How did fluid get into your mastoid airfields?

Fluid can enter the mastoid air cells due to various conditions, most commonly middle ear infections (otitis media) or sinus infections, which can cause inflammation and fluid buildup. If the Eustachian tube becomes blocked, it can prevent proper drainage, leading to fluid accumulation in the middle ear and subsequently in the mastoid air cells. Additionally, trauma or structural abnormalities in the ear can also contribute to fluid buildup in these areas.