An imbalance between specialized pro-resolving lipid mediators and pro-inflammatory leukotrienes promotes instability of atherosclerotic plaques

Chronic unresolved inflammation plays a causal role in the development of advanced atherosclerosis, but the mechanisms that prevent resolution in atherosclerosis remain unclear. Here, we use targeted mass spectrometry to identify specialized pro-resolving lipid mediators (SPM) in histologically-defined stable and vulnerable regions of human carotid atherosclerotic plaques. The levels of SPMs, particularly resolvin D1 (RvD1), and the ratio of SPMs to pro-inflammatory leukotriene B₄ (LTB₄), are significantly decreased in the vulnerable regions. SPMs are also decreased in advanced plaques of fat-fed Ldlr^−/− mice. Administration of RvD1 to these mice during plaque progression restores the RvD1:LTB₄ ratio to that of less advanced lesions and promotes plaque stability, including decreased lesional oxidative stress and necrosis, improved lesional efferocytosis, and thicker fibrous caps. These findings provide molecular support for the concept that defective inflammation resolution contributes to the formation of clinically dangerous plaques and offer a mechanistic rationale for SPM therapy to promote plaque stability.

Atherosclerosis progression is linked to inflammatory processes in the blood vessel wall. Here, the authors show that, with the progression of atherosclerosis, the resolution of inflammation is impaired as the result of an imbalance between specialized pro-resolving lipid mediators and leukotrienes.

Impact of Cognitive Dysfunction on Survival in Patients With and Without Statin Use Following Carotid Endarterectomy

BACKGROUND:

Early cognitive dysfunction (eCD) is a subtle form of neurological injury observed in ∼25% of carotid endarterectomy (CEA) patients. Statin use is associated with a lower incidence of eCD in asymptomatic patients having CEA.

OBJECTIVE:

To determine whether eCD status is associated with worse long-term survival in patients taking and not taking statins.

METHODS:

This is a post hoc analysis of a prospective observational study of 585 CEA patients. Patients were evaluated with a battery of neuropsychometric tests before and after surgery. Survival was compared for patients with and without eCD stratifying by statin use. At enrollment, 366 patients were on statins and 219 were not. Survival was assessed by using Kaplan-Meier methods and multivariable Cox proportional hazards models.

RESULTS:

Age ≥75 years (P = .003), diabetes mellitus (P < .001), cardiac disease (P = .02), and statin use (P = .014) are significantly associated with survival univariately (P < .05) by use of the log-rank test. By Cox proportional hazards model, eCD status and survival adjusting for univariate factors within statin and nonstatin use groups suggested a significant effect by association of eCD on survival within patients not taking statin (hazard ratio, 1.61; 95% confidence interval, 1.09–2.40; P = .018), and no significant effect of eCD on survival within patients taking statin (hazard ratio, 0.98; 95% confidence interval, 0.59–1.66; P = .95).

CONCLUSION:

eCD is associated with shorter survival in patients not taking statins. This finding validates eCD as an important neurological outcome and suggests that eCD is a surrogate measure for overall health, comorbidity, and vulnerability to neurological insult.

Deficits of hand coordination and laterality of carotid endarterectomy

OBJECT

Neurocognitive performance is used to assess multiple cognitive domains, including motor coordination, before and after carotid endarterectomy (CEA). Although gross motor strength is impaired with ischemia of large cortical areas or of the internal capsule, the authors hypothesize that patients undergoing CEA demonstrate significant motor deficits of hand coordination contralateral to the operative side, which is more clearly manifest in the nondominant hand than in the dominant hand with ischemia of smaller cortical areas.

METHODS

The neurocognitive performance of 374 patients was evaluated with a battery of neuropsychometric tests. Both asymptomatic and symptomatic patients undergoing CEA were included. The authors evaluated the patients' dominant and nondominant hand performance on the Grooved Pegboard test, a test of hand coordination, to demonstrate their functional laterality. Neurocognitive dysfunction was evaluated as the difference in performance before and after CEA according to group-rate and event-rate analyses. The z scores were generated for all tests using a reference group of patients who were having simple spine surgery. Dominant and nondominant motor coordination functions were evaluated as raw scores and as calculated z scores.

RESULTS

According to event-rate analysis, significantly more patients undergoing CEA of the opposite carotid artery demonstrated nondominant than dominant hand deficits of coordination (41.2% vs 26.4%, respectively, p = 0.02). Similarly, according to group-rate analysis, in patients undergoing CEA of the opposite carotid artery, raw difference scores from the Grooved Pegboard test reflected greater nondominant than dominant hand deficits of coordination (21.0 ± 54.4 vs 9.7 ± 37.0, respectively, p = 0.02).

CONCLUSIONS

Patients undergoing CEA of the opposite carotid artery are more likely to demonstrate nondominant than dominant hand deficits of coordination because of greater dexterity in the dominant hand before surgery.

Republished: Society for Neuroscience in Anesthesiology and Critical Care expert consensus statement: Anesthetic management of endovascular treatment for acute ischemic stroke

Literature on the anesthetic management of endovascular treatment of acute ischemic stroke (AIS) is limited. Anesthetic management during these procedures is still mostly dependent on individual or institutional preferences. Thus, the Society of Neuroscience in Anesthesiology and Critical Care (SNACC) created a task force to provide expert consensus recommendations on anesthetic management of endovascular treatment of AIS. The task force conducted a systematic literature review (up to August 2012). Because of the limited number of research articles relating to this subject, the task force solicited opinions from experts in this area. The task force created a draft consensus statement based on the available data. Classes of recommendations and levels of evidence were assigned to articles specifically addressing anesthetic management during endovascular treatment of stroke using the standard American Heart Association evidence rating scheme. The draft consensus statement was reviewed by the Task Force, SNACC Executive Committee and representatives of Society of NeuroInterventional Surgery (SNIS) and Neurocritical Care Society (NCS) reaching consensus on the final document. For this consensus statement the anesthetic management of endovascular treatment of AIS was subdivided into 12 topics. Each topic includes a summary of available data followed by recommendations. This consensus statement is intended for use by individuals involved in the care of patients with acute ischemic stroke, such as anesthesiologists, interventional neuroradiologists, neurologists, neurointensivists and neurosurgeons.

Radiographic absence of the posterior communicating arteries and the prediction of cognitive dysfunction after carotid endarterectomy

OBJECT

Approximately 25% of patients exhibit cognitive dysfunction 24 hours after carotid endarterectomy (CEA). One of the purported mechanisms of early cognitive dysfunction (eCD) is hypoperfusion due to inadequate collateral circulation during cross-clamping of the carotid artery. The authors assessed whether poor collateral circulation within the circle of Willis, as determined by preoperative CT angiography (CTA) or MR angiography (MRA), could predict eCD.

METHODS

Patients who underwent CEA after preoperative MRA or CTA imaging and full neuropsychometric evaluation were included in this study (n = 42); 4 patients were excluded due to intraoperative electroencephalographic changes and subsequent shunt placement. Thirty-eight patients were included in the statistical analyses. Patients were stratified according to posterior communicating artery (PCoA) status (radiographic visualization of at least 1 PCoA vs of no PCoAs). Variables with p < 0.20 in univariate analyses were included in a stepwise multivariate logistic regression model to identify predictors of eCD after CEA.

RESULTS

Overall, 23.7% of patients exhibited eCD. In the final multivariate logistic regression model, radiographic absence of both PCoAs was the only independent predictor of eCD (OR 9.64, 95% CI 1.43-64.92, p = 0.02).

CONCLUSIONS

The absence of both PCoAs on preoperative radiographic imaging is predictive of eCD after CEA. This finding supports the evidence for an underlying ischemic etiology of eCD. Larger studies are justified to verify the findings of this study. Clinical trial registration no.: NCT00597883 ( http://www.clinicaltrials.gov ).

