Prolonged disturbances of regional cerebral blood flow in transient ischemic attacks

Abstract

Regional cerebral blood flow (rCBF) was measured over both hemispheres in 20 patients with unilateral transient ischemic attacks (TIA) of the territory of the internal carotid artery on the day of the TIA. rCBF was estimated with the nontraumatic Xenon 133-inhalation technique using the initial slope index. 13 patients experienced their first TIA, 7 had several attacks. In 14 patients the first rCBFmeasurement was performed during the presentation of clinical symptoms. The 2nd rCBF-measurement was done on day 2, the last one on day 7. Scans of the 15 patients studied with CT were normal. On day 1 mean rCBFof theTIA-side was significantly lower than that of the contralateral hemispheres. 22% of all areas showed a significant reduction of flow compared to mean rCBF. Mean rCBF of both the TIA- and the contralateral side was significantly reduced compared to the bi-hemispheric mean rCBF of a control group with no history of TIA or completed strokes but at least 2 risk factors for cerebrovascular disease. Whereas mean rCBF did not change in the contralateral side it increased significantly (+ 6.9%) in the TIA-side from day 1 to day 2 but not from there to day 7. This is reflected by the increase of the total number of ROI with normal flow from day 1 to day 2. Considering the actual flow and the flow course of that tissue which was beloved to be responsible for the clinical symptoms the following regional patterns were observed: Normal rCBF in 6 patients; early return to normal concomitant to the clinical course (n = 4); delayed return to normal with ischemia on day 2 but not on day 7 (n = 3); early hyperperfusion with perifocal ischemia on day 1 (n = 2); delayed hyperperfusion on day 2 with ischemia on day 1 (n = 2); persistent ischemia (n = 3). The data indicate that transient ischemic attacks are accompanied by varying patterns of focal CBF with negligible participation of the contralateral hemisphere. 60% of all cases present with flow abnormalities on the day of the TIA and 40% on the day following the clinical symptoms. The method seems to be highly sensitive in indicating pathophysiological abnormalities in patients with transient ischemia of the brain. © 1985 American Heart Association, Inc.