SSEP Monitoring Research Articles

Feasibility of Saphenous Nerve Somatosensory-Evoked Potential Intraoperative Monitoring during Lumbar Spine Surgery: Early Results.

Retrospective review. Assess the feasibility of saphenous nerve somatosensory evoked potentials (SN-SSEP) monitoring in lumbar spine surgeries. SN-SSEPs have been proposed for detecting lumbar plexus and femoral nerve injury during lateral lumbar surgery where tibial nerve (TN)SSEPs alone are insufficient. SN-SSEPs may also be useful in other types of lumbar surgery, as stimulation of SN below the knee derives solely from the L4 root and provides a means of L4 monitoring, whereas TN-SSEPs often do not detect single nerve root injury. The feasibility of routine SN-SSEP monitoring has not been established. A total of 563 consecutive cases using both TN and SN-SSEP monitoring were included. Anesthesia was at the discretion of the anesthesiologist, using an inhalant in 97.7% of procedures. SN stimulation was performed using 13mm needle electrodes placed below the knee using 200-400μsec pulses at 15-100mA. Adjustments to stimulation parameters were made by the neurophysiology technician while obtaining baselines. Data were graded retrospectively for monitorability and cortical response amplitudes were measured by two independent reviewers. 98% of TN-SSEPs and 92.5% of SN-SSEPs were monitorable at baseline, with a mean response amplitude of 1.35μV for TN-SSEPs and 0.71μV for SN-SSEPs. A significant difference between the stimulation parameters used to obtain reproducible TN and SN-SSEPs at baseline was observed, with SN-SSEPs requiring greater stimulation intensities. Body mass index (BMI) is not associated with baseline monitorability. Out of 20 signal changes observed, 11 involved SN while TN-SSEPs were unaffected. With adjustments to stimulation parameters, SN-SSEP monitoring is feasible within a large clinical cohort without modifications to the anesthetic plan. Incorporating SN into standard intraoperative neurophysiological monitoring (IONM) protocols for lumbar spine procedures may expand the role of SSEP monitoring to include detecting injury to the lumbar plexus. 3.

Effectiveness of MEP and SSEP Monitoring in the Diagnosis of Neurological Dysfunction Immediately After Craniotomy Aneurysm Clipping.

To explore the diagnostic accuracy of motor-evoked potential (MEP) and somatosensory-evoked potential (SSEP) monitoring in predicting immediate neurological dysfunction after craniotomy aneurysm clipping. A total of 184 patients with neurosurgery aneurysms in the Affiliated Hospital of Qingdao University from April 2019 to December 2021 were retrospectively included. All patients underwent craniotomy aneurysm clipping, and MEP and SSEP were used to monitor during the operation. Receiver operating characteristic (ROC) curve analysis was used to determine the optimal cutoff value for early warning of MEP and SSEP amplitude decline and to evaluate the effectiveness of MEP and SSEP changes in predicting immediate postoperative neurological dysfunction. Among the 184 patients with intracranial aneurysms, the incidences of immediate postoperative neurological dysfunction were 44.4% (12/27) and 3.2% (5/157) in patients with intraoperative MEP changes and without changes, respectively. For SSEP, The incidence rates were 52.6% (10/19) and 4.2% (7/165), respectively, and the differences were statistically significant ( P <0.001). Significant changes in intraoperative MEP and SSEP were significantly associated with the development of immediate postoperative neurological deficits ( P <0.05). The critical values for early warning of MEP and SSEP amplitude decrease were: 61.6% ( P < 0.001, area under the curve 0.803) for MEP amplitude decrease and 54.6% ( P <0.001, area under the curve 0.770) for SSEP amplitude decrease. The sensitivity and specificity of MEP amplitude change in predicting immediate postoperative neurological dysfunction were 70.6% and 91.0%, respectively. For SSEP amplitude changes, the sensitivity and specificity were 58.8% and 95.8%, respectively. Motor-evoked potential and SSEP monitoring have moderate sensitivity and high specificity for immediate postoperative neurological dysfunction after craniotomy aneurysm clipping. Motor-evoked potential is more accurate than SSEP. Patients with changes in MEP and SSEP are at greatly increased risk of immediate postoperative neurologic deficits.

Intraoperative neurophysiological monitoring in scoliosis surgery: literature review of the last 10years.

