Subtle brain damage cannot be detected by measuring neuron-specific enolase and S-100beta protein after carotid endarterectomy

Neuron-Specific Enolase and S100B as Biomarkers of Ischemic Brain Injury During Surgery

Biochemical markers can be used in addition to neuroimaging techniques to evaluate the extent of ischemic brain injuries and to enable earlier diagnosis and faster intervention following the ischemic event. Among the potential biomarkers of ischemic brain injuries during surgery, neuron-specific enolase (NSE) and S100B are the most frequently studied and were shown to be the most promising. The aim of this review was to summarize the role of NSE and S100B as biomarkers of ischemic brain injuries that occur during selected surgical procedures, predominantly carotid endarterectomy (CEA). Some other invasive interventions that cause ischemic brain injuries, like extracorporeal membrane oxygenation, were also included. We can conclude that these biomarkers can be useful for the evaluation of ischemic brain injuries that occur during various surgical procedures. They can help to determine the most optimal conditions for performing the surgery and therefore improve the procedures to consequently minimize brain damage caused during surgery. Because of a significant delay between sample collection and obtaining the results, they are not suitable for real-time assessment of brain injuries. Some improvement can be expected with the future development of laboratory methods. The association of the changes in NSE and S100B levels during surgery with potential consequences of ischemic brain injury have been described in numerous studies. However, even in a very homogenous group of surgical procedures like CEA, these findings cannot be summarized into a common final conclusion; therefore, the prognostic value of the two markers is not clearly supported at the present time.

Rationale and Design for the Remote Ischemic Preconditioning for Carotid Endarterectomy Trial

BACKGROUND

While the perioperative stroke rate after carotid endarterectomy (CEA) is low, "silent" microinfarctions identified by magnetic resonance imaging (MRI) are common and have been correlated with postoperative neurocognitive decline. Our study will investigate the role of remote ischemic preconditioning (RIPC) as a potential neuroprotective mechanism. RIPC is a well-tolerated stimulus that, through neuronal and humoral pathways, generates a systemic environment of greater resistance to subsequent ischemic insults. We hypothesized that patients undergoing RIPC before CEA will have improved postoperative neurocognitive scores compared with those of patients undergoing standard care.

METHODS

Patients undergoing CEA will be randomized 1:1 to RIPC or standard clinical care. Those randomized to RIPC will undergo a standard protocol of 4 cycles of RIPC. Each RIPC cycle will involve 5 min of forearm ischemia with 5 min of reperfusion. Forearm ischemia will be induced by a blood pressure cuff inflated to 200 mm Hg or at least 15 mm Hg higher than the systolic pressure if it is >185 mm Hg. This will occur after anesthesia induction and during incision/dissection but before manipulation or clamping of the carotid; thus, patients will be blinded to their assignment. Before carotid endarterectomy, all patients will undergo baseline neurocognitive testing in the form of a Montreal Cognitive Assessment (MoCA) and National Institutes of Health (NIH) Toolbox. MoCA testing only will be conducted on postoperative day 1 in the hospital. The full neurocognitive testing battery will again be conducted at 1-month follow-up in the office. Changes from baseline will be compared between arms at the follow-up time points. Assuming no drop-ins or dropouts and a 10% loss to follow-up, we would need a sample size of 43 patients for 80% power per treatment arm. The primary endpoint, change in MoCA scores, will be analyzed using a random effects model, and secondary outcomes will be analyzed using either linear or logistic regression where appropriate.

CONCLUSIONS

RIPC, if shown to be effective in protecting patients from neurocognitive decline after CEA, represents a safe, inexpensive, and easily implementable method of neuroprotection.

Perioperative time course of matrix metalloproteinase-9 (MMP-9), its tissue inhibitor TIMP-1 & S100B protein in carotid surgery

Background & objectives:

Ischaemic stroke is a life burdening disease for which carotid endarterectomy (CEA) is considered a gold standard intervention. Pro-inflammatory markers like matrix metalloproteinases (MMPs) and their inhibitors (TIMPs) and S-100 Beta (S100B) may have a role in the early inflammation and cognitive decline following CEA. This study was aimed to describe the perioperative time courses and correlations between of MMP-9, TIMP-1 and S100B following CEA.

Methods:

Fifty four patients scheduled for CEA were enrolled. Blood samples were collected at four time points, T₁: preoperative, T₂: 60 min after cross-clamp release, T₃: first postoperative morning, T₄: third postoperative morning. Twenty atherosclerotic patients were included as controls. Plasma MMP-9, TIMP-1 and S100B levels were estimated by ELISA.

