Large artery intracranial stenosis in young adults with ischaemic stroke

•Symptomatic large artery intracranial stenosis was found in nearly one in 10 ischaemic strokes among French young adults.•Atherosclerosis was the leading cause of intracranial artery stenosis.•Other causes of intracranial artery stenosis, namely moyamoya disease, dissection, vasculitis and reversible cerebral vasoconstriction syndrome, were much less frequent.•The cause of intracranial artery stenosis could not be determined in almost a quarter of the patients.