Skip to main content Skip to navigation

Disease modifying drug therapy, what you need to know What is MS?

Multiple sclerosis is considered to be an autoimmune condition, whereby the immune system attacks the body's tissue, causing inflammation and damage. In MS, the immune system attacks myelin - the fatty protein that forms a sheath around nerve cells in the central nervous system (the brain and the spinal cord). This causes inflammation and damage to the myelin (called demyelination), which disrupts the way in which nerve messages are carried to and from the brain, leading to the symptoms of MS.

In the early stages of MS, it is possible for the body to repair damaged myelin (remyelination), or the central nervous system may re-route messages via different nerve pathways thereby avoiding damaged areas. However, if the nerves are left without the protection of myelin or the area of damage becomes too large, nerve fibres will be permanently destroyed and messages in that part of the central nervous system may become permanently blocked.

What are the different types of MS?

Whilst MS does not follow a set pattern, varying from person to person, there are some broad types.

Relapsing remitting
Most people are diagnosed with relapsing remitting MS. A relapse is the onset of symptoms or disability lasting at least 24 hours but, more commonly, for a number of days or weeks. The number of relapses someone experiences will vary. Typically, people will experience one or two relapses a year, followed by a period of good or complete recovery (remission). There is a tendency for recovery to become less complete over time and each relapse may leave more permanent symptoms or disability in some people.

If the rate and severity of relapses has not been controlled by treatment with one of the disease modifying drugs, this is referred to as 'highly active' relapsing remitting MS.

If someone has two or more severe, or disabling, relapses in a year and shows areas of new damage (lesions) on two consecutive MRI (magnetic resonance imaging) scans, this can be referred to as 'rapidly evolving severe' relapsing remitting MS (RES).

Secondary progressive
Many people initially diagnosed with relapsing remitting MS find that over time, often many years, the frequency of relapses decreases and eventually stops but disability gradually increases.

Primary progressive
About 10% of people will be diagnosed with primary progressive MS in which disability increases from the outset with few or no relapses.

Clinically isolated syndrome (CIS)
Clinically isolated syndrome (CIS) is an individual's first episode of neurological symptoms lasting at least 24 hours but from which it is not possible to diagnose a definite cause. For some it may be the first attack of what turns out to be MS, although not everyone who experiences a CIS will go on to develop MS and for some there may be no further symptoms.


Next page - What are disease modifying drugs?