MS is a lifelong illness. It can follow one of several different patterns.
The three most common patterns seen in MS patients are:
Relapsing remitting MS. There are relapses (episodes when symptoms suddenly get worse), followed by remissions (periods of recovery). Between relapses, the patient's condition usually is stable, without deterioration.
This type accounts for the vast majority of cases at disease onset. About half of people with relapsing remitting MS enter a secondary progressive phase (described below) over time.
Primary progressive MS. Symptoms worsen gradually and continuously. There are no episodes of relapses and remissions.
Secondary progressive MS. Someone who originally had relapsing remitting MS begins to have gradual deterioration in nerve function. This may occur with or without relapses. If relapses occur, it is called "progressive relapsing" MS.