Is Two Really Better Than One? Examining the Superiority of Dual Modality Neurophysiological Monitoring During Carotid Endarterectomy: A Meta-Analysis

Cost-benefit analysis of intraoperative neuromonitoring for cardiac surgery

BACKGROUND

Intraoperative neuromonitoring (IONM) can detect large vessel occlusion (LVO) in real-time during surgery. The aim of this study was to conduct a cost-benefit analysis of utilizing IONM among patients undergoing cardiac surgery.

METHODS

A decision-analysis tree with terminal Markov nodes was constructed to model functional outcome, as measured via the modified Rankin Scale (mRS), among 65-year-old patients undergoing cardiac surgery. Our cost-benefit analysis compares the use of IONM (electroencephalography and somatosensory evoked potential) against no IONM in preventing neurological complications from perioperative LVO during cardiac surgery. The study was performed over a lifetime horizon from a societal perspective in the United States. Base case and one-way probabilistic sensitivity analyses were performed.

RESULTS

At a baseline LVO rate of 0.31%, the mean attributable lifetime expenditure for IONM-monitored cardiac surgeries relative to unmonitored cardiac surgeries was $1047.41 (95% CI, $742.12 - $1445.10). At a critical LVO rate of approximately 3.67%, the costs of both monitored and unmonitored cardiac surgeries were the same. Above this critical rate, implementing IONM became cost-saving. On one-way sensitivity analysis, variation in LVO rate from 0% - 10% caused lifetime costs attributable to receiving IONM to range from $1150.47 - $29404.61; variations in IONM cost, percentage of intervenable LVOs, IONM sensitivity, and mechanical thrombectomy cost exerted comparably minimal influence over lifetime costs.

DISCUSSION

We find considerable cost savings favoring the use of IONM under certain parameters corresponding to high-risk patients. This study will provide financial perspective to policymakers, clinicians, and patients alike on the appropriate use of IONM during cardiac surgery.

Diagnostic accuracy of intraoperative neuromonitoring in transcarotid artery revascularization

BACKGROUND

In recent years, transcarotid artery revascularization (TCAR) has emerged as a safe and effective alternative to carotid artery stenting. While intraoperative neuromonitoring (IONM) techniques such as electroencephalogram (EEG) and somatosensory evoked potentials (SSEPs) are often employed during TCAR, there is limited research on their diagnostic accuracy.

METHODS

The authors retrospectively reviewed a multi-institutional IONM database of TCAR procedures performed with EEG and SSEP monitoring. A total of 516 TCAR procedures were included in this study. Significant changes in EEG and/or SSEPs, surgeon's interventions, resolution of significant changes, and immediate postoperative neurological outcome were documented. Sensitivity, specificity, positive and negative predictive values were calculated.

RESULTS

The incidence of intraoperative onset new neurologic deficit was 0.4%. Significant changes in EEG and/or SSEPs occurred in 5.4% of the cases. Of the cases with IONM alerts, 78.5% returned to baseline with a surgical or hemodynamic intervention. From the cases with unresolved IONM alerts, 33.3% woke up with a new neurological deficit. The overall sensitivity and specificity for IONM was 100% and 99.2%, respectively. The positive predictive value was 33.3% and the negative predictive value was 100%.

CONCLUSIONS

IONM during TCAR offers high sensitivity and specificity in predicting postoperative outcome. Patients with resolved IONM alerts had immediate neurological outcomes that were comparable to those who had no IONM alerts.

Role of Intraoperative Neuromonitoring to Predict Postoperative Delirium in Cardiovascular Surgery

OBJECTIVE

Postoperative delirium (POD) can occur in up to 50% of older patients undergoing cardiovascular surgery, resulting in hospitalization and significant morbidity and mortality. This study aimed to determine whether intraoperative neurophysiologic monitoring (IONM) modalities can be used to predict delirium in patients undergoing cardiovascular surgery.

DESIGN

Adult patients undergoing cardiovascular surgery with IONM between 2019 and 2021 were reviewed retrospectively. Delirium was assessed multiple times using the Intensive Care Delirium Screening Checklist (ICDSC). Patients with an ICDSC score ≥4 were considered to have POD. Significant IONM changes were evaluated based on a visual review of electroencephalography (EEG) and somatosensory evoked potentials data and documentation of significant changes during surgery.

