'Invisible' Brain Changes May Be Key to MS Progression

These alterations don't appear on standard brain scans, researchers say

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By Angela Pirisi
HealthDay Reporter

TUESDAY, Aug. 29, 2006 (HealthDay News) -- New research suggests that subtle, undetected changes in brain tissue affect disease progression for people with multiple sclerosis.

"We showed that these changes affect brain tissue throughout the brain, and that changes are greater for patients with secondary progressive MS than for those with the preceding phase, relapsing remitting MS," explained lead researcher Hugo Vrenken, of the VU University Medical Center in Amsterdam, The Netherlands.

His team published its findings in the September issue of Radiology.

MS is an incurable inflammatory disease of the central nervous system marked by muscle weakness, numbness and loss of coordination. Disease severity can range from the relatively benign to cases involving serious disability and death. Many experts consider MS an autoimmune disease, in which the body attacks its own tissues, especially the protective myelin sheath surrounding nerves. About 400,000 people in the United States are diagnosed with MS, according to the National Multiple Sclerosis Society.

In MS patients, standard MRI imaging sometimes reveals brain lesions or plaques that may reflect disease-linked changes in mental or physical function.

Currently, doctors use these images to help diagnose MS. However, an abnormal MRI doesn't always mean MS, and normal results don't necessarily rule out the disease.

In fact, a small proportion of MS patients, about 5 percent, have MRI results that don't reveal any lesions (or plaques) in the brain, according to the National Multiple Sclerosis Society.

What clinicians don't see on a standard MRI -- but research scientists can see, using more advanced technology -- are other, subtle changes that are also potentially related to disease course and disability.

Measuring these changes that fall "under the radar" could give doctors a better understanding of the disease, allowing them to offer patients a more clear-cut prognosis, the researchers said.

Using advanced MRI technology called "T1 mapping," the Dutch team compared the brain tissue of 67 patients with MS and 24 healthy controls. The researchers focused on changes in areas not showing up as MS lesions (or plaques) on standard MRI images.

T1 imaging showed changes occurring in MS in large parts of brain tissue that would otherwise go undetected. According to the findings, depending on the stage of the disease, these changes may occur in 10 percent to 30 percent of brain tissues not showing any visible damage on standard MRI.

Changes were more pronounced in patients with more advanced, secondary progressive MS than those with the less advanced form of the illness, called relapsing remitting MS, Vrenken said.

"This demonstrates that patients who are further along in the disease do not only develop more visible lesions, but that also the brain tissue not showing visible lesions becomes more affected," he added.

The observed brain changes were more strongly associated with clinical disability than were lesions visible on standard MRI. "This suggests that the changes, though possibly subtle, may be responsible for part of the patients' disability," Vrenken said.

"The tricky part of MS is the variability in progression of disease," noted Dr. Patricia A. O'Looney, director of biomedical research programs at the National Multiple Sclerosis Society.

MRI has been a boon to MS diagnosis since the early 1990s, allowing for earlier detection, in conjunction with other assessment tools. "It has also allowed doctors to look at the disease more objectively, by allowing them to see the damage in the brain, not just rely on whether patients feel well or bad," says O'Looney.

However, "What's missing in both research and clinical care now is a [long-term] predictor of disability," added O'Looney.

Some people can remain fully functional for 20 years before symptoms worsen, while other MS patients deteriorate quickly. Right now, what science can't tell doctors and patients at the time of diagnosis is if, when, or how fast the disease will progress.

So, any method that could predict prognosis based on brain tissue changes would be of great help to doctors, O'Looney said.

"The ultimate hope for MS patients is to stop the neuro-degeneration that happens and causes disability," said O'Looney. Right now, though, science is still unraveling just how the disease manages to do its damage.

More information

For much more on MS, head to the National Multiple Sclerosis Society.

SOURCES: Hugo Vrenken, Ph.D., department of physics and medical technology, VU University Medical Center, Amsterdam, The Netherlands; Patricia A. O'Looney, M.D., director, biomedical research programs, National Multiple Sclerosis Society; September 2006 Radiology

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