesthetic agents. Gross total/subtotal resection of tumor was achieved as per IONM warning alarms. Sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of SSEP and MEP were calculated considering postoperative neurological changes as "reference standard." Patients were followed up at postoperative day (POD) 0, 1, 7, and 30 for convalescence. Statistical Analysis  With appropriate tests of significance, statistical analysis was carried out. Receiver-operating characteristic curve was used to find cutoff point of mMC for SSEP being recordable in patients with higher neurological deficit along with calculation of sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of SSEP and MEP for prediction of intraoperative neurological injury. Results  Study included 32 patients. Baseline mean mMC value was 2.59. Under neuromonitoring, gross total resection of IDEMSCT was achieved in 87.5% patients. SSEP was recordable in subset of patients with mMC value less than or equal to 2 with diagnostic accuracy of 100%. MEP was recordable in all patients and it had 96.88% diagnostic accuracy. Statistically significant neurological improvement was noted at POD-7 and POD-30 follow-up. Conclusion  SSEP and MEP individually carry high diagnostic accuracy in detection of intraoperative neurological injuries in patients undergoing IDEMSCT surgery. MEP continues to monitor the neuraxis, even in those subsets of patients where SSEP fails to record.

Intraoperative Neurophysiological Monitoring for Intradural Extramedullary Spinal Tumours

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

Intraoperative neurophysiological monitoring (IONM) is widely used in spinal neurosurgery, particularly for intramedullary tumours. However, its validity in intradural extramedullary (IDEM) spinal tumours is less clearly defined, this being the focus of this study.

METHODS

We compared outcomes for patients that underwent resection of IDEM tumours with and without IONM between 2010 and 2020. Primary outcomes were postoperative American Spinal Injury Association (ASIA) scores. Other factors assessed were use of intraoperative ultrasound, drain placement, postoperative complications, postoperative Eastern Cooperative Oncology Group (ECOG) score, extent of resection, length of hospital stay, discharge location and recurrence.

RESULTS

163 patients were included, 71 patients in the IONM group and 92 in the non-IONM group. No significant differences were noted in baseline demographics. For preoperative ASIA D patients, 44.0% remained ASIA D and 49.9% improved to ASIA E in the IONM group, compared to 39.7% and 30.2% respectively in the non-IONM group. For preoperative ASIA E patients, 50.3% remained ASIA E and 44.0% deteriorated to ASIA D in the IONM group, compared to 30.2% and 39.7% respectively in the non-IONM group (all other patients deteriorated further). Length of inpatient stay was significantly shorter in the IONM group (P = .043). There were no significant differences in extent of resection, postoperative complications, discharge location or tumour recurrence.

CONCLUSIONS

Research focusing on the use of IONM in IDEM tumour surgery remains scarce. Our study supports the use of IONM during surgical excision of IDEM tumours.

Accuracy of Intraoperative Neuromonitoring in the Diagnosis of Intraoperative Neurological Decline in the Setting of Spinal Surgery-A Systematic Review and Meta-Analysis

STUDY DESIGN

Systematic review and meta-analysis.

OBJECTIVES

In an effort to prevent intraoperative neurological injury during spine surgery, the use of intraoperative neurophysiological monitoring (IONM) has increased significantly in recent years. Using IONM, spinal cord function can be evaluated intraoperatively by recording signals from specific nerve roots, motor tracts, and sensory tracts. We performed a systematic review and meta-analysis of diagnostic test accuracy (DTA) studies to evaluate the efficacy of IONM among patients undergoing spine surgery for any indication.

METHODS

The current systematic review and meta-analysis was performed using the Preferred Reporting Items for a Systematic Review and Meta-analysis statement for Diagnostic Test Accuracy Studies (PRISMA-DTA) and was registered on PROSPERO. A comprehensive search was performed using MEDLINE, EMBASE and SCOPUS for all studies assessing the diagnostic accuracy of neuromonitoring, including somatosensory evoked potential (SSEP), motor evoked potential (MEP) and electromyography (EMG), either on their own or in combination (multimodal). Studies were included if they reported raw numbers for True Positives (TP), False Negatives (FN), False Positives (FP) and True Negative (TN) either in a 2 × 2 contingency table or in text, and if they used postoperative neurologic exam as a reference standard. Pooled sensitivity and specificity were calculated to evaluate the overall efficacy of each modality type using a bivariate model adapted by Reitsma et al, for all spine surgeries and for individual disease groups and regions of spine. The risk of bias (ROB) of included studies was assessed using the quality assessment tool for diagnostic accuracy studies (QUADAS-2).

RESULTS

A total of 163 studies were included; 52 of these studies with 16,310 patients reported data for SSEP, 68 studies with 71,144 patients reported data for MEP, 16 studies with 7888 patients reported data for EMG and 69 studies with 17,968 patients reported data for multimodal monitoring. The overall sensitivity, specificity, DOR and AUC for SSEP were 71.4% (95% CI 54.8-83.7), 97.1% (95% CI 95.3-98.3), 41.9 (95% CI 24.1-73.1) and .899, respectively; for MEP, these were 90.2% (95% CI 86.2-93.1), 96% (95% CI 94.3-97.2), 103.25 (95% CI 69.98-152.34) and .927; for EMG, these were 48.3% (95% CI 31.4-65.6), 92.9% (95% CI 84.4-96.9), 11.2 (95% CI 4.84-25.97) and .773; for multimodal, these were found to be 83.5% (95% CI 81-85.7), 93.8% (95% CI 90.6-95.9), 60 (95% CI 35.6-101.3) and .895, respectively. Using the QUADAS-2 ROB analysis, of the 52 studies reporting on SSEP, 13 (25%) were high-risk, 10 (19.2%) had some concerns and 29 (55.8%) were low-risk; for MEP, 8 (11.7%) were high-risk, 21 had some concerns and 39 (57.3%) were low-risk; for EMG, 4 (25%) were high-risk, 3 (18.75%) had some concerns and 9 (56.25%) were low-risk; for multimodal, 14 (20.3%) were high-risk, 13 (18.8%) had some concerns and 42 (60.7%) were low-risk.

CONCLUSIONS

These results indicate that all neuromonitoring modalities have diagnostic utility in successfully detecting impending or incident intraoperative neurologic injuries among patients undergoing spine surgery for any condition, although it is clear that the accuracy of each modality differs.PROSPERO Registration Number: CRD42023384158.

