Types of multiple sclerosis
Multiple sclerosis is classified according to frequency and severity of neurological symptoms, the ability of the CNS to recover, and the accumulation of damage.
Primary progressive MS: Primary progressive MS causes steady progression of symptoms with few periods of remission. With primary progressive MS, symptoms get worse over time, but there are no relapses or remissions. Some people with primary progressive MS have brief periods of time during which their symptoms either stay the same or improve slightly. This type of MS is most often diagnosed in people over the age of 40.
Relapsing-remitting MS: In relapsing-remitting MS, symptoms come (relapses) and go (remissions). Symptoms may evolve over several days and then disappear, although some symptoms may remain. The course varies from person to person, but on average, relapses appear every two years. The period between relapses can be very long, as much as 20 years or more. A small percentage of people have only a single attack in their lifetime.
Relapsing-remitting MS is the most common form of the disease and is most frequently diagnosed between the ages of 20-40. Up to 80% of individuals with MS are diagnosed with the relapsing-remitting type. Only 50% of people with RR MS develop secondary progressive MS within the first 10 years.
Secondary progressive MS: Secondary progressive MS is initially similar to relapsing-remitting MS and eventually progresses to MS with no remission. The change from relapsing-remitting MS to secondary progressive MS generally occurs five to 15 years after the disease begins. With secondary progressive MS, neurological symptoms tend to worsen progressively, with or without superimposed relapses. Over time, it is common for secondary progressive patients to have fewer attacks (sometimes none at all), despite continual progression. About 30% of individuals with MS have secondary progressive disease.
Relapsing-progressive MS: Relapsing-progressive MS is a rare form of MS with a gradual worsening of symptoms from the beginning, with superimposed relapses and remissions.