Potential relevance of low-intensity microembolic signals by TCD monitoring.

The significance of low-intensity microembolic signals (MES), as well as their relationship with high-intensity MES, has not yet been studied. We monitored MES by TCD in 256 arteries of 229 patients with carotid stenosis. All microemboli were detected automatically without a preliminary set threshold. For those 110 patients who evidenced any emboli, the correlation between the number of high- and low-intensity MES was r = 0.50, p < 0.0001. A statistically significant relationship between both types of MES was found, with a degree of association of 0.42, as assessed by Cohen's kappa. Later occurrence of high-intensity MES based on early low-intensity MES was statistically significant, with a chi-square p = 0.0006 and a degree of association of 0.24, as assessed by Cohen's kappa. There is a significant relationship between low- and high-intensity MES, thereby indicating that many MES routinely rejected because of their low intensity are real.