How Does the Disease Progress?
The course of multiple sclerosis varies for each person. Because of this uncertainty, doctors often tell their patients that they "probably" or "possibly" have MS. Your diagnosis is based on the combination of problems, patterns of recurrence, which systems are impaired, and your test results. There is no way to predict how each person's condition will progress. It often takes years before a doctor can be certain of an MS diagnosis and have some idea on how the disease will progress.
There are four courses that MS takes:
- Relapsing-remitting MS: characterized by unpredictable acute attacks, called "exacerbations," with worsening of symptoms followed by full, partial, or no recovery of some function. These attacks appear to evolve over several days to weeks. Recovery from an attack takes weeks, sometimes months. The disease does not worsen in the periods between the attacks. This pattern usually occurs early in the course of MS in most people.
- Primary-progressive MS: characterized by a gradual but steady progression of disability, without any obvious relapses and remissions. This form of disease occurs in just 15% of all people with MS, but it is the most common type of MS in people who develop the disease after age 40.
- Secondary-progressive MS: initially begins with a relapsing-remitting course, but later evolves into progressive disease. The progressive part of the disease may begin shortly after the onset of MS, or it may occur years or decades later.
- Progressive-relapsing MS: This is the least common form of the disease and is characterized by a steady progression in disability with acute attacks that may or may not be followed by some recovery. People with progressive relapsing MS initially appear to have primary progressive MS.
Most people with MS are diagnosed between ages 20 and 40, but the unpredictable physical and emotional effects of the disease continue throughout the person's life.
What Is a True Exacerbation (Relapse) of Multiple Sclerosis?
A true exacerbation of multiple sclerosis is caused by an area of inflammation (swelling) in the nerves of the brain and spinal cord system followed by something called demyelination, which is the destruction of myelin. The myelin is the fatty sheath that surrounds and protects the nerve fibers.