Radiologically isolated syndrome (RIS) and primary progressive multiple sclerosis (PPMS)

Prior to developing MS, some people have symptoms which suggest an inflammatory-demyelinating disease. These people, who don’t fulfil the criteria to be diagnosed with definite MS, are diagnosed with clinically isolated syndrome (CIS). CIS is an early indicator of MS, but not all people with CIS will go on to have definite MS.

Like CIS, radiologically isolated syndrome (RIS) is another early indicator of demyelination but with no symptoms. RIS is usually detected incidentally in healthy people who have an MRI that shows typical MS lesions. These people may remain asymptomatic (have no symptoms), or go on to develop CIS or MS. Therefore, RIS may represent the earliest indicator of MS before symptoms appear.

A paper recently published in Annals of Neurology aimed to evaluate the predictive factors in people with RIS who evolve to primary progressive MS (PPMS).

Of the 453 people with RIS who were involved in this study, 128 went on to experience MS symptoms, of which 15 developed PPMS, during the follow-up.

According to the authors, people with RIS evolve to PPMS at the same frequency as expected from general MS populations, in an age dependent manner. Besides age, clear presence of spinal cord lesions, and being male also predict evolution to primary progressive MS.

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