A major Canadian study has found that people with multiple sclerosis do, indeed, appear more likely to have narrowed neck veins, advancing an international debate on whether there is anything behind a controversial new treatment for the nervous-system disease.
But the analysis of international research on the frequency of the condition in MS patients also found a significant and baffling inconsistency in results, precluding Canadian researchers from definitively concluding the two conditions are linked and indicating it’s still premature to give the green light to the so-called “liberation therapy” that involves opening blocked neck veins to improve blood flow.
The research, published online Monday in the Canadian Medical Association Journal, involved pulling together significant studies done around the world — some of them conflicting — on the frequency of chronic cerebrospinal venous insufficiency, or CCSVI (narrowed neck veins), in patients with and without MS.
A meta-analysis of the eight studies — from Italy, Germany, Jordan and the United States — found a huge disparity in frequency, with one reporting no association and another, by Italian surgeon Dr. Paolo Zamboni who developed the liberation treatment, reporting that 100 per cent of MS patients have CCSVI.
“Looking at the eight studies, there were more that found an association (between MS and narrowed veins), so we would have to say on the basis of the meta-analysis that it suggests there may be something there,” said lead author Dr. Andreas Laupacis, executive director of the Li Ka Shing Knowledge Institute of St. Michael’s Hospital.
A major Canadian study has found that people with multiple sclerosis do, indeed, appear more likely to have narrowed neck veins, advancing an international debate on whether there is anything behind a controversial new treatment for the nervous-system disease.
But the analysis of international research on the frequency of the condition in MS patients also found a significant and baffling inconsistency in results, precluding Canadian researchers from definitively concluding the two conditions are linked and indicating it’s still premature to give the green light to the so-called “liberation therapy” that involves opening blocked neck veins to improve blood flow.
The research, published online Monday in the Canadian Medical Association Journal, involved pulling together significant studies done around the world — some of them conflicting — on the frequency of chronic cerebrospinal venous insufficiency, or CCSVI (narrowed neck veins), in patients with and without MS.
A meta-analysis of the eight studies — from Italy, Germany, Jordan and the United States — found a huge disparity in frequency, with one reporting no association and another, by Italian surgeon Dr. Paolo Zamboni who developed the liberation treatment, reporting that 100 per cent of MS patients have CCSVI.
“Looking at the eight studies, there were more that found an association (between MS and narrowed veins), so we would have to say on the basis of the meta-analysis that it suggests there may be something there,” said lead author Dr. Andreas Laupacis, executive director of the Li Ka Shing Knowledge Institute of St. Michael’s Hospital.
“But I have done a number of meta-analyses in my career and I have never done one that has had the incredible wide variety of inconsistency in findings among studies and it really is important to get to the bottom of that,” he added.
As jurisdictions around the world are under considerable pressure to conduct clinical trials and fund liberation therapy, the new Canadian research takes an important step back to determine whether there is even an association between MS and narrowed neck veins to begin with.
Zamboni’s 2006 research suggested MS may be caused by iron deposition in the brain caused by blocked neck veins, a condition that can be treated with a relatively simple angioplasty surgery.
Sparking hope among sufferers around the world — particularly in Canada where up to 75,000 residents have MS — Zamboni’s research resulted in a surge of medical tourism. Some 1,000 Canadians with MS are believed to have travelled to other jurisdictions for the procedure.
But because of a lack of supporting scientific evidence, the Canadian Institute for Health Research last year directed Laupacis and his colleagues to review the literature. While the analysis of the eight studies showed a statistically significant link between narrowed veins and MS, Laupacis said the disparities in the findings are confounding and cannot be ignored.
“To use an analogy, one of the reasons we are convinced that smoking causes lung cancer is that almost all of the studies looking at this found the same thing. But if two-thirds of the studies found smoking caused cancer and one-third found it didn’t, we wouldn’t be nearly as convinced. We would be asking whether it is something about how the studies were conducted that led to such different results,” he said.
The quality of the eight studies varied, he noted. Many were small and had incomplete descriptions of the training of those who conducted ultrasounds to look for narrowed veins. And none reported the degree to which those doing ultrasounds knew whether their patients had MS, something that could have skewed their findings.
Laupacis said that he hopes at the very least that this latest research will temper the ferocity of the debate over liberation therapy, which has seen skeptics and proponents dig in their heels.
“If you asked me what my hope would me, it is probably a naïve hope that this might just modulate the stridency on both sides of this fractious debate.”
An accompanying CMAJ commentary said the Canadian study brings clarity to the debate by showing it’s still too early to declare CCSVI a “paradigm shift or another fad.”
It said there may be other reasons why MS patients have blocked neck veins, for example, dehydration. Many MS patients suffer bladder problems and as a result, drink less, causing mild dehydration.
http://www.thestar.com/news/article/1063526