Patients with spinal deformities undergoing corrective surgery are at risk for iatrogenic spinal cord injury (SCI) and subsequent neurological deficit. Intraoperative neurophysiological monitoring (IONM) allows early detection of SCI which enables early intervention resulting in a better prognosis. The primary aim of this literature review was to search if there are threshold values of TcMEP and SSEP in the literature that are widely accepted as alert during IONM. The secondary aim was to update knowledge concerning IONM during scoliosis surgery. PubMed/MEDLINE and Cochrane library electronic databases were used to search publication from 2012 to 2022. The following keywords were used: evoked potential, scoliosis, surgery, intraoperative monitoring and neurophysiological. We included all studies dealing with SSEP and TcMEP monitoring during scoliosis surgery. Two authors reviewed all titles and abstracts to identify studies that met the inclusion criteria. We included 43 papers. Rates of IONM alert and neurological deficit varied from 0.56 to 64% and from 0.15 to 8.3%, respectively. Threshold values varied from a loss of 50 to 90% for TcMEP amplitude, whereas it seems that a loss of 50% in amplitude and/or an increase of 10% of latency is widely accepted for SSEP. Causes of IONM changes most frequently reported were surgical maneuver. Concerning SSEP, a loss of 50% in amplitude and/or an increase of 10% of latency is widely accepted as an alert. For TcMEP, it seems that the use of highest threshold values can avoid unnecessary surgical procedure for the patient without increasing risk of neurological deficit.

Diagnostic Accuracy of Somatosensory Evoked Potentials and Electroencephalography During Endovascular Treatment of Unruptured Cerebral Aneurysms

Endovascular treatment (EVT) of unruptured cerebral aneurysms (UCA) offers a safer alternative to clipping. However, it is still associated with an increased risk for Post Procedural Neurological Deficits (PPND). Prompt recognition using intraoperative neurophysiologic monitoring (IONM) and intervention can reduce the incidence and impact of new post-operative neurological complications. We aim to evaluate the diagnostic accuracy of IONM in predicting PPND after EVT of UCA. We included 414 patients who underwent EVT for UCA from 2014 to 2019. The sensitivities, specificities, and diagnostic odds ratio of SSEP and EEG monitoring methods were calculated. We also determined their diagnostic accuracy using receiver operating characteristic (ROC) plots. The highest sensitivity of 67.7% (95% CI, 34.9-90.1%) was obtained when either modality had a change. Simultaneous changes in both modalities have the highest specificity of 97.8% (95% CI, 95.8-99.0%). The area under the ROC curve was 0.795 (95% CI, 0.655-0.935) for changes in either modality. IONM with SSEP alone or in combination with EEG has high diagnostic accuracy in detecting periprocedural complications and resultant PPND during EVT of UCA. IONM allows for confident and early intervention when obvious complications may not be evident to the endovascular professional.

What is the predictive value of intraoperative somatosensory-evoked potential monitoring for postoperative neurological deficit in intramedullary tumor resection?

The objective of this study is to determine the accuracy of somatosensory-evoked potential (SSEP) monitoring versus SSEP combined with motor-evoked potential monitoring (MEP) for predicting postoperative neurological deficits following intramedullary tumor resection. A systematic review was conducted to identify the studies examining postoperative neurological deficits following intramedullary tumor resection. The sensitivity, specificity, and diagnostic odds ratio (DOR) were calculated for each of the monitoring modalities (SSEP vs. SSEP/MEP) and presented by forest plots and receiver operating characteristic curves. The total cohort consisted of 303 patients for the SSEP group and 350 patients for the SSEP/MEP combined group. The specificity and sensitivity of SSEP monitoring were 76% and 55%, respectively. The DOR of SSEP monitoring is 5.6 (95% confidence interval [CI], 1.55–20.26, I2 = 0%). The specificity and sensitivity of SSEP/MEP monitoring were 86% and 80%, respectively. The DOR of SSEP/MEP monitoring is 30.32 (95% CI, 6.92–132.85, I2 = 0%). SSEP/MEP intraoperative monitoring offers higher sensitivity, specificity, and DOR for predicting postoperative neurological deficits following intramedullary tumor resection. Patients who had a postoperative neurological deficit were 30 times more likely to exhibit a SSEP or MEP change compared to approximately six times more likely to solely exhibit a SSEP change.