Neutrophil-lymphocyte ratio as a predictor of cognitive dysfunction in carotid endarterectomy patients

BACKGROUND

Systemic inflammation has been implicated in the development of cognitive dysfunction following carotid endarterectomy (CEA). Neutrophil-lymphocyte ratio (NLR) is a reliable measure of systemic inflammation. We hypothesize that patients with elevated preoperative NLR have increased risk of cognitive dysfunction 1 day after CEA.

METHODS

Five hundred fifty-one patients scheduled for CEA were enrolled at Columbia University in New York, NY from 1995 to 2012. NLR was retrospectively reviewed; only 432 patients had preoperative NLR values available within 2 weeks of CEA. NLR was analyzed as a continuous variable and categorically with a cutoff of ≥5 and <5 and equal tertiles, as done in previous studies.

RESULTS

Patients with cognitive dysfunction had significantly higher NLR than those without cognitive dysfunction (4.5 ± 4.0 vs 3.2 ± 2.6; P < .001). The incidence of cognitive dysfunction was significantly higher in patients with NLR ≥5 than NLR <5 (34.7% vs 12.8%; P < .001). Significantly fewer patients in the low tertile had cognitive dysfunction than in the high tertile (6.9% vs 25.9%; P <.001) and middle tertile (6.9% vs 17.4%; P = .006). In the final multivariate model, diabetes mellitus (odds ratio [OR], 2.03; 95% confidence interval [CI], 1.08-3.75; P = .03) and NLR ≥5 (OR, 3.38; 95% CI, 1.81-6.27; P < .001) were significantly associated with higher odds of cognitive dysfunction, while statin use was significantly associated with lower odds (OR, 0.48; 95% CI, 0.27-0.84; P = .01).

CONCLUSIONS

Preoperative NLR is associated with cognitive dysfunction 1 day after CEA. NLR ≥5 and diabetes mellitus are significantly associated with increased odds of cognitive dysfunction whereas statin use is significantly associated with decreased odds.

Arterial blood pressure management during carotid endarterectomy and early cognitive dysfunction

BACKGROUND

A common practice during cross-clamp of carotid endarterectomy (CEA) is to manage mean arterial pressure (MAP) above baseline to optimize the collateral cerebral blood flow and reduce the risk of ischemic stroke.

OBJECTIVE

To determine whether MAP management ≥20% above baseline during cross-clamp is associated with lower risk of early cognitive dysfunction, a subtler form of neurological injury than stroke.

METHODS

One hundred eighty-three patients undergoing CEA were enrolled in this ad hoc study. All patients had radial arterial catheters placed before the induction of general anesthesia. MAP was managed at the discretion of the anesthesiologist. All patients were evaluated with a battery of neuropsychometric tests preoperatively and 24 hours postoperatively.

RESULTS

Overall, 28.4% of CEA patients exhibited early cognitive dysfunction (eCD). Significantly fewer patients with MAP ≥20% above baseline during cross-clamp exhibited eCD than those managed <20% above (11.6% vs 38.6%, P < .001). In a multivariate logistic regression model, MAP ≥20% above baseline during the cross-clamp period was associated with significantly lower risk of eCD (odds ratio [OR], 0.18 [0.07-0.40], P < .001), whereas diabetes mellitus (OR, 2.73 [1.14-6.61], P = .03) and each additional year of education (OR, 1.19 [1.06-1.34], P = .003) were associated with significantly higher risk of eCD.

CONCLUSION

The observations of this study suggest that MAP management ≥20% above baseline during cross-clamp of the carotid artery may be associated with lower risk of eCD after CEA. More prospective work is necessary to determine whether MAP ≥20% above baseline during cross-clamp can improve the safety of this commonly performed procedure.

Phosphodiesterase 4D single-nucleotide polymorphism 83 and cognitive dysfunction in carotid endarterectomy patients

BACKGROUND

Phosphodiesterase 4D (PDE4D), through the regulation of cyclic AMP, modulates inflammation and other processes that affect atherosclerosis and stroke. A PDE4D polymorphism, single-nucleotide polymorphism (SNP) 83 (rs966221), is associated with ischemic stroke. The association of SNP 83 with postoperative cognitive dysfunction has never been investigated.

OBJECTIVE

To determine whether SNP 83 is associated with cognitive dysfunction 1 day and 1 month following carotid endarterectomy (CEA).

METHODS

Three hundred fourteen patients with high-grade carotid stenosis scheduled for CEA consented to participate in this single-center cohort study of cognitive dysfunction.

RESULTS

Patients with the C/C genotype of SNP 83 exhibited significantly more cognitive dysfunction at 1 day (29.7%) than the C/T (15.8%, P = .008) and T/T (12.7%, P = .01) genotypes. In a multivariate logistic regression model, C/T and T/T genotypes were both associated with significantly decreased odds of cognitive dysfunction compared with the C/C genotype (odds ratio, 0.45 [0.24-0.83], P = .01 and odds ratio, 0.33 [0.12-0.77], P = .02). There were no significant associations at 1 month.

CONCLUSION

The C/C genotype of SNP 83 is significantly associated with the highest incidence of cognitive dysfunction 1 day following CEA in comparison with the C/T and T/T genotypes. This PDE4D genotype may lead to accelerated cyclic AMP degradation and subsequently elevated inflammation 1 day after CEA. These observations, in conjunction with previous studies, suggest that elevated inflammatory states may be partially responsible for the development of cognitive dysfunction after CEA, but more investigation is required.

Apolipoprotein E-ε4 polymorphism and cognitive dysfunction after carotid endarterectomy

Approximately 25% of patients undergoing carotid endarterectomy (CEA) exhibit cognitive dysfunction (CD) 1 day and 1 month after CEA. The apolipoprotein E (apoE)-ε4 polymorphism has been previously identified as a robust independent risk factor for CD 1 month after CEA. We aimed to determine whether the apoE-ε4 polymorphism is also an independent risk factor for CD as early as 1 day after CEA and to confirm the previous findings at 1 month. Patients undergoing elective CEA (n=411) were enrolled with written informed consent in this follow-up observational study. CD was evaluated via an extensive neuropsychometric battery. apoE-ε4 carriers exhibited significantly more CD 1 day (30.1% versus 17.9%, p=0.01) and 1 month (25.7% versus 9.8%, p=0.001) after CEA compared to non-carriers. Multivariate regression models were generated to determine independent predictors of CD. At 1 day, apoE-ε4 was significantly associated with higher risk of CD (odds ratio [OR]: 2.24 [95% confidence interval 1.29-3.84], p=0.004), while statin use was significantly associated with lower risk (OR: 0.40 [0.24-0.67], p<0.001). At 1 month, apoE-ε4 was significantly associated with higher risk of CD (OR: 3.14 [1.53-6.38], p=0.002), while symptomatic status was significantly associated with lower risk (OR: 0.45 [0.20-0.94], p=0.03). The apoE-ε4 polymorphism is an independent risk factor for CD as early as 1 day after CEA and is confirmed to be an independent risk factor for CD at 1 month as well.

Inflammation and cognitive dysfunction in type 2 diabetic carotid endarterectomy patients

OBJECTIVE

Type 2 diabetic patients have a high incidence of cerebrovascular disease, elevated inflammation, and high risk of developing cognitive dysfunction following carotid endarterectomy (CEA). To elucidate the relationship between inflammation and the risk of cognitive dysfunction in type 2 diabetic patients, we aim to determine whether elevated levels of systemic inflammatory markers are associated with cognitive dysfunction 1 day after CEA.

RESEARCH DESIGN AND METHODS

One hundred fifteen type 2 diabetic CEA patients and 156 reference surgical patients were recruited with written informed consent in this single-center cohort study. All patients were evaluated with an extensive battery of neuropsychometric tests. Preoperative monocyte counts, HbA1c, C-reactive protein (CRP), intercellular adhesion molecule 1, and matrix metalloproteinase 9 activity levels were obtained.

