DISSOCIATION OF VASOREACTIVITY TO ACETAZOLAMIDE AND HYPERCAPNIA - COMPARATIVE-STUDY IN PATIENTS WITH CHRONIC OCCLUSIVE MAJOR CEREBRAL-ARTERY DISEASE

Background and Purpose The aim of this study was to com pare the effec t of vasodilative stimuli for the measurement of cerebrovascular react ivity obtained by acetazolamide and hypercapnia in patients with chron ic occlusive major cerebral artery disease. Methods We examined 24 pat ients with unilateral occlusive lesions of a major cerebral artery usi ng the Xe-133 inhalation technique and single-photon emission CT. Regi onal cerebral blood Row (CBF) was measured during a resting state, dur ing inhalation of 5% CO2, and 15 minutes after the administration of a cetazolamide consecutively in the same patients. Normative values of r esting CBF and acetazolamide reactivity were obtained in 21 normal sub jects. Results All patients with the exception of 1 showed an increase in CBF during hypercapnia ipsilateral to the occlusive lesion. Ipsila teral acetazolamide reactivity was preserved in 13 patients. Conversel y, 11 patients showed an absent response or paradoxical CBF reduction. Ipsilateral CO2 reactivity did not correlate with acetazolamide react ivity when all 24 patients were considered. However, there was a signi ficant correlation between acetazolamide and CO2 in the 13 patients wh o showed preserved acetazolamide reactivity (r=.60, P<.05). No signifi cant correlation was present in the remaining 11 patients with reduced acetazolamide reactivity. Although significant blood pressure augment ation was observed in hypercapnia, we could not find a correlation bet ween change of blood pressure and CO2 reactivity. Conclusions Acetazol amide identified patients with reduced vasomotor reactivity who appear ed to have preserved CO2 reactivity. Acetazolamide testing may be usef ul in the assessment of cerebral hemodynamics. However, further invest igations are necessary to assess the clinical utility of these tests.