The role of intraoperative neurophysiological monitoring in intramedullary spinal cord tumor surgery

Intramedullary tumors are a class of central nervous system tumors with an incidence of 2 to 4%. As they are located very deep and frequently cause postoperative neurological complications, surgical resection is difficult. In recent years, many surgeons have performed electrophysiological monitoring to effectively reduce the occurrence of postoperative neurological complications. Modern electrophysiological monitoring technology has advanced considerably, leading to the development of many monitoring methods, such as SSEPs, MEPs, DCM, and EMG, to monitor intramedullary tumors. However, electrophysiological monitoring in tumor resection is still being studied. In this article, we discussed the different monitoring methods and their role in monitoring intramedullary tumors by reviewing previous studies. Intratumorally tumors need to be monitored for a summary of the condition of the patient. Only by using various monitoring methods flexibly and through clear communication between surgeons and neurophysiological experts can good decisions be made during surgery and positive surgical results be achieved.

The role of intraoperative extensor digitorum brevis muscle MEPs in spinal surgery

PURPOSE

Intraoperative muscle motor evoked potentials (m-MEPs) are widely used in spinal surgery with the aim of identifying a damage to spinal cord at a reversible stage. Generally, lower limb m-MEPs are recorded from abductor hallucis [AH] and the tibialis anterior [TA]. The purpose of this work is to study an unselected population by recording the m-MEPs from TA, AH and extensor digitorum brevis (EDB), with the aim of identifying the most adjustable and stable muscles responses intraoperatively.

METHODS

Transcranially electrically induced m-MEPs were intraoperative recorded in a total of 107 surgical procedures. m-MEPs were recorded by a needle electrode placed in the muscle from TA, AH and EDB muscles in the lower extremities.

RESULTS

Overall monitorability (i.e., at least 1 Lower Limb m-MEP recordable) was 100/107 (93.5%). In the remaining 100 surgeries in 3 cases, the only muscle that could be recorded at baseline was one AH, and in other 2 the EDB. Persistence (i.e., the recordability of m-MEP from baseline to the end of surgery) was 88.7% for TA, 89.8% for AH and 93.8% for EDB.

CONCLUSION

In our series, EDB m-MEPs have demonstrated a recordability superior to TA and a stability similar to AH. The explanations may be different and range from changes in the excitability of the cortical motor neuron to the different sensitivity to ischemia of the spinal motor neuron. EDB can be used alternatively or can be added to TA and AH as a target muscle of the lower limb in spinal surgery.

Factors Related to the Deterioration of Postoperative Lower Back Pain in Hemilaminectomy Approach for Lumbar Spinal Schwannoma Resection

Objective

This study aimed to explore the related risk factors in patients who underwent hemilaminectomy for lumbar spinal schwannoma resection and who experienced deterioration of postoperative lower back pain in comparison to preoperative pain levels.

Methods

This retrospective study recruited 61 patients from the First Affiliated Hospital of An Hui Medical University between January 2018 and June 2019. All data were collected from clinical records and analyzed at 1-month and at 1-year follow-up. The visual analog scale (VAS) was used to evaluate pain, and neurologic function was assessed using the Modified McCormick Scale. Intraoperative neurophysiological monitoring was used to assess neuronal integrity and mitigate injury. Statistical analysis of the data was performed using the SPSS version 19 software.

Results

Preoperative pain improved dramatically in the 1-year follow-up (VAS: preoperative, 3.84±2.19; 1-year follow-up, 2.13±2.26; P<0.001). The pain-improved group and worsened group showed a significant difference at 1-month (VAS: 1.76±1.56; 5.54±1.26; P<0.05) and at 1-year (VAS: 0.83±1.09; 4.80±1.58; P<0.05) follow-up. The pain-improved and worsened groups had a significant difference in tumor size and hemilaminectomy removal segments at 1-month and 1-year follow-up, but A-train occurrence on electromyography could only be seen as a statistical difference in the 1-month follow-up. Logistic regression analysis revealed that tumor size was an independent risk factor for postoperative lower back pain deterioration.

Conclusion

The hemilaminectomy approach is a safe and effective method that can dramatically relieve pain in spinal lumbar schwannoma resection. Tumor size is an independent risk factor for postoperative lower back pain. A-train on spontaneous electromyography has been shown to be a reliable predictive factor for the evaluation of postoperative lower back pain. However, further detailed analysis of A-train characteristics can provide a more accurate warning during surgery.

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

BACKGROUND/PURPOSE

Extramedullary 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.

METHODS

We 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.

RESULTS

Mean 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.

DISCUSSION

Multimodal 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.

Is There a Role for Intraoperative Neuromonitoring in Intradural Extramedullary Spine Tumors? Results and Indications from an Institutional Series

While intraoperative neurophysiological monitoring (IONM) is considered a standard for intramedullary spinal cord tumor surgery, the effective role of IONM in intradural extramedullary (IDEM) tumors is still debated. We present the results of 60 patients affected by IDEM tumors undergoing surgery with the aid of IONM. Each patient was evaluated according to the modified McCormick scale (MMS) at admission, discharge and at follow-up. During surgery, motor evoked potentials (MEPs) and somatosensory evoked potentials (SEPs) were studied using the Medtronic NIM-eclipse^® 32-channel system (Medtronic Xomed, Inc. 6743 Southpoint Drive North Jacksonville FL USA). Patients' age, gender and tumor location did not affect MMS modifications. Tumors involving more than three levels had an increased likelihood of MMS worsening, while meningioma pathology was associated with worse preoperative and 1-year follow-up MMS. No MEP amplitude ratio was able to predict clinical variations, while intraoperative SEP worsening was associated with 100% risk of poor MMS at discharge and with 50% risk of poor MMS at long-term follow-up. In our opinion, SEP monitoring is a valid tool that may contribute to the preservation of the patient's neurological status. MEP monitoring is not mandatory in IDEM surgery while more studies are required to explore the feasibility and the role of D-wave in this kind of surgery.

Intradural extramedullary tumor location in the axial view affects the alert timing of intraoperative neurophysiologic monitoring

OBJECTIVE

Intraoperative neurophysiologic monitoring (IONM) reportedly helps prevent postoperative neurological complications following high-risk spinal cord surgeries. There are negative and positive reports about using IONM for intradural extramedullary (IDEM) tumors. We investigated factors affecting alerts of IONM in IDEM tumor surgery.

METHODS

We analyzed 39 patients with IDEM tumors who underwent surgery using IONM at our hospital between January 2014 and March 2021. Neurological symptoms were evaluated pre- and postoperatively using the manual muscle test (MMT). All patients were evaluated to ascertain the tumor level and location in the axial view, the operative time, intraoperative bleeding volume, and histological type. Additionally, the intraoperative procedure associated with significant IONM changes in transcranial electrical stimulation muscle-evoked potential was investigated.