Results:

TIMP-1 was decreased significantly in the CEA group (P<0.01). Plasma MMP-9 was elevated and remained elevated from T_1-4 in the CEA group (P<0.05) with a marked elevation in T₃ compared to T₁ (P<0.05). MMP-9/TIMP-1 was elevated in the CEA group and increased further by T₂ and T₃ (P<0.05). S100B was elevated on T₂ and decreased on T_3-4 compared to T₁.

Interpretation & conclusions:

Our study provides information on the dynamic changes of MMP-9-TIMP-1 system and S100B in the perioperative period. Preoperative reduction of TIMP-1 might be predictive for shunt requirement but future studies are required for verification.

Fluctuations of serum neuron specific enolase and protein S-100B concentrations in relation to the use of shunt during carotid endarterectomy

Objective

To evaluate the changes in serum neuron specific enolase and protein S-100B, after carotid endarterectomy performed using the conventional technique with routine shunting and patch closure, or eversion technique without the use of shunt.

Materials and Methods

Prospective non-randomized study included 43 patients with severe (>80%) carotid stenosis undergoing carotid endarterectomy in regional anesthesia. Patients were divided into two groups: conventional endarterectomy with routine use of shunt and Dacron patch (csCEA group) and eversion endarterectomy without the use of shunt (eCEA group). Protein S-100B and NSE concentrations were measured from peripheral blood before carotid clamping, after declamping and 24 hours after surgery.

Results

Neurologic examination and brain CT findings on the first postoperative day did not differ from preoperative controls in any patients. In csCEA group, NSE concentrations decreased after declamping (P<0.01), and 24 hours after surgery (P<0.01), while in the eCEA group NSE values slightly increased (P=ns), accounting for a significant difference between groups on the first postoperative day (P=0.006). In both groups S-100B concentrations significantly increased after declamping (P<0.05), returning to near pre-clamp values 24 hours after surgery (P=ns). Sub-group analysis revealed significant decline of serum NSE concentrations in asymptomatic patients shunted during surgery after declamping (P<0.05) and 24 hours after surgery (P<0.01), while no significant changes were noted in non-shunted patients (P=ns). Decrease of NSE serum levels was also found in symptomatic patients operated with the use of shunt on the first postoperative day (P<0.05). Significant increase in NSE serum levels was recorded in non-shunted symptomatic patients 24 hours after surgery (P<0.05).

Conclusion

Variations of NSE concentrations seemed to be influenced by cerebral perfusion alterations, while protein S-100B values were unaffected by shunting strategy. Routine shunting during surgery for symptomatic carotid stenosis may have the potential to prevent postoperative increase of serum NSE levels, a potential marker of brain injury.

Can postoperative cognitive dysfunction be avoided?

Postoperative cognitive dysfunction (POCD) refers to a postoperative decline in cognitive function compared with preoperative cognitive function. Diagnosis requires pre- and postoperative testing, the latter of which is usually performed both 7 days and 3 months postoperatively. Although several risk factors for POCD have been described, age is the only consistently reported risk factor. Postoperative cognitive dysfunction is often transient. It may last several months, and is associated with leaving the labor market prematurely and increased mortality. As the pathophysiology of POCD is still a matter of debate and is likely to be multifactorial, there are no widely accepted prophylactic and therapeutic interventions. In this article, we discuss POCD's definition, risk factors, long-term significance, and pathophysiology. We also present data on prophylactic interventions that have been investigated in clinical trials.

Subclinical neurocognitive dysfunction after carotid endarterectomy-the impact of shunting

BACKGROUND

Subclinical neurocognitive deficit after carotid endarterectomy (CEA) has been reported in 25% of patients. The influence of the type of anesthesia and shunting on early postoperative neurocognitive function remains unclear. Therefore, we analyzed the cognitive function after CEA using a battery of psychometric tests before surgery and on the first postoperative day.

METHODS

Twenty nine patients under regional and 28 under general anesthesia were included in the study. Regional anesthesia was administered inducing a superficial cervical block, and the general anesthesia was induced using a standardized manner. Then cognitive function was tested using a battery of psychometric tests before and 24 hours after surgery. S 100 beta was determined at the same time points.

