More than half of the multiple sclerosis patients in a closely watched study had narrowing of some neck veins leading from the brain, researchers said.
On the other hand, so did 22.4% of healthy controls in the first large study to test a new theory about the disease: that it's caused by such abnormally narrow veins, a condition dubbed "chronic cerebrospinal venous insufficiency."
Nevertheless, Robert Zivadinov, MD, PhD, of the University of Buffalo, said in a university news release that he is "cautiously optimistic and excited" about the results, which were originally scheduled to be presented at the annual meeting of the American Academy of Neurology in April.
"The data encourage us to continue on the same course," he said in the statement. "They show that narrowing of the extracranial veins, at the very least, is an important association in multiple sclerosis."
Zivadinov was traveling and not immediately available for further comment.
The study drew intense interest when it began enrolling patients last year, because the theory that abnormal veins play a role in multiple sclerosis -- as yet unproved -- is the first major shift in thinking about the disease in decades. (See Radical MS Theory Stirs Interest)
But experts cautioned that the press release doesn't contain enough details to allow scientists to judge the validity of the results, which in any case are partial and preliminary.
"From the press release, it's very difficult to analyze this in any way," said John Richert, MD, executive vice president for research and clinical programs at the National Multiple Sclerosis Society.
"It makes you want to see more," he told MedPage Today.
The release, which has not been subject to the usual scientific peer review, contained data on 441 volunteers, including 280 with multiple sclerosis, most of them adults.
However, that's a small fraction of the more than 1,700 volunteers, including 1,000 adults and 50 children with the disease, who are expected to be enrolled.
It also was limited to data on ultrasound scans of the volunteers. The results of magnetic resonance imaging, to test other aspects of the theory, were not given.
Blocked veins in the volunteers were studied according to five criteria, other experts noted, but what they were wasn't reported, so that it was impossible to tell if they differed from earlier studies.
The release also said the researchers saw a correlation between venous insufficiency and the progression of the disease, "but even that statement is difficult to interpret exactly," Richert said.
The Buffalo study is a follow-up to research conducted by Paolo Zamboni, MD, of the University of Ferrara in Italy, which showed chronic cerebrospinal venous insufficiency to be strongly associated with multiple sclerosis.
Zamboni also conducted a small surgical intervention trial that appeared to show a benefit to patients from opening up the veins.
Not all experts were skeptical of the reports.
The Buffalo report was a surprise mainly because its results were "less impressive" than Zamboni's findings, according to Salvatore Sclafani, MD, of SUNY Downstate College of Medicine in Brooklyn.
Sclafani said in an e-mail that the first results showed about 65% of patients had abnormal veins, but recent research puts the figure at about 90%.
"I have now studied many patients with MS and all have had abnormalities of the veins," said Sclafani, who has recently begun studying the issue.
The Buffalo results vary slightly, depending on how some "borderline" volunteers are counted, the release said.
If the 10.2% of volunteers whose results were classed as borderline were included in the normal category, the incidence of venous insufficiency was 56.4% in the multiple sclerosis patients and 22.4% in the controls.
On the other hand, if the borderline results were excluded, the proportion of affected patients rose to 62.5%, compared with 25.9% percent of healthy controls.
But the finding that a proportion of healthy controls had venous insufficiency needs further investigation, Zivadinov said in the release.
This article was developed in collaboration with ABC News
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