1. Four Known Types of MS Clinically isolated syndrome (CIS)
Relapsing-remitting MS (RRMS)
About 85% of people are diagnosed with RRMS
Primary progressive MS (PPMS)
About 15% of people experience this course
Secondary progressive (SPMS)
Most people diagnosed with RRMS will eventually transition to SPMS
There are four known types of MS:
Clinically isolated syndrome: CIS is a first episode of neurologic symptoms caused by inflammation and demyelination in the central nervous system. It is characteristic of MS but does not yet meet the criteria for a diagnosis of MS. When CIS is accompanied by brain lesions on MRI that are similar to those seen in MS, the person has a high likelihood of a second attack and a diagnosis of MS. When no brain lesions are present, the likelihood is much lower.
Relapsing-remitting MS: People with this type of MS experience clearly defined attacks (also called relapses or exacerbations). These are episodes of acute worsening followed by partial or complete recovery periods (remissions) that are free of disease progression. RRMS can be further characterized as Active (with lesion activity and/or relapses) or Not Active AND Worsening (increased disability resulting from symptoms that do not completely disappear following a relapse) or Not Worsening.
Frequency: Most common form of MS at time of initial diagnosis. Approximately 85%.
Primary-Progressive: People with this type of MS experience a slow but nearly continuous worsening of their disease from the onset of symptoms, with no distinct relapses or remissions. However, there are variations in rates of progression over time, occasional plateaus, and temporary minor improvements. PPMS can be further characterized as Active (with MRI activity and/or relapses) or Not Active AND Progressing (showing a confirmed increase in disability over a given period of time) or Not Progressing.
Frequency: Approximately 15% of people are diagnosed with PPMS.
Secondary-Progressive: 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: The majority of people with relapsing-remitting MS will eventually transition to SPMS, although early and ongoing treatment with a disease-modifying therapy has been shown to delay SPMS in many people.

2. Lublin et al, 2014

3. The purple arrows indicate new lesion activity on MRI
The purple arrows indicate new lesion activity on MRI. MRI activity can occur very early in the disease course, even before a person is aware of any symptoms.
Over time, RRMS can be Active, with new MRI activity (light blue) and/or relapses (orange). Worsening can occur when symptoms do not fully resolve following a relapse (dark red), resulting in an accumulation of disability. Periods of stability can also occur, when no new MRI activity or relapses occur (dark blue).
Lublin et al, 2014

4. Primary progressive MS is characterized by progression of disability from the onset of symptoms, without any early relapses. PPMS can have periods when it is Active, with evidence of new MRI activity or a relapse and Progression of disability (dark red) or Active without any progression of disability (light blue). Progression of disability can also occur in PPMS without new MRI activity or relapses (green). Occasional periods of stability, without any MRI activity or relapses (dark blue).
Individuals who were previously diagnosed with Progressive relapsing MS would now be considered to have PPMS that is Active.
Lublin et al, 2014

5. This graphic shows that secondary progressive MS follows after relapsing-remitting MS. SPMS can be Active, with new relapses or MRI activity, and Progressing (dark red) and it can also be Active without any progression occurring (orange). In SPMS, the disease sometimes progresses without any new MRI lesions or relapses (green). Periods of stability (dark blue) can also occur, when there are no relapses or new MRI activity.
Lublin et al, 2014