Chronic cerebrospinal venous insufficiency: current perspectives

Abstract

Abstract: This review summarizes the research to date on chronic cerebrospinal venous insufficiency (CCSVI). CCSVI was initially defined as a clinical syndrome comprising stenoses of the internal jugular and/or azygos veins, characterized by collateral venous outflows and reduced cerebral blood flow, and was found primarily in patients with multiple sclerosis. However, the published evidence on CCSVI is very discordant. Catheter venography studies gave a regular picture, with the majority of patients with multiple sclerosis presenting with demonstrable outflow abnormalities in the veins draining the central nervous system. The prevalence of these lesions was over 50%, and even higher (about 90%) when more liberal definition of an abnormality or intravascular sonography was used. Further, the results of magnetic resonance venography studies have been quite consistent, in that stenoses of the internal jugular veins have been found in 25%–70% of patients with multiple sclerosis. In contrast, Doppler sonography studies have revealed CCSVI in 0% to 100% of patients. The research is currently suggesting that CCSVI is not a single entity, but rather a group of different anatomic and functional venous abnormalities. Regarding venous outflow from the brain, a patient can present either with diminished inflow to the internal jugular veins resulting from decreased cerebral circulation or with externally compressed or hypoplastic internal jugular veins or stenotic jugular valves. Considering these many faces of CCSVI, it becomes more comprehensible as to why the results of the studies, especially those utilizing Doppler sonography, have been so discordant. Not only were investigators using different diagnostic modalities and distinct protocols, but they were not looking for the same pathology. Since these abnormalities were indeed differently prevalent in patients and healthy controls, the results inevitably became conflicting. This review suggests how future research, preferably using a multimodal approach, should be directed towards clarifying the conflicting results of studies in CCSVI. Keywords: Doppler ultrasound, jugular vein, magnetic resonance imaging, multiple sclerosis, phlebography, venous malformation