Carotid plaque morphology and risk for stroke.

The importance of carotid artery atherosclerosis in the pathogenesis of cerebral ischemia and infarction has been recognized for many years. As early as 1856, Savory pointed out this relationship, and in 1904 Chiari suggested the possibility of cerebral emboli originating from the cervical portion of the carotid artery. The concept was further popularized by Fisher's clinicopathologic reports of symptomatic carotid artery disease,and in 1954 the first paper describing a feasible technique for the surgical reconstruction of the carotid artery appeared in the literature. The pathogenic role of carotid atherosclerotic plaques in the development of stroke is thought to reflect their emboligenic properties, hemodynamic significance, or, more realistically, a combination of both. Considered in this context, the problem of assessing the effectiveness of various modes of therapy in patients with carotid artery disease has been in part the assumption that all individuals with a "carotid plaque" have an equivalent risk of suffering a stroke. It is now believed that this population is more heterogeneous than originally thought, and attention has shifted to the study of the various types of carotid artery lesions encountered in clinical practice. The focus of this shift has been the search for subgroups of patients who share certain specific types of carotid plaques and the investigation of the association between plaque morphology and the risk of ipsilateral brain infarction. The morphologic variables that have been considered may be grouped into several categories: 1) size of the plaque (and degree of stenosis caused), 2) plaque surface configuration (smooth, rough, or ulcerated), and 3) plaque histologic composition (fat, fibrous tissue, calcium, intramural hemorrhage).