SETTING

University of Pittsburgh Medical Center hospitals.

PARTICIPANTS

Patients 18 years old and older undergoing cardiovascular surgery with IONM monitoring.

MEASUREMENTS AND MAIN RESULTS

Of the 578 patients undergoing cardiovascular surgery with IONM, 126 had POD (21.8%). Significant IONM changes were noted in 134 patients, of whom 49 patients had delirium (36.6%). In contrast, 444 patients had no IONM changes during surgery, of whom 77 (17.3%) patients had POD. Upon multivariate analysis, IONM changes were associated with POD (odds ratio 2.12; 95% CI 1.31-3.44; p < 0.001). Additionally, baseline EEG abnormalities were associated with POD (p = 0.002).

CONCLUSION

Significant IONM changes are associated with an increased risk of POD in patients undergoing cardiovascular surgery. These findings offer a basis for future research and analysis of EEG and somatosensory evoked potential monitoring to predict, detect, and prevent POD.

Thrombosis or vasospasm: The utility of intraoperative neuromonitoring during TCAR

OBJECTIVES

Transcarotid artery revascularization (TCAR) has become more prevalent as a treatment modality for carotid stenosis. Many centers perform TCAR without any adjunctive neuromonitoring, for example, somatosensory-evoked potential (SSEP) and electroencephalogram (EEG).

METHODS

We present a case of transcarotid artery revascularization (TCAR) performed with concomitant somatosensory-evoked potential (SSEP) and electroencephalogram (EEG) neuromonitoring in the setting of concerning intraoperative angiographic images.

RESULTS

TCAR was undertaken for a 58 year-old man presenting with symptomatic left carotid stenosis and right ICA occlusion. Based on his comorbidities, pre-existing conditions, and the need for dual antiplatelet therapy, TCAR was offered as an alternative to standard carotid endarterectomy. Intraoperatively, following stent delivery, no flow was appreciated through the carotid stent or distal ICA. Neuromonitoring remained stable and was reassuring for distal ICA spasm with no-reflow phenomenon. The patient tolerated the procedure well and has had no stent-related complications through 10 months of follow-up.

CONCLUSION

This case highlights the utility of neuromonitoring with TCAR as an adjunct to intraoperative decision-making in the setting of suspected internal carotid artery (ICA) vasospasm versus thrombosis after stent delivery.

Median nerve somatosensory evoked potential alarm related to head and neck positioning for carotid surgery

Head positioning in carotid surgery represents an often overlooked but sensitive period in the surgical plan. A 53-year-old male presented a significant decrement in median nerve somatosensory evoked potential (mSEP) following head and neck positioning for carotid pseudoaneurysm repair before skin incision.Neurophysiological monitoring was performed with mSEP and electroencephalography early during the patient's preparation and surgery. Within five minutes after rotation and extension of the head to properly expose the surgical field, the contralateral m-SEP significantly decreased in both cortical (N20/P25) and subcortical (P14/N18) components. Partial neck correction led to m-SEP improvement, allowing to proceed with the carotid repair. We discuss possible underlying pathophysiological mechanisms responsible for these changes and highlight the relevance of an early start on monitoring to avoid neurological deficits.

Comparison of Methods for Monitoring Intra-operative Cerebral Perfusion in Patients Undergoing Carotid Endarterectomy with Selective Shunting: A Systematic Review and Network Meta-Analysis of Randomised Controlled Trials and Cohort Studies

OBJECTIVE

This study aimed to analyse the influence of different methods of monitoring cerebral perfusion (MCP) on stroke, death, and use of intraluminal shunt during carotid endarterectomy (CEA).

METHODS

A systematic review and network meta-analysis was conducted and registered in the PROSPERO registry (CRD42021246360). Medline, Embase, CENTRAL, and Web of Science were searched. Randomised controlled trials (RCTs) and cohort studies with > 50 participants that compared clinical outcomes for different MCP in patients undergoing CEA were included. Papers reporting one or a combination of two of the following MCPs were included in the analysis: awake testing (AT), near infrared spectroscopy (NIRS), electroencephalography (EEG), somatosensory evoked potential (SSEP), motor evoked potential (MEP), transcranial Doppler (TCD), and stump pressure (SP). A random effects network meta-analysis was performed using a binomial likelihood function with a specified logit link for peri-operative stroke or death and shunting as outcomes. Near infrared spectroscopy was excluded due to the lack of studies that could be used for statistical analysis.

