Intraoperative Somatosensory Evoked Potentials Research Articles

Diagnostic utility of different types of somatosensory evoked potential changes in pediatric idiopathic scoliosis correction surgery.

To evaluate the diagnostic accuracy of intraoperative somatosensory evoked potential (SSEP) monitoring and types of SSEP changes in predicting the risk of postoperative neurological outcomes during correction surgery for idiopathic scoliosis (IS) in the pediatric age group (≤ 21years). Database review was performed to identify literature on pediatric patients with IS who underwent correction with intraoperative neuromonitoring. The sensitivity, specificity, and diagnostic odds ratio (DOR) of transient and persistent SSEP changes and complete SSEP loss in predicting postoperative neurological deficits were calculated. Final analysis included 3778 patients. SSEP changes had a sensitivity of 72.9%, specificity of 96.8%, and DOR of 102.3, while SSEP loss had a sensitivity of 41.8%, specificity of 99.3%, and DOR of 133.2 for predicting new neurologic deficits. Transient and persistent SSEP changes had specificities of 96.8% and 99.1%, and DORs of 16.6 and 59, respectively. Intraoperative SSEP monitoring can predict perioperative neurological injury and improve surgical outcomes in pediatric scoliosis fusion surgery. Level 2. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Value of multi-channel somatosensory evoked potentials recording in patients undergoing scoliosis correction surgery.

We aimed to investigate the value of intraoperative multi-channel recording of somatosensory evoked potentials (SSEPs) in patients undergoing posterior instrumentation surgery with fusion. This study included 176 patients with scoliosis who underwent posterior correction surgery from January 2019 to June 2020. Among them, 88 patients underwent routine SSEPs monitoring via single-channel (Cz'-Fpz) cortical recording (control group), while the remaining 88 patients underwent multi-channel (Cz'-Fpz and C3'-C4') SSEPs monitoring in the cortex. Chi-square and Fisher's exact tests were used to analyze the influence of age, spinal deformity classification, and Cobb angle on waveform differentiation and the success rate of SSEPs monitoring. Univariate analysis revealed that age, type of scoliosis, and Cobb angle exerted significant effects on the success rate of intraoperative SSEPs monitoring, and the SSEPs waveform differentiation rate was poorest among patients with congenital scoliosis. Intraoperative monitoring results indicated that the success rate of single-channel SSEPs monitoring was 90.9%, while that of multi-channel monitoring was 98.9% (P < 0.05). Among the intraoperative alarm cases, the incidence of adverse events after single-channel SSEPs monitoring was 66.7%, while the incidence of adverse events after multi-channel SSEPs monitoring was only 28.6%. Multi-channel cortical SSEPs monitoring can effectively and accurately evaluate the function of the posterior column of the spinal cord. Use of multi-channel SSEP monitoring may help to improve the success rate of monitoring and reduce the incidence of postoperative adverse events in patients with congenital scoliosis.

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.

Diagnostic Accuracy of Somatosensory Evoked Potential monitoring during Scoliosis correction surgery in the pediatric population: A Systematic Review (P7-4.002)

