Sustained bilateral hemodynamic benefit of contralateral carotid endarterectomy in patients with symptomatic internal carotid artery occlusion

Background and Purpose-We sought to investigate whether in patients with a symptomatic internal carotid artery (ICA) occlusion, endarterectomy of a se vere stenosis of the contralateral carotid artery can establish long-term c erebral hemodynamic improvement. Methods-Nineteen patients were studied on average 1 month before and 6 mont hs after contralateral carotid endarterectomy (CEA). Volume flow in the mai n extracranial and intracranial arteries was measured with MR angiography. Collateral flow via the circle of Willis and the ophthalmic arteries was st udied with MR angiography and transcranial Doppler sonography, respectively . Cerebral metabolism and CO2 vasoreactivity were investigated with MR spec troscopy and transcranial Doppler sonography, respectively. Twelve nonopera ted patients with a symptomatic ICA occlusion and contralateral ICA stenosi s, who were matched for age and sex, served as control patients. Results-In patients who underwent surgery, flow in the operated ICA increas ed significantly (P<0.05) and flow in the basilar artery decreased signific antly (P<0.01) after CEA. On the occlusion side, mean flow in the middle ce rebral artery increased significantly from 71 to 85 mL/min (P<0.05) after C EA. The prevalence of collateral flow via the anterior communicating artery to the occlusion side increased significantly (47% before and 84% after CE A; P<0.05), while the prevalence of reversed ophthalmic artery flow on the operation side decreased significantly (42% before and 5% after CEA; P<0.05 ). In the hemisphere on the side of the ICA occlusion, lactate was no longe r detected after CEA in 80% of operated patients, whereas it was no longer detected over time in 14% of nonoperated patients (P<0.05). CO2 reactivity increased significantly in operated patients in both hemispheres (P<0.01). Conclusions-Contralateral CEA in patients with a symptomatic ICA occlusion induces cerebral hemodynamic improvement not only on the side of surgery bu t also on the side of the ICA occlusion.