RESULTS

Of 1 834 publications, 17 studies (15 cohort studies and two RCTs) including 21 538 participants were incorporated in the quantitative analysis. Electroencephalography was used in the largest number of participants (7 429 participants, six studies), while AT was used in the highest number of studies (10 studies). All monitoring modalities had worse outcomes with respect to stroke or death when compared with AT, with ORs ranging between 1.3 (95% credible interval [CrI] 0.2 - 10.9) for SSEP + MEP and 3.1 (CrI 0.3 - 35.0) for patients monitored with a combination of EEG and TCD. However, the wide CrI indicated that there is no statistically significant difference between the monitoring methods. Patients monitored with a combination of EEG and TCD had the lowest odds of being shunted, while SP had the highest odds of being shunted, also with no statistically significant difference.

CONCLUSION

There is a lack of high quality data on this topic in the literature. The present study showed no significant difference between monitoring methods investigated in the network meta-analysis.

Carotid Endarterectomy Surgeries: A Multimodality Intraoperative Neurophysiological Monitoring Approach

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

Monitoring in carotid endarterectomy

Cerebral ischemia during carotid endarterectomy occurs via several mechanisms: inadequate collateral blood flow during carotid cross-clamping, thromboembolism due to carotid manipulation, and/or rethrombosis at the surgical site. Perioperative strokes increase not only the morbidity of endarterectomy but also its short- and long-term mortality. However, while several predictors of cerebral ischemia have been identified, precise individual risk is hard to assess. Since nonselective shunting during carotid cross-clamping is neither risk-free nor eliminates perioperative stroke, it is advisable to apply intraoperative monitoring techniques for detection and reversal of cerebral ischemia, which may occur at various stages of the procedure. This chapter addresses the methods available for monitoring, with an emphasis on neurophysiologic techniques, which are preferable given their direct assessment of how a decrease in cerebral blood flow impacts brain function. These include electroencephalography, somatosensory evoked potentials, and transcranial motor evoked potentials. Details regarding the methodology, advantages, disadvantages, and interpretation of these tests will be discussed within the anatomic, physiologic, surgical, and anesthetic contexts.

Management of neurophysiological monitoring changes during carotid endarterectomy exposure

BACKGROUND

Carotid endarterectomy (CEA) is a safe and effective operation in the management of carotid stenosis. Intraoperative neurophysiologic monitoring (IONM) changes during carotid clamping has been well studied, but there is scant evidence detailing IONM changes during carotid exposure.

OBJECTIVE

We analyzed our experience with IONM changes during CEA exposure to determine whether multimodal IONM changes during exposure predict outcomes and how best to manage this challenging clinical scenario.

METHODS

We reviewed all CEAs performed at our medical center between January 2015 and June 2020 and identified patients with multimodal IONM changes during exposure of the carotid artery. Our primary outcomes were perioperative stroke and functional outcomes. Functional outcomes were measured by modified Rankin scale (mRS), with good functional outcome defined at mRS scores 0-3. We also reviewed our intraoperative IONM change management strategies.

RESULTS

Five patients (4 males, 1 female) with an average age of 67 ± 12 years had intraoperative IONM changes during carotid exposure. Among these, three patients were discharged with good functional outcome, and four patients had a good functional outcome at last follow-up. Two patients had perioperative stroke, half of which resulted in significant disability. One patient was transferred to the neuroendovascular suite intraoperatively for evaluation for thromboembolism followed by angioplasty and stenting with distal protection.

CONCLUSION

Intraoperative IONM changes during carotid exposure predict outcomes in CEA. We propose that transition to the neuroendovascular suite following significant IONM changes during carotid exposure may be a useful strategy for management of this challenging clinical scenario. This approach provides the opportunity to evaluate and treat thromboembolism and still complete carotid revascularization when appropriate. This algorithm may be particularly useful in the era of dual trained vascular neurosurgeons.

Intraoperative neurophysiologic monitoring during aortic arch surgery

OBJECTIVE

To evaluate the ability of intraoperative neurophysiologic monitoring (IONM) during aortic arch reconstruction with hypothermic circulatory arrest (HCA) to predict early (<48 hours) adverse neurologic events (ANE; stroke or transient ischemic attack) and operative mortality.