Minimally Invasive Transforaminal Lumbar Interbody Fusion with Enhanced Recovery after Surgery (ERAS): Early Experience with Initial Consecutive Cases at a Spine Naïve Community Hospital

Objective: The objective of this study was to examine a spine naïve community hospital’s ability to perform MITLIF safely and with speedy discharge via implementation of a minimally invasive spine surgery (MISS) program utilizing ERAS. Methods: Single community hospital retrospective cohort analysis for initial consecutive MITLIF cases with unilateral pedicle screws performed by a single surgeon from October 2019 to March 2021. Minimum postoperative follow-up was one year. Narcotic use was assessed per the state prescription drug monitoring program. Surgery protocol included single paraspinal incision, non-expandable 18/22 mm tube, operating microscope, fluoroscopic guidance, EMG with SSEP monitoring and Enhanced Recovery After Surgery (ERAS) protocol. Results: 52 patients were included. Average OR time, and fluoroscopy time were 143±115 minutes, and 1.00±0.47 minutes, respectively. Patients were prescribed an average of 38±33 post-operative opioid doses for an average of 8±7 days. All patients on preoperative, chronic narcotics had no prescription changes, pre-op versus post-op, despite clinical improvement. Complications included one irrigation a(1.9%) nd debridement with retention of hardware for surgical site infection, and one revision(1.9%) for displaced hardware. Discharge data included 47 (90.4%), four (7.7%), and one patients (1.9%) discharged on POD1, POD2, and beyond POD2, respectively.Conclusion: MITLIF can be safely and successfully performed at a spine naïve community hospital with excellent intraoperative metrics, a low complication rate, and speedy discharge. MITLIF performed well in multiple perioperative and postoperative variables compared to MISS techniques. Considerations for implementation of MITLIF in the community setting include special equipment, personnel training, surgeon experience, ERAS protocols and diligent patient/indication selection.

Diagnostic Value of Multimodal Intraoperative Neuromonitoring by Combining Somatosensory-With Motor-Evoked Potential in Posterior Decompression Surgery for Thoracic Spinal Stenosis.

BackgroundIntraoperative neuromonitoring (IONM) has become an increasingly essential technique in spinal surgery. However, data on the diagnostic value of IONM in predicting impending postoperative neurological deficits (PONDs) for patients who underwent posterior decompression surgery for thoracic spinal stenosis (TSS) are limited. Furthermore, patients who are at the highest risk of waveform changes during the surgery remain unknown. Our purpose was to (1) assess the diagnostic accuracy of IONM by combining somatosensory-evoked potential (SSEP) with motor-evoked potential (MEP) in predicting PONDs for patients who underwent the surgery and (2) identify the independent risk factors correlated with IONM changes in our study population.MethodsA total of 326 consecutive patients who underwent the surgery were identified and analyzed. We collected the following data: (1) demographic and clinical data; (2) IONM data; and (3) outcome data such as details of PONDs, and recovery status (complete, partial, or no recovery) at the 12-month follow-up visit.ResultsIn total, 27 patients developed PONDs. However, 15, 6, and 6 patients achieved complete recovery, partial recovery, and no recovery, respectively, at the 12-month follow-up. SSEP or MEP change monitoring yielded better diagnostic efficacy in predicting PONDs as indicated by the increased sensitivity (96.30%) and area under the receiver operating characteristic (ROC) curve (AUC) value (0.91). Only one neurological deficit occurred without waveform changes. On multiple logistic regression analysis, the independent risk factors associated with waveform changes were as follows: preoperative moderate or severe neurological deficits (p = 0.002), operating in the upper- or middle-thoracic spinal level (p = 0.003), estimated blood loss (EBL) ≥ 400 ml (p < 0.001), duration of symptoms ≥ 3 months (p < 0.001), and impairment of gait (p = 0.001).ConclusionSomatosensory-evoked potential or MEP change is a highly sensitive and moderately specific indicator for predicting PONDs in posterior decompression surgery for TSS. The independent risks for IONM change were as follows: operated in upper- or middle-thoracic spinal level, presented with gait impairment, had massive blood loss, moderate or severe neurological deficits preoperatively, and had a longer duration of symptoms.Clinical Trial Registration[http://www.chictr.org.cn]; identifier [ChiCTR 200003 2155].

Diagnostic Accuracy of SSEP Changes During Lumbar Spine Surgery for Predicting Postoperative Neurological Deficit: A Systematic Review and Meta-Analysis.

