SSEP Changes Research Articles

Reliability and Predictors of Intraoperative Neuromonitoring Changes During Intramedullary Tumor Resection: A Multicenter Experience

INTRODUCTION: Intraoperative neuromonitoring (IONM) is used in real-time to alert neurosurgeons of potential neurological changes when resecting intramedullary spinal cord tumors (IMSCTs). Previous studies have reported variable reliability of IONM. METHODS: A multicenter retrospective study was performed on patients undergoing IMSCTs surgery with neuromonitoring at the three Mayo Clinic sites between 2005 to 2022. Demographics, SSEP, MEP changes and postoperative outcomes were recorded. Specificity, sensitivity, positive predictive value (PPV), and negative predictive value (NPV) were calculated. Variables found significant on univariate analysis (p < 0.05) were applied to a multivariate model to identify predictors for IONM SSEP and MEP changes. RESULTS: 135 patients underwent surgical resection for IMSCTs using IONM. The mean age at diagnosis was 45 ± 17.9 years. Laminectomy was the most frequent index operation (96.3%). A total of 8.9% of patients presented with short-term improvement, while 70.4% presented long-term improvement on their baseline McCormick Scale. Sensitivity, specificity, PPV, NPV, accounted for 86.2%, 51%, 5.2%, 99.2% for MEP; 77.8%, 48.2%, 4.4%, 98.6% for SSEP. We found predictors of IONM changes: poorly defined MEP baseline (OR 3.004, 95% CI 1.22-7.397, p = 0.017), WHO grade II tumors (OR 2.334, 95% CI 1.043-5.223, p = 0.039), cervicomedullary junction location (OR 0.103, 95% CI 0.011-0.983, p = 0.048). Only WHO grade II tumors (OR 2.85, 95% CI 1.208-6.727, p = 0.017) was a predictor for SSEP changes. CONCLUSIONS: Our study represents the largest cohort describing sensitivity, specificity, and predictive factors for intraoperative changes and postoperative outcomes of resection of IMSCTs. A poorly defined baseline and cervicomedullary tumor location were predictors of IONM MEP changes, whiIe WHO grade II tumors were a predictor for both IONM SSEP and MEP changes.

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.

Variability of somatosensory evoked potential and motor evoked potential change criteria in thoracic spinal decompression surgery based on preoperative motor status

Background contextCombined somatosensory- and motor-evoked potential (SSEP and MEP) changes for predicting prognosis in thoracic spinal surgery have been variably reported. PurposeWe aimed to explore the validity of combined SSEP and MEP for predicting postoperative motor deficits (PMDs) in thoracic spinal decompression surgery (TSDS) and identify a relatively optimal neurophysiological predictor of PMDs in patients based on preoperative motor status. Study settingRetrospective study. Patient sampleA total of 475 patients were analyzed. Outcome MeasuresA reduction in muscle strength by more than or equal to one manual muscle testing (MMT) grade postoperatively compared with the preoperative MMT grade was identified as PMDs. Postoperative motor deficits were detected by comparing the preoperative and postoperative physical examination findings in short- and long-term follow-up visits. MethodsAll patients were divided into two subgroups according to preoperative motor status. The following data were collected: (1) demographic data; (2) IONM (intraoperative neuromonitoring) data; and (3) postoperative motor outcomes. Binary logistic regression analysis was performed to assess the efficacy of IONM change to predict PMDs. A receiver operating characteristic curve (ROC) was used to establish optimal IONM warning criteria. ResultsNinety-eight patients had severe preoperative motor deficits (Group S), and 377 patients did not (Group N). MEP and SSEP change was effective for predicting PMDs in the short term (p<.01) and long term (p<.01) for TSDS patients. In Group N, the cutoff values for predicting PMDs in the short term were a decrease of 65% in SSEP amplitude and 89.5% in MEP amplitude of the baseline value. Furthermore, the cutoff values for predicting PMDs in the short term were durations of change of 24.5 minutes for SSEP and 32.5 minutes for MEP. In Group S, however, the cutoff values for predicting PMDs in the short term were a decrease of 36.5% in SSEP amplitude and 59.5% in MEP amplitude of the baseline value. Moreover, the critical values for predicting short-term PMDs were durations of change of 16.5 minutes for SSEP and 17.5 minutes for MEP. ConclusionsThe optimal IONM changes for prediction vary depending on preoperative motor status. Combined SSEP and MEP are excellent for predicting PMDs in TSDS.

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.

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].