METHODS

This was an observational study of aortic arch surgeries requiring HCA from 2010 to 2018. Patients were monitored with electroencephalogram (EEG) and somatosensory evoked potentials (SSEP). Baseline characteristics and postoperative outcomes were compared according to presence or absence of IONM changes, which were defined as any acute variation in SSEP or EEG, compared with baseline. Multivariable logistic regression analysis was used to assess the association of IONM changes with operative mortality and early ANE.

RESULTS

A total of 563 patients underwent aortic arch reconstruction with HCA and IONM. Of these, 119 (21.1%) patients had an IONM change, whereas 444 (78.9%) did not. Patients with IONM changes had increased operative mortality (22.7% vs 4.3%) and increased early ANE (10.9% vs 2.9%). In multivariable analysis, SSEP changes were correlated with early ANE (odds ratio [OR], 4.68; 95% confidence interval [CI], 1.51-14.56; P = .008), whereas EEG changes were not (P = .532). Permanent SSEP changes were correlated with early ANE (OR, 4.56; 95% CI, 1.51-13.77; P = .007), whereas temperature-related SSEP changes were not (P = .997). Finally, any IONM change (either SSEP or EEG) was correlated with operative mortality (OR, 5.82; 95% CI, 2.72-12.49; P < .001).

CONCLUSIONS

Abnormal IONM events during aortic arch reconstruction with HCA portend worse neurologic outcomes and operative mortality and have a negative predictive value of 97.1%. SSEP might be more sensitive than EEG for predicting early ANE, especially when SSEP changes are permanent.

Comparison of Single and Dual Monitoring during Carotid Endarterectomy

We compared the rate of selective shunt and pattern of monitoring change between single and dual monitoring in patients undergoing carotid endarterectomy (CEA). A total of 121 patients underwent 128 consecutive CEA procedures. Excluding five procedures using internal shunts in a premeditated manner, we classified patients according to the monitoring: Group A (n = 72), patients with single somatosensory evoked potential (SSEP) monitoring; and Group B (n = 51), patients with dual SSEP and motor evoked potential (MEP). Among the 123 CEAs, an internal shunt was inserted in 12 procedures (9.8%) due to significant changes in monitoring (Group A 5.6%, Group B 15.7%, p = 0.07). The rate of shunt use was significantly higher in patients with the absence of contralateral proximal anterior cerebral artery (A1) on magnetic resonance angiography (MRA) than in patients with other types of MRA (p <0.001). Significant monitor changes were seen in 16 (12.5%) in both groups. In four of nine patients in Group B, SSEP and MEP changes were synchronized, and in the remaining five patients, a time lag was evident between SSEP and MEP changes. In conclusion, the rate of internal shunt use tended to be more frequent in patients with dual monitoring than in patients with single SSEP monitoring, but the difference was not significant. Contralateral A1 absence may predict the need for a shunt and care should be taken to monitor changes throughout the entire CEA procedure. Use of dual monitoring can capture ischemic changes due to the complementary relationship, and may reduce the rate of false-negative monitor changes during CEA.

Surgical Technique for Carotid Endarterectomy: Current Methods and Problems

Over the last 60 years, many reports have investigated carotid endarterectomy (CEA) and techniques have thus changed and improved. In this paper, we review the recent literature regarding operational maneuvers for CEA and discuss future problems for CEA. Longitudinal skin incision is common, but the transverse incision has been reported to offer minimal invasiveness and better cosmetic effects for CEA. Most surgeons currently use microscopy for dissection of the artery and plaque. Although no monitoring technique during CEA has been proven superior, multiple monitors offer better sensitivity for predicting postoperative neurological deficit. To date, data are lacking regarding whether routine shunt or selective shunt is better. Individual surgeons thus need to select the method with which they are more comfortable. Many surgical techniques have been reported to obtain distal control of the internal carotid artery in patients with high cervical carotid bifurcation or high plaque, and minimally invasive techniques should be considered. Multiple studies have shown that patch angioplasty reduces the risks of stroke and restenosis compared with primary closure, but few surgeons in Japan have been performing patch angioplasty. Most surgeons thus experience only a small volume of CEAs in Japan, so training programs and development of in vivo training models are important.

