A to Z of MS
Click on the relevant link for more information on a topic.
A to Z of MS Types of MS
Although the effects of multiple sclerosis can vary greatly from person to person, the condition is often categorised into one of four broad groups:
Relapsing remitting MS
The majority of people with MS are diagnosed with the relapsing remitting form. This means they will have periods when symptoms flare up aggressively - known as a relapse, an attack or an exacerbation - followed by periods of good or complete recovery - a remission.
A relapse is the appearance of a new symptom or the reappearance of old symptoms that lasts more than 24 hours. A relapse can last for considerably longer than that and may persist for weeks or months. The frequency of relapses, the severity of symptoms experienced and the length of the gap between attacks are unpredictable. Similarly, it may sometimes be difficult to determine what is a fluctuation in symptoms (a day to day worsening or improvement) and what is a relapse.
On average, people with relapsing remitting MS have one or two attacks a year. It's possible for symptoms to worsen gradually over time and for recovery from relapses to become less complete.
The term rapidly evolving severe relapsing remitting MS (RES) is used in relation to the drugs natalizumab (Tysabri) and fingolimod (Gilenya). This is a less common form of relapsing remitting MS in which someone has two or more disabling relapses in one year and evidence of increasing lesions on two consecutive MRI scans.
Secondary progressive MS
Many people who are initially diagnosed with relapsing remitting MS find that over time the frequency of relapses decreases but disability gradually increases. This is known as secondary progressive MS. As with relapsing remitting MS, people's experience of secondary progressive MS can vary widely. Some people find that the increase or progression of disability is very gradual, whilst for others it can occur more quickly.
Studies that have monitored people with MS over a long period of time suggest that after ten years, half those people who were diagnosed with relapsing remitting MS will have developed secondary progressive MS.
Primary progressive MS
About 10% of people with MS are diagnosed with a form in which disability increases from the outset. This is known as primary progressive MS (or, less commonly, chronic progressive MS). Again, there is a variety of experience of primary progressive MS. Some people can have a persistent increase in disability whilst others may experience plateaux or a more gentle worsening of symptoms.
Some people whose MS has been progressive from onset will also experience occasional relapses. Some textbooks refer to this as progressive relapsing MS.
This form of MS has infrequent, very mild attacks separated by long periods with no symptoms. It is estimated that about 15-20% of people with MS have this form of the condition. As the defining characteristic of benign MS is the long-term absence of symptoms, it can only be diagnosed retrospectively after ten or more years.
The phrase is sometimes used inaccurately to describe a period of mild symptoms following diagnosis. Subsequent disease activity may sometimes prove this instead to have been a period of remission and that the person has relapsing remitting MS.
Lublin FD, Reingold SC.
Defining the clinical course of multiple sclerosis: results of an international survey.
Neurology 1996 ;46(4):907-911.