- Relapsing-Remitting (RRMS): where symptoms fade and then return off and on for many years.
Characteristics: People with this type of MS experience clearly defined but unpredictable flare-ups (also called relapses, attacks, or exacerbations) during which time new symptoms can appear and/or old ones resurface or worsen. The relapses are followed by periods of remission (recovery), during which time the person fully or partially recovers from the deficits acquired during the relapse. Relapses can last for varying periods (days, weeks or months) and there may be partial or total remission. The disease may be inactive for months or years. The vast majority of people presenting with Multiple Sclerosis are first diagnosed with relapsing/remitting. This is typically when they are in their twenties or thirties, though diagnoses much earlier or later are known. Around twice as many women as men present with this variety.
Frequency: Most common form of MS at time of initial diagnosis. Approximately 85%.
- Secondary-Progressive (SPMS): which at first follows a relapsing-remitting course and then becomes progressive. “Progressive” means it steadily gets worse.
Characteristics: People with this type of MS experience an initial period of relapsing-remitting MS, followed by a steadily worsening disease course with or without occasional flare-ups, minor recoveries (remissions), or plateaus.
Frequency: 50% of people with relapsing-remitting MS developed this form of the disease within 10 years of their initial diagnosis, before introduction of the "disease-modifying" drugs. Long-term data are not yet available to demonstrate if this is significantly delayed by treatment.
- Primary-Progressive (PPMS): where the disease is progressive from the start.
Characteristics: People with this type of MS experience a slow but nearly continuous worsening of their disease from the onset, with no distinct relapses or remissions. However, there are variations in rates of progression over time, occasional plateaus, and temporary minor improvements. Primary Progressive differs from Relapsing/Remitting and Secondary Progressive in that onset is typically in the late thirties or early forties, men are as likely women to develop it and initial disease activity is in the spinal cord and not in the brain. Primary Progressive MS often migrates into the brain, but is less likely to damage brain areas than relapsing/remitting or secondary progressive - for example, people with Primary Progressive are less likely to develop cognitive problems. Primary Progressive MS does not have separate episodes (relapses, exacerbations). Unlike RRMS where women are twice as likely to be diagnosed than men, PPMS is equally divided between the genders.
Frequency: Relatively rare. Approximately 10%.
- Progressive-Relapsing (PRMS): where the symptoms come and go but nerve damage steadily gets worse.
Characteristics: People with this type of MS experience a steadily worsening disease from the onset but also have clear acute relapses (attacks or exacerbations), with or without recovery. In contrast to relapsing-remitting MS, the periods between relapses are characterized by continuing disease progression.
Frequency: Relatively rare. Approximately 5%.
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