Dr. Robert Zivadinov found a weaker association between a vein abnormality and MS than an earlier study found. (University of Buffalo)

More than half the patients with multiple sclerosis and up to a quarter of healthy people studied showed narrowing in their neck veins that may be a risk factor in the neurological disorder, a preliminary study has found.

Principal investigator Dr. Robert Zivadinov, an associate professor of neurology at the University of Buffalo, and his colleagues said Wednesday that 55 per cent of people with MS who were studied had narrowing of the veins that control blood flow from the brain, compared with 26 per cent of healthy control subjects, including some who were relatives of the MS patients.

Multiple sclerosis is a neurodegenerative disease that attacks the brain and spinal cord, causing inflammation and damage that can lead to paralysis and sometimes blindness.

The findings, which have not yet been peer reviewed, were based on the first 500 participants of the first blinded study that aims to determine if a condition called chronic cerebrospinal venous insufficiency, or CCSVI, is a major risk factor in MS.

In a blinded study, researchers don't know which subjects have the disease and which don't, which helps prevent bias.

CCSVI is a complex vascular condition discovered and described by Dr. Paolo Zamboni of the University of Ferrara in Italy. Zamboni's theory is that a narrowing of veins in the neck interferes with blood flow patterns from the brain. The changes in blood flow within the brain eventually cause injury to brain tissue and degeneration of neurons.

Most MS specialists believe the condition is an autoimmune disease caused by immune cells attacking neurons in the brain and spinal cord.

CCSVI link in MS remains unclear

Zamboni and Zivadinov believe CCSVI is one of the causative factors in MS, not the only cause.

"If somebody has two jugular veins closed then this is probably a high association to MS and probably the diagnosis can be established with stronger confidence," Zivadinov said in an interview Wednesday.

In December 2008, Zamboni published a pilot study online in the Journal of Neurology, Neurosurgery and Psychiatry that was not blinded, suggesting the vein abnormality was much more common in MS than Zivadinov found.

Zivadinov's findings point to a much weaker association between CCSVI and MS, said Dr. Paul O'Connor, a neurologist at the MS clinic at St. Michael's Hospital in Toronto.

"The question is not settled by any means as to what degree of association there is between CCSVI and MS, if any," said O'Connor, who is also the MS Society of Canada's national medical and clinical adviser.

Surgery concerns

Some people with MS have sought to have their veins examined in private clinics and are looking for surgeons willing to perform a procedure to unblock the veins.

"We don't know whether this vein abnormality is a cause or consequence of MS, and we certainly don't know that charging into the veins of their neck with catheters for doing these treatments, we certainly don't that that is safe or worthwhile," O'Connor cautioned.

Zivadinov also advised patients "not to just go from door to door" looking for vascular surgeons to operate on them, but to wait for the results of appropriate studies.

Since the intervention is of unknown benefit, O'Connor believes there is no need for Canadians to seek special ultrasounds on their neck within the health-care system. In Canada, clinics generally perform tests only once the value of the tests for diagnosis and treatment have been established.

Zivadinov's team expects to have more definitive findings in the second phase of the study, which will look at another 500 subjects.

Study participants will be examined using more advanced diagnostic tools. The complete data will be analyzed by an independent statistician, and will be presented at the American Academy of Neurology meeting in Toronto in April.