<h3>Objective:</h3> To evaluate the diagnostic accuracy of intraoperative somatosensory evoked potential (SSEP) monitoring in predicting the risk of perioperative neurological outcomes during scoliosis fusion surgery for idiopathic scoliosis (IS) in the pediatric age group (≤ 21 years). <h3>Background:</h3> Scoliosis correction surgery is the most effective treatment for pediatric IS. However, new neurological deficits during the surgery can potentially affect the outcomes of this surgery. Intraoperative neuromonitoring techniques like SSEP provide real-time information about the spinal cord and nerve roots and can be used as a reliable indicator to predict perioperative neurological deficits. <h3>Design/Methods:</h3> A systematic review of various databases to find literature on pediatric IS patients who underwent scoliosis correction with intraoperative neuromonitoring. Data collection included study design, patient demographics, procedure, neuromonitoring modalities, SSEP alarm criteria, SSEP changes (including reversible and irreversible changes), and perioperative neurological deficit. We calculated the sensitivity, specificity, and diagnostic odds ratio (DOR) of SSEP changes (total, transient, and persistent) and SSEP loss for predicting perioperative neurological deficits. <h3>Results:</h3> We included eighteen studies for our final analysis, with a total cohort of 4674 children. The incidence of a significant SSEP change was 3.1% (145/4674), while the incidence of a new neurological deficit was 1.01% (47/4674). The incidence of new neurological deficits in children with an intraoperative SSEP change was 28.28% (41/145), while it was 0.13% (6/4529) in children without an SSEP change. SSEP changes had a sensitivity of 72%, specificity of 97%, and DOR of 98.64, while SSEP loss had a sensitivity of 42%, specificity of 99.3%, and a DOR of 143.76 for predicting new neurologic deficit. Transient and Persistent SSEP changes had sensitivities of 37% and 39%, specificities of 97% and 99.2%, and DORs of 18.09 and 75.43, respectively. <h3>Conclusions:</h3> Intraoperative SSEP monitoring can predict perioperative neurological injury and help improve the surgical outcomes in pediatric scoliosis fusion surgery. <b>Disclosure:</b> Dr. Gorijala has nothing to disclose. Dr. Shaik has nothing to disclose. The institution of Dr. Thirumala has received research support from University of Pittsburgh. Dr. Anetakis has nothing to disclose. Jeffery Balzer has nothing to disclose. Donald Crammond has nothing to disclose. Dr. Shandal has nothing to disclose. Dr. Lee has nothing to disclose. The institution of Dr. Shaw has received research support from LSRS. The institution of Dr. Shaw has received research support from CSRS. The institution of Dr. Shaw has received research support from AO Spine. Dr. Shaw has received intellectual property interests from a discovery or technology relating to health care. Mr. Reddy has nothing to disclose.

A Prediction Model for Normal Variation of Somatosensory Evoked Potential During Scoliosis Surgery

Somatosensory evoked potential (SEP) has been commonly used as intraoperative monitoring to detect the presence of neurological deficits during scoliosis surgery. However, SEP usually presents an enormous variation in response to patient-specific factors such as physiological parameters leading to the false warning. This study proposes a prediction model to quantify SEP amplitude variation due to noninjury-related physiological changes of the patient undergoing scoliosis surgery. Based on a hybrid network of attention-based long-short-term memory (LSTM) and convolutional neural networks (CNNs), we develop a deep learning-based framework for predicting the SEP value in response to variation of physiological variables. The training and selection of model parameters were based on a 5-fold cross-validation scheme using mean square error (MSE) as evaluation metrics. The proposed model obtained MSE of 0.027[Formula: see text][Formula: see text] on left cortical SEP, MSE of 0.024[Formula: see text][Formula: see text] on left subcortical SEP, MSE of 0.031[Formula: see text][Formula: see text] on right cortical SEP, and MSE of 0.025[Formula: see text][Formula: see text] on right subcortical SEP based on the test set. The proposed model could quantify the affection from physiological parameters to the SEP amplitude in response to normal variation of physiology during scoliosis surgery. The prediction of SEP amplitude provides a potential varying reference for intraoperative SEP monitoring.

Misconceptions in IONM Part II: Does Anodal Blocking Occur and Is Bipolar Stimulation Necessary with Intraoperative Somatosensory Evoked Potentials?