RESULTS

There were 11 false-positive and 16 true-negative cases. There was one true-positive case and one false-negative case; the monitoring accuracy achieved a sensitivity of 50%, a specificity of 59%, a positive predictive value of 8%, and a negative predictive value of 94%. In the 22 alert cases, if the tumor was located anterolateral in the axial view, alerts were triggered with a significant difference (p = 0.02) during tumor resection. Alerts were generated for fifteen patients during tumor resection; nine (60%) showed waveform improvement by intervention and were classified as rescue cases.

CONCLUSION

Alert is probably triggered during tumor resection for anterolaterally located tumors. Alerts during tumor resection procedures were more likely to be rescued than other procedures in IDEM tumor surgery.

Predictive Value of Motor Evoked Potentials in the Resection of Intradural Extramedullary Spinal Tumors in Children

This study aimed to evaluate the predictive value of motor evoked potentials (MEP) in the resection of pediatric intradural extramedullary (IDEM) tumors. Additionally, we aimed to assess the impact of MEP alerts on the extent of tumor resection. Medical records of pediatric patients who underwent resection of IDEM tumors with the assistance of MEP between March 2011 and October 2020 were reviewed. The occurrence of postoperative motor deficits was correlated with intraoperative MEP alerts. Sixteen patients were included. MEP alerts appeared in 2 patients (12.5%), being reflective of new postoperative motor deficits. Among the remaining 14 patients without any intraoperative MEP alerts, no motor decline was found. Accordingly, MEP significantly predicted postoperative motor deficits, reaching sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 100% (p < 0.001). In the absence of MEP alerts, 11 out of 14 patients (78.6%) underwent GTR, while no patient with intraoperative IONM alerts underwent GTR (p = 0.025). Although MEP alerts limit the extent of tumor resection, the high sensitivity and PPV of MEP underline its importance in avoiding iatrogenic motor deficits. Concurrently, high specificity and NPV ensure safer tumor excision. Therefore, MEP can reliably support surgical decisions in pediatric patients with IDEM tumors.

Characteristics of Tc-MEP Waveforms for Different Locations of Intradural Extramedullary Tumors: A Prospective Multicenter Study of the Monitoring Committee of the Japanese Society for Spine Surgery and Related Research

STUDY DESIGN

Prospective multicenter study.

OBJECTIVE

To examine transcranial motor-evoked potential (Tc-MEP) waveforms in intraoperative neurophysiological monitoring in surgery for intradural extramedullary (IDEM) tumors, focused on the characteristics for cervical, thoracic, and conus lesions.

SUMMARY OF BACKGROUND DATA

IDEM tumors are normally curable after resection, but neurological deterioration may occur after surgery. Intraoperative neurophysiological monitoring using Tc-MEPs during surgery is important for timely detection of possible neurological injury.

METHODS

The subjects were 233 patients with IDEM tumors treated surgically with Tc-MEP monitoring at 9 centers. The alarm threshold was ≥70% waveform deterioration from baseline. A case with a Tc-MEP alert that normalized and had no new motor deficits postoperatively was defined as a rescue case. A deterioration of manual muscle test score ≥1 compared to the preoperative value was defined as postoperative worsening of motor status.

RESULTS

The 233 patients (92 males, 39%) had a mean age of 58.1 ± 18.1 years, and 185 (79%), 46 (20%), and 2 (1%) had schwannoma, meningioma, and neurofibroma. These lesions had cervical (C1-7), thoracic (Th1-10), and conus (Th11-L2) locations in 82 (35%), 96 (41%), and 55 (24%) cases. There were no significant differences in preoperative motor deficit among the lesion levels. Thoracic lesions had a significantly higher rate of poor baseline waveform derivation (0% cervical, 6% thoracic, 0% conus, P < 0.05) and significantly more frequent intraoperative alarms (20%, 31%, 15%, P < 0.05). Use of Tc-MEPs for predicting neurological deficits after IDEM surgery had sensitivity of 87% and specificity of 89%; however, the positive predictive value was low.

CONCLUSION

Poor derivation of waveforms, appearance of alarms, and worse final waveforms were all significantly more frequent for thoracic lesions. Thus, amplification of the waveform amplitude, using multimodal monitoring, and more appropriate interventions after an alarm may be particularly important in surgery for thoracic IDEM tumors.Level of Evidence: 3.

A case of chronic dysaesthesia in the torso and upper limbs: lessons from a cervical spinal cord subependymoma

INTRODUCTION

Subependymomas are slow growing WHO grade 1 tumours, typically attached to the ventricular wall of the fourth or lateral ventricles. Spinal subependymomas are rarer still and experience of their biological characteristics remains limited.

CASE PRESENTATION

A 29-year-old lady presented with chronic attacks of itchy dysaesthesia involving the left hand, neck and trunk, and associated with ipsilateral leg spasms. Recent symptomatic change involved occasional limping and left sided facial numbness but no pain. MRI showed an intradural mass surrounding most of the cervical spinal cord, which appeared scalloped extrinsically, rather than diffusely expanded, by a seemingly extramedullary lesion. At operation, the cord appeared expanded, with no clear margin or distinction between tumour and cord tissue; and the tumour was found to be intramedullary with an exophytic component, rather than extramedullary. Moderate reduction of the left abductor pollicis brevis evoked potential led to a pause in surgery. There was transient hand weakness postoperatively with full recovery, and no radiological change in the tumour morphology for a further 6 years.

DISCUSSION

An intramedullary tumour such as a spinal cord subependymoma can be mistaken radiologically for an extramedullary tumour, such as an epidermoid. If a subependymoma is suspected, given its indolent course and long-term survival, caution in the extent of surgical resection is advisable in order to avoid surgical morbidity.

Intraoperative Monitoring for Cauda Equina Tumors: Surgical Outcomes and Neurophysiological Data Accrued Over 10 Years

OBJECTIVE

Cauda equina tumors affect the peripheral nervous system, and the validities of triggered electromyogram (tEMG) and intraoperative neurophysiologic monitoring (IOM) are unclear. We sought to evaluate the accuracy and relevance of tEMG combined with IOM during cauda equina tumor resection.

METHODS

Between 2008 and 2018, an experienced surgeon performed cauda equina tumor resections using tEMG at a single institution. A cauda equina tumor was defined as an intradural-extramedullary or intradural-extradural tumor at the level of L2 or lower. The clinical presentation, extent of resection, pathology, recurrence, postoperative neurological outcomes, and intraoperative tEMG mapping and IOM data were retrospectively analyzed.

