Most common extracranial complication of ASOM is
Facial nerve paralysis
Lateral sinus thrombosis
Subperiosteal abscess
Brain abscess
Pus may break through mastoid coex leading to subperiosteal abscess which may even burst on surface leading to a discharging fistula It occurs as a sequence of mastoiditis Ref: Dhingra 7e pg 84.
Ear