"We need to assess whether or not opening up veins has any beneficial effect in changing the course of the disease," said Timothy Coetzee, chief research officer at the National Multiple Sclerosis Society.
"Many people who had the treatment said their fatigue is gone. People who had to stop working were able to go back to work, but others have not seen any improvement," said Richardson.
Fox expressed concern that patients may not fully understand the potential risks of the procedure. The risks include bleeding, blood clots, bruising and infection.
"We have patients who seek out this intervention," Fox said, "but it wasn't clear to me that patients really understood the risks involved, and it wasn't clear to me that patients were reviewing the balance of the data regarding safety and efficacy."
A clinical trial to assess the safety and efficacy of the treatment is about to get underway in Canada, and as research continues, so will the debate over CCSVI.
"There are a variety of opinions about the relationship between CCSVI and MS," said Coetzee. "Some voices will dispute it, some will support it, and some will be in-between. It's a real push-pull between different camps."
ABC News' Katie Moisse contributed to this report.