RESULTS

One hundred three patients who underwent intraoperative tEMG were included; 38 underwent only tEMG (tEMG-only group), and 65 underwent a combination of tEMG and multimodal IOM (MIOM group). There were no significant differences between the neurologic outcomes, extents of resection, or recurrence rates of the 2 groups. No significant therapeutic benefit was observed; however, the accuracy of intraoperative predetection improved with the combination of IOM and tEMG (accuracy: tEMG-only group, 86.8%; MIOM group, 92.3%). When the involved rootlet was resected despite the positive tEMG result, motor function worsened in 3 of 8 cases. The sensitivity and specificity of tEMG were 37.5% and 94.7%, respectively.

CONCLUSION

tEMG is an essential adjunctive surgical tool for deciding on and planning for rootlet resection. If the tEMG finding is negative, complete resection, involving the rootlet, may be safe. The accuracy may be further improved by using a combination of tEMG and IOM.

Correlation of Intraoperative Neurophysiological Parameters and Outcomes in Patients with Intramedullary Tumors

Introduction

Intramedullary spinal cord tumors (IMSCT) account for about 2%-4% of all central nervous system tumors. Surgical resection is the main treatment step, but might cause damage to functional tissues. Intraoperative neuromonitoring (IONM) is an adopted measure to decrease surgical complications. Below, we describe the results of IMSCT submitted to surgery under IONM at a tertiary institution.

Methods

The sample consisted of consecutive patients with IMSCT admitted to the Neurological Institute of Curitiba from January 2007 to November 2016. A total of 47 patients were surgically treated. Twenty-three were male (48.9%) and 24 were female (51.1%). The mean age was 42.77 years. The mean follow-up time was 42.7 months.

Results

Neurological status improved in 29 patients (62%), stable in 6 (13%), and worse in 12 (25%). Patients who presented with motor symptoms at initial diagnosis had a worse outcome compared to patients with sensory impairment and pain (P = 0.026). Patients with a change in electromyography had worse neurological outcomes compared to patients who did not show changes in monitoring (P = 0.017).

Discussion and Conclusion

No prospective randomized high evidence study has been performed to date to compare clinical evolution after surgery with or without monitoring. In our sample, surgical resection was well succeeded mainly in oligosymptomatic patients with low preoperative McCormick classification and no worsening of IONM during surgery. We believe that microsurgical resection of IMSCT with simultaneous IONM is the gold standard treatment and achieved with good results.

Correlations between preoperative clinical factors and treatment outcome of spinal meningiomas - A retrospective study of a series of 31 cases

Background:

The purpose of the current study is to identify the correlations between the most important preoperative clinical factors and the outcome of surgery of spinal meningiomas (SM).

Methods:

We performed a retrospective analysis of the medical history, clinical, paraclinical, neuroimaging, and surgical protocol data in 31 patients with SM who underwent surgical resection at our institution from January 2011 to July 2020. The degree of resection was assessed on the Simpson scale. The modified McCormick scale was used to monitor the effect and outcome of treatment at admission, discharge, and at further follow-up.

Results:

The average age of the patients was 65 years (37-78). Vertebral pain and motor deficits were the most common initial symptoms that occurred in 26 (89.6%) and 29 (93.5%) patients, respectively. Sphincter disorders were found in 9 (29%) patients. Total resection (Simpson Grade I – II) was achieved in 29 patients (93.5%). We achieved a favorable outcome (McCormick Gr. I to III) in 93.3% of patients. The degree of the neurological deficit (P = 0.026) and the presence of sphincter disorders (P = 0.009) were the preoperative clinical factors that most significantly correlated with the outcome of treatment.

Conclusion:

The outcome from the surgical treatment of SM correlated significantly with the degree of the preoperative neurological deficit. Therefore, patients presenting with more severe symptoms are expected to have worse outcomes.

Neurophysiological Intraoperative Monitoring in the Elderly

INTRODUCTION

Intraoperative neurophysiological monitoring (IONM) is widely used to prevent nervous system injury during surgeries in elderly patients. However, there are no studies that describe the characteristics and changes in neurophysiological tests during the IONM of patients aged 60 years and older. The study aims to describe and compare IONM changes during surgeries in adult patients aged 18 to 59 years with those aged 60 years and older.

METHODS

We performed a comparative retrospective study of patients aged 18 to 59 years versus those 60 aged years and older who underwent IONM during 2013 to 2018 in Mexico City. Sociodemographic characteristics were recorded and compared. Intraoperative neurophysiological monitoring techniques, their changes, and surgical procedures for both groups were analyzed and compared using descriptive statistics, Mann-Whitney U, Fisher, and χ2 tests. The sensitivity, specificity, and positive and negative predictive values were calculated.

RESULTS

In total, 195 patients were analyzed: 104 patients, 68.63 ± 6.54 years old (elderly group) and 91 patients, 42.3 ± 10.5 years old (younger group). No differences were found in the rates of signal change during IONM between the group of elderly patients and the younger group. The sensitivity, specificity, and positive and negative predictive values were 80%, 99%, 80%, and 99%, respectively.

CONCLUSIONS

Elderly patients have a similar rate of changes in IONM signals compared with younger patients during heterogeneous surgeries guided by IONM.

Intraoperative evoked potentials in patients with ossification of posterior longitudinal ligament

Preoperative somatosensory evoked potentials (preSEPs) are used to evaluate the severity of myelopathy, and intraoperative neurophysiological monitoring (IONM) is used to reduce iatrogenic damage during operations. However, the correlation between preSEPs and IONM on postoperative neurologic deterioration (PND) in ossification of the posterior longitudinal ligament (OPLL) has not been studied. Thus, under the hypothesis that the patients with deteriorated preSEPs would be more likely to have significant changes in intraoperative SEPs (ioSEPs), and that this would be correlated with PND, we investigated the prognostic value of preSEPs on IONM and PND. This retrospective study included 265 patients who underwent preSEPs and IONM between January 2015 and July 2019. Muscle strength, the sensory scale of the Japanese Orthopaedic Association score examined within 3 days preoperatively, and at 48 h and 4 weeks postoperatively, was analysed. PreSEPs and intraoperative SEPs (ioSEPs) were recorded by stimulating the median and tibial nerves. Intraoperative motor evoked potentials (ioMEPs) were elicited by transcranial electrical stimulation over the motor cortex. PreSEPs latency prolongation of the median and tibial nerves showed significant correlations with ioSEPs. PMD at 48 h or 4 weeks after surgery correlated with ioSEPs and ioMEPs amplitudes. Postoperative sensory deterioration (PSD) at 48 h or 4 weeks after surgery correlated with latency prolongation of ioSEPs. There was a positive correlation between amount of blood loss and maximum percentage of ioSEPs latency prolongation and a negative correlation with PMD at 48 h and 4 weeks postoperatively. PreSEPs predict significant changes in ioSEPs. Furthermore, bleeding control is important to reduce PMD in OPLL.