Long-term cognitive decline and mortality after carotid endarterectomy

OBJECTIVES

To date no studies have evaluated long term cognitive decline after carotid endarterectomy (CEA). We evaluated whether participants who had CEA were at increased risk of cognitive decline over participants who didn't undergo CEA.

PATIENTS AND METHODS

The patients in the study were participants in the Cardiovascular Health Study (CHS), a study of 5201 men and women over the age of 65 who were recruited from four communities (Pittsburgh, Pennsylvania; Sacramento, California; Winston-Salem, North Carolina; Hagerstown, Maryland) in 1988-89. The outcomes measured were 1) Decline in 3MSE and digit symbol substitution test (DSST) scores after CEA compared to before CEA. 2) All-cause mortality in CHS cohort among participants who did and did not have CEA.

RESULTS

CEA patients had significantly greater annual decrease in the DSST scores -2.43 (SD 4.21) compared to those who did not have a CEA -1.1 (SD 2.57) (p < 0.001) but this was not seen in the 3MSE scores. CEA patients had increased the risk of decline in DSST (OR 2.41, 95 % CI 1.49, 3.88) and 3MSE (OR 2.17, 95 % CI 1.35, 3.48) scores after adjusting for age, gender, race and educational status. CEA was associated with all-cause mortality in the long term with a HR of 2.72 (95 % CI 2.22, 3.34) after adjusting for covariates. Participants with lower baseline 3MSE scores HR 1.39 (1.27, 1.51), lower DSST scores <34 HR 1.69(1.54, 1.85) were more likely deceased.

CONCLUSIONS

CEA patients are at increased risk of lower scores on 3MSE and DSST testing in the long term. Mortality in the CHS cohort was higher in participants who underwent CEA. Further, lower 3MSE and DSST scores increased the risk of mortality.

Ocular blood flow by laser speckle flowgraphy to detect cerebral ischemia during carotid endarterectomy

Laser speckle flowgraphy (LSFG) is a noninvasive technique that can measure relative blood flow velocity in the optic fundus contributed by the ophthalmic artery, the main first branch originating from the internal carotid artery (ICA). The aim of this study was to assess the feasibility of ocular blood flow measurement by LSFG to detect ischemic stress due to carotid clamping during carotid endarterectomy (CEA). Nineteen patients undergoing CEA with ocular blood flow measurement by LSFG and intraoperative monitoring (IOM) were prospectively enrolled between August 2016 and March 2019. The mean blur rate (MBR) of ocular blood flow by LSFG, representing relative blood flow of the branch of the retinal artery originating from the optic nerve head, was compared between before and after carotid clamping during CEA. The correlation between the reduction ratio of MBR and the regional saturation oxygen (rSO₂) index by near infrared spectroscopy was investigated. Ocular blood flow measurement by LSFG could not be performed in one patient with a severe cataract. In the other 18 patients, LSFG could be performed in all 106 sessions during surgery. The MBR reduction ratio between before and after carotid clamping ranged from - 12 to 100%. The MBR reduction ratio was positively correlated with the rSO₂ index (r = 0.694, 95% confidence interval: 0.336-0.877, p = 0.001). The MBR reduction ratio of ocular blood flow by LSFG after carotid clamping was significantly correlated with the rSO₂ index. The ocular blood flow by LSFG could be considered an adjunct modality for evaluating cerebral ischemic tolerance during CEA.

Practice guidelines for the supervising professional: intraoperative neurophysiological monitoring

The American Society of Neurophysiological Monitoring (ASNM) was founded in 1989 as the American Society of Evoked Potential Monitoring. From the beginning, the Society has been made up of physicians, doctoral degree holders, Technologists, and all those interested in furthering the profession. The Society changed its name to the ASNM and held its first Annual Meeting in 1990. It remains the largest worldwide organization dedicated solely to the scientifically-based advancement of intraoperative neurophysiology. The primary goal of the ASNM is to assure the quality of patient care during procedures monitoring the nervous system. This goal is accomplished primarily through programs in education, advocacy of basic and clinical research, and publication of guidelines, among other endeavors. The ASNM is committed to the development of medically sound and clinically relevant guidelines for the performance of intraoperative neurophysiology. Guidelines are formulated based on exhaustive literature review, recruitment of expert opinion, and broad consensus among ASNM membership. Input is likewise sought from sister societies and related constituencies. Adherence to a literature-based, formalized process characterizes the construction of all ASNM guidelines. The guidelines covering the Professional Practice of intraoperative neurophysiological monitoring were initially published January 24th, 2013, and subsequently that document has undergone review and revision to accommodate broad inter- and intra-societal feedback. This current version of the ASNM Professional Practice Guideline was fully approved for publication according to ASNM bylaws on February 22nd, 2018, and thus overwrites and supersedes the initial guideline.

