Abstract TP419: Cognitive Correlates of Posterior Circulation Insufficiency

Abstract

Background: The territory of posterior circulation, supplied by vertebrobasilar artery (VA/BA) and their branches, includes brainstem, cerebellum, thalamus and temporal/occipital lobes. These regions are known to be involved in cognitive processes; however, the role of posterior circulation insufficiency in cognition has not yet been studied. Objective: To determine the cognitive correlates of posterior circulation insufficiency. Methods: Prospectively recruited (1) patients with >70% stenosis of the VA or/and BA and (2) age-/sex-matched controls. Patients with additional anterior circulation abnormalities (>70% stenosis or/and infarcts), dementia, major depression and functional independence (mRS>1) were excluded. All participants underwent brain MRA and neuropsychological tests containing cognitive domains of verbal memory, language, visuospatial and executive functions. Multivariate linear logistic regression analyses were used to determine the association between the presence of severe VA/BA stenosis and the scores of neuropsychological tests. Results: There were 30 patients (26 males; mean age: 61.4, 28-79 years) and 30 age/sex-matched healthy subjects free of cerebrovascular abnormality included. Among patient group, infarcts were found in pons (n=11), cerebellum (8), medulla (4) and temporal lobe (1). Seven patients had no brain infarcts. The patterns of vascular involvement were: unilateral VA (9, 30%), Unilateral VA and BA (5, 16.7%), bilateral VA (4, 13.3%), bilateral VA and BA (11, 36.7%), and isolated BA (1, 3.3%). Multivariate analyses adjusting for age, sex, education years, and vascular risk factors (HTN, DM, hyperlipidemia and cigarette smoking) showed that VA/BA severe stenosis was associated with a lower scores on verbal memory test (regression coefficient = -1.7, p = 0.003) and visuospatial function test (-2.3, 0.015) but not the other neuropsychological tests. Statistical significance remained when the presence of infarct was taken into adjustment. Conclusion: VA/BA severe stenosis is associated with a poorer performance on verbal memory and visuospatial functions. Our results suggest that the role of posterior circulation in vascular cognitive impairment might be underestimated.