The correlation of carotid plaque pathohistologic features and neurological symptoms: a meta-analysis of observational studies.

OBJECTIVE To investigate the association between the pathological features of carotid plaque and ipsilateral symptoms of cerebral ischemia. MATERIALS AND METHODS We sought to identify clinical observational studies comparing the incidence of pathological features between symptomatic and asymptomatic carotid plaques in terms of ulceration, thrombosis and intraplaque hemorrhage (IPH), published between 1996 and 2006. A search on, PubMed was supplemented by a review of bibliographies of relevant articles and lists of references in it. Odds ratios (OR) for the presence of each feature as a role in the pathogenesis of neurological events were calculated and combined by a meta-analysis. RESULTS We integrated 16 clinical studies totaling 2839 plaques harvested at endarterectomy procedures. The reported incidence for each feature was highly variable. The methods in defining ulceration, thrombosis and IPH were very heterogeneous. The time intervals between the latest onset of ischemic symptoms and pathological examinations varied greatly. Overall, the incidence of ulcerated plaques in the symptomatic group were significantly higher than that in the asymptomatic group (study number, n=10; OR, 2.32; 95% CI, 1.90-2.83. A random-effect model was performed among studies regarding surface thrombosis because an apparent trend for heterogeneity was observed (n=6; OR, 1.57; 95% CI, 0.68-3.64). There was no difference with respect to IPH between the two groups (n=11; OR, 1.09; 95% CI, 0.91-1.32). CONCLUSIONS Ulcerated carotid plaque is significantly correlated with the production of neurological events, whereas thrombosis fails to correlate with ischemic symptoms because of the presence of substantial heterogeneity. The association between IPH and clinical presentations is less clear.