Predictors of cross-clamp-induced intraoperative monitoring changes during carotid endarterectomy using both electroencephalography and somatosensory evoked potentials

OBJECTIVE

The efficacy of selective shunting during carotid endarterectomy (CEA) using intraoperative monitoring (IOM) for detection of cerebral ischemia is well established. There is mounting evidence that monitoring of both electroencephalography (EEG) and somatosensory evoked potentials (SSEPs) increases the sensitivity of cerebral ischemia detection. Predictors of cerebral ischemia requiring selective shunt placement using IOM of both EEG and SSEPs have not been previously identified.

METHODS

Consecutive patients who underwent CEA between January 1, 2000, and December 31, 2010, were retrospectively analyzed. Primary end points were IOM changes at any time during the operation or IOM changes with carotid cross-clamping. Risk factors assessed included demographics; baseline comorbidities; severity of ipsilateral and contralateral disease; symptomatic status; and use of statin, antiplatelet, and beta-blocker medications. Univariate and multivariate logistic regression was used for analysis.

RESULTS

During the 11-year study period, a total of 758 patients underwent 804 CEAs (mean age, 70.6 ± 9.5 years; 59.8% male; 39.2% symptomatic) using IOM of both SSEPs and EEG for selective shunting guidance. Postoperative stroke rate was 1.37%; 27.1% of patients had significant SSEP or EEG changes, and 49.1% of these were clamp induced (within 5 minutes of cross-clamping). Of these patients, 83.2% received a shunt (11.4% overall). The most common reason that a shunt was not placed after cross-clamp-induced changes was that the changes resolved with further blood pressure elevation (8 of 17 patients). Clamp-induced IOM changes were predictive of postoperative stroke (odds ratio [OR], 5.5; P = .005). Risk factors for clamp-induced IOM changes were contralateral carotid occlusion (OR, 2.5; P = .01), symptomatic stenosis (OR, 1.8; P = .006), and diabetes (OR, 1.6; P = .03), whereas there was a trend toward increased risk with female sex (OR, 1.5; P = .08). Risk factors for any IOM change (clamp and nonclamp induced) were symptomatic carotid stenosis (OR, 1.8; P < .001), use of beta blockers (OR, 1.5; P = .03), and female sex (OR, 1.5; P = .02).

CONCLUSIONS

Whereas some patients can be expected to experience IOM changes by monitoring of SSEPs and EEG, a much smaller percentage will receive a shunt. Contralateral carotid occlusion, symptomatic stenosis, diabetes, and female sex increase the risk of clamp-induced IOM changes and should be anticipated to need a shunt. Patients receiving beta blockers are likely to experience IOM changes during the operation that are not associated with clamping.

Meta-Analysis of Perioperative Stroke and Mortality in Transcatheter Aortic Valve Implantation

Transcatheter aortic valve implantation (TAVI) is a rapidly evolving safe method with decreasing incidence of perioperative stroke. There is a void in literature concerning the impact of stroke after TAVI in predicting 30-day stroke-related mortality. The primary aim of this meta-analysis was to determine whether perioperative stroke increases risk of stroke-related mortality after TAVI. Online databases, using relevant keywords, and additional related records were searched to retrieve articles involving TAVI and stroke after TAVI. Data were extracted from the finalized studies and analyzed to generate a summary odds ratio (OR) of stroke-related mortality after TAVI. The stroke rate and stroke-related mortality rate in the total patient population were 3.07% (893 of 29,043) and 12.27% (252 of 2,053), respectively. The all-cause mortality rate was 7.07% (2,053 of 29,043). Summary OR of stroke-related mortality after TAVI was estimated to be 6.45 (95% confidence interval 3.90 to 10.66, p <0.0001). Subgroup analyses were performed among age, approach, and valve type. Only 1 subgroup, transapical TAVI, was not significantly associated with stroke-related mortality (OR 1.97, 95% confidence interval, 0.43 to 7.43, p = 0.42). A metaregression was conducted among females, New York Heart Association class III/IV status, previous stroke, valve type, and implantation route. All failed to exhibit any significant associations with the OR. In conclusion, perioperative strokes after TAVI are associated with >6 times greater risk of 30-day stroke-related mortality. Transapical TAVI is not associated with increased stroke-related mortality in patients who suffer from perioperative stroke. Preventative measures need to be taken to alleviate the elevated rates of stroke after TAVI and subsequent direct mortality.

