How much radiologically isolated syndrome suggestive of multiple sclerosis is multiple sclerosis?

Abstract

In spite of the progress in Neuroimmunology, a specific biomarker for the diagnosis of multiple sclerosis (MS) remains to be defined. Meanwhile, as growing enthusiasm has been associated with the development of new therapeutic options and the recent evidence that the disease-modifying agents may be more beneficial for MS patients if initiated as early as possible following disease onset 1 , investigators and clinicians alike continuously search for early signs of the disease.The incorporation of specific magnetic resonance imaging (MRI) features for dissemination in space and in time 2,3 into the diagnostic criteria for MS by the International Panel 4 and their revisions in 2005 5 and 2010 6 have allowed the earlier diagnosis of MS in patients, who still lack complete clinical evidence of dissemination in both space and time. However, the occurrence of symptoms consistent with neurologic dysfunction of the central nervous system still lingers as a basic requirement for its diagnosis. Additionally, as long as a specific biomarker is not introduced into clinical practice, alternative diagnoses must be excluded.The diagnosis of MS is particularly challenging in a group of patients who present no history of symptoms consistent with MS or objective signs of neurologic dysfunction, whose brain MRI shows abnormal signals with spatial dissemination, which is highly suggestive of demyelinating disease. Such findings have been described in first-degree relatives of patients with MS who are at particular risk 7 , in some subjects with history of psychiatric disorders 8 , and surprisingly in other patients who undergo MRI scans for reasons that were not related to the MS investigation. The term radiologically isolated syndrome (RIS) was recently introduced to describe these individuals 9 . In this Issue of Arquivos de Neuro-Psiquiatria, Maia Júnior et al. 10 report their observations on the clinical and imaging features of 12 Brazilian patients with RIS during a median follow-up period of 49 months. Reasons for acquisition of brain MRI in their cohort as in other published series varied widely. The most frequent reasons for the first MRI scan in RIS patients in the reported series included migraine and other types of headache; trauma and radiculalgia; depression; epilepsy; endocrinopathies; and cognitive dysfunction. One half of the patients in the Brazilian cohort showed temporospatial dissemination of the MRI lesions on a second MRI scan during the follow-up period, whereas two subjects developed symptoms of neurologic dysfunction, as a clinically isolated syndrome (CIS), or recurring symptoms compatible with the diagnosis of clinically definite MS (CDMS).Similar features of the Brazilian series had already been demonstrated in a French cohort in the initial description of RIS, in 2008 11 , and in subsequent published series 9,12,13 . In the published cohorts, during the follow-up period, many patients not only developed an increased number of T2-lesions on MRI, an evidence of temporospatial dissemination -and the...