Abstract W P164: Effects of Extracranial Carotid Stenosis on Intracranial Blood Flow

Abstract

Objectives: To determine the effects of degree of stenosis, stenosis length, and residual lumen on intracranial blood flow in patients with extracranial carotid stenosis. Methods: Records of patients who underwent stenting for extracranial carotid stenosis at our institution between 2004-2012 and had flow rates obtained using quantitative magnetic resonance angiography were retrospectively reviewed. Measurements of degree of stenosis, stenosis length, and residual lumen were made from cerebral angiography images. Results: 18 patients had both complete anatomic and flow data available. Mean age was 66 years. Degree of stenosis ranged from 60% to 90%. 61% had symptomatic stenosis. Univariate analysis demonstrated that higher percentage of stenosis and smaller residual lumen (mm) are associated with a significant decrease in ipsilateral internal carotid artery (ICA) flow ( P =0.027 and P =0.007, respectively). Stenosis length (mm) was not significantly associated with ipsilateral ICA flow ( P =0.08). On multiple regression analysis, both degree of stenosis and residual lumen remained predictive of ipsilateral ICA flow ( P =0.005 and P =0.007, respectively). Neither degree of stenosis, stenosis length, or residual lumen were significantly associated with ipsilateral MCA flow (P=0.38, 0.18, and 0.86, respectively), and baseline ICA flow was not predictive of ipsilateral MCA flow ( P =0.37). Conclusions: Degree of stenosis and residual lumen diameter are highly predictive of ICA, but not MCA flow, in the setting of carotid stenosis. Local hemodynamic effects of the stenosis do not translate directly to the distal vasculature, as intracranial flows can be maintained through collateral flow. Figure: Ipsilateral ICA flow and residual lumen. Increasing residual lumen is associated with significant ipsilateral ICA flow increase ( P =0.007, correlation coefficient=0.61).