RESULTS

A statistical difference was found between the results of the testing before and after CEA: decline in digit symbol test (9%), perceptual speed (6%), and spatial working memory (44%) and improvement in verbal fluency (6%) and attention (5%). The only intraoperative factor that correlated with the cognitive dysfunction was shunt insertion; patients with a shunt had a lower perceptual speed (P=0.005) and worse spatial working memory (P=0.004). No correlation was found between the type of anesthesia or S 100 beta level and any psychometric test, but these results might be influenced by the small sample size in our study.

CONCLUSIONS

Shunt insertion was the only parameter correlated with cognitive decline on the first day after CEA. Regional anesthesia might offer indirect benefit because of a reduced need of shunting in wakeful patients. Larger studies are required to clarify the role of shunting and type of anesthesia in early neurocognitive deficit after CEA and its impact on the quality of life.

Remote ischemic preconditioning for cerebral and cardiac protection during carotid endarterectomy: results from a pilot randomized clinical trial

Remote ischemic preconditioning (RIPC) is a physiological mechanism whereby brief ischemia-reperfusion episodes attenuate damage by subsequent prolonged ischemic insults. It reduces myocardial injury following cardiac and aortic aneurysm surgery. We aimed to determine whether RIPC affects neurological or cardiac injury following carotid endarterectomy (CEA). Patients were preconditioned using 10 minutes of lower limb ischemia-reperfusion. The primary neurological outcome was saccadic latency deterioration. The primary cardiac outcome measure was increased in serum troponin I >0.15 mg/dL. In all, 70 patients were randomized, of whom 55 completed the neurological surveillance protocol. Although there were fewer saccadic latency deteriorations in the RIPC arm, this did not reach statistical significance (32% versus 53%; P = .11). The primary cardiac outcome occurred in 1 patient in each arm (P = .97). There were no adverse events related to the preconditioning protocol. Remote ischemic preconditioning appears safe in patients with CEA. Large-scale trials are required to determine whether RIPC confers clinical benefits.

The Neurological Morbidity of Carotid Revascularisation: Using Markers of Cellular Brain Injury to Compare CEA and CAS

AIM

This comparative study attempts to evaluate the profile of S-100beta and Neuron-Specific Enolase (NSE), biomarkers of brain injury, in patients undergoing carotid endarterectomy (CEA) and carotid artery stenting (CAS) and to correlate this with haemodynamic and embolic events detected using trans-cranial Doppler (TCD).

METHODS

52 patients with internal carotid artery stenosis requiring intervention were recruited. 24 patients underwent CAS, and 28 underwent CEA. TCD was performed peri-operatively to record mean Middle Cerebral Artery (MCA) velocity and number of High Intensity Transient Signals (HITS) in the MCA of the operated side. Serum was drawn pre-operatively and at six time points in a 48 hour post-operative period, and then assayed using automated commercial equipment. Within and between group variability in markers were assessed by Generalized Estimation Equations modelling.

RESULTS

CAS caused more HITS (p=0.028) but less haemodynamic disturbance (p=0.0001) than CEA. Treatment modality (CAS versus CEA) had no direct effect on S-100 changes (p=0.467). NSE levels declined after revascularisation in the CAS group but not after CEA (p=0.002). S-100beta levels rose in patients who had higher numbers of HITS (p=0.002). S-100beta and NSE were not associated with changes in MCA velocity (p>0.5). S-100beta alone increased significantly at 24 hours in those patients with a post-operative neurological deficit (p=0.015).

CONCLUSIONS

Trans-cranial Doppler findings suggest that the mechanisms of rise in S-100beta and NSE levels may differ and may be due to increased peri-operative micro-embolisation and cerebral hypoperfusion respectively. Further studies are required to assess the clinical significance of these observed changes.

Neuropsychological consequences of endarterectomy and endovascular angioplasty with stent placement for treatment of symptomatic carotid stenosis: a prospective randomised study

BACKGROUND AND PURPOSE

Previous studies compared carotid endarterectomy (CEA) and carotid artery stent placement (CAS) for treatment of symptomatic carotid artery stenosis. Whereas most previous studies showed both treatment modalities to be associated with a comparable risk of periprocedural cerebrovascular complications, these previous studies have shown significantly more microemboli and significantly more lesions in diffusion-weighted MR imaging after CAS compared to CEA. The clinical relevance of these differences remains unknown. We therefore compared the neuropsychological consequences of CAS and CEA and additionally measured the S100beta protein, a marker of cerebral damage.