RESULTS

In a multivariate logistic regression model constructed to identify predictors of cognitive dysfunction in type 2 diabetic CEA patients, each unit of monocyte counts (odds ratio [OR] 1.76 [95% CI 1.17-2.93]; P=0.005) and CRP (OR 1.17 [1.10-1.29]; P<0.001) was significantly associated with higher odds of developing cognitive dysfunction 1 day after CEA in type 2 diabetic patients.

CONCLUSIONS

Type 2 diabetic patients with elevated levels of preoperative systemic inflammatory markers exhibit more cognitive dysfunction 1 day after CEA. These observations have implications for the preoperative medical management of this high-risk group of surgical patients undergoing carotid revascularization with CEA.

Middle cerebral artery pulsatility index and cognitive improvement after carotid endarterectomy for symptomatic stenosis

OBJECT

Transcranial Doppler (TCD) is frequently used to evaluate peripheral cerebral resistance and cerebral blood flow (CBF) in the middle cerebral artery prior to and during carotid endarterectomy (CEA). Patients with symptomatic carotid artery stenosis may have reduced peripheral cerebral resistance to compensate for inadequate CBF. The authors aim to determine whether symptomatic patients with reduced peripheral cerebral resistance prior to CEA demonstrate increased CBF and cognitive improvement as early as 1 day after CEA.

METHODS

Fifty-three patients with symptomatic CEA were included in this observational study. All patients underwent neuropsychometric evaluation 24 hours or less preoperatively and 1 day postoperatively. The MCA was evaluated using TCD for CBF mean velocity (MV) and pulsatility index (PI). Pulsatility index ≤ 0.80 was used as a cutoff for reduced peripheral cerebral resistance.

RESULTS

Significantly more patients with baseline PI ≤ 0.80 exhibited cognitive improvement 1 day after CEA than those with PI > 0.80 (35.0% vs 6.1%, p = 0.007). Patients with cognitive improvement had a significantly greater increase in CBF MV than patients without cognitive improvement (13.4 ± 17.1 cm/sec vs 4.3 ± 9.9 cm/sec, p = 0.03). In multivariate regression model, a baseline PI ≤ 0.80 was significantly associated with increased odds of cognitive improvement (OR 7.32 [1.40-59.49], p = 0.02).

CONCLUSIONS

Symptomatic CEA patients with reduced peripheral cerebral resistance, measured as PI ≤ 0.80, are likely to have increased CBF and improved cognitive performance as early as 1 day after CEA for symptomatic carotid artery stenosis. Revascularization in this cohort may afford benefits beyond prevention of future stroke. Clinical trial registration no: NCT00597883 ( ClinicalTrials.gov ).

Reduced middle cerebral artery velocity during cross-clamp predicts cognitive dysfunction after carotid endarterectomy

Transcranial Doppler (TCD) is a useful monitor that can be utilized during carotid endarterectomy (CEA). Cognitive dysfunction is a subtler and more common form of neurologic injury than stroke. We aimed to determine whether reduced middle cerebral artery (MCA) mean velocity (MV) predicts cognitive dysfunction and if so, whether a threshold of increased risk of cognitive dysfunction can be identified. One hundred twenty-four CEA patients were included in this observational study and neuropsychometrically evaluated preoperatively and 24 hours postoperatively. MCA-MV was measured by TCD and percentage of baseline during cross-clamp was calculated (MV(cross-clamp)/MV(baseline)). Patients with cognitive dysfunction had significantly lower MV during cross-clamp than those without cognitive dysfunction (33.1 ± 13.7 cm/s versus 39.6 ± 16.0 cm/s, p=0.02). In the final multivariate model, each percent reduction in MV was significantly associated with greater risk of cognitive dysfunction (odds ratio [OR]: 0.05 [95% confidence interval {CI} 0.01-0.23], p < 0.001) while statin use was associated with lower risk (OR: 0.33 [95% CI 0.12-0.92], p = 0.03). Using receiver operator characteristic curve analysis, the Youden index identified 72% of baseline MV during cross-clamp as the cutoff of maximum discrimination. Significantly more patients with MV < 72% of baseline during cross-clamp exhibited cognitive dysfunction than patients with MV ≥ 72% of baseline (74.1% versus 27.1%, p < 0.001). Reduced MCA-MV during cross-clamp is a predictor of cognitive dysfunction exhibited 24 hours after CEA. MCA-MV reduced to <72% of baseline, or a ≥28% reduction from baseline, is the threshold most strongly associated with increased risk of cognitive dysfunction. These observations should be considered by all clinicians that utilize intraoperative monitoring for CEA.

Complement polymorphisms and cognitive dysfunction after carotid endarterectomy

OBJECT

The role of genetic polymorphisms in the neurological outcome of patients after carotid endarterectomy (CEA) remains unclear. There are single nucleotide polymorphisms (SNPs) that predispose patients to postoperative cognitive dysfunction (CD). We aim to assess the predictability of three complement cascade-related SNPs for CD in patients having CEAs.

METHODS

In 252 patients undergoing CEA, genotyping was performed for the following polymorphisms: complement component 5 (C5) rs17611, mannose-binding lectin 2 (MBL2) rs7096206, and complement factor H (CFH) rs1061170. Differences among genotypes were analyzed via the chi-square test. Patients were evaluated with a neuropsychometric battery for CD 1 day and 1 month after CEA. A multiple logistic regression model was created. All variables with univariate p < 0.20 were included in the final model.

RESULTS

The C5 genotypes A/G (OR 0.26, 95% CI 0.11-0.60, p = 0.002) and G/G (OR 0.22, 95% CI 0.09-0.52, p < 0.001) were significantly associated with lower odds of exhibiting CD at 1 day after CEA compared with A/A. The CFH genotypes C/T (OR 3.37, 95% CI 1.69-6.92, p < 0.001) and C/C (OR 3.67, 95% CI 1.30-10.06, p = 0.012) were significantly associated with higher odds of exhibiting CD at 1 day after CEA compared with T/T. Statin use was also significantly associated with lower odds of exhibiting CD at 1 day after CEA (OR 0.43, 95% CI 0.22-0.84, p = 0.01). No SNPs were significantly associated with CD at 1 month after CEA.

CONCLUSIONS

The presence of a deleterious allele in the C5 and CFH SNPs may predispose patients to exhibit CD after CEA. This finding supports previous data demonstrating that the complement cascade system may play an important role in the development of CD. These findings warrant further investigation.

Statins reduce neurologic injury in asymptomatic carotid endarterectomy patients

BACKGROUND AND PURPOSE

Statins are neuroprotective in a variety of experimental models of cerebral injury. We sought to determine whether patients taking statins before asymptomatic carotid endarterectomy exhibit a lower incidence of neurological injury (clinical stroke and cognitive dysfunction).

METHODS

A total of 328 patients with asymptomatic carotid stenosis scheduled for elective carotid endarterectomy consented to participate in this observational study of perioperative neurological injury.

RESULTS

Patients taking statins had a lower incidence of clinical stroke (0.0% vs 3.1%; P=0.02) and cognitive dysfunction (11.0% vs 20.2%; P=0.03). In a multivariate regression model, statin use was significantly associated with decreased odds of cognitive dysfunction (odds ratio, 0.51 [95% CI, 0.27-0.96]; P=0.04).

CONCLUSIONS

Preoperative statin use was associated with less neurological injury after asymptomatic carotid endarterectomy. These observations suggest that it may be possible to further reduce the perioperative morbidity of carotid endarterectomy. Clinical Trial Registration- URL: http://www.clinicaltrials.gov. Unique identifier: NCT00597883.

Does Cognitive Dysfunction after Carotid Endarterectomy Vary by Statin Type or Dose?

