BOSTON — A new study challenges the long-held belief that multiple sclerosis damages nerves in the brain solely by stripping off their insulation.
The research found that the disease actually severs nerve fibers in the brain, causing irreversible damage that probably begins even before symptoms are noticed.
The research raises the possibility that patients should begin treatment very early in the disease.
“This paper changes our perception of the underlying nature of multiple sclerosis,” said Dr. Richard Rudick of the Cleveland Clinic Foundation, a co-author of the study.
Experts long believed that MS did its damage almost exclusively by attacking myelin, the protecting covering on nerve fibers, in the brain and spine. This was thought to interfere with the fibers’ ability to transmit signals and led to the many different symptoms of MS.
The new study shows that besides stripping off myelin, the disease frequently slices through the nerve fibers themselves, destroying their ability to carry messages.
Rudick said the study is the first to actually visualize these severed cells through a microscope, although indirect hints of this have been building up for several years. For instance, magnetic resonance imaging — MRI — has shown that MS victims’ brains actually shrink, suggesting loss of nerve cells.
Dr. Stephen Reingold of the National Multiple Sclerosis Society said the earlier clues had already led many experts to conclude that the disease damages and perhaps cuts nerve cells.
While the latest finding is likely to be news to practicing physicians, Reingold said, “this will not be a surprise to scientists in the field.”
The study, directed by Dr. Bruce D. Trapp, was published in Thursday’s issue of the New England Journal of Medicine.
About 350,000 Americans have MS, and it most often begins when victims are in their 20s. Symptoms often include numbness, tingling, poor coordination, slurred speech and weakness.
While the precise cause is unknown, experts know that inflammation — perhaps caused by a misguided attack on the body’s immune system — damages the nerves.