What is Multiple Sclerosis?

Multiple sclerosis (MS) is a progressive condition (ie the symptoms get worse over time) which affects the nervous system by damaging the myelin sheath which is a fatty substance which surrounds the nerve fibres. This damage leaves scarring (sclerosis) or lesions which prevent signals from moving efficiently along the nerve.

Multiple sclerosis affects differnent people in different ways and to different degrees. The damage done by MS can lead to the nerve signals that control muscle co-ordination, strength, vision and sensation becoming slowed or blocked.

It has previously been thought that MS only affects the myelin sheath, it now appears that some nerves (axons) may be affected and that the damage to these "may be more closely correlated with preogression of disability".

There are several diffent types of multiple sclerosis:

• 80% of people have the relapsing-remitting form of MS which comprises of periods of relapse followed by periods of remission;
• Some people have benign MS which starts with a small number of mild attacks from which a complete recovery is made;
• 12% of people have primary progressive MS which doesn't have any remission phases, the symptoms gradually develop and worsen over time;
• Many people with the relapsing-remitting type of MS later develop a type known as secondary progressive whereby either the disability does not go away between attacks or that the periods of remission disappear and are replaced by a steady progression of disability. Fifty per cent of people with remitting relapsing MS will develop secondary progressive MS within the first ten years.

There are approximately 85,000 people in the UK with MS. Most people first develop the condition between the ages of twenty and forty. Women are slightly more likely to be affected than men.

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