Radiologically isolated syndrome or subclinical multiple sclerosis: MAGNIMS consensus recommendations

The widespread use of brain magnetic resonance imaging (MRI) has greatly increased findings of unanticipated asymptomatic intracranial abnormalities of uncertain clinical significance. These incidental findings on brain MRI are of various nature and origin and only rarely include abnormalities that could be interpreted as inflammatory or demyelinating lesions(1). However, the increase of unexpected MRI alterations has overall augmented the awareness for findings that have the morphology, size, location and distribution highly suggestive of a demyelinating disease. This has led to the definition of radiologically isolated syndrome (RIS), which was recently introduced to describe those asymptomatic subjects with brain MRI abnormalities suggestive of multiple sclerosis (MS) and lacking historical accounts of prior demyelinating events or an identifiable better reason for the observed changes(2). Since its first description, RIS has been widely debated and the risk of RIS evolving into MS has been investigated. According to existing data, a number of RIS subjects evolve to MS over time, demonstrating that RIS, at least in some cases, represents a preclinical stage of MS. RIS, however, is an entity that still needs to be better defined, with a number of issues needing to be addressed. These include the lack of expert guidelines on the management of RIS subjects and criteria that can establish the extent to which MRI lesions fulfilling the RIS criteria in asymptomatic subjects may represent subclinical MS or may be related to abnormalities that are not related to MS. We provide here expert recommendations that can help distinguish between subjects with low risk of developing MS and those that can be diagnosed with subclinical MS. Suggestions for the management of subjects stratified by risk for a future demyelinating event will also be provided. A summary of the main proposed recommendations is given in Table 1.