What are the different types of MS?

No two cases of MS are exactly the same. Each person will have a different set of symptoms, and the timing and severity of relapses, as well as disease progression, will differ from person to person. However, doctors and researchers do use certain terms to characterize the nature of a person's condition. 

To better develop appropriate management plans, MS has typically been divided into classifications, or types. At diagnosis, a person is most likely to be classified as having one of the following:

  • Clinically-Isolated Syndrome (CIS)  – A first and single neurological episode of inflammation or demyelination in the central nervous system lasting at least 24 hours, considered to be probable MS.
  • Primary-Progressive (PPMS) – in PPMS, the progression of neurological dysfunction and/or disability is present from the onset of MS, without any distinct relapses or remissions. Temporary, minor improvements may be experienced, but are not common.
  • Relapsing-Remitting MS (RRMS) – This form of MS is, by far, the most common form of the disease. RRMS is defined by clearly identifiable attacks lasting days or weeks, with periods between relapses being stable and absent of disease progression. After an attack, many people experience a full recovery, but some will experience residual loss in mental or physical function upon recovery. 

Those diagnosed with RRMS may eventually transition to a fourth category: 

  • Secondary-Progressive (SPMS) – Begins with an RMS classification that becomes consistently progressive and includes more frequent relapses with minor remission. Loss of physical and mental function are accumulated without recovery between attacks.

Over time, healthcare providers will monitor whether a person’s classification changes and may describe the state of the person’s MS with these terms:

  • Active Experiencing relapses of neurological symptoms, or has new or enlarging lesions visible on MRI.
  • Inactive/Stable – No apparent relapse or progression is noted.
  • Worsening – Experiencing an increase in neurological dysfunction or disability as a result of either relapses or progression.
In describing which treatments are effective, these categories may be grouped together. Relapsing forms of MS (RMS)  is a category which may include CIS, RRMS, and active SPMS. Progressive forms of MS (PMS) is a category which includes inactive/worsening SPMS and PPMS.