An additional monitoring of regional cerebral oxygen saturation to HMPAO SPECT Study during balloon test occlusion. Stroke

Background and Purpose—To increase the reliability of 99mTc–hexamethyl propyleneamine oxime (HMPAO) single photon emission computed tomography (SPECT) study in the evaluation of hemodynamic change with balloon test occlusion (BTO) of the internal carotid artery, we attempted to clarify the usefulness of additional monitoring of regional oxygen saturation of the brain (rSO2). Methods—During BTO, rSO2 monitoring with transcranial near infrared spectroscopy was performed 17 times on 16 patients. Asymmetrical distribution of the tracer was classified visually as follows: group 1, little or no asymmetry, and group 2, moderate or severe asymmetry. Seven regions of interest (ROI) were defined in the middle cerebral artery area of each hemisphere, and the asymmetry index (AI)52003(Cnon2Coccl)/(Cnon1Coccl)), where Cnon5mean counts on the nonoccluded side, and Coccl5mean counts on the occluded side were also calculated. Then, mean AI (MAI) was obtained from AI of 7 ROIs for each study. Results—Of the 17 procedures, 10 BTOs were in group 1 and 5 BTOs were in group 2. Two patients did not undergo SPECT study because of the immediate appearance of a neurological deficit with BTO; they were defined as group 3. The MAI in group 1 was 2.663.3%, which was significantly smaller than the MAI in group 2 (25.665.0%, P,0.02). The DrSO2 (baseline rSO22rSO2 during ICA occlusion) with BTO in group 1 was 1.561.4 % (n510), which was statistically smaller than that in group 2 (5.561.3%, n54, P,0.05). The DrSO2 in group 3 was 9.060.0 % (n52). I