Cerebral hemodynamics in asymptomatic and symptomatic patients with high-grade carotid stenosis undergoing carotid endarterectomy

Abstract

Background and Purpose - Asymptomatic patients with carotid stenosis benefit less from carotid endarterectomy (CEA) than symptomatic patients because the risk of embolic events is lower, but it is not known whether the hemodynamic effect of CEA is different between the groups. We evaluated hemodynamics of symptomatic and asymptomatic patient groups before and after CEA. Methods - Forty-six independent patients with a unilateral high-grade carotid stenosis, 23 asymptomatic and 23 symptomatic, underwent dynamic susceptibility contrast MRI (DSC-MRI) and transcranial Doppler ultrasound (TCD) evaluation before CEA and 3 and 100 days afterward. Quantitative perfusion parameters were calculated separately in selected regions of white and gray matter and watershed regions in each hemisphere, and mean transit time (MTT) maps were assessed visually by 2 independent observers. Vasomotor reactivity was determined with breath-holding index and flow impedance with pulsatility index ipsilaterally. Results - In contrast to the asymptomatic carotid stenosis group, symptomatic carotid stenosis patients had preoperatively increased MTT and lower cerebral blood flow values in the ipsilateral hemisphere, more in white matter and watershed regions than in gray matter. Visually detected perfusion deficits were associated with symptomatic status. The interhemispheric asymmetries were abolished by CEA. The improving trend over time was greater in the symptomatic carotid stenosis group and was best seen in MTT. On TCD, pulsatility index was lower in symptomatic carotid stenosis patients preoperatively, with no postoperative difference, whereas the breath-holding index improved only in the symptomatic carotid stenosis group after CEA. Conclusions - Patients with asymptomatic and symptomatic carotid stenosis differ significantly by means of DSC-MRI and TCD before and in response to CEA.