A narrowing of the veins from the brain is unlikely as a cause for multiple sclerosis, say researchers from B.C. and Saskatchewan who found the narrowing is a common and normal finding in most people.
Italian Paolo Zamboni made headlines in Canada four years ago for his belief that clearing blocked or narrowed neck veins could relieve MS symptoms. Since then probably more than 3,000 Canadians have gone out of country for dilation treatment, said Dr. Anthony Traboulsee of the University of British Columbia.
In Tuesday's online issue of the The Lancet, Traboulsee and his co-authors published their findings on the prevalence of narrowing, known as chronic cerebrospinal venous insufficiency or CCSVI, in people with MS, their siblings and unrelated healthy controls.
Using catheter venography to directly visualize veins, the researchers found three people tested positive for CCSVI:
- One of 65 (2 per cent) of those with MS.
- One of 46 (2 per cent) of siblings.
- One of 32 (3 per cent) on unrelated controls.
"This was a big surprise to all of us," Traboulsee told reporters. "We were really expecting to find many more people with this feature."
When the researchers used ultrasound to look for CCSVI, they found narrowing in more than 50 per cent of all three groups.
The hypothesis that vein narrowing has a role in the cause of MS is unlikely since its prevalence was similar in all three groups, the study's authors concluded.
'Death knell' for CCSVI
The study was solid and well-balanced, Dr. Paul Friedemann of the neurology department at Charité University in Berlin and Dr. Mike Wattjes of MS Center Amsterdam said in a journal commentary accompanying the research.
The study "sounds a death knell" for the disease hypothesis of CCSVI, the pair said. It is "now absolutely clear that no reason exists to allocate any further resources to chronic cerebrospinal venous insufficiency research, be they financial or intellectual."
The Lancet study, which cost about $450,000, was funded by the MS Society of Canada, Saskatoon City Hospital Foundation, Lotte and John Hecht Memorial Foundation, Vancouver Coastal Health Foundation and Woldridge Foundation.
Meanwhile, even though this study has disproved the theory, Traboulsee will continue to conduct a blinded, randomized control trial of the treatment on 100 people in Vancouver, Winnipeg, Montreal and Quebec City. So far, seven people have undergone angioplasty or a sham procedure, he said.
Traboulsee's clinical trial, which will cost more than $5-million and follow participants for two years, is funded by the Canadian Institutes of Health Research and the MS Society of Canada.
In an email, the MS Society said it remains "committed to funding research that will answer the questions of those who live with the disease."
Traboulsee said that given that MS is a leading cause of disability in Canada and that some patients have reported improvements after the procedure, it's important for the research to continue to learn more about how MS manifests in symptoms like fatigue and brain fog that are poorly understood.
"Best-case scenario, we learn more about the disease. Worse-case scenario, we just prove it's a placebo effect."
While CCSVI as defined by Zamboni doesn't exist, it's possible that patients are reporting improvements by happenstance through a different mechanism, Traboulsee speculated, such as if stretching a vein triggers nerves that improves symptoms.
The Canadian research shows the importance of blinding and the need for independent groups to validate Zamboni's initial findings, he added.
Results from the clinical trial are expected in the fall of 2015.