Disease Modifying Treatment Options in Very Early Onset Multiple Sclerosis—What Choice for Onset Under Age 5 Years?

Background/Objectives: Very early pediatric onset multiple sclerosis (POMS) is rare; clinical studies using disease modifying treatments (DMTs) have not been performed. Clinicians rely on studies performed at older age. This review resulted due to difficulties faced by clinicians and off label use of DMTs at this age. Methods: A literature review be-tween 1980 – 2025 of very early POMS with onset before age 5 has been performed searching for outcome without or with DMTs. The curated database of the selected patients was analyzed using computed descriptive and integrated cohort-level estimates. The clinical, paraclinical, treatment and outcome characteristics were analyzed. Statistical analysis used JASP, with GenAI-assisted verification. Treatment outcome of a 16 year old patient with very early POMS starting at 2 years 4 months that consecutively received interferon, immunoglobulins and natalizumab is presented. Results: 101 patients with very early POMS presented at onset ataxic syndrome (57.4%), pyramidal syndrome (41.4%), ophthalmoplegia (10.3%) and optic neuritis (6.9%). In evolution 22.7% had seizures. Half of the patients were not treated. Among those treated, acute steroid therapy was administered; 11 received DMTs: interferon, glatiramer acetate, dimethyl fumarate, azathioprine (three) and only two – high-efficacy therapies (natalizumab, rituximab). Our patient had partial remission under interferon, relapses when stopped and replaced by immunoglobulins and 9 years relapse-free interval when natalizumab was introduced. Conclusions: Early treatment with high efficiency DMTs should be considered in very early POMS; association with known increased neuroplasticity at this age may improve prognosis, allowing good recovery of acquired disability.