Risk factors for chronic cerebrospinal venous insufficiency (CCSVI) in a large cohort of volunteers. oleh Kresimir Dolic, Bianca Weinstock-Guttman, Karen Marr, Vesela Valnarov, Ellen Carl, Jesper Hagemeier, Christina Brooks, Colleen Kilanowski, David Hojnacki, Murali Ramanathan, Robert Zivadinov