New data on CCSVI from Canadian study using ‘gold standard’ technique
A research group from the University of British Columbia, Vancouver Coastal Health, and University of Saskatchewan published a study in the U.K. medical journal The Lancet, reporting on the prevalence of chronic cerebrospinal venous insufficiency (CCSVI) in people with MS, their unaffected siblings and healthy volunteers. The MS Society of Canada/National MS Society (USA) joint funded study enrolled 177 participants across three centres in Canada, broken down as follows:
- 67 people with relapsing-remitting MS
- 12 people with progressive MS
- 55 siblings unaffected by MS
- 43 healthy people who were controls
Dr. Anthony Traboulsee and his team evaluated each group to look for indications of narrowing of the internal jugular and azygous veins. According to Italian vascular surgeon Dr. Paolo Zamboni, who in 2009 identified CCSVI as a potential cause of MS, the internal jugular and azygous veins are affected in MS, resulting in decreased blood flow from the brain resulting in inflammation. Dr. Zamboni created a list of venous structural and functional abnormalities that define CCSVI that can be identified using various imagine techniques, particularly ultrasound. His ultrasound criteria are now used in other CCSVI studies to determine if similar results can be replicated in other people with MS.
In this study, Dr. Traboulsee and colleagues used ultrasound and catheter venography, the latter technique involving insertion of a plastic tube. The tube allows entry of dyes that would enhance x-ray visualization of the veins in the head and neck.
What they found:
Using catheter venography, CCSVI as described by Dr. Zamboni was detected in 2% of people with MS, 2% of unaffected siblings of people with MS, and 3% of the healthy control group. Catheter venography was also used to detect narrowing of the veins. Vein narrowing was seen in 74% of people with MS, 66% of siblings, and 70% of healthy controls.
Using ultrasound, CCSVI as described by Dr. Zamboni was detected in 44% of participants with MS, 31% of unaffected siblings of people with MS, and 45% of healthy controls. Ultrasound also showed that 41 out of 79 people with MS (52%) displayed no structural abnormalities in their head and neck veins.
Overall, results from the study display no association between CCSVI and MS, and that the significance of venous narrowing in MS symptoms is still in question.
According to Dr. Traboulsee, only a few studies have employed catheter venography to evaluate the prevalence of CCSVI in people with MS. In the article he stated that this technique is a “gold standard procedure that has been proposed as a guide for decision making in endovascular treatment”. As research on CCSVI ensues and data surfaces, standardizing protocols which accurately observe and measure vein blockage and impeded blood flow becomes increasingly important.
It is apparent from the data that the prevalence of CCSVI is higher when looking at ultrasound data in comparison to venography. This is likely due to differences in the sensitivities and specificities of the techniques, which means that one would detect alterations in the veins that the other could not. What is most important here is that the percentage of people with CCSVI is the same for all groups (people with MS, their unaffected siblings and healthy individuals), which confers no association between the condition and MS.
Interestingly, researchers found a high rate of vein narrowing in the healthy control group, which according to Dr. Traboulsee has not been previously reported.
“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.”
The recent research findings from the study led by Dr. Anthony Traboulsee indicate there is no connection between CCSVI and MS. The pan-Canadian Clinical Trial that is already underway will continue to investigate whether venous dilation procedures could be beneficial for treatment of MS symptoms. Dr. Traboulsee remains committed to evaluating CCSVI procedures with robust methods and utilizing patient-focused outcomes. We respect and honour the personal health care decisions of those who live with MS and remain committed to funding research that will answer the questions of those who live with the disease.
Traboulsee AL et al. Prevalence of extracranial venous narrowing on catheter venography is similar in people with MS, their siblings, and unrelated healthy controls: a blinded case-control study. The Lancet 2013 Oct 8 [Epub ahead of print].