ABSTRACT Current intraoperative somatosensory evoked potential (SSEP) guidelines recommend bipolar stimulation with the anode at or near the crease of the wrist and the cathode 2–4 cm proximal to the anode for median nerve SSEPs. The rationale for this cathode proximal bipolar configuration appears to be the avoidance of anodal blocking; however, there is a paucity of experimental support for the existence of anodal blocking. Evidence that bipolar stimulation preferentially drives stimulation from the cathode better than monopolar cathodal or monopolar anodal in peripheral nerves in human neurophysiology is also lacking. This study compared anode proximal to anode distal bipolar stimulation of median nerve SSEPs and the efficacy of monopolar cathode to monopolar anode stimulation in generating median, ulnar, and tibial nerve SSEPs. No difference in median nerve cortical SSEP amplitude was observed between anode proximal and anode distal bipolar stimulation at supramaximal stimulation suggesting cathode proximal bipolar is equal to anode proximal bipolar stimulation at supramaximal intensity. This data suggests that anodal blocking does not occur inintraoperative SSEPs. Furthermore, no differences were observed in ulnar, median, and tibial nerve SSEP cortical or subcortical amplitudes and latencies between monopolar cathodal or monopolar anodal stimulation suggesting monopolar cathode and anode stimulation are equally effective at evincing intraoperative SSEPs at supramaximal intensity.

Intraoperative motor and somatosensory evoked potential monitoring during surgical clipping of ruptured and unruptured intracranial aneurysms: a comparative study.

The current study investigated the correlation between intraoperative motor evoked potential (MEP) and somatosensory evoked potential (SSEP) monitoring and both short-term and long-term motor outcomes in aneurysm patients treated with surgical clipping. Moreover, the authors provide a relatively optimal neurophysiological predictor of postoperative motor deficits (PMDs) in patients with ruptured and unruptured aneurysms. A total of 1017 patients (216 with ruptured aneurysms and 801 with unruptured aneurysms) were included. Patient demographic characteristics, clinical features, intraoperative monitoring data, and follow-up data were retrospectively reviewed. The efficacy of using changes in MEP/SSEP to predict PMDs was assessed using binary logistic regression analysis. Subsequently, receiver operating characteristic curve analysis was performed to determine the optimal critical value for duration of MEP/SSEP deterioration. Both intraoperative MEP and SSEP monitoring were significantly effective for predicting short-term (p < 0.001 for both) and long-term (p < 0.001 for both) PMDs in aneurysm patients. The critical values for predicting short-term PMDs were amplitude decrease rates of 57.30% for MEP (p < 0.001 and area under the curve [AUC] 0.732) and 64.10% for SSEP (p < 0.001 and AUC 0.653). In patients with an unruptured aneurysm, the optimal critical values for predicting short-term PMDs were durations of deterioration of 17 minutes for MEP (p < 0.001 and AUC 0.768) and 21 minutes for SSEP (p < 0.001 and AUC 0.843). In patients with a ruptured aneurysm, the optimal critical values for predicting short-term PMDs were durations of deterioration of 12.5 minutes for MEP (p = 0.028 and AUC 0.706) and 11 minutes for SSEP (p = 0.043 and AUC 0.813). The authors found that both intraoperative MEP and SSEP monitoring are useful for predicting short-term and long-term PMDs in patients with unruptured and ruptured aneurysms. The optimal intraoperative neuromonitoring method for predicting PMDs varies depending on whether the aneurysm has ruptured or not.

Intraoperative neurophysiological monitoring during urgent surgical extracranial internal carotid artery recanalization

ObjectiveThe clinical outcome of surgical extracranial internal carotid artery (eICA) recanalization may be adversely affected by intraoperative ischemia. Median nerve somatosensory evoked potential (SEP) amplitude correlates well with cerebral blood flow.Our study presents the value of intraoperative SEP and selective shunting in the prevention of intraoperative ischemia development during urgent eICA recanalization. MethodsProspective recruitment of patients with acute unilateral eICA occlusion. All underwent surgical recanalization with intraoperative monitoring of scalp median SEPs. Preoperative clinical findings, cerebral collaterals, and 3 month functional outcome were evaluated. ResultsThe cohort consisted of 33 patients. Intraoperative SEP amplitude decreased significantly in 6 (18.2%). An intraluminal shunt was inserted twice (6.1%), surgical complications occurred in 6 (18.2%), intracerebral hemorrhage was not found.Favorable outcome 3 months after surgery according to the modified Rankin scale (mRS 0–2) was achieved in 28 (84.8%), 3 patients died (9.1%). ConclusionsIntraoperative SEP during urgent eICA recanalization seems to be beneficial.Thanks to the effective measure based on the intraoperative SEP changes, the clinical outcome in four(12.1%) could be positively affected. SignificanceThe results suggest that selective shunting based on intraoperative median SEPs may prevent intraoperative ischemia and may improve overall outcome of urgent eICA recanalization.

