Commonest extracranial complication of CSOM
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 which is a most common complication Ref: Dhingra 7e pg 84.
Petrositis
Labyrinthitis
Subperiosteal abscess
Facial nerve paralysis
Ear