Abstract T P89: Unilateral Cerebral Atrophy Secondary to Extracranial Carotid Stenosis

Abstract

Background: Moderate to severe or bilateral carotid stenosis is associated with cerebral atrophy and cognitive decline. Prior studies have evaluated global atrophy and its correlation with the degree of stenosis. It is unclear whether carotid stenosis can lead to unilateral cerebral changes. Objective: To evaluate for unilateral cerebral atrophy in asymptomatic patients with moderated to severe extracranial unilateral carotid stenosis. Methods: Subjects were selected from patients who had undergone carotid vascular imaging and MRI of the brain, from January 2007 to January 2013 at our institution. Patients with history of TIA or ischemic stroke were excluded. Carotid stenosis (CS) group consisted of patients with unilateral moderate to severe carotid stenosis (n=9). Patients without any stenosis (n=5) were used as controls. T1-weighted brain images (FOV 256 x 256 x128, resolution 1.5 x 1.5 x 5 mm) were registered to Talairach space using FSL software. Non-brain tissue was removed using the BET module. Segmentation into gray matter (GM), white matter (WM), and cerebrospinal fluid (CSF) was done with the FAST tool. Total brain volume (TBV) was calculated as the sum of three tissue types (GM + WM + CSF). Total number of voxels in each hemisphere was calculated for GM, WM and CSF. Index of Asymmetry (IoA), was defined as the absolute value of inter-hemispheric voxel difference divided by TBV. IoA for each tissue type was compared between subjects and controls using Student’s t-test. Results: Mean age was 63.7±7.8 and 57.4 ±6.0 for the CS and control groups, respectively. Average gray matter IoA for CS was significantly increased compared to controls (1.4% v. 0.7, p < 0.02). Average white matter IoA was similar between the groups (0.6% v. 0.7%, p< 0.36). There was a trend for increased CSF IoA in the CS group compared to controls, but it did not reach statistical significance (1.8% v. 0.9%, p < 0.10). Conclusion: Moderate to severe carotid stenosis can lead to unilateral cerebral atrophy in the absence of other neurological symptoms. Further prospective studies with larger cohorts of the patients are required.