Chapter 13 - Intraoperative neurophysiology in intramedullary spinal cord tumor surgery

Intramedullary spinal cord tumor (ISCT) surgery is challenged by a significant risk of neurological injury. Indeed, while most ISCT patients arrive to surgery in good neurological condition due to early diagnosis, many experience some degree of postoperative sensorimotor deficit. Thus, intraoperative neuromonitoring (IONM) is invaluable for providing functional information that helps neurosurgeons tailor the surgical strategy to maximize resection while minimizing morbidity. Somatosensory evoked potential (SEP), muscle motor evoked potential (mMEP), and D-wave monitoring are routinely used to continuously assess the functional integrity of the long pathways within the spinal cord. More recently, mapping techniques have been introduced to identify the dorsal columns and the corticospinal tracts. Intraoperative SEP decline is not a sufficient reason to abandon surgery, since SEPs are very sensitive to anesthesia and surgical maneuvers. Yet, a severe proprioceptive deficit may adversely impact daily life, and the value of SEPs should be reconsidered. While mMEPs are good predictors of short-term motor outcome, the D-wave is the strongest predictor of long-term motor outcome, and its preservation during surgery is essential. Mapping techniques are promising but still need validation in large cohorts of patients to determine their impact on clinical outcome. The therapeutic rather than merely diagnostic value of IONM in spine surgery is still debated, but there is emerging evidence that IONM provides an essential adjunct in ISCT surgery.

Efficacy of Carotid Artery Stenting Performed under General Anesthesia with Somatosensory Evoked Potential Monitoring

ObjectivesDuring carotid artery stenting (CAS), hemodynamics may be affected by the carotid sinus reflex in some cases. Although general anesthesia has been reported to stabilize intraoperative hemodynamics, the patient's neurological condition must be assessed indirectly. Therefore, we investigated the changes in intraoperative hemodynamics and perioperative complications of CAS under general anesthesia and evaluated the efficacy of somatosensory evoked potential (SEP) monitoring in detecting a reduction in perfusion during CAS. Materials and methodsFrom April 2011 to August 2016,57 consecutive patients who underwent CAS under general anesthesia were evaluated. The follow-up period ranged from 3 to 8 years. During CAS, anesthesiologists monitored and managed the hemodynamics. SEP monitoring was performed during the CAS procedure in all patients. ResultsIntraoperative hypotension (systolic blood pressure ≤ 100 mmHg) was evident in 16 patients (28.1%), and 13 patients (22.8%) experienced intraoperative bradycardia; however, all of these cases were promptly managed under general anesthesia. None of the patients showed systolic blood pressure < 50 mmHg from baseline. Regarding perioperative complications, none of the patients exhibited myocardial infarction or postoperative hyperperfusion symptoms, and there was no mortality. Among 21 patients (36.8%) with a decrease in the intraoperative SEP, 3 (5.3%) exhibited transient ischemic symptoms and 1 (1.8%) had postoperative infarction. ConclusionsCAS under general anesthesia is a safe and effective management option in terms of intraoperative hemodynamic stability. In addition, our findings indicate that SEP monitoring could be helpful in evaluating transient postoperative cerebral ischemia or cerebral infarction after CAS.

