Association between impaired carbon dioxide reactivity and ischemic lesions in arterial border zone territories in patients,with unilateral internal carotid artery occlusion

Context: Ischemic lesions in patients with internal carotid artery (ICA) steno-occlusive disease can be categorized on the basis of their location and presumed cause: external border zone infarcts, internal border zone infarcts, cortical infarcts, lacunar infarcts, and periventricular lesions. Objective: To evaluate the association between the prevalence and size of ischemic lesions and cerebral vasomotor reactivity in patients with unilateral occlusion of the ICA. Design: Cross-sectional study. Setting: Referral center. Patients: Seventy consecutive patients were included in this study. All patients had a transient or minor disabling retinal or cerebral ischemia that was associated with unilateral occlusion of the ICA. Ischemic lesions on magnetic resonance imaging were identified on hard copies, and volume measurements were obtained by a magnetic resonance workstation. Vasomotor reactivity was assessed with transcranial Doppler ultrasonography with carbon dioxide challenge. Main Outcome Measures: Prevalence and size of ischemic lesions. Results: In the hemisphere ipsilateral to the ICA occlusion, we found an increased prevalence of internal border zone infarcts (P = .01), external borders zone infarcts (P < .001), and territorial infarcts (P = .02) compared with the contralateral hemisphere. Hemispheres with a carbon dioxide reactivity less than or equal to 18% demonstrated a significant increase in prevalence (P = .007) and volume (P = .003) of internal border zone infarcts compared with hemispheres with a carbon dioxide reactivity greater than or equal to 19%. No association between carbon dioxide reactivity and any other type of ischemic lesion was found. Conclusion: In patients with an ICA occlusion, only internal border zone infarcts demonstrate a significant association with diminished cerebral hemodynamics.