The ear is a very delicate organ responsible for both hearing and balance. The mastoid cavity is a pocket of air cells within the bone behind the ear that can sometimes become chronically infected. On occasion, recurrent infections will result in a hole in the eardrum. The hole may then result in additional ear infections, ear drainage, and ear pain. Sometimes an abnormal growth called a cholesteatoma can form in the mastoid cavity or the space behind the ear drum. This is a benign growth that can do a lot of damage to the ear and can result in chronic infection. As the cholesteatoma grows it can erode the normal tissues including the bones of hearing or the balance center.