Venous outflow as a criterion of impairment of cerebral vascular reserve

Aim The purpose of this work is to evaluate if the asymmetry of venous outflow between the two hemispheres is a reliable criterion of impairment of the cerebral vascular reserve among symptomatic patients harbouring a spontaneous atherosclerotic occlusion of internal carotid artery. Methods. From January 1995 to December 2007,7 symptomatic patients, affected from occlusion of internal carotid artery, were submitted to a low-flow by-pass between the superficial temporal artery and the middle cerebral artery owing to the presence of an impairment of cerebral vascular reserve diagnosed by TC-Doppler, SPECT or perfusion-CT with acetazolamide challenge. Conventional angiography was always performed. Angiographic studies of these patients were reviewed in order to find out the presence of asymmetry of the venous outflow. In the same period 35 patients harbouring an occlusion of the carotid artery in the neck and a normal cerebral reserve underwent cerebral angiography in our departments in Monza. Angiographic studies, of this latter group of patients, were also retrospectively analyzed with the same purpose. Results. All patients, with a poor cerebral reserve, showed an asymmetry of venous outflow >3 s omolateral at the carotid occlusion. Patients, with a normal cerebral reserve, showed an asymmetry of venous outflow <2 s. Conclusions. Asymmetry of venous outflow were correlated to an impaired cerebral reserve also in chronic conditions as atherosclerotic spontaneous occlusion of internal carotid artery. Our data are a further support to the reliability of this criterion in case of therapeutic sacrifice of internal carotid artery.