Azevedo, Christina

Radiologically isolated syndrome (RIS), in which asymptomatic demyelinating-appearing lesions are detected incidentally on MRI, can be a pre-clinical form of multiple sclerosis (MS). In this study, we measured cerebellar volumes on 3D T1-weighted 3T MR images in 21 individuals with RIS and 38 age- and sex-matched healthy controls (HC). Normalized cerebellar white matter volume and the anterior cerebellar gray matter volume were significantly decreased in RIS compared to HC ( p = 0.003 and p = 0.005, respectively). Our findings support reports of regional brain atrophy in RIS prior to the development of a seminal attack related to inflammatory demyelination.

ObjectiveThe aim of this work was to evaluate the preprogressive phase in subjects with radiologically isolated syndrome (RIS) who evolve to primary progressive multiple sclerosis (PPMS).MethodsA multicenter RIS cohort was previously established. Demographic, clinical, and radiological characteristics of subjects with RIS that evolved directly to PPMS were compared to those that developed a relapsing disease course from onset (clinically isolated syndrome [CIS] or relapsing‐remitting MS) and were also compared to two other population‐ and clinic‐based PPMS cohorts.ResultsOf the 453 subjects with RIS, 128 evolved to symptomatic MS during the follow‐up (113 developed a first acute clinical event consistent with CIS/MS, 15 evolved to PPMS). PPMS prevalence (11.7%) and onset age (mean ± standard deviation; 49.1 ± 12.1) in the RIS group were comparable to other PPMS populations (p > 0.05). Median time to PPMS was 3.5 years (range, 1.6–5.4). RIS evolved to PPMS more commonly in men (p = 0.005) and at an older age (p < 0.001) when compared to CIS/MS, independent of follow‐up duration. Subjects who evolved to PPMS had more spinal cord lesions (100%) before symptomatic evolution than those that developed CIS/MS (64%) and those that remained asymptomatic (23%) within the follow‐up period (P = 0.005). Other MRI characteristics in the preprogressive phase of PPMS were indistinguishable from CIS/MS.InterpretationSubjects with RIS evolve to PPMS at the same frequency as expected from general MS populations in an age‐dependent manner. Besides age, unequivocal presence of spinal cord lesions and being male predicted evolution to PPMS. Our findings further suggest that RIS is biologically part of the MS spectrum. Ann Neurol 2016;79:288–294