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

Abstract

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.

Figures

FIGURE 1

S100B levels. A, S100B levels (mean ± standard error) were measured preoperatively (Baseline), at the time of cross-clamping (PreClamp), and 24, 48, and 72 hours postoperatively for the injured and uninjured patient groups. There was no significant difference in baseline S100B values for the groups; however, there were significant differences at each of the remaining time points (*P < 0.05). B, when changes from baseline values were calculated, patients with cognitive dysfunction exhibited significantly greater increases in S100B levels than did patients without cognitive dysfunction at 24 (*P < 0.05), 48 (***P < 0.001), and 72 (**P < 0.01) hours after surgery.

FIGURE 2

NSE levels. A, NSE levels (mean ± standard error) were measured preoperatively (Baseline), at the time of cross-clamping (PreClamp), and 24, 48, and 72 hours postoperatively for the injured and uninjured patient groups. There were no significant differences in the NSE values for the groups at any time point. B, when changes from baseline values were calculated, the injured and uninjured patient groups exhibited similar NSE values at 24, 48, and 72 hours after surgery.