Quantified hemodynamic parameters of the venous system in multiple sclerosis: A systematic review

Abstract

BackgroundMultiple Sclerosis (MS) is a complex neurodegenerative condition that is influenced by a combination of genetic and environmental factors. Included in these factors is the venous system, however, the extent to which it influences the etiology of MS has yet to be fully characterised. The aim of this review is to critically summarize the literature available concerning the venous system in MS, primarily concerning specific data on the venous pressure and blood flow in this system. MethodsA systematic review was conducted with the application of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria. The advanced search functions of both the Scopus and PubMed databases were used to conduct the literature search, resulting in 136 unique articles initially identified. Applying relevant exclusion criteria, 22 of the studies were chosen for this review. ResultsThe selected studies were analysed for venous pressure and blood flow related findings, with 14 studies contributing data on the internal jugular vein (IJV) flow rate, 5 on blood flows of the intracranial venous sinuses, 2 on blood flow pulsatility and 6 supplying information relevant to the venous pressure (3 studies contributed to multiple areas). The general findings of the review included that the IJV flow was not significantly different between MS patients and controls, however, there were variances between stenotic (S) and non-stenotic (NS) MS patients. Due to the limited data in the other two areas defined in this review, further research is required to establish if any variances in MS are present. ConclusionIt remains unclear if there are significant differences in many flow variables between MS patients and controls considered in this review. It would be advantageous if future work in this area focused on understanding the hemodynamics of this system, primarily concerning how the flow rate, venous pressure and vascular resistance are related, and any impact that these factors have on the etiology of MS.