A controversial theory about the cause of multiple sclerosis swept through the medical community in the past year, offering hope to millions of sufferers desperate for a therapy.
But a large study by Buffalo researchers raises doubt about whether multiple sclerosis is caused by blockages in the veins that drain the brain and, instead, suggests the blockages may be a result of the disease.
The University at Buffalo researchers found that only 56.1 percent of the multiple sclerosis patients studied, and 38.1 percent of individuals who had experienced their first neurological episode, had the blockages known as chronic cerebrospinal venous insufficiency, or CCSVI.
"While this may suggest an association between MS and CCSVI, association does not imply causality," said Dr. Robert Zivadinov, associate professor of neurology at UB.
MS affects 2.5 million people worldwide, including 500,000 in the United States, and its prevalence in Buffalo is significantly higher than average.
The study in the latest issue of the journal Neurology looked at 449 patients -- 289 people with MS, 163 who were healthy, 26 with other neurological diseases and 21 who had experienced their first neurological episode. It also found that 42.3 percent of participants classified as having other neurological diseases, as well as 22.7 percent of healthy individuals who were examined, also showed signs of CCSVI.
The highest prevalence of CCSVI occurred in patients with two types of MS, suggesting that the vein blockages are a consequence of MS, said Zivadinov, lead author and president of the International Society for Neurovascular Disease.
A 2009 study by an Italian researcher, Dr. Paolo Zamboni, found a relationship between MS and signs of abnormal blood drainage in veins.
He proposed that the narrowing of veins restricts normal outflow of blood from the brain, causing alterations in the blood flow patterns within the brain that eventually cause injury to neurons. He also suggested that the damage involved buildup of iron deposits in veins. The body needs iron, but too much of it is linked to brain disorders.
The theory upset current thinking on MS, a disease thought to be the result of an abnormal immune system attacking the brain, nerves and spinal cord.
Controversy ensued as patients, largely through the Internet, lobbied the medical community to embrace Zamboni's theory.
Last year, the National MS Society and the Multiple Sclerosis Society of Canada devoted $2.4 million for research grants to study the role of CCSVI in MS.
Meanwhile, some doctors rushed to perform balloon angioplasty or place stents in veins to reduce MS symptoms, even though the theory remained unproven and Zamboni's work involved few patients and was uncontrolled, meaning there was not another group studied to compare results.
At least two patients died from a procedure that advocates called "liberation therapy."
"Web sites, blogs, Facebook pages and other social network media promoted the CCSVI theory as salvation for patients with MS," wrote Drs. Robert J. Fox and Alex Rae-Grant in an editorial that accompanied the UB study. "It became clear that the CCSVI theory went far beyond the traditional clinical research enterprise and had become a media-driven phenomenon."
The doctors advised colleagues to neither jump on the CCSVI bandwagon nor miss it by dismissing the theory, a conclusion echoed by Zivadinov.
He said more studies are needed to learn if CCSVI is important in some MS patients. If so, researcher must determine who is the best candidate for angioplasty, if it's shown that the procedure is safe and effective for relieving symptoms.
The latest study also prompted new questions about the link between iron deposits and brain disorders, such as Alzheimer's disease.
"We actually opened more pages in the story of CCSVI," Zivadinov said.