Our previous work demonstrates that asymptomatic carotid endarterectomy (CEA) patients demonstrate less perioperative neurologic injury, defined as stroke and early cognitive dysfunction (eCD) observed within 24hr of CEA, when taking statins pre-operatively. This study examines whether the incidence of eCD observed 24hr after asymptomatic CEA varies as a function of statin type or dose. Patients with asymptomatic carotid stenosis scheduled for CEA consented to participate in an observational IRB-approved study (N=324). Patients were evaluated with an extensive battery of neuropsychometric tests pre-operatively and 24hr post-operatively. Of the 324 consented patients, 200 were taking statins. Patients taking pravastatin and fluvastatin exhibited no eCD, while patients taking lovastatin (17.7%) and rosuvastatin (16.7%) exhibited incidences of eCD similar to those not taking statins (20.2%). Patients taking simvastatin exhibited a significantly lower incidence of eCD than those taking atorvastatin (3.0% vs. 16.0%, P=0.005). Patients taking a maximal dose of any statin exhibited a significantly lower incidence of eCD than patients taking sub-maximal doses (2.7% vs. 15.9%, P=0.002). These observations suggest that the incidence of eCD may in fact vary as a function of statin type and that maximal doses may be the optimal dose for patients undergoing CEA. This variation may be due to the physico-chemical properties of statins such as lipophilicity, molecular size, and blood brain barrier penetrability. These findings should be used to inspire randomized prospective work to determine the safety, feasibility, and outcomes of optimizing statin use prior to CEA.

Current status of endovascular stroke treatment

The management of acute ischemic stroke is rapidly developing.Although acute ischemic stroke is a major cause of adult disability and death, the number of patients requiring emergency endovascular intervention remains unknown, but is a fraction of the overall stroke population. Public health initiatives endeavor to raise public awareness about acute stroke to improve triage for emergency treatment, and the medical community is working to develop stroke services at community and academic medical centers throughout the United States. There is an Accreditation Council for Graduate Medical Education–approved pathway for training in endovascular surgical neuroradiology, the specialty designed to train physicians specifically to treat cerebrovascular diseases. Primary and comprehensive stroke center designations have been defined, yet questions remain about the best delivery model. Telemedicine is available to help community medical centers cope with the complexity of stroke triage and treatment. Should comprehensive care be provided at every community center, or should patients with complex medical needs be triaged to major stroke centers with high-level surgical,intensive care, and endovascular capabilities? Although the answers to these and other questions about stroke care delivery remain unanswered owing to the paucity of empirical data, we are convinced that stroke care regionalization is crucial for delivery of high-quality comprehensive ischemic stroke treatment. A stroke team available 24 hours per day, 7 days per week requires specialty skills in stroke neurology, endovascular surgical neuroradiology, neurosurgery, neurointensive care, anesthesiology, nursing, and technical support for optimal success. Several physician groups with divergent training backgrounds (i.e., interventional neuroradiology, neurosurgery,neurology, peripheral interventional radiology, and cardiology) lay claim to the treatment of stroke patients,particularly the endovascular or interventional methods. Few would challenge neurologists over the responsibility for emergency evaluation and triage of stroke victims for intra intravenous fibrinolysis, even though emergency physicians are most commonly the first to evaluate these patients. There are many unanswered questions about the role of imaging in defining best treatment. Perfusion imaging with CT or MRI appears to have relevance even though its role remains undefined and is the subject of ongoing research. Meanwhile, investigators are exploring new, and perhaps more specific,imaging methods with cerebral metabolic rate of oxygen and cellular acid-base imbalance. There are currently 6 ongoing trials of stroke intervention, many with proprietary technologies and private funding, competing for the same patient population as multicenter trials funded by the NIH. At the same time, much of the interventional stroke treatment currently occurs outside of trials in the community and academic settings without the collection of much-needed data. Market forces will certainly shape future stroke therapy, but it is unclear whether the current combination of private and public funding for these endeavors is the best method of development.

The effect of antihypertensive class on intraoperative pressor requirements during carotid endarterectomy

BACKGROUND

Certain classes of antihypertensive drugs have been associated with intraoperative hypotension, and frequently, patients are receiving multiple classes of antihypertensive medications. We sought to determine whether one class of antihypertensive medication either alone, or in combination with other classes of antihypertensive medications, increased the probability of intraoperative hypotension, determined by the amount of vasopressor required during carotid endarterectomy (CEA) performed under general anesthesia with specific arterial blood pressure management.

METHODS

This is a post hoc analysis of 252 patients scheduled for elective CEA under general anesthesia, all of whom participated in a prospective evaluation of cognitive dysfunction. Patients were characterized by class and number of preoperative antihypertensive medications taken. A predetermined anesthetic regimen was administered to all patients, with a phenylephrine infusion titrated to maintain mean arterial blood pressure at baseline before clamping the carotid artery, and approximately 20% above baseline during clamping. Computerized anesthesia records were used to record hemodynamics and to quantify medication administered intraoperatively.

RESULTS

Patients taking diuretics as part of their antihypertensive regimen required significantly more (1.6 times) total intraoperative phenylephrine than those not taking diuretics, independently of the number of other antihypertensive medications. This difference in the phenylephrine requirement occurs only during the preclamp period, i.e., from induction to application of carotid artery clamping for the maintenance of preoperative blood pressure. However, in contrast to this result, there is no difference in pressor requirement comparing classes of antihypertensive medications to increase the mean arterial blood pressure 20% above baseline during the period when the carotid artery is clamped.

CONCLUSION

Diuretics are associated with increased vasopressor requirements in patients having a CEA under general anesthesia in the preclamp period, which is likely true for any patient having a general anesthetic.

Polymorphisms in complement component 3 (C3F) and complement factor H (Y402H) increase the risk of postoperative neurocognitive dysfunction following carotid endarterectomy

BACKGROUND

Up to 28% of patients undergoing carotid endarterectomy (CEA) are estimated to experience neurocognitive dysfunction following surgery. The complement cascade plays a central role in ischaemia-reperfusion injury. The authors investigated the effect of common polymorphisms in the complement component 3 (C3F) and complement factor H (CFH Y402H) genes on incidence of neurocognitive dysfunction post-CEA.

METHODS

This study examined a nested cohort of prospectively recruited patients receiving elective CEA, who were genotyped for the C3F or Y402H polymorphisms. Each patient underwent a standard battery of eight neuropsychometric tests before, and 1 day and 30 days after, surgery.

RESULTS

57 of 142 (40%) CEA patients had at least one copy of the C3F allele (C3F+), and 17 of 137 (12%) patients had two copies of the CFH Y402H allele (Y402H++). At postoperative day 1, patients were three times (OR 3.05, p=0.045) or six times (OR 6.41, p=0.006) more likely to experience moderate-to-severe neurocognitive dysfunction if they carried the C3F+ or Y402H++ genotype, respectively. Patients with both risk genotypes had an almost eightfold risk of dysfunction (OR 7.67, p=0.046). Right-hand-dominant C3F+ subjects undergoing right-side CEA performed significantly worse on tests of visuospatial function than C3F- subjects. At day 30, C3F+ and Y402H++ genotypes trended towards significance as predictors of dysfunction (p=0.07 and p=0.22, respectively).

CONCLUSION

The C3F and Y402H polymorphisms are strong independent predictors of moderate-to-severe neurocognitive dysfunction at 1 day following CEA. Furthermore, patients undergoing right-sided CEA are predisposed to deficits associated with cortex ipsilateral to the operative carotid artery.