METHODS

A total of 48 patients with symptomatic carotid artery stenosis greater than 70 % (according to ECST criteria) were enrolled and 45 patients participated in the follow-up. The patients were randomly assigned for CEA (24 patients) or CAS (21 patients). S100beta protein values were evaluated 2 hours before the procedure, as well as one and two hours thereafter. Patients were assessed before treatment, and again 6 and 30 days after treatment using a comprehensive neuropsychological test battery.

RESULTS

Patients of the CAS and the CEA groups did not significantly differ in terms of age, gender, education, degree of carotid artery stenosis, cerebrovascular symptoms and vascular risk factors. Following previously used criteria, a cognitive change in patients was assumed to have occurred when there was a decline of more than one standard deviation in two or more tests assessing various cognitive domains. Six days and 30 days after the treatment both groups showed a comparable number of patients with cognitive changes compared to baseline. There were no significant differences in S100beta protein values.

CONCLUSION

These results provide some reassurance that CAS is not associated with greater cognitive deterioration than CEA is.

S-100B Release during Carotid Endarterectomy under Local Anesthesia

The neuronal protein S-100B has been found to be an indicator of cellular brain damage. The aim of the study was to evaluate whether cross-clamping of the carotid artery for carotid endarterectomy (CEA) under local anesthesia is associated with the same S-100B release pattern as during general anesthesia, where an increase in S-100B concentration in the jugular vein blood of 120% has been reported. In 45 consecutive patients undergoing CEA under local anesthesia, serum S-100B samples were drawn before surgery (T1), before carotid cross-clamping (T2), before cerebral reperfusion (T3), after reperfusion but before the end of surgery (T4), and 6 hr postoperatively (T5). At T1 and T5, blood samples were drawn only from the radial artery. Intraoperatively (T2-T4), samples were collected from the internal jugular vein additionally. S-100B levels were determined using an immunoluminometric assay (LIAISON) Sangtec 100; Sangtec, Bromma, Sweden). In eight patients, it was necessary to insert an intraluminal shunt because of signs of cerebral ischemia. In the remaining 37 patients, median carotid clamping time was 40 min. There were no neurological complications. There were no differences in baseline S-100B levels regarding gender and symptomatology. Median baseline (T1) and postoperative (T5) S-100B levels were identical (0.077 microg/L). All blood samples from the jugular vein showed significantly higher median S-100B levels than the corresponding arterial blood samples. Only slight increases of 13% and 18% were found during cross-clamping (T3) compared to the first intraoperative measurement (T2) in the venous and arterial samples, respectively, which was followed by decreases of 5% and 18%, respectively (T3-T4). S-100B release did not differ at any time point between patients who needed and patients who did not need a shunt, in either the arterial or the venous blood samples. During uncomplicated CEA under local anesthesia, there is no relevant increase of S-100B. These results are different from those reported when CEA is done under general anesthesia.

Postoperative cognitive dysfunction: incidence and prevention

Postoperative cognitive dysfunction (POCD) is a decline in cognitive function for weeks or months after surgery. Due to its subtle nature, neuropsychological testing is necessary for its detection. The interpretation of literature on POCD is difficult because of numerous methodological limitations, particularly the different definitions of POCD and the lack of data from control groups. POCD is common after cardiac surgery, and recent studies have now verified that POCD also exists after major non-cardiac surgery, although at a lower incidence. The risk of POCD increases with age, and the type of surgery is also important because there is a very low incidence associated with minor surgery. Regional anaesthesia does not seem to reduce the incidence of POCD, and cognitive function does not seem to improve after carotid surgery as has previously been suggested.

Serum S-100B protein levels during and after successful carotid artery stenting or carotid endarterectomy

PURPOSE

To characterize the course of S-100B serum levels, a reliable marker for cellular brain damage, in patients undergoing carotid artery stenting (CAS) or endarterectomy (CEA) for carotid artery stenosis compared to control groups undergoing hemithyroidectomy (HT) or coronary angiography (CA).

METHODS

Forty-six consecutive patients scheduled for revascularization of internal carotid artery (ICA) stenosis were included in the study. Fourteen patients (11 men; median age 70 years, interquartile range [IQR] 63-74) were selected for treatment with CAS, while CEA was performed in 31 patients (24 men; median age 68 years, IQR 54-78) during the same time period. Fourteen consecutive patients (8 men; median age 60 years, IQR 48-70) undergoing CA for suspected coronary heart disease and 14 patients (10 women; median age 36 years, IQR 26-54) undergoing HT for a single thyroid nodule served as controls.

