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There is no association between MS (multiple sclerosis) and venous narrowing, specifically the narrowing of the veins from the brain to the heart (extracranial veins), researchers reported in The Lancet.
Canadian scientists found no statistically significant difference between venous narrowing rates in patients with MS compared to other people without MS, including siblings.
These findings challenge a controversial theory that MS is linked to CCSVI (chronic cerebrospinal venous insufficiency).
In 2009, Dr. Zamboni and a group of researchers defined CCSVI as "ultrasound-detectable abnormalities in the anatomy and blood flow in the veins draining blood from the brain and back." According to Zamboni's study, CCSVI was much more prevalent in people with MS compared to the rest of the population.
Those who support this theory believe that MS is a consequence of the narrowing of extracranial nerves which leads to flow abnormalities and blockage. They suggest that a number of MS patients may be effectively treated by angioplasty to unblock or widen the veins (liberation procedure).
There is research currently underway on whether angioplasty treatment might benefit patients with MS. So far, imaging studies have had inconclusive results regarding a potential link between venous narrowing and MS.
In this latest study, Dr. Katherine Knox at the University of Saskatchewan in Saskkatoon, and Dr. Anthony Traboulsee at the University of British Columbia and Vancouver Coastal Health in Vancouver, both in Canada, set out to examine the extracranial veins of 79 MS patients, 55 of their siblings (without MS), and 43 controls (healthy unrelated volunteers).
The researchers used ultrasound and catheter venography. Catheter venography involves injecting a special dye into the vein and then taking an x-ray - the dye shows up in the images.
Dr Traboulsee explained:
"Until now, most studies of venous narrowing have used ultrasound imaging to establish whether venous narrowing is present. While ultrasound is a relatively simple and inexpensive way of looking at veins, it's not necessarily the most accurate imaging technique, so in our study, we also used catheter venography - usually thought of as the gold standard of venous imaging - to measure whether any narrowing of the veins was present."
The team found that at least two thirds of the participants across all three groups had narrowing of the extracranial veins greater than 50%, according to the catheter venography scans.
Narrowing of extracranial veins was present in:
Dr. Traboulsee said there was not a statistically significant difference within the three groups.
When they used the overall CCSVI criteria put forward by Zamboni and his team, this latest study found that just one of the MS participants, one of their siblings and one of the controls tested positive.
The team also found that Zamboni's ultrasound criteria for CCSVI was not accurate - it only identified venous narrowing in 42% of cases confirmed by the more reliable imaging technique.
Dr Traboulsee said:
"Our results confirm that venous narrowing is a frequent finding in the general population, and is not a unique anatomical feature associated with multiple sclerosis. This is the first study to find high rates of venous narrowing in a healthy control group, as well as the first to show that the ultrasound criteria usually used to 'diagnose' CCSVI are unreliable, so if there is a connection between venous narrowing and MS, it remains unknown, and it would certainly appear to be much more complicated than current theories suggest."
In the same journal, Dr. Friedemann Paul and Dr. Mike Wattjes write in a linked Comment that these new results sound like the "death knell" for Zamboni's CCSVI hypotheses as a disease entity.
They wrote "If chronic cerebrospinal venous insufficiency actually existed, the ultrasound findings of this study and previous studies would suggest that up to half of the general and otherwise healthy population should be judged to be seriously ill because of venous insufficiency of the cervical veins. The fact that some changes in the venous system have been described in association with multiple sclerosis does not imply causality."
"A lively discussion has emerged recently as to whether funding of chronic cerebrospinal venous insufficiency research is, or was, a waste of valuable time, money, and intellectual energy. The work by Traboulsee and colleagues should be viewed as the definitive conclusion to this discussion. Although it is laudable that the Multiple Sclerosis Society of Canada and other sources have funded this seminal study, which would probably not have received funding otherwise, now it is absolutely clear that no reason exists to allocate any further resources to chronic cerebrospinal venous insufficiency research, be they financial or intellectual."
The study was funded by the MS Society of Canada. It is part of a series of studies examining CCSVI.
In a landmark pilot study of "liberation treatment", scientists at the University of Buffalo found that opening veins does not help MS patients. In fact, they reported that in some cases patients got worse after treatment.
Written by Christian Nordqvist
Copyright: Medical News Today
Not to be reproduced without the permission of Medical News Today.
”Prevalence of extracranial venous narrowing on catheter venography in people with multiple sclerosis, their siblings, and unrelated healthy controls: a blinded, case-control study, Anthony L Traboulsee, Katherine B Knox, Lindsay Machan, Yinshan Zhao, Irene Yee, Alexander Rauscher, Darren Klass, Peter Szkup, Robert Otani, David Kopriva, Shanti Lala, David K Li, Dessa Sadovnick; The Lancet - Published Online October 9th, 2013 http://dx.doi.org/10.1016/S0140-6736(13)61747-X. Accessed on October 8th, 2013.
Visit our Multiple Sclerosis category page for the latest news on this subject.
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