This study is a meta-analysis of prospective and retrospective studies identified in PubMed, Web of Science, and Embase with outcomes of patients who received intraoperative somatosensory-evoked potential (SSEP) monitoring during lumbar spine surgery. The objective of this study is to determine the diagnostic accuracy of intraoperative lower extremity SSEP changes for predicting postoperative neurological deficit. As a secondary analysis, we evaluated three subtypes of intraoperative SSEP changes: reversible, irreversible, and total signal loss. Lumbar decompression and fusion surgery can treat lumbar spinal stenosis and spondylolisthesis but carry a risk for nerve root injury. Published neurophysiological monitoring guidelines provide no conclusive evidence for the clinical utility of intraoperative SSEP monitoring during lumbar spine surgery. A systematic review was conducted to identify studies with outcomes of patients who underwent lumbar spine surgeries with intraoperative SSEP monitoring. The sensitivity, specificity, and diagnostic odds ratio (DOR) were calculated and presented with forest plots and a summary receiver operating characteristic curve. The study cohort consisted of 5607 patients. All significant intraoperative SSEP changes had a sensitivity of 44% and specificity of 97% with a DOR of 22.13 (95% CI, 11.30-43.34). Reversible and irreversible SSEP changes had sensitivities of 28% and 33% and specificities of 97% and 97%, respectively. The DORs for reversible and irreversible SSEP changes were 13.93 (95% CI, 4.60-40.44) and 57.84 (95% CI, 15.95-209.84), respectively. Total loss of SSEPs had a sensitivity of 9% and specificity of 99% with a DOR of 23.91 (95% CI, 7.18-79.65). SSEP changes during lumbar spine surgery are highly specific but moderately sensitive for new postoperative neurological deficits. Patients who had postoperative neurological deficit were 22 times more likely to have exhibited intraoperative SSEP changes.Level of Evidence: 2.

Optimization of factors for the prevention of spinal cord ischemia in thoracic endovascular aortic repair.

Spinal cord ischemia following thoracic endovascular aortic repair (TEVAR) is a devastating complication. This study seeks to demonstrate how a standardized protocol to prevent spinal cord ischemia affects incidence in patients undergoing TEVAR. Using CPT codes 33880 and 33881, all TEVAR procedures performed at a single tertiary care center from January 2017 to December 2018 were examined. Patients who had concomitant ascending aortic repairs or a TEVAR for traumatic indications were excluded from analysis, leaving 130 TEVAR procedures. Comorbid conditions, procedural characteristics, extent of coverage, peri-procedural management strategies, and post-operative outcomes were collected and analyzed retrospectively. One hundred thirty patients undergoing TEVAR were examined for four perioperative variables: postoperative hemoglobin greater than 10 g/dL, subclavian revascularization, preoperative spinal drain placement, and somatosensory evoked potential monitoring (SSEP). All conditions were met in 46.2% (60/130) of procedures; 37.8% (28/74) in emergent/urgent cases and 61.5% (32/52) in elective cases. Of patients who required subclavian coverage, 87.1% (54/62) underwent subclavian revascularization; 70.8% (92/130) of patients received spinal drains preoperatively; 68.5% (89/130) of patients had SSEP monitoring; 73.8% (93/130) of patients obtained a postoperative hemoglobin of >10 g/dL. Out of all patients, two (1.5%) developed spinal cord ischemia. Incidence of spinal cord ischemia in our cohort was low at 1.5% (2/130). Individual and bundled interventions for the prevention of spinal cord ischemia were unable to demonstrate a statistically significant effect given the low rate. Nonetheless, we advocate for a proactive approach for the prevention of spinal cord ischemia given our experience in this complex population.

Scoliosis in chronic neuronopathic Gaucher disease: Characterization in the treatment era

Intraoperative monitoring (IOM) using somatosensory-evoked potentials (SSEPs) plays an important role in reducing iatrogenic neurologic deficits during corrective pediatric idiopathic procedures for scoliosis. However, for unknown reasons, recent reports have cited that the sensitivity of SSEPs to detect neurologic deficits has decreased, in some to be less than 50%. This current trend, which is coincident with the addition of transcranial motor-evoked potentials, is surprising given that SSEPs are robust, reproducible responses that were previously shown to have sensitivity and specificity of >90%.Our primary aim was to assess whether SSEPs alone can detect impending neurologic deficits with similar sensitivity and specificity as originally reported. Our secondary aim was to estimate the potential predictive value of adding transcranial motor-evoked potentials to SSEP monitoring in idiopathic scoliosis procedures.This was a retrospective review to analyze the efficacy of SSEP monitoring in the group of pediatric instrumented scoliosis fusion cases.We retrospectively reviewed all consecutive cases of patients who underwent idiopathic scoliosis surgery between 1999 and 2009 at Children’s Hospital of Pittsburgh. We identified 477 patients who had the surgery with SSEP monitoring alone. Exclusion criteria included any patients with neuromuscular disorders or unreliable SSEP monitoring. Patients who had incomplete neurophysiology data or incomplete postoperative records were also excluded.Major outcomes measured were clinically significant postoperative sensory or motor deficits, as well as significant intraoperative SSEP changes.Continuous interleaved upper- and lower-extremity SSEPs were obtained throughout the duration of all procedures. We considered a persistent 50% reduction in primary somatosensory cortical amplitude or a prolongation of response latency by >10% from baseline to be significant. Persistent changes represent significant deviation in SSEP amplitude or latency in more than two consecutive averaged trials. Patients were classified into one of four categories with respect to SSEP monitoring: true positive, false positive, true negative, and false negative. The sensitivity, specificity, positive predictive value, and negative predictive value were then calculated accordingly.Our review of 477 idiopathic scoliosis surgeries monitored using SSEPs alone revealed a new deficit rate of 0.63% with no cases of permanent injury. Sensitivity = 95.0%, specificity = 99.8%, positive predictive value = 95%, negative predictive value = 99.8%. Using evidence-based epidemiologic measures, we calculated that the number needed to treat was 1,587 patients for one intervention to be performed that would have been missed by SSEP monitoring alone. In addition, the number needed to harm, which represents the increase in false positives with the addition of transcranial electrical motor-evoked potentials, was 200.SSEP monitoring alone during idiopathic scoliosis continues to be a highly reliable method for the detection and prevention of iatrogenic injury. Our results confirm the high sensitivity and specificity of SSEP monitoring alone published in earlier literature. As such, we suggest the continued use of SSEP alone in idiopathic scoliosis surgeries. At this time we do not believe there are sufficient data to support the addition of MEP monitoring, although more studies and revised criteria for the use of MEP may provide added value for its use in the future.

