Canadian researchers say they have found no evidence that restricted blood flow in the veins of the head and neck is linked to the development of multiple sclerosis. The researchers say their findings debunk a controversial theory that suggests vein blockages are responsible for MS symptoms, but critics say the researchers used outmoded techniques to detect the condition.
In a study published online Wednesday in the journal PLOS ONE, researchers from McMaster University in Ontario say they failed to find any blockages in the internal jugular, vertebral or deep cerebral veins in 99 of 100 patients with MS, compared with 100 subjects with no history of the disease.
For the study, the researchers conducted ultrasounds and MRIs on the head and neck veins of all study subjects to look for evidence of chronic cerebrospinal venous insufficiency (CCSVI), essentially blockages in the head and neck veins that prevent blood from properly draining from the brain.
It is Italian researcher Dr. Paolo Zamboni who first suggested that CCSVI is linked to MS, and he reported that patients’ symptoms were alleviated after undergoing angioplasty to clear the blockages, a treatment that has become known as the “liberation therapy.”
The Ontario researchers say that this is the first Canadian study to find “compelling evidence” that CCSVI is not involved in MS.
“There will be those who will still want to believe that CCSVI is a real phenomenon, but the reality is that most of the European studies are negative to the theory of CCSVI,” lead researcher Ian Rodger, professor emeritus in the Michael G. DeGroote School of Medicine at McMaster, told CTV News.
“Our study bolsters that.”
Rodger said doctors who are performing angioplasty on patients “have to be very confident that you are seeing blocked veins, and we, with our study, do not.”
Rodger noted that the ultrasound technician involved in his study spent a week training with Zamboni in Italy.
Critics of the study, however, say the tests for CCSVI were conducted in 2010, a year before the testing protocol was updated.
Researchers who are also conducting studies on CCSVI and its role in MS say ultrasound is no longer the standard for testing, and the MRI scans were not conducted on the part of the neck most associated with blockages.
“Any study that is solely based on these techniques will be of limited value to the MS community,” Dr. Anthony Traboulsee of the University of British Columbia told CTV News.
Traboulsee has been part of a study, awaiting publication, on the prevalence of CCSVI using ultrasound, MRI and venogram, a scan conducted inside the veins using dye. His technicians found vein flow abnormalities in 60 per cent of those with MS, a very different result than the Hamilton study.
Traboulsee and his team are now conducting a clinical trial to diagnose and treat patients in a study that will compare patients who receive angioplasty to open any blocked veins and those who receive a placebo treatment. It is a collaborative effort of the Canadian Institutes of Health Research, the MS Society of Canada and the provinces of B.C. and Quebec.
The findings from the Ontario team will not halt his study, he said, which includes both ultrasound and venograms to test for blockages. Traboulsee reports that 60 per cent of MS patients in his study show evidence of CCSVI using ultrasound and venograms.
Traboulsee said the Ontario study is “well-designed,” but is “so out of keeping with everybody else’s work, it tells me it’s not a problem with the researchers, it’s a problem with the ultrasound.”
Traboulsee says venograms – angriograms conducted inside the veins – are the best way to detect blockages or other blood-flow problems.
An Italian study also released Wednesday that was evaluating the feasibility and safety of the angioplasty procedure found blockages in 98 per cent of the 1,200 study subjects using ultrasound with venograms.
The lead author of that study, Dr. Tommaso Lupattelli, said the Ontario study may have failed to find CCSVI in MS patients because the technicians only trained on the ultrasound technique for one week. His technicians trained for one year.
“I can’t judge what my colleagues have done,” Lupattelli told CTV. “I can just say that if they can’t find CCSVI in patients with multiple sclerosis it’s probably due to the fact that they don’t have a very good learning curve.”
Zamboni, who was not involved in either study, said Wednesday that the Ontario group, “did not follow the recommended protocol” for ultrasound.
“In my opinion, there are several technical short-comings,” he said.
Rodger defended his team’s work, saying that 2010 testing protocols are “fair and objective.”
“We are very confident of the measurements we made,” he said. “I would be confident that what we have done is correct.”
High rates of MS in Canada
Multiple sclerosis is a neurological disease that can cause impaired vision, hearing and speech, extreme fatigue and paralysis. The MS Society of Canada says the disease is most often diagnosed between the ages of 15 and 40, and women are three times as likely to develop the disease as men.
Canada has one of the highest MS rates in the world. There is no known cause of the disease.
Four years ago, Zamboni proposed that CCSVI might play a role in the development of MS, and that symptoms could be alleviated by using balloon angioplasty to open up the neck veins.
The angioplasty procedure is not offered in Canada. However, patients from Canada and around the world have flocked to clinics in countries such as India, Poland and Mexico that offer the treatment.
Zamboni’s research sparked several studies around the world, and the results have been mixed.
In March, a small clinical trial of 30 MS patients at the University of Buffalo found that while the angioplasty procedure is safe, it did not alleviate symptoms, halt disease progression or otherwise improve quality of life.
MRI scans also showed an increase in brain lesions in patients who had the procedure.
The researchers suggested, however, that a study that includes a much larger cohort of patients is required to definitely prove their findings. They also said that their findings did not prove that CCSVI does not play a role in MS.
Also last year, an observational study of residents of Newfoundland and Labrador who travelled abroad for the procedure found it led to no measurable benefit.