Intraoperative Transcranial Electrical Motor Evoked Potential (TceMEP) as a Therapeutic Tool in Spine Surgery: A Case Series Report

ABSTRACT We report two cases of unilateral loss of TceMEP secondary to spinal instrumentation errors and the subsequent recovery of TceMEP responses following prompt intervention. During the period of TceMEP loss, there were no concomitant SSEP changes beyond the threshold criteria. Postoperative physical examination revealed normal strength and motion in the affected extremities in both patients. These cases illustrate that in addition to being a reliable intraoperative diagnostic tool, TceMEP monitoring displays therapeutic usefulness in appraising corrective actions to the existential risk of neurological injuries.

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.

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.

The Significance of Upper Extremity Neuromonitoring Changes During Thoracolumbar Spine Surgery.

This is a retrospective matched-pair cohort study. To investigate the significance of upper extremity (UE) neuromonitoring changes in patients undergoing thoracolumbar surgery in prone position. Peripheral nerve injuries in the UEs due to the prone positioning during prolonged thoracolumbar spinal procedures can cause diminished postsurgical outcomes. Intraoperative neuromonitoring has been utilized to alert the surgeon of the development of such injuries. Patients who developed intraoperative ulnar somatosensory-evoked potential (SSEP) signal changes during posterior thoracolumbar surgery were identified and compared with a group of patients who did not develop such signal changes. The patients in 2 groups were pair-matched on the number of vertebral levels undergoing surgery. Data regarding intraoperative attempts to resolve signal changes and outcomes were collected. In total, 843 patients underwent thoracic, lumbar, or thoracolumbar spine surgeries in the prone position with intraoperative ulnar SSEPs neuromonitoring data available. Of these, 37 patients (4.4%) had intraoperative signal changes in the UEs. An equal number of patients without signal changes were also selected. In each group, 6 patients underwent thoracic, 20 patients underwent lumbar, and 11 patients underwent thoracolumbar procedures. In 8 patients (21.6%), there was no resolution of SSEP signal changes despite intraoperative attempts. The 2 groups were similar with respect to age and comorbidities. There was no significant difference in the mean body mass index (P=0.22). The mean duration of the procedures was 324 minutes in the SSEP signal change patients and 260 minutes in the patients without SSEP signal changes (P=0.03). No patient with UE SSEP changes had a clinically detectable neurological deficit postoperatively. UE SSEP signal changes during multilevel posterior thoracolumbar procedures are more likely to occur as the duration of the operation increases. The presence of UE signal changes does not coincide with clinically significant peripheral neuropathies. Level III.

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.

Risk factors for positioning-related somatosensory evoked potential changes in 3946 spinal surgeries

The goal of this study was to evaluate the risk factors associated with positioning-related SSEP changes (PRSC). The study investigated the association between 18 plausible risk factors and the occurrence of intraoperative PRSC. Risk factors investigated included demographic variables, comorbidities, and procedure related variables. All patients were treated by the University of Pittsburgh Medical Center from 2010 to 2012. We used univariate and multivariate statistical methods. 69 out of the 3946 (1.75%) spinal surgeries resulted in PRSC changes. The risk of PRSC was increased for women (p < 0.001), patients older than 65years of age (p = 0.01), higher BMI (p < 0.001) patients, smokers (p < 0.001), and patients with hypertension (p < 0.001). No associations were found between PRSC and age greater than 80 years, diabetes mellitus, cardiovascular disease, and peripheral vascular disease. Three surgical situations were associated with PRSC including abnormal baselines (p < 0.001), patients in the "superman" position (p < 0.001), and patients in surgical procedures that extended over 200min (p = 0.03). Patients with higher BMIs and who are undergoing spinal surgery longer than 200min, with abnormal baselines, must be positioned with meticulous attention. Gender, hypertension, and smoking were also found to be risk factors from their odds ratios.

