COMPARISON OF CARBON-DIOXIDE RESPONSIVENESS OF CEREBELLAR BLOOD-FLOW BETWEEN AFFECTED AND UNAFFECTED SIDES WITH CROSSED CEREBELLAR DIASCHISIS

Background and Purpose Concerning vasoreactivity of cerebellar blood f low (CeBF) in patients affected with crossed cerebellar diaschisis (CC D), several controversies have been reported. One is reduced asymmetry of CeBF after acetazolamide administration in Tc-99m hexamethylpropyl eneamine oxime single-photon emission-computed tomography, and the oth er is persistent asymmetry with alternation in PaCO2 using the Xe-133 clearance method. The purpose of this study is to examine whether CeBF vasoreactivity in the side affected with CCD is the same as that in t he, unaffected side. Methods We analyzed CeBF during hypocapnia, normo capnia, and hypercapnia performed in 27 patients with cerebrovascular disease (age range, 38 to 73 years; mean age, 62.0 +/- 8.5 years) affe cted by CCD. CeBF was measured using (H2O)-O-15 and positron emission tomography. Results The CeBF ratio of CCD-affected side to CCD-unaffec ted side was consistent during the perturbation of PaCO2. This ratio w as 0.82 +/- 0.08 for PaCO2 elevation and 0.83 +/- 0.07 for PaCO2 lower ing. Both were not significantly different from unity. Conclusion The percent change of CeBF per millimeter of mercury PaCO2 change was unif orm across affected and unaffected sides with CCD. These findings are consistent with our recent findings observed in activated cerebral tis sue during photic stimulation.