P02.01 Analysis of Multimodal Intraoperative Monitoring During Intramedullary Spinal Ependymoma Surgery

Abstract BACKGROUND To evaluate the validity of intraoperative somatosensory-evoked potential (SSEP) and motor-evoked potential (MEP) monitoring according to two different warning criteria for 6 months after intramedullary spinal ependymoma (IMSE) surgery. MATERIAL AND METHODS To evaluate the validity of intraoperative somatosensory-evoked potential (SSEP) and motor-evoked potential (MEP) monitoring according to two different warning criteria for 6 months after intramedullary spinal ependymoma (IMSE) surgery. RESULTS The success rates of SSEP and MEP monitoring were 84.9% and 83.7%, respectively. There was one indeterminate case in SSEP and six in MEP. All-or-none criterion in SSEP and MEP monitoring showed higher specificity, PPV, and DOR than 50% decline criterion during 6 months. During the follow up, 37 of 38 extremities (97.4%) and 21 of 29 extremities (72.4%) were observed the improvement of sensory and motor deficit, respectively. Seven indeterminate cases also showed good clinical outcomes. However, most patients remained some degree of neurologic deficit. CONCLUSION Many false positive and false negative results of SSEP and MEP monitoring occurred immediately postoperative period. All-or-none criterion was more beneficial for IMSE surgery than 50% decline criterion. This trend was maintained until 6 months after surgery.

Venous vascular malformations and compressive neuropathy

Abstract Background Venous malformations (VMs) are slow flowing congenital vascular malformations that demonstrate continuous growth. They are prone to bleeding and frequent invasion of adjacent structures. It is therefore important to differentiate them from schwannomas, which can appear similar on imaging. Currently, the literature demonstrates only a few examples of pathology misdiagnosed as a schwannoma, and of VMs associated with neurological deficits. We will illustrate the characteristics and management of VMs causing compressive neuropathy in the cervical and upper extremity regions and contrast them against the features of peripheral nerve sheath tumors. Case description Two case reports are presented, one of a 55-year-old woman with a chronic cervical mass due to a venous malformation (VM) originally misdiagnosed as a schwannoma, and another of a 35-year-old man with a vascular malformation of predominantly venous pathology in the antecubital fossa. Both patients were surgically managed. Conclusions Patients presented with chronic pain, weakness and paresthesia. Venous malformations were seen as thinly encapsulated, multilobular, heterogeneously enhancing lesions with internal fluid levels and venous lakes. Post-contrast septate enhancement, intrinsic foci of T1 hyperintensity, phleboliths, T2 hyperintensity, and nodular enhancement of torturous vessels we also noted. MEP, SSEP, and EMG monitoring was used during surgical resection. Both patients had favorable outcomes.

The Efficacy of Intraoperative Neurophysiological Monitoring to Detect Postoperative Neurological Deficits in Transforaminal Lumbar Interbody Fusion Surgery.

