Embolization via collateral circulation during carotid stenting with the distal balloon protection system

Purpose: To describe a potential route for embolization to the middle cerebral artery (MCA) during carotid stenting with the distal balloon protection system. Case Report: An 82-year-old man with symptomatic severe carotid artery stenosis underwent elective carotid stenting with distal-balloon protection. Despite complete occlusion of the distal internal carotid artery, frequent emboli were detected in the ipsilateral MCA by transcranial Doppler (TCD) during the procedure. Intracranial angiography, performed during the distal-balloon protection, revealed filling of the MCA through collaterals from the ipsilateral external carotid artery. The procedure was successfully completed without complications. The patient remains asymptomatic at 6 months. Conclusions: During carotid stenting with distal-balloon protection, asymptomatic embolization into the ipsilateral MCA may occur through collateral circulation. The clinical significance of these emboli is uncertain.