Abstract WP126: Transcranial Doppler and Microemboli Detection. Relationships to Symptomatic Status and Histopathology Findings

Abstract

Introduction: Microemboli, as detected by transcranial Doppler (TCD), are hypothesized to be associated with carotid plaque instability and symptomatic subject status associated with motor, sensory, visual and speech deficits of stroke and transient ischemic attack (TIA). However, the current clinical exam does not assess sequeli of small emboli and probable differences between symptomatic and asymptomatic plaques. The purpose of this study was to determine the relationship between symptomatic status, microemboli presence and histopathology findings. Methods: TCD examination was performed on 60 study subjects for an hour to assess the presence of microemboli, prior to undergoing clinically indicated carotid endarterectomy. Macroscopic scoring for cholesterol, thrombus, calcium and ulceration were performed with a dissecting microscope. Histopathological examination, with high power magnification on fixed plaque was scored for hemorrhage, hemosiderin, inflammation, percent cholesterol and calcium. Pearson’s chi-squared test was used to assess the frequency of microemboli between symptomatic and asymptomatic subjects. Logistic regression was used to analyze the relationship between operative and histopathology plaque findings and presence of microemboli. Results: The frequency of microemboli signals, as detected with TCD, was not significantly different between symptomatic and asymptomatic subject groups (p=0.88) nor was there any difference observed in the macroscopic or histopathology scoring of these plaques (p-values all > 0.05). The presence of microemboli was associated with an ulceration score (regardless of symptomatic or asymptomatic status, p=0.034), with a one level increase in ulceration rating associated with an odds ratio of 5.86 (95% [CI] 1.55, 4.34). Conclusion: These findings suggest that both symptomatic and asymptomatic subjects (with clinical indications for carotid endarterectomy) may have plaque with similar features of instability and ability to create emboli. Thus, identifying new ways to measure plaque instability may provide important information for optimizing treatment to prevent future stroke. It also suggests that present clinical exam does not detect the sequeli of small emboli.