An observational study of pre-operative transcranial Doppler examinations to predict cerebral hyperperfusion following carotid endarterectomies.

The objective of this observational study was to determine whether pre-operative transcranial Doppler measurements could identify patients at risk for early cerebral hyperperfusion following carotid endarterectomies. Fifty-five patients (mean age 64.4 years) with symptomatic internal carotid artery stenosis were included. Pre-operative transcranial Doppler measurements included middle cerebral artery blood flow velocities at normocapnia, pulsatility indices and estimation of the cerebro-vascular reserve capacity ipsilateral to the internal carotid artery stenosis. The percentage change in blood flow velocities before and at the end of the procedure was calculated. Early cerebral hyperperfusion was defined as an increase of mean blood flow velocity of more than 100% at the end of the carotid endarterectomy. Early cerebral hyperperfusion was observed in 9.2%. Cerebral hyperperfusion was seen in patients with a subtotal carotid artery stenosis in combination with reduced pre-operative blood flow velocity and pulsatility. The post-operative stroke incidence in patients with an early cerebral hyperperfusion was tenfold higher compared to patients who did not experience early hyperperfusion. A prospective clinical trial is warranted to determine whether transcranial Doppler parameters can be used to indicate patients at risk for reperfusion strokes following carotid endarterectomies.