243. Should somatosensory evoked potentials and motor evoked potentials monitoring be routinely used in all posterior cervical operations for degenerative conditions of the cervical spine?

<h3>BACKGROUND CONTEXT</h3> Posterior decompression with or without instrumented fusion (PCF) are some of the most common procedures undertaken by spine surgeon. PCF can be the preferred approach for treating patients with cervical spinal traumatic fractures, degenerative spondylosis, deformity tumors, infection and vascular malformations. Intraoperative monitoring is helpful during cases where direct or indirect manipulation of the cord is expected. However, whether neuromonitoring is necessary in routine PCF surgery for degenerative cervical spine conditions remains unknown. <h3>PURPOSE</h3> Here we evaluate the utility of somatosensory evoked potential (SSEP) and motor evoked potential (MEP) monitoring as a tool for predicting postoperative neurologic deficits during PCF for degenerative cervical spine conditions. <h3>STUDY DESIGN/SETTING</h3> Retrospective review of prospectively collected clinical data. <h3>PATIENT SAMPLE</h3> This study included 498 patients who underwent posterior cervical operations for degenerative conditions of the cervical spine, excluding indications such as tumor, trauma, deformity, vascular lesions, and infection. <h3>OUTCOME MEASURES</h3> Sensory and motor neurologic deficit postoperatively. <h3>METHODS</h3> We retrospectively reviewed cases in which PCF was performed for a variety of cervical spine conditions at our institute over a 5-year period. SSEP monitoring was performed in all patients with MEP monitoring performed in only a subset of patients. Patients who had neurologic deficits postoperatively were then identified and detailed analysis was performed to ascertain whether SSEP or MEP monitoring accurately predicted onset of postoperative deficits. The sensitivity, specificity and predictive value of each monitoring paradigm was then determined. <h3>RESULTS</h3> We retrospectively evaluated clinical outcomes and intraoperative monitoring data in 757 patient and identified 498 patients who underwent posterior cervical operations for degenerative conditions of the cervical spine, excluding indications such as tumor, trauma, deformity, vascular lesions, and infection. Forty percent were female, 60% were male with ages ranging from 22 to 93 years-old (mean 67 years-old). SSEP were monitored for all 498 patients during surgery (121 patients [24.3%] had both MEP and SSEP monitoring). Twenty-one patients (4.2%) had neurological deficits after surgery in this cohort. SSEP monitoring had a higher specificity and sensitivity than MEP monitoring for detecting neurologic compromise intraoperatively in PCF cases (91% vs 79% and 60% vs 20% respectively). The positive (PPV) and negative predictive values (NPV) of SSEP monitoring in picking up intraoperative changes that translated to postoperative neurologic deficit were 30% and 97% respectively whereas PPV and NPV of MEP monitoring were 6% and 96% respectively. <h3>CONCLUSIONS</h3> Taken together, these data suggest that intraoperative SSEP and MEP monitoring during PCF is not reliable at predicting postoperative neurologic deficits. With their relatively high NPV, however, MEP and more so SSEP are useful to provide peace of mind intraoperatively when no abnormalities are detected. Thus, use of SSEP and MEP monitoring in PCF should only be limited to cases where the risk of postoperative neurologic deficit is high. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

Application of multimodal neuroelectrophysiological monitoring technology in surgical treatment of thoracic tuberculosis

