Editorial

multiple sclerosis: investigating the truth The hypothesis that extra-cranial venous flow ab-normalities leading to a stagnant venous return contrib-ute to the pathogenesis of multiple sclerosis (MS) has generated passionate debate over the past 2 years. The introduction of the term chronic cerebrospinal venous insufficiency (CCSVI) and its potential pathologic relationship to MS continues to dominate discussion in the patient and scientific communities, greatly facilitated by the media and internet fora. This hypothesis gained attraction by seminal pathological and magnetic resonance imaging (MRI) work demonstrating an asso-ciation between plaques and veins in the central nervous systemof patients withMS. At the heart of this debate are two issues: (i) does CCSVI exist as an abnormality o