Delayed arousal

Elderly patients have medical and psychological problems affecting all major organ systems. These problems may alter the pharmacokinetics and/or pharmacodynamics of medications, or expose previous neurologic deficits simply as a result of sedation. Delayed arousal, therefore, may arise from structural problems that are pre-existent or new, or metabolic or functional disorders such as convulsive or nonconvulsive seizures. Determining the cause of delayed arousal may require clinical, chemical, and structural tests. Structural problems that impair consciousness arise from a small number of focal lesions to specific areas of the central nervous system, or from pathology affecting the cerebrum. In general, focal or multifocal lesions can be identified by computerized tomography, or diffusion-weighted imaging. An algorithm is presented that outlines a workup for an elderly patient with delayed arousal.

Incidence of moderate to severe cognitive dysfunction in patients treated with carotid artery stenting

OBJECTIVE

Approximately 25% of patients with carotid artery stenosis treated with carotid endarterectomy develop cognitive dysfunction (CD) between 1 day and 1 month after surgery compared with a control group. We hypothesized that patients with carotid artery stenosis treated with carotid artery stenting (CAS) performed under cerebral embolic protection also develop CD at similar time points compared with a control group.

METHODS

Twenty-four patients scheduled for elective CAS were enrolled in a prospective institutional review board-approved study to evaluate cognitive function with a battery of 6 neuropsychometric tests before, and 1 day and 1 month after, CAS. Test performance was compared with 23 patients undergoing coronary artery procedures (control group). The mean and standard deviation of the difference scores in the control group were used to generate Z scores. We used a previously described point system to transform negative Z scores into injury points for each neuropsychometric test. Global performance is presented as average deficit score (sum of injury points divided by the number of completed tests). All patients underwent the procedures with mild sedation. Results were analyzed in 2 ways: group-rate and event-rate analysis. Outcome was dichotomized by defining moderate to severe CD as average deficit score at least 1.5 standard deviations worse than the control group. Fisher tests and multivariate logistic regression models were used to analyze group performance.

RESULTS

Control patients tended to be younger and had a lower incidence of stroke or previous transient ischemic attack. One day after surgery, 41% of patients (10 of 24) treated with CAS developed moderate to severe CD (P = 0.0422). Average deficit score was also significantly higher in the CAS group at 1 day (P = 0.0265). These differences were independent of age and history of stroke/transient ischemic attack. Interestingly, we found that the absence of oral statin medication may increase the probability of CD. By 1 month, 9% of patients (1 of 11) treated with CAS presented with CD. Other patients were lost to follow-up.

CONCLUSION

CAS is associated with a decline in cognitive performance that is at least moderate 1 day after surgery.

Evoked potential monitoring identifies possible neurological injury during positioning for craniotomy

Somatosensory-evoked potential (SSEP) monitoring is commonly used to detect changes in nerve conduction and prevent impending nerve injury. We present a case series of two patients who had SSEP monitoring for their surgical craniotomy procedure, and who, upon positioning supine with their head tilted 30 degrees-45 degrees, developed unilateral upper extremity SSEP changes. These SSEP changes were reversed when the patients were repositioned. These cases indicate the clinical usefulness of monitoring SSEPs while positioning the patient and adjusting position accordingly to prevent injury.

Intraoperative magnesium infusion during carotid endarterectomy: a double-blind placebo-controlled trial

OBJECT

Recent data from both experimental and clinical studies have supported the use of intravenous magnesium as a potential therapy in the setting of cerebral ischemia. This study assessed whether intraoperative magnesium therapy improves neuropsychometric testing (NPT) following carotid endarterectomy (CEA).

METHODS

One hundred eight patients undergoing CEA were randomly assigned to receive placebo infusion or 1 of 3 magnesium-dosing protocols. Neuropsychometric testing was performed 1 day after surgery and compared with baseline performance. Assessment was also performed on a set of 35 patients concurrently undergoing lumbar laminectomy to serve as a control group for NPT. A forward stepwise logistic regression analysis was performed to evaluate the impact of magnesium therapy on NPT. A subgroup analysis was then performed, analyzing the impact of each intraoperative dose on NPT.

RESULTS

Patients treated with intravenous magnesium infusion demonstrated less postoperative neurocognitive impairment than those treated with placebo (OR 0.27, 95% CI 0.10-0.74, p = 0.01). When stratified according to dosing bolus and intraoperative magnesium level, those who were treated with low-dose magnesium had less cognitive decline than those treated with placebo (OR 0.09, 95% CI 0.02-0.50, p < 0.01). Those in the high-dose magnesium group demonstrated no difference from the placebo-treated group.

CONCLUSIONS

Low-dose intraoperative magnesium therapy protects against neurocognitive decline following CEA.

Inducible nitric oxide synthase promoter polymorphism affords protection against cognitive dysfunction after carotid endarterectomy

BACKGROUND AND PURPOSE

Cognitive dysfunction occurs in 9% to 23% of patients during the first month after carotid endarterectomy (CEA). A 4-basepair (AAAT) tandem repeat polymorphism (either 3 or 4 repeats) has been described in the promoter region of inducible nitric oxide synthase (iNOS), a gene with complex roles in ischemic injury and preconditioning against ischemic injury. We investigated whether the 4-repeat variant (iNOS(+)) affects the incidence of cognitive dysfunction after CEA.

METHODS

One-hundred eighty-five CEA and 60 spine surgery (control) subjects were included in this nested cohort analysis. Subjects underwent a battery of 7 neuropsychometric tests before and 1 day and 1 month after surgery. Multivariate logistic regression analyses were performed to determine if the iNOS promoter variant was independently associated with the incidence of cognitive dysfunction at 1 day and 1 month. Further, all right-hand-dominant CEA subjects were grouped by operative side and performance on each test was compared between iNOS(+) and iNOS(-) groups.

RESULTS

Forty-four of 185 CEA subjects had at least 1 iNOS promoter allele containing 4 copies of the tandem repeat (iNOS(+)). iNOS(+) status was significantly protective against moderate/severe cognitive dysfunction 1 month after CEA. Right-hand-dominant iNOS(+) CEA subjects undergoing left-side CEA performed significantly better than iNOS(-) subjects on a verbal learning test and those undergoing right-side CEA performed significantly better on a test of visuospatial function.

CONCLUSIONS

We demonstrate an iNOS promoter polymorphism variant provides protection against moderate/severe cognitive dysfunction 1 month after CEA. Further, this protection appears to involve cognitive domains localized ipsilateral to the operative carotid artery.

Intravascular ultrasound of symptomatic intracranial stenosis demonstrates atherosclerotic plaque with intraplaque hemorrhage: a case report

BACKGROUND

Intracranial artery stenosis is assumed to represent atherosclerotic plaque. Catheter cerebral arteriography shows that intracranial stenosis may progress, regress, or remain unchanged. It is counterintuitive that atherosclerotic plaque should spontaneously regress, raising questions about the composition of intracranial stenoses. Little is known about this disease entity in vivo. We provide the first demonstration of in vivo atherosclerotic plaque with intraplaque hemorrhage using intravascular ultrasound (IVUS).

CASE DESCRIPTION

A 35-year-old man with multiple vascular risk factors presented with recurrent stroke failing medical therapy. Imaging demonstrated left internal carotid artery occlusion, severe intracranial right internal carotid artery stenosis, and cerebral perfusion failure. Cerebral arteriography with IVUS confirmed 85% stenosis of the petrous right carotid artery due to atherosclerotic plaque with intraplaque hemorrhage. Intracranial stent-supported angioplasty was performed with IRB approval. The patient recovered without complication.

CONCLUSIONS

This case supports the premise that symptomatic intracranial stenosis can be caused by atherosclerotic plaque complicated by intraplaque hemorrhage similar to coronary artery plaque. IVUS provides additional characteristics that define intracranial atherosclerosis and high-risk features. To our knowledge, this is the first report of stroke due to unstable atherosclerotic plaque with intraplaque hemorrhage in vivo.

