A long-awaited Canadian trial of a controversial experimental treatment for multiple sclerosis has been given the go-ahead and will soon begin recruiting patients, Health Minister Leona Aglukkaq announced Friday.

Ms. Aglukkaq, in Halifax for a meeting with provincial and territorial health ministers, said about 100 MS patients will be enrolled in the trial to assess the safety and efficacy of the procedure to unblock narrowed neck veins.

The condition — dubbed chronic cerebrospinal venous insufficiency, or CCSVI — has been proposed as a possible cause of MS by Italian vascular surgeon Paolo Zamboni.

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More than three years ago, Dr. Zamboni hypothesized that narrowed and twisted veins in the neck and chest prevent blood from draining properly from the brain, resulting in iron deposits that could cause the brain lesions typical of MS.

The disease causes the destruction of myelin, the protective sheath around nerves throughout the body, leading to progressive physical and cognitive disability.

Dr. Anthony Traboulsee, medical director of the UBC Hospital MS Clinic, will lead the $6-million study, which will be conducted initially in Vancouver and Montreal.

Medical and ethical approval is also being sought for parts of the trial to be conducted in Quebec City and Winnipeg, Dr. Traboulsee said Friday from Vancouver.

Participants will be split randomly into two groups: half the patients will get the treatment for CCSVI, while the other half will get a sham procedure.

Then halfway through the trial, the two groups will switch, with the treated group getting the fake vascular surgery and the untreated group receiving the real thing.

None of the participants will know which treatment they got or when — a study design aimed at preventing subjective responses by patients when researchers evaluate effects of the treatment on their disease progression, he said.

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"This pan-Canadian controlled study will allow us to monitor MS patients over a two-year period and obtain scientific evidence on the safety and efficacy of the CCSVI procedure in the long term," said Dr. Traboulsee.

The study is being funded by the federal government, the provinces where the trial will take place, and the MS Society of Canada.

"As we move through this important new phase of MS research, we look forward to Dr. Traboulsee and his team furthering the work of the Canadian research community and providing more insights about CCSVI for those living with MS," said Yves Savoie, president and CEO of the MS Society.