Hemispheric symptoms and carotid plaque echomorphology

Purpose: In patients with carotid bifurcation disease, the risk of stroke m ainly depends on the severity of the stenosis, the presenting hemispheric s ymptom, and, as recently suggested, on plaque echodensity. We tested the hy pothesis that asymptomatic carotid plaques and plaques of patients who pres ent with different hemispheric symptoms are related to different plaque str ucture in terms of echodensity and the degree of stenosis. Methods: Two hundred sixty four patients with 295 carotid bifurcation plaqu es (146 symptomatic, 149 asymptomatic) causing more than 50% stenosis were examined with duplex scanning. Thirty-six plaques were associated with amau rosis fugax (AF), 68 plaques were associated with transient ischemic attack s (TIAs), and 42 plaques were associated with stroke. B-mode images were di gitized and normalized using linear scaling and two reference points, blood and adventitia. The gray scale median (GSM) of blood was set to 0, and the GSM of the adventitia was set to 190 (gray scale range, black = 0; white = 255). The GSM of, the plaque in the normalized image was used as the objec tive measurement of echodensity. Results: The mean GSM and the mean degree of stenosis, with 95% confidence intervals, for plaques associated with hem ispheric symptoms were 13.3 (10.6 to 16) and 80.5 (78.3 to 82.7), respectiv ely; and for asymptomatic plaques, the mean GSM and the mean degree of sten osis were 30.5 (26.2 to 34.7) and 72.2 (69.8 to 74.5), respectively. Furthe rmore, in plaques related to AP, the mean GSM and the mean degree of stenos is were 7.4 (1.9 to 12.9) and 85.6 (82 to 89.2), respectively; in those rel ated to TIA, the mean GSM and the mean degree of stenosis were 14.9 (11.2 t o 18.6) and 79.3 (76.1 to 82.4), respectively; and in those related to stro ke, the mean GSM and the mean degree of stenosis were 15.8 (10.2 to 21.3) a nd 78.1 (73.4 to 82.8), respectively. Conclusion: Plaques associated with hemispheric symptoms are more hypoechoi c and more stenotic than those associated with no symptoms. Plaques associa ted with AP are more hypoechoic and more stenotic than those associated wit h TIA or stroke or those without symptoms. Plaques causing TIA and stroke h ave the same echodensity and the same degree of stenosis. These findings co nfirm previous suggestions that hypoechoic plaques are more likely to be sy mptomatic than hyperechoic ones. They support the hypothesis that the patho physiologic mechanism fbr AF is different from that for TIA and stroke.