Anatomical risk factors for internal carotid artery dissection: a novel metric (LB50)

Abstract

Internal carotid artery (ICA) dissections are a major cause of ischemic stroke in young adult population, with 70% occurring in persons aged 35‐50. Past studies investigated vascular pathology within the layers of the vessel, such as atherosclerosis, fibromuscular dysplasia, and connective tissue disease (CTD). Yet, these risk factors are uncommon in young patients, and CTD accounts for only 1‐5% of spontaneous arterial dissections. A putative mechanism for these events involves aberrant anatomical variants in the exposed cervical portion of the ICA; 75% of spontaneous dissections occur in this region, usually 2cm from the ICA/ECA bifurcation. In this study, we measured external diameter, bifurcating angle, and extracranial vessel length in a mixed sample of cadaveric dissections from SUNY Downstate anatomy laboratory (n=24). Measures were used to calculate a novel metric of vascular resistance using Poiseuille’s Law, which we termed the “relative vascular resistance” (RVR), at the instance of bifurcation. Results showed measures significantly non‐normally distributed (p<0.05), with RVR varying by many orders of magnitude. These results corroborated with 3‐D radiological reconstructions of this region, as well as 2‐dimensional Doppler ultrasound in live patients. We propose that the RVR at bifurcation be further studied as a predictor of ICA dissection risk in young adults.