A new Canadian study is casting doubt on the link between blocked neck veins and multiple sclerosis, after finding no difference in the proportion of abnormalities in the veins of MS patients and healthy controls.

The study, published Monday in The Canadian Medical Association Journal, found no link between chronic cerebrospinal venous insufficiency (CCSVI) and MS.

Using ultrasound and MRI technology, University of Calgary neurologist Dr. Fiona Costello and her colleagues tested the criteria used to diagnose a patient with CCSVI on a group of MS patients and healthy controls.

They compared the ultrasound results of 120 patients and 60 controls and found a "high" proportion of both groups met one or more of the criteria required for a CCSVI diagnosis.

Their results showed that 58 per cent of MS patients and 63 per cent of the healthy controls met one or more of the proposed criteria.

"We detected no differences in the proportion of venous outflow abnormalities between patients with multiple sclerosis and healthy controls," the study's authors conclude.

"Moreover, our study revealed significant methodologic concerns regarding the proposed diagnostic criteria for chronic cerebrospinal venous insufficiency that challenge their validity."

Dr. Paolo Zamboni first put forth his theory that constricted veins in the head and neck were linked to MS in 2009. Zamboni also postulated that a vein-widening procedure, which he called the "liberation treatment," could improve the symptoms of MS patients.

Since that time, hundreds of MS patients have sought the treatment, often paying to have it done overseas. As well, several studies have examined Zamboni's theory, with many poking holes in his work.

A recent study published last October in The Lancet also found that a narrowing of the veins leading from the brain was just as prevalent in healthy individuals as it was in patients with MS.

Meanwhile, a separate survey found that a group of Canadian MS patients who left the country to get the controversial "liberation treatment" were relatively satisfied with the results, despite receiving sub-optimal care.

Of the 124 participants, nearly 60 per cent said they received no follow-up investigations at the centre where they had received the procedure. More than 40 per cent said they had no follow-up care of any kind.

Jamie Greenfield, a data analyst at the University of Calgary's MS Research Program, said only 6 per cent of the survey respondents reported that they had not been told of potential adverse side effects. Some potential risks, such as stent migration or kidney damage resulting from the dyes used to help locate blocked veins, were rarely raised, she said.

Despite these findings, 50 per cent of the patients rated their overall satisfaction with the procedure as good or better. As well, 122 of the 124 participants said their procedure was successful, with 79 per cent reporting no complications and 19 per cent saying it was "successful with some trouble."

Greenfield presented the results of the survey at the joint meeting of the Consortium of Multiple Sclerosis Centers and the Americas Committee for Treatment and Research in Multiple Sclerosis in Dallas over the weekend. The results of her presentation were published in MedPage Today.

Barrie, Ont. resident Steve Garvie opted to have the liberation treatment in 2010. He told CTV News that it was only because of the procedure that he was able to attend his daughter's recent wedding in Boston.

"I walked her down the aisle and had the father and daughter dance with her," he said. "I feel truly blessed. Without the procedure I would be either cheering her on from my wheelchair in government housing, or I would not be on this earth to have this joy."

With files from CTV News’ Medical Correspondent Avis Favaro