Multiple sclerosis is a degenerative disease of the central nervous system.
According to the World Health Organisation, multiple sclerosis affects about 2.5m individuals worldwide, of which about 1% die each year.
What is multiple sclerosis?
Mutiple sclerosis attacks the nervous system. Initially it causes loss of balance, reduced vision and bouts of localised paralysis.
Eventually, patients may become totally paralysed and wheelchair-bound.
There are several kinds of mutiple sclerosis.
Relapsing-remitting MS: Patients initially experience one or more bouts of illness, followed by complete or partial recovery. Patients are clinically stable between relapses.
Secondary-progressive MS: Patients start out with the relapsing-remitting form of the disease, but relapses become more severe and remissions less complete, shorter in duration, and eventually non-existent.
Primary Progressive MS: There is no history of relapses. Instead symptoms worsen and patients become gradually more disabled over time.
What causes multiple sclerosis?
Multiple sclerosis appears to be caused by a chemical found naturally in the body called interferon gamma. Under normal circumstances this chemical helps to activate the immune system to attack foreign invaders, such as viruses and bacteria.
In multiple sclerosis patients interferon gamma causes the immune system wrongly to identify body cells as foreign invaders.
As a result, the myelin sheath coating nerves in the brain and spinal cord is destroyed by mistake.
As a consequence, tranmission between nerve cells slows down and becomes irregular.
What treatment is available?
There is no cure for MS, but drugs can be used to reduce the number and severity of MS relapses, and to reduce the number of new attacks.
However, it is not yet known whether these drugs will slow down the rate of disability in the long term.
Four MS disease modifying drugs are licensed in the UK for treating relapsing-remitting MS:
In clinical trials, the four drugs reduced MS relapse rate by approximately one third over a two-year period and (in some trials) reduced the severity of relapses.
It also appears that beta interferon has some benefit for people with secondary progressive MS, but only where relapses are the cause of increasing disability.
Beta interferon is not known to benefit people who are already severely disabled.
And as yet there is no evidence that any of the drugs can help people with primary progressive MS.
The four licensed disease modifying drugs are available on the NHS under the 'Risk Sharing Scheme' to patients who meet specific criteria.
The 'risk' element of the scheme involves a sharing of the financial risk between the NHS and the participating pharmaceutical companies.
Is other treatment available?
Other treatments are focused on managing specific symptoms of the disease, such as bladder problems or fatigue.
A drug containing cannabis compounds, Sativex, has shown promise in helping to control the pain associated with MS.
This page contains basic information. If you are concerned about your health, you should consult a doctor.
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