Evaluation of vasomotor reactivity by transcranial Doppler and acetazolamide test before and after extracranial-intracranial bypass in patients with internal carotid artery occlusion.

The aim of this trial was to evaluate the effectiveness of extracranial-intracranial bypass with respect to vasomotor reactivity in patients with internal carotid artery occlusions and absent vasomotor reactivity, comparing them with a control group treated conservatively.To test vasomotor reactivity in 104 patients with unilateral occlusion of the internal carotid artery, we measured blood flow velocity in the middle cerebral artery by transcranial Doppler sonography both at rest and after injection of acetazolamide. Among the 39 patients who failed to show increased mean blood flow velocity after the acetazolamide test distal to an occluded internal carotid artery by greater than or equal to 10%, 14 subjects subsequently underwent extracranial-intracranial bypass surgery (group A) and 14 age- and sex-matched subjects in whom no such procedure was done composed the control group (group B). Follow-up examinations were performed 3-6 months postoperatively and in the control group 3-6 months after initial e...