Despite the extensive use of intraoperative neurophysiological monitoring (IONM) in spinal procedures, there is no standard guideline for what types of IONM tests should be monitored during lumbar procedures with instrumentation. Moreover, the efficacy of IONM during transforaminal lumbar interbody fusion (TLIF) surgery in detecting postoperative neurological deficits has not been well described. To analyze waveform changes from individual IONM tests (somatosensory evoked potentials [SSEP], motor evoked potentials [MEP], and electromyography [EMG]) during TLIF and compare the sensitivity and specificity of these tests in order to determine the best combination to detect postoperative neurological deficits. Two hundred seventy-five consecutive TLIF cases with IONM between 2010 and 2014 were reviewed, and new postoperative sensory and motor deficits were documented. Sensitivity and specificity for each IONM test in detecting postoperative sensory and/or motor deficits were analyzed. SSEP and EMG tests were performed on all 275 patients with 66 patients undergoing additional MEP tests. A total of 7 postoperative deficits have been reported: 2 sensory and 5 motor deficits. MEP test had high sensitivity (80.0%) and specificity (100%) in detecting motor deficits. However, SSEP changes failed to detect sensory deficits and EMG test had high false-positive rates for detecting both sensory (100%) and motor deficits (97.3%). MEP test should be incorporated in monitoring protocols during spinal procedures that involve instrumentations below vertebral level L1 such as TLIF, as it provides high sensitivity and specificity in detecting postoperative motor deficits. In addition, we propose modifying the standard lower extremity SSEP monitoring protocol to correspond to the vertebral levels being operated on.

Analysis of Multimodal Intraoperative Monitoring During Intramedullary Spinal Ependymoma Surgery

To evaluate the validity of intraoperative somatosensory-evoked potential (SSEP) and motor-evoked potential (MEP) monitoring according to 2 different warning criteria during 6 months from intramedullary spinal ependymoma surgery. Twenty-six patients who underwent intramedullary spinal ependymoma surgery with intraoperative monitoring from January 2010 to June 2017 were retrospectively analyzed. We examined the sensitivity, specificity, positive predictable value, negative predictable value, and diagnostic odds ratio of SSEP and MEP monitoring for each extremity according to 2 warning criteria: 50% decline and all-or-none. The postoperative motor deficit was evaluated using the Medical Research Council scale. The postoperative neurologic deficit was followed up during 6 months. Eighty-six extremities were evaluated. The success rates of SSEP and MEP monitoring were 84.9% and 83.7%, respectively. Indeterminate cases were 1 in SSEP and 6 in MEP. All-or-none criterion in SSEP and MEP monitoring showed greater specificity, positive predictable value, and diagnostic odds ratio than 50% decline criterion during 6 months. The validity of SSEP was high in the upper extremity, whereas that of MEP was high in the lower extremity. During the follow-up, 37 of 38 extremities (97.4%) and 18 of 29 extremities (62.1%) showed improvement in sensory and motor deficit, respectively. Seven indeterminate cases also showed good clinical outcomes. Many false-positive and false-negative results of SSEP and MEP monitoring occurred during the immediate postoperative period. All-or-none criterion was more beneficial for assessing postoperative neurologic status than 50% decline criterion. This trend was maintained until 6 months after surgery.

Diagnostic value of somatosensory evoked potential changes during carotid endarterectomy for 30-day perioperative stroke

ObjectivesSomatosensory evoked potentials (SSEPs) have proven useful as an intraoperative modality to predict perioperative stroke during carotid endarterectomy (CEA). However, the predictive value of SSEPs for predicting stroke 30 days postoperatively remains unclear. The primary objective is to evaluate the efficacy of intraoperative SSEP change in predicting the risk of stroke in the postoperative period beyond 24 h but within 30 days. Our secondary aim is to evaluate the predictive value of each subcategory of SSEP change. MethodsWe performed a meta-analysis of 25 prospective/retrospective studies from PubMed, Web of Science, and Embase regarding SSEP monitoring for postoperative outcomes in symptomatic and asymptomatic CEA patients. ResultsA 8307-patient cohort composed the total sample population, of which 54.17% had symptomatic CS. For SSEP change and stroke greater than 24 h but within 30 days, the diagnostic odds ratio was 8.68. The diagnostic odds ratio was 3.88 for transient SSEP change and stroke; 49.29 for persistent SSEP change and stroke; 36.45 for transient SSEP loss and stroke; and 281.35 for persistent SSEP loss and stroke. ConclusionsPatients with SSEP changes are at increased risk of perioperative stroke within the entire 30-day period. There is a noticeable step-wise increase in the predicted risk of stroke with the severity of SSEP changes. SignificanceSSEP changes can serve as a predictor for 30-day perioperative stroke during CEA.

Diagnostic Accuracy of Somatosensory Evoked Potential Monitoring in Evaluating Neurological Complications During Endovascular Aneurysm Treatment.