Somatosensory Evoked Potentials and Electroencephalography during Carotid Endarterectomy Predict Late Stroke but not Death

BACKGROND

Late stroke and death rates are anticipated to be higher in patients undergoing carotid endarterectomy (CEA) compared with healthy counterparts. However, little is known regarding predictors other than the baseline comorbidities. We have recently shown that dual intraoperative somatosensory evoked potentials (SSEPs) and electroencephalography (EEG) monitoring improves the ability to predict perioperative strokes. We seek to determine if dual intraoperative monitoring (IOM) can further predict long-term strokes and death.

METHODS

Consecutive patients who underwent CEA under dual SSEP and EEG IOM between January 1, 2000 and December 31, 2010 were analyzed. Patients were divided in 2 groups, those with and those without IOM changes. IOM changes were classified as either occurring during carotid cross-clamp placement or at any time during the operation. End points were time to stroke and death. Log-rank tests and Cox regression analysis were used to identify predictors of postoperative stroke and death.

RESULTS

A total of 853 CEAs (mean age 70.6 ± 9.5 years, 58.7% male, 38.9% symptomatic) were performed during the study period with a mean clinical follow-up of 48 ± 38 months. One hundred seven patients (13.6%) had significant SSEP or EEG changes at the time of clamping, while considerably more patients (217, 25.4%) had SSEP and/or EEG changes recorded at any point during the procedure, including clamping. Baseline characteristics including rates of bilateral disease, statin use, and antiplatelet use were similar between groups. Female gender, symptomatic disease, and significant contralateral carotid stenosis were more frequent in the group with IOM changes. The overall stroke-free survival rate at 5 years was significantly higher in patients without IOM changes (94.7% vs. 88.2%, P < 0.05) and at 10 years (86.1% vs. 78.0%, P < 0.05). Despite differences in stroke-free survival, overall survival at 10 years was not different between groups (44.0% in patients with IOM changes vs. 42.8% in patients without, P = 0.7). Renal insufficiency (hazards ratio [HR] 2.13, P = 0.03), diabetes (HR 1.84, P = 005), and age > 80 at the time of operation (HR 3.24, P = 0.001) were significant predictors of late stroke, while statins were significantly protective (HR 0.55, P = 0.05). Controlling for these factors, IOM changes (HR 2.5, P = 0.004) were a strong predictor of long-term risk of stroke after CEA.

CONCLUSION

Intraoperative SSEP and/or EEG changes are predictive of late stroke but not death following CEA indicating a need for further elucidation and management of the underlying risk factors driving the elevated stroke risk in this subset of CEA patients.

Intraoperative Neurophysiological Monitoring for Endoscopic Endonasal Approaches to the Skull Base: A Technical Guide

Intraoperative neurophysiological monitoring during endoscopic, endonasal approaches to the skull base is both feasible and safe. Numerous reports have recently emerged from the literature evaluating the efficacy of different neuromonitoring tests during endonasal procedures, making them relatively well-studied. The authors report on a comprehensive, multimodality approach to monitoring the functional integrity of at risk nervous system structures, including the cerebral cortex, brainstem, cranial nerves, corticospinal tract, corticobulbar tract, and the thalamocortical somatosensory system during endonasal surgery of the skull base. The modalities employed include electroencephalography, somatosensory evoked potentials, free-running and electrically triggered electromyography, transcranial electric motor evoked potentials, and auditory evoked potentials. Methodological considerations as well as benefits and limitations are discussed. The authors argue that, while individual modalities have their limitations, multimodality neuromonitoring provides a real-time, comprehensive assessment of nervous system function and allows for safer, more aggressive management of skull base tumors via the endonasal route.