Understanding Different Types of MS
Reviewed by: HU Medical Review Board | Last reviewed: November 2019. | Last updated: December 2023
What is clinically isolated syndrome?
When a first episode occurs but the person does not show all the signs of MS, it is called clinically isolated syndrome (CIS). This episode must last for at least 24 hours. If a brain MRI shows lesions, the person is likely to experience more neurologic symptoms and episodes. More episodes may lead to a diagnosis of relapsing-remitting MS. If no lesions are found, the person is much less likely to develop MS. Early treatment of CIS helps delay onset of full MS.1
What is relapsing-remitting MS?
Relapsing-remitting MS (RRMS) is the most common form of MS, affecting more than 8 out of 10 people with MS. A person with RRMS experiences off-and-on worsening of symptoms or the sudden appearance of new symptoms that interfere with normal neurologic function.
These episodes are called relapses, attacks, exacerbations, or flare-ups. Relapses are often followed by partial or complete recovery (remission).
What is secondary progressive MS?
At first, the symptoms of secondary progressive MS (SPMS) come and go. Eventually, the person sees a gradual and steady increase in disability without distinct relapses and remissions. At first, relapses are caused by inflammation, but over time SPMS symptoms are caused by nerve damage and loss. The resulting increase in disability may be gradual, slow, quick, or change over time. There may be relapses and periods of stability.2
People with RRMS may gradually progress to SPMS within 10 years. Ninety percent of people with RRMS transition to SPMS within 25 years.2
What is primary progressive MS?
Primary progressive MS occurs in about 15 percent of people with MS. People with PPMS experience worsening symptoms from the beginning. They do not experience a cycle of relapses and remissions. PPMS can be active or not active, with progression of disability, or without progression.1
PPMS involves less inflammation and brain lesions that other types of MS. People with PPMS tend to have lesions on the spinal cord, making it harder to diagnose. This form of MS tends to appear 10 years later than relapsing MS. People with PPMS have more problems walking and remaining in the workforce.3
Other types of MS
Pediatric MS is rare with between 8,000 and 10,000 children living with MS in the U.S. Only about 3 percent to 5 percent of people with MS develop symptoms before age 18. Most children are diagnosed with relapsing-remitting MS. Children often experience more relapses but slower progression of their disease.4,5
Another condition is known as radiologically isolated syndrome (RIS). RIS may be diagnosed in someone who shows MS-like lesions on their brain or spinal cord but has no neurological symptoms of MS.1
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