Somatosensory evoked potential (SSEP) monitoring is used extensively for early detection and prevention of neurological complications in patients undergoing many different neurosurgical procedures. However, the predictive ability of SSEP monitoring during endovascular treatment of cerebral aneurysms is not well detailed. To evaluate the performance of intraoperative SSEP in the prediction postprocedural neurological deficits (PPNDs) after coil embolization of intracranial aneurysms. This population-based cohort study included patients ≥18 years of age undergoing intracranial aneurysm embolization with concurrent SSEP monitoring between January 2006 and August 2012. The ability of SSEP to predict PPNDs was analyzed by multiple regression analyses and assessed by the area under the receiver operating characteristic curve. In a population of 888 patients, SSEP changes occurred in 8.6% (n = 77). Twenty-eight patients (3.1%) suffered PPNDs. A 50% to 99% loss in SSEP waveform was associated with a 20-fold increase in risk of PPND; a total loss of SSEP waveform, regardless of permanence, was associated with a greater than 200-fold risk of PPND. SSEPs displayed very good predictive ability for PPND, with an area under the receiver operating characteristic curve of 0.84 (95% CI 0.76-0.92). This study supports the predictive ability of SSEPs for the detection of PPNDs. The magnitude and persistence of SSEP changes is clearly associated with the development of PPNDs. The utility of SSEP monitoring in detecting ischemia may provide an opportunity for neurointerventionalists to respond to changes intraoperatively to mitigate the potential for PPNDs.

Efficacy of Intraoperative Neurophysiologic Monitoring for Pediatric Cervical Spine Surgery

Clinical case series. To investigate the efficacy of intraoperative neuromonitoring in pediatric cervical spine surgery. Intraoperative neuromonitoring (IONM) consisting of somatosensory-evoked potentials (SSEP) and transcranial motor-evoked potentials (tcMEP) has been shown to effectively prevent permaneny neurologic injury in deformity surgery. The role of IONM during pediatric cervical spine surgery is not well documented. Advances in cervical spine instrumentation have expanded the surgical options in pediatric populations. The goal of this study is to report the ability of IONM to detect neurologic injury during pediatric cervical spine instrumentation. A single institution database was queried for pediatric-aged patients who underwent cervical spine instrumentation and fusion between 2011 and 2014. Age, diagnosis, surgical indication, number of instrumented levels, and a complete IONM were extracted. Sensitivity and specificity for the detection of neurologic deficits were calculated with exact 95% confidence intervals. Positive and negative predictive values were calculated with estimated 95% confidence intervals. Sixty-seven patients who underwent cervical spine instrumentation were identified with a mean age of 11.6 years (range 1-18). Diagnoses included instability (27), congenital (11), kyphosis (8), fracture (7), tumor (7), arthritis (4), and basilar invagination (3). Mean number of vertebral levels fused was 4 (range 2-7). All patients underwent cervical instrumentation with SSEP and tcMEP monitoring. A significant change in tcMEP monitoring was observed in 7 subjects (10%). There were no corresponding SSEP changes in these patients. The sensitivity of combined IONM was 75% [95% CI = 24.9, 98.7] and the specificity was 98.5% [92.7, 99.9]. tcMEP is a more sensitive indicator to spinal cord injury than SSEP, which is consistent with previous studies. IONM changes in 10% of a patient population are significant enough to warrant intraoperative determination if true SCI has occurred or is underway and intervene accordingly. 4.

A randomized crossover study of the effects of lidocaine on motor- and sensory-evoked potentials during spinal surgery

Background ContextLidocaine has emerged as a useful adjuvant anesthetic agent for cases requiring intraoperative monitoring of motor-evoked potentials (MEPs) and somatosensory-evoked potentials (SSEPs). A previous retrospective study suggested that lidocaine could be used as a component of propofol-based intravenous anesthesia without adversely affecting MEP or SSEP monitoring, but did not address the effect of the addition of lidocaine on the MEP and SSEP signals of individual patients. PurposeThe purpose of this study was to examine the intrapatient effects of the addition of lidocaine to balanced anesthesia on MEPs and SSEPs during multilevel posterior spinal fusion. Study DesignThis is a prospective, two-treatment, two-period crossover randomized controlled trial with a blinded primary outcome assessment. Patient SampleForty patients undergoing multilevel posterior spinal fusion were studied. Outcome MeasuresThe primary outcome measures were MEP voltage thresholds and SSEP amplitudes. Secondary outcome measures included isoflurane concentrations and hemodynamic parameters. MethodsEach participant received two anesthetic treatments (propofol 50 mcg/kg/h and propofol 25 mcg/kg/h+lidocaine 1 mg/kg/h) along with isoflurane, ketamine, and diazepam. In this manner, each patient served as his or her own control. The order of administration of the two treatments was determined randomly. ResultsThere were no significant within-patient differences between MEP threshold voltages or SSEP amplitudes during the two anesthetic treatments. ConclusionsLidocaine may be used as a component of balanced anesthesia during multilevel spinal fusions without adversely affecting the monitoring of SSEPs or MEPs in individual patients.

