Chronic cerebrospinal venous insufficiency (CCSVI or CCVI) is a term invented by Italian researcher Paolo Zamboni in 2008 to describe compromised flow of blood in the veins draining the central nervous system. Zamboni hypothesized that it might play a role in the cause or development of multiple sclerosis (MS). Zamboni also devised a surgical procedure which the media nicknamed a liberation procedure or liberation therapy, involving venoplasty or stenting of certain veins. Zambonis ideas about CCSVI are very controversial, with significantly more detractors than supporters, and any treatments based on his ideas are considered experimental.There is no scientific evidence that CCSVI is related to MS, and there is no good evidence that the surgery helps MS patients. Zambonis first published research was neither blinded nor did it have a comparison group. Zamboni also did not disclose his financial ties to Esaote, the manufacturer of the ultrasound specifically used in CCSVI diagnosis. The "liberation procedure" has been criticized for possibly resulting in serious complications and deaths, while its purported benefits have not been proven. In 2012, the United States Food and Drug Administration states that it is not clear if CCSVI exists as a clinical entity and that these treatments may cause more harm. In 2017 they emphasized that this use of balloon angioplasty is not an approved use. In a 2017 study Zamboni et al. stated "Venous PTA cannot be recommended for patients with relapsing-remitting multiple sclerosis."
One of the studies identified three factors contributing to patients going abroad seeking treatment: a loss of faith in the Canadian health system when it did not provide access to CCSVI treatment in Canada, hope in the new treatment as a solution for their worsening health, and trust in the MS community and the organizations, clinics and doctors facilitating or providing the desired operation. Conversely, the other study concluded that sense of community and cooperation (from family, MS groups and the general population) was a key motivating factor. Other motivating factors included media reports, perception of approval from their health providers, the apparent low risk of the operation, or accessibility of the hospital that offered the procedure directly or through a medical tourism company. On the other hand, hesitating factors included the cost and effort required for the operation, the mistrust of foreign health systems, the underlying rationale for the operation, or advice against the procedure from trusted health providers.In 2013, a case-control study found evidence against the involvement of chronic cerebrospinal venous abnormalities in MS. Later in 2013 a study found that vein narrowing appears to be present equally in those with and without MS on ultrasound and catheter venography. The results of the study were described as a "death knell" for Zambonis theory. Another study released by the University of British Columbia in 2017 was described as a "definitive debunking" of liberation therapy.