T94. Stable “Crossover” TcMEP with post-op weakness in CEA

Introduction Carotid endarterectomies can be performed in patients with carotid artery stenosis in order to prevent future strokes. Electroencephalogram and somatosensory evoked potentials are intraoperative neuromonitoring modalities used to provide the surgeon with real-time feedback in detecting decreases in cerebral blood flow during carotid artery clamping. This may help the surgeon decide whether to shunt the carotid artery, which has potential complications. Transcranial motor evoked potentials have been used as an adjunct to EEG and SSEPs to monitor carotid endarterectomies, with Malcharek et al. reporting 0.4% false-negative TcMEPs in a review of 264 patients. We report a case where TcMEPs remain unchanged with unilateral SSEP changes that was associated with new post-operative deficits. Methods This is a case report of a 54 year old female with multiple vascular risk factors and a prior stroke three months prior with trace right upper (RUE) and lower (RLE) weakness. She presented with acute worsening of weakness and numbness, due to severe narrowing of the proximal left internal carotid artery. She underwent left carotid endarterectomy for symptomatic carotid stenosis. Three-channel EEG, SSEP with stimulation at the median nerve and posterior tibial nerve, and TcMEPs of the upper and lower extremities were setup for intraoperative neuromonitoring. The patient was anesthetized with propofol and fentanyl. Results Baseline SSEPs in all four extremities were adequate. TcMEPs were reproducible in all four extremities, except the left foot had variable responses. Of note, there were TcMEP responses ipsilateral to the hemisphere of stimulation. Seventy minutes post-incision, EEG showed burst suppression and the surgeons clamped the left carotid artery. Two minutes post-clamping, the right sided SSEP began to decrease in amplitude. The RUE and RLE SSEPs became absent at 10 min and 19 min post-clamping, respectively. TcMEPs run after the SSEPs changes were unchanged from baseline and the surgeons moved forward without shunting. At 42 min post-clamping, surgeons completed the CEA and removed the clamp. The RLE SSEP returned 3 min after unclamping, and the RUE SSEP 29 min after unclamping. The RLE SEP improved to baseline, but the RUE SEP amplitude remained significantly diminished. Left sided SSEPs were stable and bilateral TcMEPs remained unchanged throughout the entire surgery. EEG demonstrated burst suppression without any notable asymmetry. Pre-operative exam showed RUE drift and 4+/5 strength on RLE. Post-operative exam revealed flaccid RUE. Her RLE motor strength was anti-gravity, but she did not follow commands for individual muscle groups. Conclusion TcMEPs may be an unreliable measure of the nervous system when crossover responses are present in the limbs ipsilateral to the hemisphere of stimulation. In this left CEA, right-sided SSEP changes correctly heralded potential injury immediately after clamping, while right-sided TcMEPs remained unchanged.

T93. When should monitoring end? A case report

Introduction Transcranial motor evoked potentials (TcMEP) is the preferred modality for monitoring corticospinal tract integrity during spine surgery. In practice, final TcMEPs are obtained immediately after rod placement, during washout, or during early stages of closing before administration of inhalational agents. This raises the question: “When should monitoring conclude?” We present a case of a 63-year male who underwent T8-L4 posterior fusion, T12-L2 laminectomy and L1 partial corpectomy. In this surgery, we performed intraoperative neurophysiological monitoring during the entire case through suturing of the skin. During the final stages of skin closure, both TcMEP and somatosensory (SSEP) signals decreased significantly in the bilateral lower extremities. The surgeons subsequently re-opened the incision site and discovered a large blood clot compressing the dura. Methods Patient presented with severe back pain and workup revealed a pathological L1 fracture with cord compression. At the onset of the surgery, anesthesia administered total intravenous anesthesia and avoided neuromuscular blockade . We obtained SSEPs and TcMEPs continuously throughout the case. Evoked potentials were unchanged until the stapling of skin during final stages of closure when TcMEPs were suddenly lost in the bilateral tibialis , gastocnemius and intrinsic feet muscle and significantly decreased in the bilateral vastus muscles. Upper extremity TcMEPs were stable. Upon further monitoring, bilateral lower extremity SSEPs were lost as well. There were no changes in anesthetic regimen. After reporting these findings, the surgical team completed staple closure and performed a clinical examination after extubation. Results During clinical examination, the patient demonstrated loss of motor function in bilateral lower extremities with preservation of movement in bilateral upper extremities. The patient was reintubated and repositioned to the prone position for wound exploration. Upon re-initiation of neuromonitoring, the bilateral lower extremity TcMEPs and SSEPs remained absent. Surgeons discovered the epidural blood clot compressing the ventral dura during wound exploration. After immediate evacuation of the hematoma, bilateral TcMEP signals returned in lower extremities, right greater than left. SSEPs also demonstrated partial recovery. Clinically, the patient woke up without deficit. Conclusion Loss of bilateral TcMEPs alone or in combination with SSEP changes warrant immediate due diligence. In this case, early intervention prevented further damage to nerve roots affected by the expanding hematoma. Because significant changes in signals can occur at any time, neurophysiological monitoring should be performed until final closure.

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.

Prognostic value of SSEP change subcategories for perioperative stroke during CEA: A systematic review

Prognostic value of SSEP change subcategories for perioperative stroke during CEA: A systematic review

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.