Diagnostic accuracy of somatosensory evoked potential and electroencephalography during carotid endarterectomy

Background and Purpose: Perioperative stroke risk following carotid endarterectomy (CEA) is reported to be approximately 2–3%. The diagnostic accuracies of intraoperative EEG and SSEP monitoring during CEA have been studied separately. However, to date, the effectiveness of simultaneous EEG and SSEP monitoring during CEA has only been evaluated in small study populations. This study examined the diagnostic accuracy of combined EEG and SSEP monitoring in a large (N = 1165) patient population.Methods: This study included 1165 patients who underwent CEA from 2000 to 2012 at the University of Pittsburgh Medical Center. The sensitivities, specificities, and diagnostic odds ratio of EEG and SSEP monitoring methods were examined separately and together. Receiver operating characteristic curves were plotted to assess sensitivity and specificity of single and combined Intraoperative monitoring (IONM) methods.Results: Maximum sensitivity was obtained with multimodality monitoring with an IONM change in either EEG or SSEP of 50.00 (95% CI, 30.66–69.34). The specificity of simultaneous EEG and SSEP changes was 93.95 (95% CI, 92.28–95.35%). Maximum area under ROC curve obtained for IONM change in either EEG or SSEP was 0.660 (95% CI, 0.547–0.773, p-value 0.004).Conclusion: The diagnostic accuracy of multimodality IONM during CEA is higher than an approach using single modality IONM. Simultaneous EEG and SSEP monitoring improves the likelihood of detecting periprocedural strokes after CEA. Neuro protective therapies to prevent periprocedural strokes can be based on changes in SSEP and EEG during CEA.

Significant Alerts in Intraoperative Neurophysiologic Monitoring during Severe Spinal Deformity Surgeries- A Categorical Description Experience in Tertiary Care Referral Center from the Subcontinent

Introduction Intraoperative Neurophysiological monitoring (IONM) has become a standard of care in spinal deformity surgeries to minimize the incidence of new onset neurological deficit. It has largely averted the use of historic intraoperative wake-up test. The risk of new neurologic deficit, in such cases, is high and frequency of significant alerts in neuro-monitoring can distress the surgeon so it is essential for the surgeon to know about the various categories of alerts and their management. Study Design Retrospective review of all spinal deformity surgeries performed with IONM in an Indian hospital over a period from 2011–2015. Material and Methods All except two patients were subjected to IONM by transcranial electrical motor evolked potentials (TCeMEP) during the spinal deformity surgery. These two patients were monitored with SSEP. Patients were included in the study only if complete demographic data, operative reports and neuromonitoring data and post-operative neurological data were available for review. A significant IONM alert during MEP monitoring was defined as 80% or more decrement in the MEP amplitude, or Increase in threshold of 100 V or more from baseline. During SSEP monitoring, significant alert was defined as 50% or greater decrease from baseline in the amplitude or latency prolongation by 10% or more. A full neurologic recovery was defined as a return to baseline for all MEP and SSEP signals. The systemic and surgical causes of IONM alerts and the postoperative neurological status were recorded. Results Total 43 patients underwent the surgery for severe spinal deformities with neuromonitoring. The average age was 13.2 years (6–38), and male:female ratio was 11:32. Diagnoses included idiopathic scoliosis (26), congenital scoliosis (6), congenital kyphosis (5), congenital kyphoscoliosis (2), post-infectious kyphosis (3), and post-traumatic kyphosis (1). The average kyphosis was 84; (45–136); the average scoliosis was 89; (62–128). There were total 21 IONM alerts in 16 patients (37%). The most common causes were Hypotension (5), drug induced (4), distraction (4), deformity correction (3), SPO/Ponte/PSO osteotomies (2), Tachycardia (2) and Screw placement (1). Reversal of the inciting cause resulted in complete reversal of the alert in 90% of the times. Two patients wake up with neurodeficit (Screw placement and deformity correction) which recovered over few weeks. One patient showed persistent alerts but wake up without any deficit. Conclusion IONM alerts are frequent during severe spinal deformity surgery. In our study more than 50% of the alerts were associated with anesthetic management (hypotension, drugs and tachycardia). So in case of significant alert, surgeon should not get stressed out but to analyze whether the cause is systemic and the first step is to maintain the mean blood pressure. However, the most common cause of persistent IONM alert were screw malposition and deformity correction. Careful surgical technique supported by IONM and their interpretation can reduce neurologic mishaps.