Radiologically isolated syndrome as early multiple sclerosis: evolution of diagnostic criteria and management

Radiologically isolated syndrome (RIS) is currently considered an early preclinical stage of multiple sclerosis (MS). RIS is characterized by typical brain or spinal cord lesions indicative of autoimmune inflammatory demyelination.

The aim of the study was to assess the frequency of RIS according to the updated 2023 criteria among a cohort of the Novosibirsk MS Center and to determine the time to the first clinical episode of demyelination. A secondary objective of the study was to conduct a comparative analysis of MRI quality characteristics in subgroups of patients with and without two-year MRI activity, as well as in subgroups of patients with and without conversion to MS throughout the entire follow-up period.

Material and methods. The study design was retrospective, with analysis of baseline and follow-up data. MRI activity in patients with RIS was measured annually. Forty-five patients who met the 2023 RIS criteria were included in the analysis.

Results and discussion. MRI activity, defined as the appearance of two or more new lesions or one or more contrast-enhancing lesions, was detected in 30 of 45 (67 %) patients during two-year follow-up. Patients with MRI activity were more likely to progress to definitive MS than patients without MRI activity (53.0 and 6.7 %, respectively, p < 0.001). Multiple logistic regression confirmed an increased risk of developing a first clinical episode in the group of patients with subsequent MRI activity (odds ratio 16.01, 95% confidence interval 1.52–168.17, p = 0.02). Earlier diagnosis of multiple sclerosis at the preclinical stage became possible after the introduction of the updated McDonald criteria (2024). Among asymptomatic RIS patients, compliance with the new MS criteria was confirmed in 71 % (20/28).

Conclusions. The study confirmed the presence of spinal lesions on the initial MRI as a key prognostic risk factor for clinical conversion of RIS to MS. The use of user-friendly biomarkers in real-world clinical practice may increase the potential for personalized clinical intervention and requires further study.

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