Single-Staged Management of Pediatric Neuropathic Scoliosis with Intradural-Extramedullary Schwannoma and Improvement in Intraoperative Neuromonitoring: A Case Report

CASE

A 16-year-old girl with lumbar prominence presented to our outpatient clinic complaining of sporadic back pain without paresthesia. Radiographic investigation revealed a 68° left thoracolumbar curve with the apex at L1. Preoperative magnetic resonance imaging identified a mass at T10-11, subsequently confirmed by pathology as a schwannoma. She was treated surgically with resection and posterior spinal fusion in a single-staged procedure under neuromonitoring guidance. Intraoperative improvement in motor evoked potentials after resection informed the decision to perform simultaneous deformity correction.

CONCLUSION

We discuss the unusual coincidence of a schwannoma with scoliosis and our management algorithm based on operative changes in neuromonitoring.

Poor derivation of Tc-MEP baseline waveforms in surgery for ventral thoracic intradural extramedullary tumor: Efficacy of use of the abductor hallucis in cases with a preoperative non-ambulatory status

Most thoracic intradural extramedullary tumors (IDEMT) are benign lesions that are treated by gross total resection and spinal cord decompression. Intraoperative transcranial-motor evoked potential (Tc-MEP) monitoring is important for reducing postoperative neurological complications. The purpose of this study is to examine the characteristics of Tc-MEP waveforms in surgery for thoracic IDEMT resection based on location of the tumor relative to the spinal cord. The subjects were 56 patients who underwent surgery for thoracic IDEMT from 2010 to 2018. The waveform derivation rate for each lower muscle was examined at baseline and intraoperatively. 56 patients had a mean age of 61.7 years, and 21 (38%) were non-ambulatory before surgery. The tumors were schwannoma (n = 28, 50%), meningioma (n = 25, 45%), and neurofibroma (n = 3, 5%); and the lesions were dorsal (n = 29, 53%) and ventral (n = 27, 47%). There was a significantly higher rate of undetectable waveforms in all lower limb muscles in the ventral group compared to the dorsal group (15% vs. 3%, p < 0.05). In non-ambulatory cases, the derivation rate at baseline was significantly lower for ventral thoracic IDMETs (47% vs. 68%, p < 0.05). The abductor hallucis (AH) had the highest waveform derivation rate of all lower limb muscles in non-ambulatory cases with a ventral thoracic IDMET. Spinal cord compression by a ventral lesion may be increased, and this may be reflected in greater waveform deterioration. Of all lower limb muscles, the AH had the highest derivation rate, even in non-ambulatory cases with a ventral IDEMT, which suggests the efficacy of multichannel monitoring including the AH.

Management of Extramedullary Intradural Spinal Tumors: The Impact of Clinical Status, Intraoperative Neurophysiological Monitoring and Surgical Approach on Outcomes in a 12-Year Double-Center Experience

Objective: Intradural Extramedullary (IDEM) tumors are usually treated with surgical excision. The aim of this study was to investigate the impact on clinical outcomes of pre-surgical clinical conditions, intraoperative neurophysiological monitoring (IONM), surgical access to the spinal canal, histology, degree of resection and intra/postoperative complications.

Methods: This is a retrospective observational study analyzing data of patients suffering from IDEM tumors who underwent surgical treatment over a 12 year period in a double-center experience. Data were extracted from a prospectively maintained database and included: sex, age at diagnosis, clinical status according to the modified McCormick Scale (Grades I-V) at admission, discharge, and follow-up, tumor histology, type of surgical access to the spinal canal (bilateral laminectomy vs. monolateral laminectomy vs. laminoplasty), degree of surgical removal, use and type of IONM, occurrence and type of intraoperative complications, use of Ultrasonic Aspirator (CUSA), radiological follow-up.

Results: A total number of 249 patients was included with a mean follow-up of 48.3 months. Gross total resection was achieved in 210 patients (84.3%) mostly in Schwannomas (45.2%) and Meningiomas (40.4%). IONM was performed in 162 procedures (65%) and D-wave was recorded in 64.2% of all cervical and thoracic locations (99 patients). The linear regression diagram for McCormick grades before and after surgery (follow-up) showed a correlation between preoperative and postoperative clinical status. A statistically significant correlation was found between absence of worsening of clinical condition at follow-up and use of IONM at follow-up (p = 0.01) but not at discharge. No associations were found between the choice of surgical approach and the extent of resection (p = 0.79), the presence of recurrence or residual tumor (p = 0.14) or CSF leakage (p = 0.25). The extent of resection was not associated with the use of IONM (p = 0.91) or CUSA (p = 0.19).

Conclusion: A reliable prediction of clinical improvement could be made based on pre-operative clinical status. The use of IONM resulted in better clinical outcomes at follow-up (not at discharge), but no associations were found with the extent of resection. The use of minimally invasive approaches such as monolateral laminectomy showed to be effective and not associated with worse outcomes or increased complications.

Multimodal Intraoperative Monitoring During Microsurgical Treatment of Spinal Dural Arteriovenous Fistula

We report here a case to illustrate the potential intraoperative multimodal monitoring options available for safe ligation of spinal dural arteriovenous fistula (DAVF). The success of microsurgical treatment depends on the correct identification of the arterial feeder and monitoring the functional integrity of the corticospinal tract.

Spinal meningiomas: Treatment outcome and long-term follow-up

BACKGROUND

Spinal intradural tumors can be classified as intradural extramedullary or intramedullary tumors. Spinal meningiomas are among the most frequent intradural, extramedullary tumors (IDEMs), representing 12 % of all meningiomas and 25-45 % of all intradural spinal tumors.

OBJECTIVE

To evaluate postoperative outcome, defined by mortality, tumor recurrence and modified Rankin Scale in patients with spinal meningiomas. Furthermore, to identify factors related to these outcome measures and define possible prognosticators.

METHODS

A large single center retrospective analysis of 166 consecutive spinal meningioma patients during a 29-year period (1989-2018).

