Mastoidectomy is a surgery done to remove mastoid air cells, which is part of the skull bone, behind the ear. There are various types of mastoidectomies, and this is dependent on the condition that you have and the extent of the disease. This surgery is done under General Anaesthesia. Most commonly, you would have a C shaped scar hidden behind your ear. Other times, there might just be a small scar just at the top of the ear, near the hair line. The most common reasons to undergo this surgery would be if you have cholesteatoma, or infection of the mastoid air cells (otomastoiditis). Mastoidectomy can also be done as part of other procedures, such as tympanoplasty (repair of ear drum perforation), cochlear implant and ossiculoplasty.