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Despite conflicting and inconsistent evidence, the popularity of Dr. Paolo Zamboni’s theory has spread like wildfire in recent years, fuelled by a strong social media campaign led by MS patients and those interested in supporting the cause.Alessandro Vincenzi/The Globe and Mail

A study published Tuesday is providing further confirmation that a controversial theory arguing multiple sclerosis is caused by neck vein abnormalities is not credible.

The findings have prompted a prominent multiple sclerosis expert in the U.S. to criticize the Canadian federal government for throwing money and support into this area, despite scant evidence linking problems with neck veins to the development of the debilitating autoimmune disease.

"The debate in the scientific community was brief, swift and is over," said David Hafler, chairman of the neurology department at the Yale School of Medicine. "The government has squandered precious resources not using peer-review, but instead using emotion and theologic belief and I think shame on the Canadian government for bowing into those pressures."

The federal government has earmarked $5.5-million for the study.

The idea MS is caused by narrowed or abnormal neck veins came to prominence after Italian doctor Paolo Zamboni published research showing a group of MS patients all had the vein problems, while healthy controls did not. Dr. Zamboni, who calls the condition chronic cerebrospinal venous insufficiency (CCSVI), said the disease can be treated, possibly even cured, through a relatively simple vein-widening procedure.

In the latest study, published Tuesday in the journal Radiology, researchers in Italy used MRI scans to look at the neck veins of MS patients. Researchers found the presence of abnormal neck veins in 25 out of 39 MS patients and 14 out of 26 healthy volunteers. After measuring the brain blood flow, the researchers concluded there was no relationship between cerebral blood flow, volume in white matter of the brain and severity of disability of patients.

In other words, vein abnormalities had no impact on neurological function or disease progression in patients, and may just be an "epiphenomenon," or an accidental event that has nothing to do with the disease itself.

Despite conflicting and inconsistent evidence, the popularity of Dr. Zamboni's theory spread like wildfire in recent years, fuelled by a strong social media campaign led by MS patients and those interested in supporting the cause. Advocates have organized protests and pressured governments across the country to allow access to the vein-widening procedure in Canada, while thousands of patients decided to travel to private clinics overseas and pay for the pricey surgery out-of-pocket.

Supporters of the movement made significant headway when the federal government announced last year it would fund trials to determine the safety and effectiveness of the procedure. But as more evidence emerges disputing any link between neck vein problems and MS, it hardly seems like a victory.

Newfoundland researchers reported in June that patients who had undergone the vein-widening procedure showed no measurable improvement. The province spent nearly half a million dollars on the research.

Dr. Hafler was involved in a study published last year that found many patients with MS share more than two dozen genetic variants, most of which are pivotal to the immune system. That seems to suggest the disease is, as researchers have long thought, an autoimmune condition, not a vascular disease.

The consequences of the popularization of the controversial theory can't be ignored. Several patients, including at least two Canadians, have died after seeking the vein-widening treatment at private clinics.

The U.S. Food and Drug Administration issued a warning about the treatment after receiving a number of reports of injuries and deaths.

Still, this likely won't deter the outspoken faction that supports the blocked-veins theory. On social networking sites such as Facebook, evidence disputing the CCSVI theory is often dismissed as the result of misleading evidence, improper scientific methods or conflicts of interest from researchers with ties to drug companies.

Health Minister Leona Aglukkaq was unavailable for comment Tuesday, but her office said the government is committed to helping patients with MS. Officials did not respond to criticism over its role in funding trials of the controversial vein-widening procedure.

As Dr. Hafler points out, it's hard to argue with credible scientific research, particularly when a growing number of studies all point to the fact blocked veins have no impact on the development or course of MS.

"Everyone approached it with an open mind," he said. "And one study after the other has failed to replicate the basic findings."

Meanwhile, MS patients continue to struggle with an incurable disease. Although there are drug treatments available, many have serious side effects and can't reverse the disease or completely stop its progression.