RESULTS

Female to male ratio was 5.15 to 1. Of all 166 resected tumors, 159 were WHO grade I and seven were WHO grade II. Histopathologically, the psammomatous type was most common (42.8 %). The thoracic region was the most frequent location (71.1 %), followed by cervical and lumbar locations. A complete resection (Simpson I-III) was achieved in 88.7 %. In 12 cases (7.2 %) recurrences of a spinal meningioma occurred after an interval of 0.70-13.78 years. Postoperative complications consisted of CSF leakage and wound healing problems. Three patients died of direct postoperative complications (1.8 %), nine patients died in follow-up due to unrelated causes. Post-operative complications were related to the overall outcome (p = 0.029). Clinical outcome showed improvement in 117 patients out of 148 (79.1 %) according to modified Rankin Scale; 24 patients remained stable and 7 patients deteriorated. Patients with pre-existing bladder/bowel problems and incomplete resections had higher chance of recurrences. Younger patients also had a higher recurrence rate. Follow-up ranged from 0 to 23 years, median of 0.77 years, most were discontinued after 2 years.

CONCLUSIONS

The primary treatment of spinal meningiomas remains surgery. Complete resection of spinal meningiomas is achieved in most of the cases, however preserving and improving neurological status has priority over complete tumor resection. Morbidity and mortality is relatively low. Longer follow-up periods are recommended, since recurrences can occur after 10-15 years.

Barriers of neurophysiology monitoring in spine surgery: Latin America experience

Background:

Intraoperative neurophysiological monitoring (IOM) has become valuable in spine surgery. Unfortunately, it is not always available in many spine centers, especially in developing countries. Our aim was to evaluate the accessibility and barriers to IOM in spine surgery in Latin America.

Methods:

We designed a questionnaire to evaluate the characteristics of surgeons and their opinions on the usefulness of IOM for different spine operations. The survey was sent to 9616 members and registered users of AO Spine Latin America (AOSLA) from August 1, 2019, to August 21, 2019. Major variables studied included nationality, years of experience, specialty (orthopedics or neurosurgery), level of complexity of the hospital, number of spine surgeries performed per year by the spine surgeon, the types of spinal pathologies commonly managed, and how important IOM was to the individual surgeon. General questions to evaluate use included accessibility, limitations of IOM usage, management of IOM changes, and the legal value of IOM. The results were analyzed and compared between neurosurgeon and orthopedics, level of surgeon experience, and country of origin.

Results:

Questionnaires were answered by 200 members of AOSLA from 16 different countries. The most common responses were obtained from orthopedic surgeons (62%), those with more than 10 years of practice (54%); majority of surgeons performed more than 50 spine surgeries per year (69%) and treated mainly spine degenerative diseases (76%). Most surgeons think that IOM has a real importance during surgeries (92%) and not just a legal value. Although surgeons mostly considered IOM essential to scoliosis surgery in adolescents (70%), thoracolumbar kyphosis correction (68%), and intramedullary tumors (68%), access to IOM was limited to 57% for economic reasons. Of interest, in 64% of cases, where IOM was available and significant change occurred, the actual operative procedures were significantly altered.

Conclusion:

Despite the fact that 68% of spine surgeons believe IOM to be indispensable for complex spine surgery, cost remains the main barrier to its use/availability in Latin America.

Decompensation of a Thoracic Meningioma Below the Operated Level: A Dramatic and Unexpected Complication

BACKGROUND

Paraplegia after lumbar spinal surgery has been previously described. It was generally provoked by a missed thoracic compression because of degenerative processes, arachnoid cyst, and spinal cord tumor such as meningioma. We describe here a case of a patient with neurofibromatosis type 2 (NF-2) with multiple spinal meningiomas that developed postoperative paraplegia because of decompensation of spinal cord compression below and far from the operated level.

CASE DESCRIPTION

A 54-year-old woman with NF-2 was followed-up for multiple spinal meningiomas (C7-T1, T6-7, T9-10 levels). Surgery for the symptomatic and larger lesion (C7-T1) was scheduled. Postoperatively, the patient was found to have paraplegia with sensor anesthesia below the level of the T6 vertebra. An urgent spinal magnetic resonance imaging (MRI) scan was performed revealing the absence of complication at the operated level (C7-T1) but the appearance of a marked intramedullary hyperintensity at the T6-7 level. An urgent T6-7 laminectomy and removal of the meningioma was performed. The postoperative phase was marked by a poor recuperation. Spinal MRI scan at 3 months clearly showed a severely injured spinal cord at the T6-7 level consistent with the neurologic status of the patient.

CONCLUSIONS

We report here the first case of acute neurologic deterioration after decompensation of a spinal cord compression below the operated level in spinal intradural surgery. Neurosurgeons must be aware of this possible complication when treating patients with multiple spinal meningiomas.

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

OBJECTIVE

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.

METHODS

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.

RESULTS

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%.

CONCLUSIONS

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.

Intraoperative neurophysiological monitoring for intradural extramedullary spinal tumors: predictive value and relevance of D-wave amplitude on surgical outcome during a 10-year experience

OBJECTIVEThe purpose of this study was to evaluate the technical feasibility, accuracy, and relevance on surgical outcome of D-wave monitoring combined with somatosensory evoked potentials (SSEPs) and motor evoked potentials (MEPs) during resection of intradural extramedullary (IDEM) spinal tumors.METHODSClinical and intraoperative neurophysiological monitoring (IONM) data obtained in 108 consecutive patients who underwent surgery for IDEM tumors at the Institute for Scientific and Care Research "ASMN" of Reggio Emilia, Italy, were prospectively entered into a database and retrospectively analyzed. The IONM included SSEPs, MEPs, and-whenever possible-D-waves. All patients were evaluated using the modified McCormick Scale at admission and at 3, 6, and 12 months of follow-up .RESULTSA total of 108 patients were included in this study. A monitorable D-wave was achieved in 71 of the 77 patients harboring cervical and thoracic IDEM tumors (92.2%). Recording of D-waves in IDEM tumors was significantly associated only with a preoperative deeply compromised neurological status evaluated using the modified McCormick Scale (p = 0.04). Overall, significant IONM changes were registered in 14 (12.96%) of 108 patients and 9 of these patients (8.33%) had permanent loss of at least one of the 3 evoked potentials. In 7 patients (6.48%), the presence of an s18278 caudal D-wave was predictive of a favorable long-term motor outcome even when the MEPs and/or SSEPs were lost during IDEM tumor resection. However, in 2 cases (1.85%) the D-wave permanently decreased by approximately 50%, and surgery was definitively abandoned to prevent permanent paraplegia. Cumulatively, SSEP, MEP, and D-wave monitoring significantly predicted postoperative deficits (p = 0.0001; AUC = 0.905), with a sensitivity of 85.7% and a specificity of 97%. Comparing the area under the receiver operating characteristic curves of these tests, D-waves appeared to have a significantly greater predictive value than MEPs and especially SSEPs alone (0.992 vs 0.798 vs 0.653; p = 0.023 and p < 0.001, respectively). On multiple logistic regression, the independent risk factors associated with significant IONM changes in the entire population were age older than 65 years and an anterolateral location of the tumor (p < 0.0001).CONCLUSIONSD-wave monitoring was feasible in all patients without severe preoperative motor deficits. D-waves demonstrated a statistically significant higher ability to predict postoperative deficits compared with SSEPs and MEPs alone and allowed us to proceed with IDEM tumor resection, even in cases of SSEP and/or MEP loss. Patients older than 65 years and with anterolateral IDEM tumors can benefit most from the use of IONM.

