Types of Multiple Sclerosis

Clinically isolated syndrome (CIS) refers to a first episode of neurologic symptoms caused by inflammation and demyelination in the central nervous system. Symptoms of CIS vary from person to person but commonly include:

• Vision problems (optic neuritis)
• Vertigo
• Loss of sensation in the face
• Weakness in the arms and legs, with one side of the body affected more than the other
• Loss of control of bodily movements (ataxia)
• Bladder problems

To meet the definition of CIS, the episode must last at least 24 hours. Though an episode like this is typical of MS, not all people who have CIS go on to develop MS.

A person with CIS has a high likelihood of a second episode of neurologic symptoms and a diagnosis of relapsing-remitting MS if an MRI (magnetic resonance imaging) shows brain lesions that are similar to those seen in MS. Without those lesions, the likelihood of an MS diagnosis is much lower.

According to the 2017 diagnostic criteria for MS, a person with CIS may be diagnosed with MS if a brain MRI shows:

• Specific signs of an earlier episode of damage in a different location and
• Active inflammation in a region other than the one causing the current symptoms

As MRI technology improves, diagnosing MS will be quicker and easier. In the meantime, people with CIS who are considered at high risk for developing MS may be treated with a disease-modifying therapy with approval for that purpose from the U.S. Food and Drug Administration (FDA). Studies show that early treatment of CIS delays the onset of MS.

This graphic shows the kinds of disease activity that may occur in RRMS over time. But each person’s experience with RRMS is unique. After a relapse, the new symptoms may disappear without causing a higher level of disability. Or they may partially disappear, also resulting in higher disability. As part of a relapse, an MRI often detects new lesions, as shown by the arrows. However, the person may not notice symptoms of the new lesions that indicate MS activity.

Secondary progressive MS (SPMS) follows the initial relapsing-remitting course. Some people diagnosed with RRMS eventually go on to have a secondary progressive course, in which neurologic function worsens progressively or disability accumulates over time. SPMS may be:

• Not active or
• Active, with relapses or signs of new MRI activity during a specified period of time 
• Without progression or
• With progression or signs of disability accumulation over time, with or without relapses or new MRI activity

This graphic shows the kinds of disease activity that may occur in SPMS over time. But each person’s experience with SPMS is unique. SPMS follows relapsing-remitting MS. Disability increases over time, with or without signs of disease activity or relapses, or changes on an MRI. In SPMS, the person may have occasional relapses, as well as periods of stability.

With PPMS, neurologic function worsens or disability accumulates as soon as symptoms appear, without early relapses or remissions. PPMS may be:

• Not active or
• Active, with an occasional relapse or signs of new MRI activity over a specified period of time
• Without progression or
• With progression or signs of accumulating disability over time, with or without relapse or new MRI activity

Approximately 15% of people with MS are diagnosed with PPMS.

This graphic shows the kinds of disease activity that may occur in PPMS over time. But each person’s experience with PPMS is unique. PPMS can have brief periods of stability, with or without a relapse or new MRI activity. It can also have periods of increasing disability, with or without new relapses or lesions on an MRI.