Takotsubo cardiomyopathy associated with anesthesia: three case reports

Takotsubo cardiomyopathy is a form of transient, reversible left ventricular dysfunction that can mimic an acute coronary event. However, cardiac catheterization often reveals normal coronary arteries. Patients are often postmenopausal women who experience acute physical or emotional distress. The prognosis for this entity is quite favorable. In this report, we present three cases of Takotsubo cardiomyopathy in patients having procedures involving anesthesia. Each case illustrates a different etiology for the syndrome: Patient, procedure, and anesthetic management.

A study of cognitive dysfunction in patients having carotid endarterectomy performed with regional anesthesia

BACKGROUND

In previous studies, we found that approximately 25% of patients having carotid endarterectomy with general anesthesia (CEA general) develop cognitive dysfunction compared with a surgical control Group 1 day and 1 mo after surgery. In this study, we tested the hypothesis that patients having CEA with regional anesthesia (CEA regional) will develop significant cognitive dysfunction 1 day after surgery compared with a control group of patients receiving sedation 1 day after surgery. We did not study persistence of dysfunction.

METHODS

To test this hypothesis, we enrolled 60 patients in a prospective study. CEA regional was performed with superficial and deep cervical plexus blocks in 41 patients. The control group consisted of 19 patients having coronary angiography or coronary artery stenting performed with sedation. A control group is necessary to account for the "practice effect" associated with repeated cognitive testing. The patients from the CEA regional group were enrolled at New York Medical Center and the control group at Columbia-Presbyterian Medical Center. The cognitive performance of all patients was evaluated using a previously validated battery of neuropsychometric tests. Differences in performance, 1 day after compared with before surgery, were evaluated by both event-rate and group-rate analyses.

RESULTS

On postoperative day 1, 24.4% of patients undergoing CEA regional had significant cognitive dysfunction, where "significant" was defined as a total deficit score > or =2 SD worse than the mean performance in the control group.

CONCLUSIONS

Patients undergoing CEA regional had an incidence of cognitive dysfunction which was not different than patients having CEA general as previously published and compared with a contemporaneously enrolled group.

Post-carotid endarterectomy neurocognitive decline is associated with cerebral blood flow asymmetry on post-operative magnetic resonance perfusion brain scans

OBJECTIVE

Up to 25% of patients experience subtle declines in post-operative neurocognitive function following, otherwise uncomplicated, carotid endarterectomy (CEA). We sought to determine if post-CEA neurocognitive deficits are associated with cerebral blood flow (CBF) abnormalities on post-operative MR perfusion brain scans.

METHODS

We enrolled 22 CEA patients to undergo a battery of neuropsychometric tests pre-operatively and on post-operative day 1 (POD 1). Neurocognitive dysfunction was defined as a two standard deviation decline in performance in comparison to a similarly aged control group of lumbar laminectomy patients. All patients received MR perfusion brain scans on POD 1 that were analysed for asymmetries in CBF distribution. One patient experienced a transient ischemic attack within 24 hours before the procedure and was excluded from our analysis.

RESULTS

Twenty-nine percent of CEA patients demonstrated neurocognitive dysfunction on POD 1. One hundred percent of those patients with cognitive deficits demonstrated CBF asymmetry, in contrast to only 27% of those patients without cognitive impairment. Post-CEA cognitive dysfunction was significantly associated with CBF abnormalities (RR=3.75, 95% CI: 1.62-8.67, p=0.004).

CONCLUSION

Post-CEA neurocognitive dysfunction is significantly associated with post-operative CBF asymmetry. These results support the hypothesis that post-CEA cognitive impairment is caused by cerebral hemodynamic changes. Further work exploring the relationship between CBF and post-CEA cognitive dysfunction is needed.

Deep Hypothermic Circulatory Arrest for Complex Cerebral Aneurysms: Lessons Learned

OBJECTIVE

Deep hypothermic circulatory arrest is a useful adjunct for treating complex aneurysms. Decreased cerebral metabolism and resultant ischemic tolerance create an environment suitable for devascularizing high-risk lesions. However, the advent of modern imaging modalities, innovative cerebral revascularization strategies, and the emergence of endovascular stenting and coiling limit the number of aneurysms requiring this surgical intervention. We present 66 patients with intracranial aneurysms who underwent surgical clipping under deep hypothermic arrest and attempt to identify patients well-suited for this procedure.

METHODS

This study was conducted during a 15-year period and examined patients with aneurysms of the anterior and posterior cerebral circulation. Demographics, aneurysm characteristics, and surgical factors were evaluated as predictors of functional outcome.

RESULTS

Patient age and the duration of cardiac arrest were independent predictors of early clinical outcome (P &lt; 0.05). Our experience suggests that the ideal patient is younger than 60 years old and harbors few medical comorbidities. Individuals with large aneurysms of the anterior communicating artery, internal carotid artery bifurcation, posterior inferior cerebellar artery, midbasilar, or vertebral arteries and with an absence of thrombosis and calcium may be most likely to experience favorable outcomes. Circulatory arrest should not exceed 30 minutes. Postoperative computed tomographic scanning and timely anesthetic emergence allow for early detection of hemorrhage. Complete dissection of the aneurysm before bypass and avoiding extreme hypothermia yield a low incidence of life-threatening postoperative hematomas.

CONCLUSION

Hypothermic circulatory arrest is a useful technique for neuroprotection during the clipping of complex cerebral aneurysms. This procedure, however, has several associated risks. Patient factors, pathoanatomic characteristics, and surgical parameters may be used to guide patient selection.

Neuropsychological dysfunction in the absence of structural evidence for cerebral ischemia after uncomplicated carotid endarterectomy

OBJECTIVE

Neurocognitive dysfunction has been shown to occur in roughly 25% of patients undergoing carotid endarterectomy (CEA). Despite this, little is known about the mechanism of this injury. Recently, several groups have shown that new diffusion weighted imaging (DWI)-positive lesions are seen in 20% of patients undergoing CEA. We investigated to what degree neurocognitive dysfunction was associated with new DWI lesions.

METHODS

Thirty-four consecutive patients undergoing CEA were subjected to pre- and postoperative cognitive evaluation with a battery of neuropsychological tests. Postoperative magnetic resonance imaging was performed in all patients within 24 hours of surgery. Lesions that showed high signal on DWI and restricted diffusion on apparent diffusion coefficient maps but no abnormal high signal on the fluid-attenuated inversion recovery images were considered hyperacute.

RESULTS

Cognitive dysfunction was seen in eight (24%) patients. New hyperacute DWI lesions were seen in three (9%). Only one (13%) of the patients with cognitive dysfunction had a new DWI lesion. Two thirds of the new DWI lesions occurred in the absence of cognitive deterioration. Patients with cognitive dysfunction had significantly longer carotid cross-clamp times.

CONCLUSION

Neurocognitive dysfunction after CEA does not seem to be associated with new DWI positive lesions.

High dose magnesium infusions are not associated with increased pressor requirements after carotid endarterectomy

INTRODUCTION

Although magnesium provides cerebral protection in animal stroke models, magnesium therapy has significant side effects in humans. Therefore, we sought to examine the incidence of alpha-agonist treated hypotension in our ongoing, prospective, randomized, double-blind, placebo-controlled Phase I/IIa dose escalation study of magnesium therapy in patients undergoing carotid endarterectomy.

METHODS

Eighty patients undergoing elective carotid endarterectomy were randomly assigned to a placebo control group (n = 38) or to one of the three intravenous magnesium groups. Magnesium levels were obtained before induction, and then 15 minutes, 1 hour, 2 hours, 6 hours, 12 hours, and 24 hours after a loading dose and infusion. After surgery, a target systolic blood pressure range was chosen, and the amount and duration of phenylephrine needed to maintain that pressure was compared across treatment groups.

RESULTS

All treatment groups achieved levels significantly different from baseline at 12 and 24 hours (P < 0.01). Magnesium treatment did not significantly increase the proportion of patients requiring pressure support. For those requiring pressure support, the amount and average duration of phenylephrine required was not different between control patients and those receiving magnesium, even when the individual minimum systolic blood pressures required were subdivided on the basis of dose of magnesium administered.