Intraoperative Neurophysiologic Monitoring for Lumbar Intradural Schwannomas: Does It Affect Clinical Outcome?

OBJECTIVE

Intraoperative multimodal neuromonitoring (IONM) is considered valuable for the early detection and prevention of any neurologic compromise during spine surgery. It has also become the standard of care at many institutions to improve the surgical outcome and be a safety net for both clinical and medicolegal concerns.

METHODS

Our experience and outcomes in 46 consecutive cases of lumbar intradural schwannoma resection were reviewed with respect to clinical outcomes and patient safety, before and after the integration of IONM into our clinical practice.

RESULTS

Total surgical resection of schwannomas in the lumbar spine led to improved health-related quality of life for patients. The standard technique for microsurgical resection of schwannomas requires identifying and resecting the fiber of origin for the schwannoma, guided with triggered electromyographic monitoring. However, whether this changed the surgical strategy, because spinal roots that gave rise to the schwannoma were frequently found to be nonfunctional during surgery, remains unclear. In our series of 46 patients, we did not recognize any additional motor deficit after the surgery, regardless of the use of IONM.

CONCLUSIONS

Despite our analysis proving no difference in clinical outcomes with or without the use of IONM during surgical excision of lumbar schwannomas, we still prefer using IONM as a standard approach. It adds to the confidence and ease of mind of the surgeon during resection and also provides valuable data in cases of medicolegal disputes. However, it comes with an increased cost and lengthened surgical procedure.

Intraoperative Neurophysiological Monitoring in Surgical Treatment of Spinal Dural Arteriovenous Fistulas: Technique and Results

Objective and Background:

Data on intraoperative neurophysiological monitoring (IOM) during surgery of spinal dural arteriovenous fistulas (SDAVFs) are lacking. The purpose of this study was to evaluate the role of IOM during microsurgery for SDAVFs.

Materials and Methods:

From March 2007 to March 2013, 12 patients had microsurgery with IOM for SDAVFs. The IOM included somatosensory-evoked potentials, motor-evoked potentials (MEPs), and – in selected cases – D-Waves. All patients were evaluated at admission and at follow-up (6, 12, and 24 months) with Aminoff–Logue Disability Scale for Gait-Aminoff–Logue Disability Scale (G-ALS) and Micturition-Aminoff–Logue Disability Scale (M-ALS).

Statistical Analysis Used:

Logistic regression was used for detecting the clinical risk factors influencing neurological functions after the treatment.

Results:

During surgery, we registered the absence of significant modifications of evoked potentials in nine cases (75%), while improvement of MEPs occurred in three cases (25%). No false-negative case was registered, and IOM predicted the absence of new postoperative neurological deficit in all patients. At 24-month follow-up, nine patients improved their overall neurological status, while three patients remained stable. At univariate analysis, Aminoff–Logue Disability Scales for Gait and Micturition (G + M-ALS) score at 24-month follow-up was directly associated with the duration of symptom before the surgery (P = 0.024), preoperative G-ALS (P = 0.02), M-ALS (P = 0.022), and G + M-ALS scores (P = 0.045), and improvement of IOM after occlusion of the fistula (P = 0.025).

Conclusions:

In our series, no significant worsening of evoked potentials occurred and subsequently the surgical strategy was not changed by IOM. However, no false-negative case was registered, and IOM predicted the absence of new postoperative neurological deficit in all patients. Patients with improvement of IOM parameters after occlusion of the fistula had greater chances of postsurgical improvement at the univariate analysis.

Surgically Treated Primary Spinal Cord Neoplasms in Southeastern Nigeria

Background:

Primary spinal cord tumors are not as frequently encountered as their cranial counterparts. They could present in such an indolent manner that requires a reasonable index of suspicion for their diagnosis to be considered.

Objective:

The objective of this study is to analyze the incidence and pattern of primary spinal cord and appendage neoplasms in patients surgically treated in our institution over a decade of practice.

Materials and Methods:

A retrospective review of clinical, radiological, and histopathology profiles of patients surgically treated for primary spinal cord tumor from 2006 to 2016 was carried out. Retrieved data were analyzed using SPSS version 21.

Results:

Out of 472 spine procedures were performed within the study period 17 (3.6%) cases of histologically proven primary spinal cord tumors were identified. The age of patients ranged between 17 and 77 years with a mean age was 45 years. The male: female ratio was 1:1.1. Motor deficit and pain were the most common presenting symptoms seen in 35.3% and 29.4% of patients, respectively. Meningiomas are the most common histological diagnosis (70.6%), distantly followed by Schwannoma (17.6%). The most common location of the tumors was intradural extramedullary (70.6%). All patients had gross total resection of tumor with no perioperative mortality.

Conclusion:

Meningioma is the most common surgically treated primary spinal cord tumor in our setting. Surgery is associated with good outcome.

Utility of Intraoperative Monitoring in the Resection of Spinal Cord Tumors: An Analysis by Tumor Location and Anatomical Region

STUDY DESIGN

Retrospective review of institutional data.

OBJECTIVE

The aim of this study was to assess the utility of somatosensory-evoked potentials (SSEP) and transcranial electric motor-evoked potentials (MEP) in the resection of spine tumors and evaluate the ability of both single and multi-modal monitoring to predict postoperative neurological deficits.

SUMMARY OF BACKGROUND DATA

Although the utility of intraoperative monitoring (IOM) is well established in scoliosis and degenerative surgery, studies in spine tumor patients have been limited.

