Located behind the ear, the mastoid bone connects to the middle ear and, when healthy, is filled with air. Infection or disease in the ear or elsewhere can cause the mastoid to fill with fluid, mucus or excess tissue (such as a cholesteatoma, a benign tumor that may grow out of a healing perforated eardrum and cause hearing damage). When medications and other non-surgical treatments such as antibiotics or professional cleaning fail to resolve the problem, mastoidectomy may be performed. Complications from surgery are rare but may include drainage from the ear, infection, temporary dizziness or loss of taste on one side of the tongue.