To explore the value of multimodal neuroelectrophysiological monitoring technology in the evaluation of spinal cord and nerve root function for the treatment of thoracic tuberculosis with debridement and bone grafting and posterior internal fixation by transcostal transverse process approach. The clinical data of 25 patients with thoracic tuberculosis underwent debridement and bone grafting and posterior vertebral arch internal fixation by transcostal transverse process approach from December 2018 to September 2019 was retrospectively analyzed. Among these 25 patients, including 14 males and 11 females;aged from 20 to 83 years old, with a mean of (63.45±9.65) years;there were 3 cases of single vertebral body destruction, 13 cases of 2 vertebral bodies destruction, and 9 cases of 3 or more vertebral bodies destruction. All surgical patients underwent intraoperative detection of somatosensory evoked potential(SEP) and transcranial electric stimulation-motor evoked potential(TES-MEP);and electromyography (EMG) was used to monitor the pedicle screw placement and lesion removal. The erythrocyte sedimentation rate(ESR) was used to evaluate the decline of inflammatory indexes, the visual analogue scale (VAS) was used to evaluate the thoracic spine pain, and the Cobb angle and Oswestry Disability Index(ODI) were used to evaluate the improvement of function. All 25 patients were successfully monitored. Five patients had abnormal SEP waveforms during operation, 3 cases were caused by intraoperative clearing of lesions and spinal cord compression during irrigation, timely replacement of instruments and gestures, and adjustment of irrigation water flow rate returned the waveform to normal; one case was caused by a decrease in systolic blood pressure, and the waveform returned to normal after timely treatment of increased blood pressure;after 1 case of SEP waveform abnormality, the operation was suspended for 10 minutes and recovered spontaneously, and the waveform abnormality did not reappear until the end of the operation. Seven patients had abnormal TES-MEP waveforms, 5 cases occurred when the pedicle screw was inserted, the nail path was adjusted in time, and the waveform recovered after nail repositioning;one case was caused by tilting the operation bed during operation, and the waveform gradually recovered after adjusting the tilt angle of operation bed; one case occurred during the correction of the pedicle screw and rod system, and the waveform gradually returned to normal after the contralateral screw and rod correction were completed during operation. In 5 cases, the EMG burst potential was detected at the same time when the TES-MEP waveform was abnormal. After adjustment, the EMG burst potential disappeared. There was no abnormality in the TES-MEP and SEP waveforms at the same time. Postoperative VAS, ESR, Cobb angle, and ODI were improved compared with preoperatively (P<0.05). In patients with thoracic tuberculosis, the use of debridement and bone grafting and posterior internal fixation by transcostal transverse process approach combined with intraoperative SEP, TES-MEP and EMG monitoring can timely reflect the spinal cord and nerve root function, avoid intraoperative injuries while achieving good fixation and lesion removal.

수술 중 체성감각유발전위감시에서 인터리브자극방식의 임상적 유용성

Intraoperative somatosensory evoked potentials (SSEPs) play a role in reducing postoperative complication. The method of obtaining the SSEP of both upper and lower limbs includes not only a method obtained by serially stimulating each limb, but also an interleave method using auto-sequence. We retrospectively reviewed the clinical and intraoperative monitoring records of 15 patients who underwent both upper and lower limbs intraoperative SSEPs at our hospital from March to September 2020. We compared the amplitude, latency, and acquisition time of the results in each patient when stimulated in serial mode and interleave mode, respectively. Interleave mode stimulation showed no difference in latency, greater amplitude, and shorter acquisition time compared to serial mode stimulation. There were no postoperative complications in 15 patients who underwent intraoperative SSEPs with interleave mode stimulation. Interleave stimulation using auto-sequence can be a clinically useful method for monitoring intraoperative SSEPs of both upper and lower limbs.

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.

Efficacy of evoked potential monitoring for predicting postoperative motor status in internal carotid artery aneurysm surgeries.

