[Update guide on pediatric multiple sclerosis].

Multiple Sclerosis (MS) is a chronic, immune-mediated demyelinating disorder of the central nervous system. Approximately 10% of cases present before 18 years of age, constituting paediatric-onset MS (POMS). Compared with adults, children with MS exhibit higher relapse rates and shorter intervals between the first event and subsequent relapses, yet generally demonstrate better recovery. The latest revision of the diagnostic criteria (2024) incorporates: the optic nerve as an additional location; specific MRI radiologically isolated syndrome; and CSF kappa free light chain as an adjunctive biomarker. In paediatric populations, the typically high burden of inflammatory lesions and high relapse rate warrants special consideration. The principal differential diagnosis is MOG-antibody-associated disease, Evidence indicates that early initiation of high-efficacy disease-modifying therapies is associated with improved long-term outcomes.