The course of MS is unpredictable. Some people are minimally affected by the condition, whilst others may experience more frequent relapses leading to varying levels of disability over time. Although the course of the condition can vary between individuals there are four main types of MS based on how the condition presents and may progress.
Approximately 85% of people are diagnosed with relapsing-remitting MS (RRMS). People with RRMS usually experience clearly defined attacks, or relapses, which either present as new symptoms, or an increase in the severity of existing symptoms. These attacks subside with either full, or partial, recovery. There is also usually no noticeable progression of the condition between attacks. On average people with RRMS will experience one – two attacks each year.
Without treatment, after about 10 years, attacks become less noticeable but disability level may increase.
This less common type of MS affecting approximately 10% of cases, is characterised by a gradual, but steady progression of disability from the onset. In most cases, there are no obvious plateaus or remissions, however, some people will experience occasional plateaus, and minor temporary improvements.
Secondary-Progressive MS (SPMS) can develop in a person who was initially diagnosed with RRMS.
Historical studies of people with RRMS, over a long period of time, suggest that after 19 years, approximately half of those diagnosed with RRMS will have developed secondary progressive MS.
Whilst MS does become less ‘inflammatory’ and involves fewer attacks, SPMS is characterised by gradual and irreversible progression.
In this relatively rare course of MS, people experience a steady worsening of the condition from the beginning, but with clear attacks and deteriorating neurological function along the way. They may, or may not, experience some recovery following attacks, but the condition will continue to progress without remissions.
References: MS Australia
Knowledge is Power Volume 1.
Read more at: MS Trust