This study aimed to investigate the efficacy of intraoperative motor evoked potential (MEP) and somatosensory evoked potential (SSEP) monitoring for predicting postoperative motor deficits (PMDs) in patients with internal carotid artery (ICA) aneurysms. The data for 138 patients with ICA aneurysms who underwent surgical clipping as well as their intraoperative neuromonitoring data were retrospectively reviewed. The efficacy of MEP/SSEP changes for predicting PMDs was assessed using binary logistic regression analysis. Subsequently, receiver operating characteristic curve analysis was used to obtain a supplementary critical value of the MEP/SSEP deterioration duration. The sensitivity and specificity of MEP changes for predicting PMDs were 0.824 and 0.843, respectively. For SSEP changes, the sensitivity and specificity were 0.529 and 0.959, respectively. MEP and SSEP changes were identified as independent predictors for short-term (p = 0.002 and 0.011, respectively) and long-term PMDs (p = 0.040 and 0.006, respectively). The supplementary critical value for MEP deterioration duration for predicting PMDs was 14min (p = 0.007, AUC = 0.805). For SSEP, the value was 14.5min (p = 0.042, AUC = 0.875). The MEP/SSEP changes adjusted by those optimal values were also identified as independent predictors for short-term (p < 0.001 and p = 0.005, respectively) and long-term PMDs (p = 0.019 and 0.003, respectively). Intraoperative MEP and SSEP deterioration durations are effective in predicting PMDs in patients with ICA aneurysms.

Arterial collateral anatomy predicts the risk for intra-operative changes in somatosensory evoked potentials in patients undergoing carotid endarterectomy: a prospective cohort study

BackgroundDuring carotid endarterectomy (CEA), significant amplitude decrement of somatosensory evoked potentials (SEPs) is associated with post-operative neurological deficits.ObjectiveTo investigate the association between an incomplete circle of Willis and/or contralateral ICA occlusion and subsequent changes in intra-operatively monitored SEPs.MethodsWe performed a retrospective analysis of a single center, prospective cohort of consecutive patients undergoing CEA over a 42-month period after reviewing the collateral arterial anatomy on pre-operative radiological imaging. The primary endpoint was an intra-operative decline in SEPs > 50% compared to the baseline value during arterial cross-clamping. Univariate and multivariate logistic regression analyses were performed to investigate a potential association between contralateral ICA occlusion, incomplete circle of Willis, and subsequent alteration in SEPs.ResultsA total of 140 consecutive patients were included, of which 116 patients (82.9%) had symptomatic carotid stenosis of at least 50% according to the classification used in the North American Carotid Surgery Trial (NASCET) (Stroke 22:711–720, 1991). Six patients (4.3%) showed contralateral ICA occlusion, 22 patients (16%) a missing/hypoplastic anterior communicating artery (Acom) or A1 segment, and 79 patients (56%) a missing ipsilateral posterior communicating artery (Pcom) or P1 segment. ICA occlusion and missing segments of the anterior circulation (missing A1 and/or missing Acom) were associated with the primary endpoint (p = 0.003 and p = 0.022, respectively).ConclusionContralateral ICA occlusion and missing anterior collaterals of the circle of Willis increase the risk of intra-operative SEP changes during CEA. Pre-operative assessment of collateral arterial anatomy might help identifying patients with an increased intra-operative risk.

Peripheral Nerve Injury in Thoracic Surgery Detected by Automated Somatosensory Evoked Potential Monitoring.

Study Objective. Our objectives were to estimate the incidence of symptoms of peripheral nerve injury (sPNI) in thoracic surgical patients undergoing video-assisted thoracic surgery or open thoracotomy and to determine whether intraoperative somatosensory evoked potentials (SSEPs) waveform changes correlate with postoperative peripheral neuropathic symptoms. Methods. We conducted a prospective observational study in the operating room of a tertiary hospital. We measured SSEPs intraoperatively and assessed patients for sPNI postoperatively. Results. Forty-four patients consented. Six were excluded from analysis. We found that 42% (95% confidence interval [CI] = 26% to 57%) of patients undergoing thoracic surgery had significant changes in SSEP amplitude and latency. Furthermore, 16% (95% CI = 4% to 28%) of patients had new postoperative symptoms of sensory or motor deficits in an upper extremity. We calculated a sensitivity of 66.7% (95% CI = 29.0% to 100%) and a specificity of 50% (95% CI = 33% to 67.3%) for the identification of sPNI based on automated intraoperative SSEP changes. Conclusions. We identified the incidence of SSEP changes in thoracic surgery (42%) and the incidence of postoperative sPNI after thoracic surgery (16%). We identified a positive correlation between intraoperative SSEP changes and postoperative sPNI, which after multivariate analysis was not significant given the small sample size of the study. By the time sensory and/or motor changes are detected postoperatively, it may be too late to reverse the nerve damage. Future versions of the EPAD device could provide anesthesiologists a way to monitor for the development of sPNI, and make changes before a potential injury becomes permanent.

