High Dose Steroids in Children With Stroke

Inclusion Criteria: 1. Informed consent of the legal representative of the trial participant documented by signature 2. Age \> 6 months \& \< 18 years at time of stroke 3. Randomisation possible within 48 hours of diagnosis and maximum 96 hours after stroke onset 4. Unilateral arteriopathy according to the following criteria: * Newly acquired neurologic deficits * Specific neuroimaging (MRA) features of either * unilateral stenosis, or * unilateral vessel irregularities within the Central Nervous System (CNS) 5. Unless otherwise defined in the national addendum: Female participants age ≥ 13: Negative pregnancy test (blood or urine) Exclusion Criteria: 1. Previous stroke 2. Known syndromal disorders, as e.g. Trisomy 21, Neurofibromatosis type 1 3. Known genetic vasculopathies as e.g. posterior fossa anomalies, hemangioma, arterial anomalies, cardiac anomalies and eye anomalies syndrome (PHACES), actin alpha 2 (ACTA II) 4. Moyamoya or sickle cell disease 5. Small vessel cerebral vasculitis (primary CNS vasculitis) 6. Bilateral arteriopathy 7. Arterial dissection(s) 8. Evidence of underlying systemic disorders, as e.g. lupus, rheumatoid problems 9. Secondary CNS angiitis due to infections (meningitis, endocarditis, borreliosis), or generalised angiitis due to rheumatic or other autoimmune problems 10. Progressive large to medium childhood primary angiitis of the CNS (cPACNS ) with 2 of the following 3 criteria: 1. pre-existing progressive neurocognitive dysfunction 2. bilateral MRI lesions/vessel involvement 3. small vessel arterial stenosis 11. On steroid treatment at disease onset 12. Contraindication to steroid treatment as e.g. a congenital or acquired immunodeficiency 13. Inability to follow the procedures of the study, e.g. due to language problems 14. Participation in another interventional study within the 30 days preceding the indication stroke and during the present study