A new study provides more evidence that multiple sclerosis (MS) is not caused by a blood vessel condition, as some research has suggested.

The new findings follow a study last month in which Dr. Ellen Marder from the Dallas Veterans Affairs Medical Center and her colleagues reviewed the current literature on the condition, called chronic cerebrospinal venous insufficiency, or CCSVI. They couldn't find any convincing data to suggest that narrowing blood vessels in CCSVI are behind MS.

Based on those findings, Marder's group said MS patients should not undergo surgery to open up those blood vessels.

Now they've reported on another study, in which they found that people with MS are no more likely to have signs of CCSVI on ultrasound tests than people without MS.

The researchers say the results, and recent reports from other investigators, "call into question" whether CCSVI actually does play a role in causing MS, and whether there's really any point in trying to treat the blood vessel condition.

In Archives of Neurology, they summarize the history of the suggested link between MS and CCSVI. In 2009, Italian researchers first suggested that people with MS were more likely to have narrowing of the veins that run from the brain and spine to the heart, which could cause some blood to leak back into the brain.

Doctors then proposed that correcting the situation through surgery might ease MS symptoms, such as movement and balance problems.

But more recent studies haven't shown clearly whether people with MS are more likely than others to have CCSVI, or whether an invasive vessel-opening surgery could have any benefit.

In their current study, Marder's team took ultrasound images inside and outside the brains of 18 people with MS, all U.S. veterans, and another 11 people of the same age and gender without MS. On those scans, they looked for the proposed signs of CCSVI, including a lack of blood flow, or backward blood flow,  in veins in the head and neck, as well as narrowing of those veins.
Four MS patients had one of those signs show up on their ultrasounds, but so did four people in the comparison group.

"We don't think (CCSVI) is the cause of multiple sclerosis," Marder recently told Reuters Health. "We would not advise our patients to be tested for this or act on any recommendations based on this sort of testing."

Still, some researchers have continued pushing for a link between MS and CCSVI, and a few doctors have started offering procedures to MS patients to open their veins, surgeries typically given to people at risk of heart attack that carry bleeding and infection risks.

Timothy Coetzee, chief research officer at the National Multiple Sclerosis Society, said there are still conflicting opinions about what role CCSVI might play in the disease, and that while this study adds evidence to that debate, it doesn't shut the door on it.

"In my mind the jury's still somewhat out on what it means for MS," he told Reuters Health.

His organization has handed out over $2 million to fund research on CCSVI, and Coetzee said he hopes those studies will help "draw some conclusions" on what the condition might mean for MS care. "We need to be sure that ideas are tested and validated because of the impact that has on people" with MS, he said.

In the end, he added, what matters most is that people with MS talk with their own doctors about the best treatment for their condition.