METHODS

A series of consecutive patients who underwent resection with the use of IOM at a single institution between August 2009 and March 2013 was identified. Demographic, clinical, and neuromonitoring data were collected preoperatively, during surgery, at the moment of discharge, and at a 6-month follow-up visit. Three cohorts were established based on the anatomical location of the tumor: intramedullary, intradural extramedullary, and extradural. Additional groupings were formed based on spinal region. Patients with significant changes in SSEPs or MEPs during surgery were identified and the rate of neurological deficits was assessed.

RESULTS

A total of 52 patients were analyzed. A change in SSEPs or MEPs was detected in 11 (21.2%) cases whereas 14 patients (26.9%) developed permanent postoperative deficits. SSEPs predicted deficits in the resection of intramedullary tumors (P = 0.015) (area under cover, AUC = 0.83), and intradural extramedullary tumors (P = 0.048; AUC = 0.70). MEP monitoring did not predict postoperative deficits in the resection of intramedullary (P = 0.21; AUC = 0.69) or intradural extramedullary tumors (P = 0.31; AUC = 0.63). Neither SSEPs nor MEPs predicted deficits for extradural tumors.

CONCLUSION

The efficacy of IOM in spine tumor resection is dependent on tumor location relative to the spinal cord and dura. The accuracy of SSEPs and their ability to predict postoperative deficits was greatest for intramedullary lesions. For this series, MEP and multi-modal monitoring did not confer a benefit in predicting permanent neurological deficits.

LEVEL OF EVIDENCE

4.

Versatility of sub-occipital approach for foramen magnum meningiomas: a single centre experience

BACKGROUND

Foramen magnum meningiomas (FMM) represent a challenge for neurosurgeons. Multiple surgical strategies have been reported to treat these lesions in their variable location. Contemporary technical innovations allow the utilization of common sub-occipital craniotomy to treat ventrally, ventro-laterally and dorsally located FMMs. We present our technique and experience.

METHODS

From November 2004 to November 2015, we treated 14 patients with FMM at the Department of Neurosurgery of the Santa Maria delle Grazie Hospital in Pozzuoli, Naples, Italy. There were 10 females and 4 males, with a mean age of 64.5 years (range, 55-77 years). All patients had high field magnetic resonance imaging (MRI) with contrast enhancement preoperatively, which led to the radiological diagnosis. A sub-occipital craniotomy was performed in all patients as well as the removal of the posterior arch of C1. Partial removal of C2 was necessary in 2 patients. Neck pain was the most common symptom of presentation. Paraparesis was present in patients in 3 patients. Upper limbs dysesthesia or pain existed in 3 cases.

RESULTS

Thirty days after surgery neck pain and dysesthesia decreased in all patients affected. Neurological improvement was observed in 2 patients affected by weakness in lower limbs at 6 months follow up. Paraparesis was unchanged in 1 patient. Two patients presented transient worsening after surgery. Transient dysphagia occurred in one case and postoperative hemorrhage with subsequent surgery in another patient. We had no postoperative mortality.

CONCLUSIONS

FMM surgery should be tailored to the lesion at hand as in most instances it is possible to avoid the use of extensive skull base approaches.

Intraoperative neurophysiological mapping and monitoring in spinal tumor surgery: sirens or indispensable tools?

Spinal tumor (ST) surgery carries the risk of new neurological deficits in the postoperative period. Intraoperative neurophysiological monitoring and mapping (IONM) represents an effective method of identifying and monitoring in real time the functional integrity of both the spinal cord (SC) and the nerve roots (NRs). Despite consensus favoring the use of IONM in ST surgery, in this era of evidence-based medicine, there is still a need to demonstrate the effective role of IONM in ST surgery in achieving an oncological cure, optimizing patient safety, and considering medicolegal aspects. Thus, neurosurgeons are asked to establish which techniques are considered indispensable. In the present study, the authors focused on the rationale for and the accuracy (sensitivity, specificity, and positive and negative predictive values) of IONM in ST surgery in light of more recent evidence in the literature, with specific emphasis on the role of IONM in reducing the incidence of postoperative neurological deficits. This review confirms the role of IONM as a useful tool in the workup for ST surgery. Individual monitoring and mapping techniques are clearly not sufficient to account for the complex function of the SC and NRs. Conversely, multimodal IONM is highly sensitive and specific for anticipating neurological injury during ST surgery and represents an important tool for preserving neuronal structures and achieving an optimal postoperative functional outcome.

Minimally invasive removal of lumbar intradural extramedullary lesions using the interlaminar approach

OBJECT Posterior midline laminectomy or hemilaminectomy has been successfully applied as the standard microsurgical technique for the treatment of spinal intradural pathologies. However, the associated risks of postoperative spinal instability increase the need for subsequent fusion surgery to prevent potential long-term spinal deformity. Continuous efforts have been made to minimize injuries to the surrounding tissue resulting from surgical manipulations. The authors report here their experiences with a novel minimally invasive surgical approach, namely the interlaminar approach, for the treatment of lumbar intraspinal tumors. METHODS A retrospective review was conducted of patients at the Second Affiliated Hospital of Zhejiang University School of Medicine who underwent minimally invasive resection of lumbar intradural-extramedullary tumors. By using an operative microscope, in addition to an endoscope when necessary, the authors were able to treat all patients with a unilateral, paramedian, bone-sparing interlaminar technique. Data including preoperative neurological status, tumor location, size, pathological diagnosis, extension of resections, intraoperative blood loss, length of hospital stay, and clinical outcomes were obtained through clinical and radiological examinations. RESULTS Eighteen patients diagnosed with lumbar intradural-extramedullary tumors were treated from October 2013 to March 2015 by this interlaminar technique. A microscope was used in 15 cases, and the remaining 3 cases were treated using a microscope as well as an endoscope. There were 14 schwannomas, 2 ependymomas, 1 epidermoid cyst, and 1 enterogenous cyst. Postoperative radiological follow-up revealed complete removal of all the lesions and no signs of bone defects in the lamina. At clinical follow-up, 14 of the 18 patients had less pain, and patients' motor/sensory functions improved or remained normal in all cases except 1. CONClUSIONS When meeting certain selection criteria, intradural-extramedullary lumbar tumors, especially schwannomas, can be completely and safely resected through a less-invasive interlaminar approach using a microscope, or a microscope in addition to an endoscope when necessary. This approach was advantageous because it caused even less bone destruction, resulting in better postoperative spinal stability, no need for facetectomy and fusion, and quicker functional recovery for the patients. Individualized surgical planning according to preoperative radiological findings is key to a successful microsurgical resection of these lesions through the interlaminar space.