CONCLUSION

There were no significant differences detected in the 1) percentage of patients requiring pressor support, 2) the duration of postoperative pressor support, or 3) the amount of phenylephrine support needed between controls and magnesium treated patients. The percentage of patients requiring pressure support depended on the minimum systolic blood pressure ordered after surgery.

Predictors of neurocognitive decline after carotid endarterectomy

OBJECTIVE

Although the incidence of stroke after carotid endarterectomy (CEA) is low (1-3%), approximately 25% of patients experience subtle declines in postoperative neuropsychometric function. No studies have investigated the risk factors for this neurocognitive change. We sought to identify predictors of postoperative neurocognitive dysfunction.

METHODS

We enrolled 186 CEA patients, with both symptomatic and asymptomatic stenosis, to undergo a battery of neuropsychometric tests preoperatively and on postoperative Days 1 and 30. Neurocognitive dysfunction was defined as a two standard deviation decline in performance compared with a similarly aged control group of lumbar laminectomy patients. Univariate logistic regression was performed for age, sex, obesity, smoking, symptomatology, diabetes mellitus, hypertension, hypercholesterolemia, use of statin medication, previous myocardial infarction, previous CEA, operative side, duration of surgery, duration of carotid cross-clamp, and weight-adjusted doses of midazolam and fentanyl. Variables achieving univariate P < 0.10 were included in a multivariate analysis. Data is presented as (odds ratio, 95% confidence interval, P-value).

RESULTS

Eighteen and 9% of CEA patients were injured on postoperative Days 1 and 30, respectively. Advanced age predicted neurocognitive dysfunction on Days 1 and 30 (1.93 per decade, 1.15-3.25, 0.01; and 2.57 per decade, 1.01-6.51, 0.049, respectively). Additionally, diabetes independently predicted injury on Day 30 (4.26, 1.15-15.79, 0.03).

CONCLUSIONS

Advanced age and diabetes predispose to neurocognitive dysfunction after CEA. These results are consistent with risk factors for neurocognitive dysfunction after coronary bypass and major stroke after CEA, supporting an underlying ischemic pathophysiology. Further work is necessary to determine the role these neurocognitive deficits may play in appropriately selecting patients for CEA.

Comparison of electrophysiologic monitors with clinical assessment of level of sedation

OBJECTIVE

To assess the correlation between 2 clinical sedation scales and 2 electroencephalographic (EEG)-based monitors used during surgical procedures that required mild to moderate sedation.

PATIENTS AND METHODS

Patients scheduled for elective surgery participated in this Institutional review board-approved study from March 2003 to February 2004. Level of sedation was determined both clinically using the Ramsay and the Observer's Assessment of Alertness/Sedation scales and with 2 EEG measures (the Bispectral Index version XP [BIS XP] or the Patient State Analyzer [PSA 4000]). Correlation between these 2 measures of sedation were tested using nonparametric statistical tests.

RESULTS

The BIS XP monitor was used in 26 patients, and the PSA 4000 monitor was used in 24 patients. The Ramsay and Observer's Assessment of Alertness/Sedation scores correlated with each other (r = -0.96; P < .001) and with both the BIS XP (r = -0.89 and r = 0.91, respectively; P < .001) and the PSA 4000 (r = -0.80 and r = 0.80, respectively; P < .001) values. However, this correlation was strongest only at the extremes. Between the BIS XP and PSA 4000 values of 61 and 80, the clinical sedation scores varied greatly.

CONCLUSION

On the basis of our results, these EEG-based monitors cannot reliably distinguish between light and deep sedation.

APOE-epsilon4 predisposes to cognitive dysfunction following uncomplicated carotid endarterectomy

BACKGROUND

Between 9% and 23% of patients undergoing otherwise uncomplicated carotid endarterectomy (CEA) develop subtle cognitive decline 1 month postoperatively. The APOE-epsilon4 allele has been associated with worse outcome following stroke.

OBJECTIVE

To investigate the ability of APOE-epsilon4 to predict post-CEA neurocognitive dysfunction.

METHODS

Seventy-five patients with CEA undergoing elective CEA were prospectively recruited in this nested cohort study and demographic variables were recorded. Patients were evaluated before and 1 month after surgery with a standard battery of five neuropsychological tests. APOE genotyping was performed by restriction fragment length polymorphism analysis in all patients. Neuropsychological deficits were identified by comparing changes (before to 1 month post-operation) in individual performance on the test battery. Logistic regression was performed for APOE-epsilon4 and previously identified risk factors.

RESULTS

Twelve of 75 (16%) CEA patients possessed the APOE-epsilon4 allele. Eight of 75 (11%) patients experienced neurocognitive dysfunction on postoperative day 30. One month post-CEA, APOE-epsilon4-positive patients were more likely to be cognitively injured (42%) than APOE-epsilon4-negative patients (5%) (p = 0.002). In multivariate analysis, the presence of the APOE-epsilon4 allele increased the risk of neurocognitive dysfunction at 1 month 62-fold (62.28, 3.15 to 1229, p = 0.007). Diabetes (51.42, 1.94 to 1363, p = 0.02), and obesity (24.43, 1.41 to 422.9, p = 0.03) also predisposed to injury.

CONCLUSION

The APOE-epsilon4 allele is a robust independent predictor of neurocognitive decline 1 month following CEA.

Elevations in preoperative monocyte count predispose to acute neurocognitive decline after carotid endarterectomy for asymptomatic carotid artery stenosis

BACKGROUND AND PURPOSE

Although the incidence of major stroke attributable to carotid endarterectomy (CEA) is low (1% to 2%), approximately 25% of patients experience subtle postoperative neurocognitive dysfunction. This study examines whether preoperative leukocyte profiles predict cognitive outcome in asymptomatic CEA patients.

METHODS

Sixty-nine asymptomatic CEA patients underwent neuropsychometric testing preoperatively and on postoperative day 1 (POD1). Preoperative white blood cell counts and differentials were obtained. Logistic regression was performed for risk factors for neurocognitive decline. Variables achieving univariate P<0.10 were included in multivariate analysis.

RESULTS

Eighteen (26%) patients experienced neurocognitive decline on POD1; multivariate analysis demonstrated that preoperative monocyte count (P=0.011) and age (P=0.02) independently predicted outcome.

CONCLUSIONS

Preoperative monocyte count and age are independently associated with acute neurocognitive decline after CEA for asymptomatic stenosis.

Bilateral bispectral index monitoring during suppression of unilateral hemispheric function

Bispectral Index (BIS) has been used to monitor level of "sedation" based on the electroencephalogram (EEG). Patients evaluated for surgery to control a seizure disorder undergo Wada testing, during which one hemisphere is rendered functionally inactive after injecting a short-acting barbiturate. We surmised that the BIS values would reflect these functional changes. Eight epileptic patients were enrolled. A full array of 21 EEG electrodes and 2 BIS XP (Quatro) strips over each frontal region of the scalp were applied. The EEG was continuously recorded. BIS values from each hemisphere were recorded every minute. Angiography was performed by advancing a catheter into each internal carotid artery. Amobarbital or methohexital was injected until the patient developed a hemiparesis. The EEG confirmed a significant lateralized cortical effect of the barbiturate. Repeated measures analysis of variance was used to analyze the differences between the BIS values from monitor electrode strips placed on the left (left BIS) and the right (right BIS) sides of the head as well as the differences in the left and right BIS values before and after each injection of the barbiturate. Injection of barbiturate into either the left or right internal carotid artery produced a significant change on the 21-electrode EEG. However, there was no difference between left BIS to right BIS values (P = 0.84). With repeated injections of barbiturates, some patients became sedated. At these times, both left BIS and right BIS values decreased together before and after injection of barbiturate. The BIS monitor was unable to distinguish significant hemispheric EEG and clinical functional changes except when the patient became sedated.

