While there is no way to predict with any certainty how an individual’s disease will progress, four basic MS disease courses (also called types or phenotypes) have been defined by the International Advisory Committee on Clinical Trials of MS in 2013
: clinically isolated syndrome, relapsing remitting, secondary progressive and primary progressive. In 2020, the same committee published a clarifying paper
, highlighting the need for time framing the modifiers “activity” and “progression” and guidance for using the terms “worsening” or “progression” to describe the disease.
Although not considered a course of MS, radiologically isolated syndrome (RIS)
has been used to classify those with abnormalities on MRI of the brain and/or spinal cord consistent with lesions of MS - not explained by another diagnosis - and who also have no past or current neurological symptoms or abnormalities found on neurological exam. Often these individuals have had an MRI because of other symptoms, such as headache, and were found to have lesions that appear similar to those seen in MS.
A 2020 study
found a little over half of people with RIS go on to develop MS within ten years. There are no specific treatment guidelines for RIS and additional research is needed to further define what factors increase the likelihood that someone with RIS will develop MS. Monitoring of MRI and neurological symptoms, and neurological examination are generally recommended to quickly identify changes. If the diagnosis is MS, treatment can be started early. Research interest in RIS is high and several studies are ongoing
, which could provide more guidance for monitoring and treatment.