Correlation of cerebral angiographic and CT/MRI findings in transient ischemic attack

Abstract

The diagnosis of transient ischemic attack (TIA) is based on a history of neurological deficit followed by rapid recovery of normal neurological function. TIA has been attributed to microembolic and hemodynamic phenomena associated with atheromatous plaque deposition in large vessels or cardioembolism. However, some cases of TIA have been recognized with no angiographic abnormalities or cardioembolic sources. The present study was therefore conducted to elucidate further the heterogeneous mechanisms of TIA. Forty-five patients with TIA involving the internal carotid artery (age 63.9 ± 9.9 yr, mean ± SD) were initially enrolled in the study. We performed CT/MRI and cerebral angiography (3 or 4 vessels) in all patients. Cases directly attributable to cardioembolism were eliminated from the study. Those with over 25% stenosis of a large extracranial artery were designated as angiographically abnormal (AGA +), and those with less than 25% stenosis, or with normal findings were diagnosed as AGA (-). A total of 26 patients were classified as AGA (+) and 19 patients as AGA (-). These two patient groups were compared on the basis of their CT/MRI findings, frequency and duration of ischemic attacks, and major risk factors. Small infarctions in the basal ganglion and/or subcortical white matter were found in 9 out of the 26 AGA (+) patients (34.6%), as opposed to 16 out of the 19 patients (84.2%) in the AGA (-) group. The incidence of abnormal CT/MRI findings was significantly different between the two groups (p < 0. 001). The symptoms suggestive of TIA were consistent with large vessel abnormalities in 84.6% of the patients. These findings suggested that microembolic mechanisms probably played a major role in the TIA of the AGA (+) group, whereas ischemia at the level of the cerebral perforating arteries was a more important factor in the AGA (-) group. The frequency and duration of ischemic attacks did not differe between the AGA (+) and AGA (-) groups. Similarly, the major risk factors did not differ between the two groups. Seven patients suffered a complete cerebral infarction during the 5-year followup period, but these patients were significantly older (p <0.05) than those who were free of infarction.