Scientists still looking for MS cause
April 23, 2008Recommend
By Jeanne Millsap special to the herald news
Multiple sclerosis is another one of those mysterious diseases of the
nervous system. As with many other neurological diseases, scientists
haven't yet figured out what causes it, but they are stumbling on
promising clues in their research.
Also mysterious to new MS patients is which of them will develop the
devastating progressive symptoms that could leave them bedridden,
unable to speak or write, or even paralyzed, and which of them might
have only the occasional relapse that will leave them still able to
live out a relatively normal lifestyle.
According to Dr. Nitin Nadkarni, a Silver Cross neurologist who has a
special interest in MS, there is a subset of about 15 percent of MS
patients whose disease will run a "relatively benign" course, with
relapses running perhaps only every 10 years.
Most MS patients aren't so lucky. Nadkarni said most begin with
remitting and relapsing MS, which means they are suddenly struck with
symptoms of the disease, then those symptoms gradually fade away.
Initially, the symptoms may seem to completely or partially disappear.
But MS patients eventually usually succumb to a downward spiral of
disabilities. Many remitting and relapsing patients become chronic-
progressive, which means the symptoms don't have a remission -- they
just continue getting worse.
This can lead to a significant disability, Nadkarni said, with
patients in a wheelchair or bed-bound.
Nerve disease
Multiple sclerosis is a nerve disease that affects the brain and
spinal cord. It eats away at the "white matter," or myelin sheaths
that wrap around certain brain cells. Myelin sheaths help nerves
carry their electrical impulses. With their myelin gone or damaged,
the nerves have difficulty carrying those impulses.
The optic nerve might not be able to carry impulses from the eyes,
causing blindness. Depending on what myelin sheaths are damaged on
which nerves, symptoms can be muscle weakness, trouble with
coordination and balance, thinking and memory problems, and
sensations such as numbness, prickling, or pins and needles.
Oligodendrocytes are also damaged in MS. They are the cells that make
and nurture myelin sheaths. In the beginning of MS, myelin is
destroyed, but the oligodendrocytes jump right in and repair the
damage to the myelin. That's when the patient goes into remission.
But as the disease progresses, the damage cannot be as easily
repaired, and the symptoms may remain rather than go into remission.
Not autoimmune
Nadkarni said he wouldn't classify MS as an autoimmune disease. The
immune system is involved, he said, but it might not be a case of
immune cells going awry. One theory is that MS is a case of immune
cells doing what they do normally, although they are not found where
they are usually located.
There is not a hard-and-fast explanation for the cause of MS yet,
Nadkarni said, and there are a few theories.
One is that there is a break in the blood-brain barrier that lets
immune cells inside the brain where they aren't normally found.
The blood-brain barrier is a tight barrier between the blood and the
cells of the brain that keeps many compounds and cells out of the
sensitive brain tissue. If there is a break in this barrier that
allows activated lymphocytes, which are immune cells, into the brain,
a theory suggests that these lymphocytes might begin attacking the
brain or, in this case, the myelin and the oligodendrocytes.
This is a relatively new theory, Nadkarni said, one that has been
around only the last three or four years.
Other theories
There are other theories on the causes of MS. Some postulate that a
virus causes it or a heavy metal or lack of vitamin D in childhood.
There is also some kind of genetic component in MS, because it is
more common in those with northern European ancestry.
MS is more common in women than in men, too. Its onset is normally
between the years of 20-40, and the severity of the disease seems to
be worse the older the onset of symptoms.
Nadkarni said the development of MRI revolutionized the diagnosis of
MS. With it, neurologists can see specific areas of "plaques" in the
brain, which are lesions where the myelin and oligodendrocytes have
been damaged.
There are many treatments for MS, most of which are costly
injectables and many of which have some hefty side effects.
The drugs aim to return function after an attack, prevent new
attacks, and prevent disability.
There are also a couple of treatments for patients who fail to
respond to conventional treatments. One is a monoclonal antibody that
binds to lymphocytes to prevent them from entering the brain. Another
is a chemotherapy, but that treatment has harsh side effects.
Stem cell therapy is experimental and still in trial, and Nadkarni
said he is hopeful of its outcome with MS patients.
With stem cell therapy, patients have some of their young stem cells
withdrawn from their blood, then all of the immune cells in their
bodies are destroyed with chemotherapy. Those initial stem cells are
then injected back in, with the hopes they will migrate to the brain
and form new oligodendrocytes.
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StemCells subscribers may also be interested in these sites:
Children's Neurobiological Solutions
http://www.CNSfoundation.org/
Cord Blood Registry
http://www.CordBlood.com/at.cgi?a=150123
The CNS Healing Group
http://groups.yahoo.com/group/CNS_Healing
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