The effects of propofol, small-dose isoflurane, and nitrous oxide on cortical somatosensory evoked potential and bispectral index monitoring in adolescents undergoing spinal fusion

In this study we compared the effects of propofol, small-dose isoflurane, and nitrous oxide (N(2)O) on cortical somatosensory evoked potentials (SSEP) and bispectral index (BIS) monitoring in adolescents undergoing spinal fusion. Twelve patients received the following anesthetic maintenance combinations in a randomly determined order: treatment #1: isoflurane 0.4% + N(2)O 70% + O(2) 30%; treatment #2: isoflurane 0.6% + N(2)O 70% + O(2) 30%; treatment #3: isoflurane 0.6% + air + O(2) 30%; treatment #4: propofol 120 microg . kg(-1) . min(-1) + air + O(2) 30%. Cortical SSEP amplitudes measured during anesthesia maintenance with treatment #3 (isoflurane 0.6%/air) were more than those measured during maintenance with treatment #1 (isoflurane 0.4%/N(2)O 70%) (P < 0.0001) and treatment #2 (isoflurane 0.6%/N(2)O 70%) (P < 0.0052). Cortical SSEP amplitudes measured during treatment #4 (propofol 120 microg . kg(-1) . min(-1)/air) were more than treatment #1 (isoflurane 0.4%/N(2)O 70%) (P < 0.0001), treatment #2 (Iso 0.6%/N(2)O 70%) (P < 0.0007), and treatment #3 (isoflurane 0.6%/air) (P < 0.0191). In addition, average BIS values measured during treatments 1, 2, 3 and 4 were 62, 62, 61, and 44 respectively. Only treatment #4 (propofol 120 microg . kg(-1) . min(-1)/air) uniformly maintained BIS values less than 60. Our study demonstrates that propofol better preserves cortical SSEP amplitude measurement and provides a deeper level of hypnosis as measured by BIS values than combinations of small-dose isoflurane/N(2)O or small-dose isoflurane alone.

Failure of intraoperative jugular bulb S-100B and neuron-specific enolase sampling to predict cognitive injury after carotid endarterectomy

OBJECTIVE

Cognitive decline occurs in 25% of patients after carotid endarterectomy (CEA). Elevated serum concentrations of S-100B and neuron-specific enolase (NSE) occur after stroke, and serum S-100B levels at 24 hours are associated with clinical outcome after both stroke and CEA. We hypothesized that we could detect acute elevations in serum levels of these markers obtained intraoperatively from the jugular bulb (JB) and that these elevations would predict cognitive dysfunction postoperatively as measured by neuropsychometric test performance.

METHODS

Forty-three patients scheduled for elective CEA were assessed with a battery of neuropsychometric tests before and 1 day after surgery. Before the carotid artery was clamped, a 6-French Fogarty catheter was inserted into the facial vein and threaded 6 cm rostrally into the JB. Serum samples were withdrawn from this catheter and simultaneously from a radial arterial catheter (A-line) at three time points: before clamping, 15 minutes into clamping, and after unclamping the carotid artery. Concentrations between groups were compared by analysis of variance and paired t tests.

RESULTS

Total deficit scores were significantly worse in 13 (30%) of the 43 patients 1 day after surgery. There was a trend toward elevations in JB concentrations of S-100B relative to A-line levels 15 minutes after cross-clamping (11% elevation, P = 0.079, paired t test). In addition, 15 minutes after clamping of the carotid artery, levels of S-100B from the JB were significantly elevated compared with levels at baseline (P = 0.040, one-way analysis of variance). No significant changes were found between any time point in levels of S-100B from the A-line blood or of NSE from either the JB or the A-line. Subtle cognitive decline after CEA was not correlated with intraoperative levels of S-100B or NSE, but there was a weak, statistically nonsignificant, association between a rise in 15-minute S-100B levels and cognitive injury that was not seen with JB samples.

CONCLUSION

Although intraoperative levels of S-100B and NSE from the JB failed to predict cognitive injury, carotid cross-clamping, independent of injury, seems to be associated with early elevations in S-100B.

Sex-based differences in serum cardiac troponin I, a specific marker for myocardial injury, after cardiac surgery

BACKGROUND

Prevalence and causes of sex-based differences in morbidity and mortality secondary to cardiovascular disease remain controversial. Cardiac troponin I (cTnI) is a sensitive and specific marker for myocardial injury. Serial cTnI measurements have been used to identify perioperative myocardial cell injury.

OBJECTIVE

To determine whether sex influences the extent of myocardial injury during cardiac surgery, we measured perioperative cTnI in male and female patients.

DESIGN

A total of 17 male and 17 female patients were prospectively studied in an age- and case-matched manner. Arterial cTnI were obtained preinduction, 30 mins after the application of the aortic cross-clamp, at arrival to the intensive care unit, and on postoperative day 1.

SETTING

Tertiary cardiac surgery center at a major teaching hospital.

RESULTS

There was no difference between men and women in body mass index (kg/m2), duration of cardiopulmonary bypass, and aortic cross-clamp times. Preoperative cTnI measurements were similar in men (0.24 +/- 0.15 ng/mL) and women (0.25 +/- 0.13 ng/mL, mean +/- sem). The maximum serum cTnI occurred on postoperative day 1 in all patients, and it was 3-fold higher in men (18.5 +/- 5.7 ng/mL) compared with women (6.4 +/- 1.0 ng/mL).

CONCLUSIONS

Men had markedly higher serum cTnI compared with women, although they were case matched with respect to age and cardiac risk factors. Our results may suggest there may be sex-related differences in the myocardial response to ischemia and reperfusion injury or intrinsic differences between the male and female myocardium.

Anesthesia for intraoperative neurophysiologic monitoring of the spinal cord

Intraoperative neurophysiologic monitoring (INM) using somatosensory and motor evoked potentials (MEPs) has become popular to reduce neural risk and to improve intraoperative surgical decision making. Intraoperative neurophysiologic monitoring is affected by the choice and management of the anesthetic agents chosen. Because inhalational and intravenous anesthetic agents have effects on neural synaptic and axonal functional activities, the anesthetic effect on any given response will depend on the pathway affected and the mechanism of action of the anesthetic agent (i.e., direct inhibition or indirect effects based on changes in the balance of inhibitory or excitatory inputs). In general, responses that are more highly dependent on synaptic function will have more marked reductions in amplitude and increases in latency as a result of the synaptic effects of inhalational anesthetic agents and similar effects at higher doses of intravenous agents. Hence, recording cortical somatosensory evoked potentials and myogenic MEPs requires critical anesthetic choices for INM. The management of the physiologic milieu is also important as central nervous system blood flow, intracranial pressure, blood rheology, temperature, and arterial carbon dioxide partial pressure produce alterations in the responses consistent with the support of neural functioning. Finally, the management of pharmacologic neuromuscular blockade is critical to myogenic MEP recording in which some blockade may be desirable for surgery but excessive blockade may eliminate responses. A close working relationship of the monitoring team, the anesthesiologist, and the surgeon is key to the successful conduct and interpretation of INM.

Cerebral injury predicted by transcranial Doppler ultrasonography but not electroencephalography during carotid endarterectomy

When shunts are selectively used during carotid endarterectomy, the adequacy of collateral cerebral blood flow (CBF) after the carotid artery is clamped is determined by monitors based on different physiologic measurements. In this series of three patients, we used electroencephalography (EEG) to measure neuronal electrical activity and transcranial Doppler ultrasonography (TCD) to measure CBF velocity. In each of our cases, the EEG was unchanged from preclamp values, while TCD CBF velocity was dramatically reduced. All three patients had transient neuropsychometric or neurologic changes after surgery, which resolved.