People with multiple sclerosis (MS) can typically experience one of four disease courses, each of which might be mild, moderate, or severe.
Relapsing-remitting MS (RRMS)
RRMS is the most common disease course. It is characterised by clearly defined attacks of deteriorating neurologic function. These attacks, which are called relapses, flare-ups, or exacerbations, are followed by partial or complete recovery periods (remissions) during which no disease progression occur. Approximately 85% of people are initially diagnosed with relapsing-remitting MS.
Primary-progressive MS (PPMS)
PPMS is characterised by a continuous, gradual decline in a person’s physical abilities from the beginning with no distinct relapses or remissions. A person with PPMS does not experience acute attacks. The rate of progression may vary over time, with occasional stability and temporary minor improvements. Approximately 10% of people are diagnosed with primary-progressive MS.
Secondary-progressive MS (SPMS)
Following an initial period of relapsing-remitting MS, many people develop a secondary-progressive disease course in which the disease worsens more steadily, with or without occasional flare-ups and minor recoveries. Before disease-modifying medications became available, approximately 50% of people with relapsing-remitting MS developed this form of the disease within ten years. Long-term data are not yet available to determine if treatment significantly delays this transition.
Progressive-relapsing MS (PRMS)
Approximately 5% of people diagnosed with MS appear to have PRMS. The course is characterised by a steady decline in abilities accompanied by sporadic attacks. They may or may not experience some recovery following these relapses, but the disease continues to progress without remissions.
How is MS diagnosed?
MS may not be diagnosed for months or even years after the onset of the disease due to the broad range of the symptoms. Neurologists record detailed histories and make use of the following tests to determine the presence of the disease:
Although the disorder is chronic and incurable, life expectancy can be normal or almost normal. Most people with MS continue to walk and function at work with minimal disability for 20 or more years.
Females and people who were young (less than 30 years of age) when the disease started, as well as those with a relapsing-remitting pattern who experience infrequent attacks, have the best outlook.
Most people return to normal or near-normal function between attacks. Over time, there is greater loss of function with less improvement between attacks and many require a wheelchair to get around. People with a support system are often able to remain in their homes.