RESULTS

All procedures were completed successfully. During ICA clamping in CEA patients without postoperative neurological deficits, median S-100B serum levels transiently increased from 0.04 to 0.26 ng/mL (p<0.01) and returned to baseline levels after declamping. Median S-100B serum levels of CAS patients without neurological impairment remained at baseline values. No increase in S-100B levels occurred in either control group. Three CEA patients who suffered from neurological deficits (1 transient ischemic attack and 1 major stroke) showed sustained elevation of S-100B serum levels 6 hours after extubation.

CONCLUSION

In patients without neurological complications, CEA but not CAS was associated with a transient increase in the S-100B serum levels. Results indicate that the increase in S-100B does not originate from extracerebral sources, but rather appears to represent an impairment of the blood-brain barrier integrity or subtle brain cell damage probably due to hypoperfusion during clamping. Sustained elevation of S-100B serum levels corresponded to the development of postoperative neurological deficits.

Rapid measurement of S-100B serum protein levels by Elecsys S100 immunoassay in patients undergoing carotid artery stenting or endarterectomy

OBJECTIVES

This study was designed to apply the rapid Elecsys S100 immunoassay for real-time measurement of S100 protein serum levels indicating acute brain damage in patients undergoing carotid artery stenting (CAS) or endarterectomy (CEA).

DESIGN AND METHODS

Data of 14 CAS patients were compared to those of 43 CEA and 14 control patients undergoing coronary angiography (CA). S100 serum levels were measured by the full-automatic Elecsys S100 immunoassay and compared to those obtained by the well-established LIA-mat S100 system.

RESULTS

In contrast to CAS and CA patients, median S100 serum levels of CEA patients significantly increased to 0.24 ng/mL before declamping, but subsequently returned to baseline. Three CEA patients with neurological deficits showed sustained elevated S100 levels 6 h after extubation. Absolute S100 values were not significantly different between the two methods. Bland-Altman plot analyses displayed a good agreement, mostly indicating slightly smaller values applying the Elecsys S100 system.

CONCLUSIONS

The Elecsys S100 system appears to be suitable for rapid real-time detection of neurological deficits in patients undergoing CAS and CEA. Persistent elevations of Elecsys S100 levels during CEA were associated with prolonged neurological disorders, whereas transient increases seem to represent impaired blood-brain barrier integrity without neurological deficits.

Impairment of blood-brain barrier integrity during carotid surgery as assessed by serum S-100B protein concentrations

During carotid endarterectomy (CEA) the internal carotid artery is cross-clamped for a period of several minutes. This maneuver may cause cerebral hypoperfusion and/or impairment of the blood-brain barrier (BBB) even in cases where clinical signs are absent. The aim of the present study was to examine whether such alterations could be detected by monitoring the cerebral marker S-100B protein concentrations during and after CEA in the serum. Twenty-five consecutive patients (17 M/8 F, mean age: 64.2 years, range 47-79 years) undergoing elective CEA at our department were studied. All of these patients were without perioperative neurological deficit. Intraoperative samples were collected from internal jugular and peripheral venous blood: 1) before carotid cross-clamping; 2) immediately before declamping; 3) after clamp release. Postoperative samples were taken from peripheral blood at 6 and 24 h, respectively. S-100B was assayed in sera using an immunoluminometric technique. During carotid cross-clamping, S-100B protein concentrations in the ipsilateral jugular serum significantly (p < 0.02) increased to pre-clamp values. After declamping, however, S-100B returned to the baseline level. No differences were seen between the responses of hypertensive and normotensive patients. There was no correlation between carotid occlusion time and S-100B protein concentrations. In the peripheral venous serum no significant changes in S-100B concentrations were detected during or after CEA. We presume that the elevation of S-100B protein concentration during CEA in patients with no neurological deficits indicates the transient opening of the BBB elicited by carotid cross-clamping.

