A clinical trial test of a vein-opening procedure for multiple sclerosis suggests it does not improve symptoms, and in a few patients symptoms worsened.

The small pilot study was designed to test the safety and effectiveness of using balloons to unblock veins in the neck and chest of people with MS.

Dr. Paolo Zamboni, left, and Dr. Robert Zivadinov have studied whether multiple sclerosis is triggered by vascular problems and have suggested it can be treated by using angioplasty to unblock vessels. (Nathan Denette/Canadian Press)

Chronic cerebro-spinal venous insufficiency or CCSVI is a hypothesis put forward by Italian vascular surgeon Dr. Paolo Zamboni. He suspects that narrowed neck veins create a backup of blood that can lead to lesions in the brain and inflammation.

On Friday, researchers at the University of Buffalo discussed the findings of their clinical trial involving 10 MS patients in an initial safety trial of the real and fake procedures and 20 who were randomized to receive treatment or a placebo.

"All the outcomes that we looked at — which had to do with clinical disease, functional status, quality of life, cognition — there was no appreciable difference between the two arms," principal investigator Dr. Adnan Siddiqui, an assistant professor of neurosurgery at the University of Buffalo, said in an interview.

When the investigators reviewed the MRI data, Siddiqu said they found new activity in patients who received the balloon angioplasty treatment.

"It is telling us that there is likely no benefit of balloon angioplasty in patients who have MS and have CCSVI and there is a possibility that at least in the early term, because this is six months, there is evidence there may actually be increased disease activity from balloon angioplasty."

The evidence of increased disease activity was surprising to the researchers, who were in the dark about who received the treatment until the data was analyzed.

"When we looked at these patients' disease activity, what we found there was rather surprising and unexpected and quite to the opposite of what we had originally premised, which was increased disease activity in patients who were treated as compared to the other group," said principal investigator Dr. Adnan Siddiqui, an assistant professor of neurosurgery at the University of Buffalo.

The trial was the first double-blinded, randomized, placebo-control test of the treatment.

Siddiqui said he's "concerned enough to suggest that patients not receive this treatment outside rigorously controlled clinical trials. That's important because not only did we not show any benefit in a very carefully selected cohort that was most likely to show benefit, we saw none. Instead we saw potential for harm."

Study co-principal investigator Dr. Robert Zivadinov said their findings over the last three years have indicated that CCSVI is more prevalent in MS patients than in healthy controls but the cause or consequence of these vein abnormalities isn't known.

Zivadinov said more than 30,000 people with MS have had the procedure.

The findings are to be presented at a session on Wednesday at the annual American Academy of Neurology meeting in San Diego.

The 12-month followup period for the study concludes this month. At that point, the researchers will decide how to proceed in trying to better understand the disease.

Michelle Walsh of Beechy, Sask., advocates for MS treatment and followup. Walsh had the procedure in July 2010 in Bulgaria and then twice in California. Since then, Walsh said her lesions have gotten smaller and she hasn't had an MS flare-up.

Walsh said the procedure hasn't been proven as an MS treatment yet and that a larger trial is needed.

With files from CBC's Amina Zafar and Laura MacNaughton