(RxWiki News) While the exact cause of multiple sclerosis (MS) remains unclear, research over the years has pointed to some potential culprits. Now, it seems that one possible cause of MS could be ruled out.
A recent study found that chronic cerebrospinal venous insufficiency (CCSVI), first introduced as a possible factor contributing to MS in 2009, was not more common among patients with MS than people who were healthy.
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This study was led by Fiona Costello, MD, of the University of Calgary in Alberta, Canada.
MS is an inflammatory disease that damages the myelin sheath, the protective layer that forms around nerves in the central nervous system. Damage to myelin leads to problems with the transmission of nerve signals between the brain and spinal cord.
CCSVI is a condition in which veins narrow abnormally, restricting blood flow from the brain. It was thought that people with MS had this problem, which kept immune cells from circulating, leading to many of the inflammatory problems experienced by people with MS.
However, Dr. Costello and colleagues tested this hypothesis, and they did not find major differences in blood flow from the brain between people with MS and healthy individuals.
For their study, these researchers enrolled 120 patients with varying types of MS. Most (86 patients) had relapsing-remitting MS, which is when a patient has periods of symptom flare-ups followed by periods of partial or complete recovery.
In the MS group, the average time a person had the disease was 10.5 years. Sixty people who did not have MS were also enrolled in the trial.
The researchers interviewed and collected data on all of the study participants, who then received a grade regarding their level of disability. They all had an extracranial ultrasound (an image of the brain produced by using high-frequency sound waves). They also had gadolinium-enhanced magnetic resonance venography (medical imaging that takes pictures of the veins, using the image-enhancing chemical agent gadolinium).
The investigators wanted to see if participants would meet one or more of the ultrasound criteria used to diagnose CCSVI.
Results showed that 58 percent of those with MS met one of the criteria, but so did 63 percent of the healthy individuals.
A total of 20 percent of those with MS met two or more of the criteria, and 10 percent of healthy participants also met two or more of the criteria.
The study authors noted that ultrasound showed that in both people with MS and healthy controls, the veins leading from the brain were equally clear.
The authors concluded that there were no differences between the two groups in terms of blood flow through the veins.
According to Dr. Matthew McCoyd, assistant professor of neurology at Loyola University in Chicago, these findings are disappointing in so far as CCSVI does not lead to diagnosis or treatment of those with MS, but other studies looking at CCSVI have suggested the same. “This is what we want with MS trials,” he told dailyRx News.
Dr. McCoyd said neurologists want there to be rigorous trials that check the validity of anything that may point to the source of the disease or a treatment, even if they prove something is not what they thought it was. “I think these are really important studies," he said.
The idea that venous insufficiency might cause MS was very novel, he added. Researchers think genetics are involved, and perhaps environmental or geographical factors, but they don’t have much idea as to what triggers the disease. “It’s great to look outside the box,” he said.
This study was published June 2 in the Canadian Medical Association Journal (CMAJ).
The authors disclosed receiving funding from various sources, including pharmaceutical companies, and one of the authors, Richard Frayne, is co-inventor of a technique used for magnetic resonance venography in this study.
This study was funded by the Multiple Sclerosis Society of Canada.