S100B in brain damage and neurodegeneration

S100B is a calcium-binding peptide produced mainly by astrocytes that exert paracrine and autocrine effects on neurons and glia. Some knowledge has been acquired from in vitro and in vivo animal experiments to understand S100B's roles in cellular energy metabolism, cytoskeleton modification, cell proliferation, and differentiation. Also, insights have been gained regarding the interaction between S100B and the cerebral immune system, and the regulation of S100B activity through serotonergic transmission. Secreted glial S100B exerts trophic or toxic effects depending on its concentration. At nanomolar concentrations, S100B stimulates neurite outgrowth and enhances survival of neurons during development. In contrast, micromolar levels of extracellular S100B in vitro stimulate the expression of proinflammatory cytokines and induce apoptosis. In animal studies, changes in the cerebral concentration of S100B cause behavioral disturbances and cognitive deficits. In humans, increased S100B has been detected with various clinical conditions. Brain trauma and ischemia is associated with increased S100B concentrations, probably due to the destruction of astrocytes. In neurodegenerative, inflammatory and psychiatric diseases, increased S100B levels may be caused by secreted S100B or release from damaged astrocytes. This review summarizes published findings on S100B regarding human brain damage and neurodegeneration. Findings from in vitro and in vivo animal experiments relevant for human neurodegenerative diseases and brain damage are reviewed together with the results of studies on traumatic, ischemic, and inflammatory brain damage as well as neurodegenerative and psychiatric disorders. Methodological problems are discussed and perspectives for future research are outlined.

Serum concentration of S-100 protein in assessment of cognitive dysfunction after general anesthesia in different types of surgery

BACKGROUND

S-100 protein serum concentration (S-100) serves as a marker of cerebral ischemia in cardiac surgery, head injury and stroke. In these circumstances S-100 corresponds well with the results of neuropsychological tests. The aim of the present study was to investigate the value of S-100 and neuron specific enolase (NSE) in reflecting postoperative cognitive deficit (POCD) after general surgical procedures.

METHODS

One hundred and twenty patients undergoing vascular, trauma, urological or abdominal surgery were investigated. Serum values of S-100 and NSE were determined preoperatively and 0.5, 4, 18 and 36 h postoperatively. Neuropsychological tests for detecting POCD were performed preoperatively and on day 1, 3, and 6 after the operation. A decline of more than 10% in neuropsychological test results was regarded as POCD. Furthermore, we retrospectively compared the S-100 in patients with and without POCD in different types of surgery.

RESULTS

According to our definition, forty-eight patients had POCD (95% confidence interval: 37.5-58.5). These patients showed higher serum concentrations of S-100 (median 024 ng/ml; range 0.01-3.3 ng/ml) compared with those without POCD (n=69; median 0.14 ng/ml; range 0-1.34 ng/ml) 30 min postoperatively (P=0.01). Neuron specific enolase was unchanged during the course of the study. Differences of S-100 in patients with and without POCD were found in abdominal and vascular surgery but not in urological surgery.

CONCLUSION

When all patients are pooled, S-100 appears to be suitable in the assessment of incidence, course and outcome of cognitive deficits. We suspect that in some surgical procedures, such as urological surgery, S-100 appears to be of limited value in detecting POCD. Neuron specific enolase did not reflect neuropsychological dysfunction after noncardiac surgery.

Serum S100B protein levels are correlated with subclinical neurocognitive declines after carotid endarterectomy

OBJECTIVE

Carotid endarterectomy (CEA) is an effective means of stroke prevention among appropriately selected patients; however, neuropsychometric testing has revealed subtle cognitive injuries in the early postoperative period. The purpose of this study was to establish whether serum levels of two biochemical markers of cerebral injury were correlated with postoperative declines in neuropsychometric test performance after CEA.

METHODS

Fifty-five consecutive patients underwent a battery of neuropsychometric tests 24 hours before and 24 hours after elective CEA. Two patients were excluded because of postoperative strokes. The pre- and postoperative serum levels of S100B protein and neuron-specific enolase for injured patients, defined as those who exhibited significant declines in neuropsychometric test performance (n = 12), were compared with the levels for uninjured patients (n = 41).

RESULTS

There were no significant differences in the baseline S100B levels for the two groups. Injured patients exhibited significantly higher S100B levels, compared with uninjured patients, at 24, 48, and 72 hours after surgery (P < 0.05). There were no significant differences in neuron-specific enolase levels for injured and uninjured patients at any time point.

CONCLUSION

These data suggest that subtle cerebral injuries after CEA, even in the absence of overt strokes, are associated with significant increases in serum S100B but not neuron-specific enolase levels. Analyses of earlier time points in future studies of subtle cognitive injuries and biochemical markers of cerebral injury after CEA may be revealing.