Preoperative White Matter Disease Severity Predicts Intraoperative Cerebral Desaturation During Carotid Endarterectomy.

Abstract

Objective: Carotid endarterectomy carries the risk of cerebral ischemia during carotid clamping. Traditional risk stratification relies on anatomic factors such as contralateral stenosis, yet these predictors demonstrate limited sensitivity for intraoperative hypoperfusion. White matter hyperintensities (WMH), quantified by the Fazekas scale, reflect chronic cerebral small vessel disease and impaired cerebrovascular reactivity. Whether baseline WMH burden predicts intraoperative cerebral oxygen desaturation during carotid clamping remains unknown. Methods: This prospective, single-center cohort study enrolled patients undergoing carotid endarterectomy with continuous bilateral near-infrared spectroscopy (NIRS) monitoring. The primary outcome was the maximum contralateral regional cerebral oxygen saturation (rSO₂) decrease within 2 min after carotid clamp placement compared with the pre-clamp baseline. The primary predictor was the contralateral hemisphere Fazekas score assessed on preoperative brain MRI. Multivariable linear regression adjusted for age, contralateral carotid stenosis, clamping time, and shunt use. Results: Of 173 patients screened, 58 with complete data were included in the final analysis. Th average age was 69. 2 ± 7 years, 37.9% were female, significant contralateral stenosis was present in four cases, and the average exclusion time was 30.1 ± 9.7 min. In multivariable regression, a higher contralateral Fazekas score was independently associated with greater contralateral rSO₂ desaturation during carotid clamping (unstandardized β = 0.008, standardized β = 0.287, p = 0.035). The association remained statistically significant after adjustment for all covariates. The overall model explained 8.8% of variance in contralateral desaturation (R² = 0.088). Conclusions: Contralateral white matter disease severity, quantified by Fazekas score, was independently associated with greater contralateral cerebral oxygen desaturation during carotid clamping. This finding supports the concept that baseline microvascular disease modifies acute ischemic tolerance independent of large-vessel anatomy. Preoperative Fazekas scoring may enhance risk stratification and inform individualized neuromonitoring strategies during carotid endarterectomy.