It is difficult to predict the progress of multiple sclerosis (MS) in an individual. Broadly, there are four main types of MS, categorised by the way in which the condition progresses.
Relapsing-remitting MS (RRMS) is the most common kind of MS.
When a person has an RRMS attack (also known as a relapse or flare) it will typically be followed by a full or partial recovery. The condition may remain stable between attacks. People with RRMS tend to experience one or two attacks a year.
Without treatment, after about ten years, attacks become less noticeable, but disability level may increase.
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.
Of people initially diagnosed with relapsing-remitting (RRMS), about half will go on to develop secondary-progressive (SPMS) within ten years and 90% within 25 years.
Secondary-progressive MS tends to progress steadily over time.
This is a less common type of MS, affecting approximately 10% of cases. As the name implies, this type of MS is progressive from the outset.
A person with primary-progressive MS does not experience recovery or remission of symptoms but rather a gradual progression of disability.