The effect from different numbers of segmental arteries ligation to the spinal cord in the clinical practice of posterior vertebral column resection correction.

In using posterior vertebral column resection (PVCR) to treat severe kyphoscoliosis, it is unavoidable to ligate and cut off several segmental arteries (SAs) of the spinal cord for exposure and hemostasis, but which would raise the neurological risks. The aim of this study is to explore the changes of intraoperative spinal cord monitoring (IOM) following ligating different numbers of SAs in PVCR. Twenty-one consecutive patients with severe kyphoscoliosis were included and treated by PVCR correction. In operation, according to ligate different numbers of SAs, the IOM changes were recorded, respectively. Examinations of the covariance between different numbers of SAs ligations and IOM changes were performed to reveal the effect to the spinal cord by SAs ligations. In all the 21 cases, averaging 1.9 pairs of SAs were ligated. With the increased numbers of ligations, SSEP amplitudes and latencies were changed more obviously: from 1 to 3 pairs ligations, the mean decreased percentages of amplitudes were from 53.20 to 78.15%, the mean increased percentages of latency were from 1.23 to 1.40%, and the mean durations of decreased SSEP amplitudes were from 3.23 to 5.2min; but without abnormal MEP changes. None occurred postoperative or delayed neurological deficit. Correlation analysis identified significant correlations between the number of SAs ligation and decreased percentage of SSEP amplitude (r=0.945, P<0.0001), and between the number of SAs being ligated and the duration of SSEP change (r=0.945, P=0.0002). Following the increased number of SAs ligation, the amplitude of SSEP is decreased more obviously with a much longer duration of recovery and the risk to spinal cord will be increased greatly. In the PVCR correction on the basis of spinal shortening, the numbers of SAs ligations should be as less as possible for neurological safety.

170 The Accuracy of Multimodality Intraoperative Neuromonitoring to Predict Postoperative Neurological Deficits Following Cervical Laminoplasty

Abstract The utility multimodality intraoperative neuromonitoring (IONM) to predict postoperative neural deficits following cervical laminoplasty remains unclear. The purpose of this study is to determine whether multimodality IONM can predict postoperative C5 palsy. We retrospectively reviewed 131 consecutive patients with cervical myelopathy who underwent open door laminoplasty utilizing motor evoked potential (MEP) monitoring combined with somatosensory-evoked potentials (SSEP) and free-running electromyography (EMG). We reviewed abnormal findings in the IONM record including EMG, MEP, and SSEP changes documented as transient or persist at the end of surgery. Postoperative C5 palsy occurred in 3 patients (2.2%). Two were acute in onset and one occurred 4 days postoperatively. Significant MEP alerts occurred in 12 patients. Four patients had MEP intraoperative alerts in their deltoid or biceps, of which 2 alerts were transient and 2 alerts were persistent at the end of surgery. Significant intraoperative SSEP change was not observed in this study. For the prediction of postoperative acute-onset C5 palsy, MEP alerts in the deltoid or biceps had 100% sensitivity and 98.4% specificity. Transient or persistent MEP alerts in the deltoid or biceps have the same positive predictive value with sensitivity of 50.0% and specificity of 99.2%. The incidence of any neurological deficit including C5 palsy during laminoplasty while utilizing multimodality IONM was relatively low. MEP alerts in the deltoids or biceps had 100% sensitivity and 98.4% specificity to predict a postoperative acute C5 palsy.

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.

Contemporaneous Evaluation of Intraoperative Ulnar and Median Nerve Somatosensory Evoked Potentials for Patient Positioning: A Review of Four Cases

ABSTRACTSomatosensory evoked potentials (SSEPs) are a valuable tool for assessing changes in peripheral nerve pathways caused by patient positioning during spinal surgeries. These changes, when left undiagnosed, may lead to postoperative neurological sequelae. Why an upper extremity SSEP attenuates due to positioning is not necessarily clear and can be multifactorial, affecting the peripheral nerves or elements of the brachial plexus. A conduction block can occur at any point along the course of the nerve secondary to entrapment, compression, and ischemia. These mechanisms of injury may be caused by extreme body habitus, the length of the procedure, or the patient’s metabolic underpinnings. The goal of neuromonitoring for positional injury is to predict and prevent both peripheral nerve and brachial plexus injuries. Using ulnar and median nerve SSEPs contemporaneously may lead to better identification of compromised structures when an SSEP change to one or both of the nerves occurs. The investigators provide four case reports where intraoperative SSEP assessment of contemporaneous ulnar and median nerves prevented postoperative upper extremity neural deficits.