The atherosclerotic plaque in the thoracic aorta has been considered as a potential source of cerebral or peripheral embolization. Especially, complex type of atherosclerotic plaques in the thoracic aorta have strongly been associated with cerebral embolism in ischemic stroke and transesophageal echocardiography(TEE) is a useful diagnostic tool for evaluation of thoracic aorta atherosclerosis. The aim of this study was to evaluate the prevalence and significance of complex type of thoracic atherosclerotic plaques in the patients with cryptogenic stroke who have neither cardiac source nor significant carotid atherosclerosis.

From 1993 to 1998, TEE and carotid Doppler sonography were performed in 58 consecutive patients with ischemic stroke and in 30 control patients without ischemic stroke. We divided the former into two groups. One is known-cause stroke(n=37) group and the other is Cryptogenic stroke group(n=21). We evaluated cardiogenic source of embolism, thoracic aorta atherosclerotic plaques as well as carotid atherosclerosis by carotid Doppler sonography and TEE. Aortic atherosclerosis was classified as grade 1: normal-appearing aortic intima, grade 2: extensive intimal thickening, grade 3: sessile atheroma protruding <5mm, grade 4: atheroma protruding >5mm, and grade 5: mobile atheroma. Carotid atherosclerosis was categorized as significant if luminal stenosis of either common carotid artery or internal carotid artery is greater than 50%.

1) There was no statistically significant difference among the three groups in age, gender, diabetes mellitus, hyperlipidemia and smoking. 2) Hypertension was more common in the cryptogenic stroke group(p<0.05). Atrial fibrillation was more common in the known-cause and control group than in the cryptogenic group(p<0.005). 3) The carotid atherosclerosis was found in 7(12%) out of 58 consecutive patients with ischemic stroke. 4) The thoracic aortic atherosclerotic plaque was located primarily on descending aorta. The complex type of plaque was found in 8(38%) out of 21 patients with cryptogenic stroke. The complex type of plaque was found in 10(27%) out of 37 patients with known-cause stroke. The complex type of plaque was found in 3(10%) out of 30 patients with known-cause stroke.

These results suggest that complex type of thoracic atherosclerotic plaques in cryptogenic stoke can be considered as potential source of ischemic stroke and we suggest that a patient with cerebral embolism without a source identified by the routine transthoracic echocardiograpy or carotid sonography shoud undergo transesophageal echocardiography to evaluate the thoracic aorta atheroma.