Hua, Le H.

Importance While the typical onset of multiple sclerosis (MS) occurs in early adulthood, 2% to 10% of cases initially present prior to age 18 years, and approximately 5% after age 50 years. Guidance on approaches to differential diagnosis in suspected MS specific to these 2 age groups is needed. Observations There are unique biological factors in children younger than 18 years and in adults older than age 50 years compared to typical adult-onset MS. These biological differences, particularly immunological and hormonal, may influence the clinical presentation of MS, resilience to neuronal injury, and differential diagnosis. While mimics of MS at the typical age at onset have been described, a comprehensive approach focused on the younger and older ends of the age spectrum has not been previously published. Conclusions and Relevance An international committee of MS experts in pediatric and adult MS was formed to provide consensus guidance on diagnostic approaches and key clinical and paraclinical red flags for non-MS diagnosis in children and older adults.

Objective The radiologically isolated syndrome (RIS) represents the earliest detectable pre‐clinical phase of multiple sclerosis (MS). This study evaluated the impact of therapeutic intervention in preventing first symptom manifestation at this stage in the disease spectrum. Methods We conducted a multi‐center, randomized, double‐blinded, placebo‐controlled study involving people with RIS. Individuals without clinical symptoms typical of MS but with incidental brain MRI anomalies consistent with central nervous system (CNS) demyelination were included. Within 12 MS centers in the United States, participants were randomly assigned 1:1 to oral dimethyl fumarate (DMF) 240 mg twice daily or placebo. The primary endpoint was the time to onset of clinical symptoms attributable to a CNS demyelinating event within a follow‐up period of 96 weeks. An intention‐to‐treat analysis was applied to all participating individuals in the primary and safety investigations. The study is registered at ClinicalTrials.gov , NCT02739542 (ARISE). Results Participants from 12 centers were recruited from March 9, 2016, to October 31, 2019, with 44 people randomized to dimethyl fumarate and 43 to placebo. Following DMF treatment, the risk of a first clinical demyelinating event during the 96‐week study period was highly reduced in the unadjusted Cox proportional‐hazards regression model (hazard ratio [HR] = 0.18, 95% confidence interval [CI] = 0.05–0.63, p = 0.007). More moderate adverse reactions were present in the DMF (34 [32%]) than placebo groups (19 [21%]) but severe events were similar (DMF, 3 [5%]; placebo, 4 [9%]). Interpretation This is the first randomized clinical trial demonstrating the benefit of a disease‐modifying therapy in preventing a first acute clinical event in people with RIS. ANN NEUROL 2023;93:604–614