Assesment of Functional Results for the Lesions Located in Eloquent Areas with Using Intraoperative Cortical-Subcortical Stimulation and Cortical Mapping.

To assess the classical and functional imaging features of patients with pathology located in the eloquent areas of the brain who were admitted to our centre between October 2012 and February 2018. We also studied intraoperative somatosensory evoked potential (SEP), motor evoked potentials (MEP), phase reversal, cortical mapping, the extent of resection and the calculation of postoperative morbidity. We compared our results with previous studies in which this technique was not used. The patient records of 163 patients were reviewed retrospectively after approval by the institutional ethics committee and comparisons were made with reports in the literature. The lesion was localised in the visual cortex in eight of the 163 patients. We did not encounter any abnormality in the VEP recordings, so the surgeries were continued. The remaining 155 cases were followed by intraoperative SEP and MEP monitoring. We observed a greater than 50% decrease in the amplitude and an increase in latencies that was greater than 10% in intraoperative MEP and SEP monitoring in 24 patients of 155. Although 8 of 24 patients with abnormal SEP and MEP values were corrected with manuveurs, 6 patients developed increased neurological deficits postoperatively. In conclusion, all of these methods should not be seen as competitive with each other; they could be considered as complementary. All of these methods are helpful for a surgical team regarding loss of neurological function. The rate of loss might be up to 100% and irreversible despite corrective maneveurs.

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.

Diagnostic accuracy of somatosensory evoked potentials during intracranial aneurysm clipping for perioperative stroke.

Somatosensory evoked potentials (SSEPs) are utilized during aneurysm clipping to detect intraoperative ischemia. We assess the diagnostic accuracy of SSEPs in predicting perioperative stroke during aneurysm clipping. A retrospective review was conducted of 429 consecutive patients who underwent surgical clipping for ruptured and unruptured cerebral aneurysms with intraoperative SSEP monitoring from 2006 to 2013. The relationship between perioperative stroke and SSEP changes was analyzed by calculating the sensitivity, specificity, and area under a Receiving Operating Characteristic curve. Sensitivity and specificity were 42% and 90%, respectively. Area under the curve was 0.66 (95% confidence interval, 0.53-0.79). Reclassification of reversible temporary clip changes to correct for paradoxical classification of SSEP false positives raised the sensitivity from 42 to 65% (p = 0.041, Chi squared test). EEG (electroencephalography) changes increased the specificity (98% vs. 90%, p < 0.001, McNemar's test), but not sensitivity (48% vs. 42%, p = 0.621, McNemar's test) of SSEPs for perioperative stroke. A stepwise logistic regression model selected SSEP amplitude loss (p = 0.006, OR = 3.7 [95% CI 1.5-9.2]) and the SSEP change duration (p = 0.034, OR = 1.8 [95% CI 1.1-3.1]) as independent predictors of perioperative stroke. SSEP changes induced by temporary clipping were highly reversible compared to other SSEP changes (94% vs. 60%, p = 0.003, Fisher exact test), and typically responded to clip removal or readjustment. SSEP changes have high specificity and modest sensitivity for perioperative stroke. Stroke risk is a function of both the magnitude of SSEP amplitude loss and the duration of its loss. Given the modest sensitivity, patients may benefit from multimodal monitoring including motor-evoked potentials during cerebral aneurysm surgery.