What does it mean if the arteries around your brain are inflamed?

Risky business: This implies arteritis or vasculitis and several variations exist. Need to specify a diagnosis as prognosis does vary. But here's the point, the blood vessels can obstruct and decrease blood flow, which results in stroke. The weakened arteries may rupture causing a hemorrhage. Hopefully, your question does not relate to you or close ones, but if so, discuss with physicians.