Background and purpose Patients who require sacrifice of the internal carotid artery (ICA) have a substantial risk of stroke, despite preoperative testing with temporary balloon occlusion (TBO). The purpose of this study is to examine the incidence and mechanisms of stroke after permanent carotid artery occlusion in this population.

Methods Consecutive patients undergoing TBO testing from March 2002 to December 2011 were identified. The protocol included 30 min of balloon occlusion, continuous intraprocedural neurological assessment, angiographic imaging of collateral flow during the occlusion, and perfusion imaging. Clinical records were reviewed for procedure results, procedural complications, and the incidence and causes of stroke, transient ischemic attack (TIA) and death over 6 months. Strokes were categorized as thromboembolic or hypoperfusion based on available clinical and imaging data.

Results One hundred and fifty carotid occlusion tests were performed during the study period, including 84 women and 66 men. No procedural strokes were recorded. Thirty-seven patients (25%) had permanent occlusion of the tested ICA. Six of the 37 patients had ipsilateral stroke (16.2%) and three experienced TIA (8.1%). Two strokes occurred in the immediate postoperative period (thromboembolic), two strokes occurred within days of ICA occlusion (hypoperfusion), and two strokes occurred at least 30 days from the time of ICA occlusion (thromboembolic).

Conclusions The rate of ischemic stroke following carotid sacrifice remains high and most strokes are thromboembolic in nature. Our testing protocol did not eliminate the risk of hypoperfusion-related stroke. Delayed venous phase by angiography may be a better indicator of hemodynamic tolerance than perfusion imaging.