Relapsing-remitting multiple sclerosis (RRMS) is characterized by clearly defined attacks of worsening neurologic function. These attacks — often called relapses, flare-ups or exacerbations
— are followed by partial or complete recovery periods (remissions), during which symptoms
improve partially or completely, and there is no apparent progression of disease. RRMS is the most common disease course at the time of diagnosis. Approximately 85 percent of people are initially diagnosed with RRMS, compared to 10-15 percent with progressive forms of the disease.
Relapsing-remitting MS is defined by inflammatory attacks on myelin (the layers of insulating membranes surrounding nerve fibers in the central nervous system (CNS)), as well as the nerve fibers themselves. During these inflammatory attacks, activated immune cells cause small, localized areas of damage which produce the symptoms of MS
. Because the location of the damage is so variable, no two people have exactly the same symptoms.
How does RRMS differ from progressive types of MS?
While RRMS is defined by attacks of inflammation (relapses) in the CNS, progressive forms of MS involve much less of this type of inflammation.
People with RRMS tend to have more brain lesions — also called plaques or scars — on magnetic resonance imaging (MRI) scans, and these lesions contain more inflammatory cells.
People with primary-progressive MS (PPMS) tend to have more spinal cord lesions, which contain fewer inflammatory cells.
In RRMS, women are affected two to three times as often as men; in PPMS, the number of women and men are approximately equal.
RRMS is diagnosed earlier than the progressive disease courses:
Most people with RRMS are diagnosed in their 20s and 30s (although it can occur in childhood or later adulthood), while the onset of PPMS tends to be in ones 40s or 50s.
The transition to SPMS generally occurs in people who have been living with RRMS for at least 10 years.
The most common symptoms reported in RRMS include episodic bouts of fatigue, numbness, vision problems, spasticity or stiffness, bowel and bladder problems, and problems with cognition (learning and memory or information processing). People with progressive forms of MS are more likely to experience gradually worsening problems with walking and mobility, along with whatever other symptoms they may have.