Are Strokes More Likely To Result from Severe Carotid Atherosclerotic Stenoses? If Not, Why Not?

The authors studied by carotid duplex ultrasonography 478 unselected el-derly patients (age sixty to one hundred one years, mean 82±8), in their long-term health care facility. Of these, 108 had previously experienced strokes owing to atherothrombotic brain infarcts, documented by a neurologist, and 370 had not. The degree of extracranial internal or common carotid narrowing in these patients was classified by standard Vmax Doppler criteria as 0-40%, 40-80%, and 80-100 % luminal diameter reduction. The authors found that 87 % of the patients had little or no carotid stenosis (0-40 % luminal diameter reduction). Nevertheless, 79 % of the previous strokes had occurred in these patients, and the incidence of strokes in this group was 21%. Severe, but not mild or moderate, degrees of carotid obstruction (80-100 % luminal diameter reduction) were associated with a 100 % stroke inci-dence. The authors conclude that strokes most commonly result from causes other than ischemia due to in situ severe extracranial internal or common carotid stenosis or occlusion