People with multiple sclerosis may show blocked neck veins as a result of the disease rather than as a cause, a large study published Wednesday suggests.

The findings cast doubt on the theory that blocked or narrowed veins are a main cause of MS, study author Dr. Robert Zivadinov of the University of Buffalo said.

The findings published in the journal Neurology were consistent with thinking that the condition — also known as chronic cerebrospinal venous insufficiency, or CCSVI — is more common in patients with multiple sclerosis but not to the degree first reported by Italian doctor Paolo Zamboni.

"These findings indicate that CCSVI does not have a primary role in causing MS," said Zivadinov, who has worked with Zamboni.

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Dr. Paolo Zamboni, left, and Dr. Robert Zivadinov speak at a neurology seminar last year. New findings indicate that narrowed neck veins don't play a primary role in causing MS, Zivadinov says. (Nathan Denette/Canadian Press)

Zamboni proposed that multiple sclerosis may be linked with vascular problems, and that using angioplasty, or ballooning, to open blocked neck veins can help treat MS symptoms by changing blood flow patterns.

Patients eager for surgery

For more than a year, Canadians with MS have been leaving the country to get the surgery, despite reluctance from neurologists at home.

 Zivadinov's study looked at 499 people with a Doppler ultrasound:

  • 289 people with MS.
  • 63 healthy controls.
  • 26 people with other neurological diseases such as Parkinson's.
  • 21 with a clinically isolated syndrome that can be a precursor to MS.  

An ultrasound technician, who did not know which group the subjects were in, did the test.

The team found 56 per cent of people in the MS group met the criteria for CCSVI, as did 23 per cent of the healthy controls and 46 per cent of people with other neurological diseases.

CCSVI was more prevalent in people with progressive forms of MS, at 89 per cent of cases, than with the relapsing-remitting form, at 49 per cent, Zivadinov found.

Contributing role?

"An increased prevalence in progressive as compared with relapsing disease leaves open the possibility that CCSVI may be playing a contributory role in, or be a consequence of, the disease, or may be age-related," Dr. Robert Fox of the Cleveland Clinic Foundation in Cleveland, wrote in a journal editorial accompanying the study.

The findings add to several smaller, international studies that have also found no link.

"The studies are now showing some very confusing things about all of this," said Halifax neurologist Dr. Jock Murray.

"I think it again says people should be hesitant about going off to other countries, paying large amounts of money for something that has not even been clarified to be beneficial as yet."

Dr. Barry Rubin of Toronto General Hospital noted that Zivadinov is associated with Zamboni, yet the Buffalo doctor's work is part of a body of research calling Zamboni's hypothesis into question.

Symptoms improve

Canadian scientists are also weighing in. Seven studies are looking at the relationship between CCSVI and multiple sclerosis. Both Saskatchewan and Manitoba are starting clinical trials of the procedure, and Newfoundland and Labrador is monitoring patients who've had the treatment.

The monitoring is for Canadians such as Caroline McNeill of Langley, B.C., who travelled to California to have her neck veins reopened using balloon angioplasty. She has had the procedure twice before, and noted lingering benefits such as feeling less tired.

"The numbness on my fingers has started to come back again, and I have really bad dizziness and vertigo," McNeill told her doctor.

She plans to return to Newport Beach in Southern California for a stent later this month.

Ottawa resident Andrew Katz, who has MS and uses a wheelchair, has also had balloon angioplasty. Katz called the new findings "interesting," but noted they go against what how people who've had the treatment often say.

"You still have to look at the fact that people are improving," said Katz. "I know lots of people that have had this done and they're better. How do you explain that?"

With files from CBC's Kelly Crowe and Pauline Dakin