Infections of the outer ear usually clear up completely in about a week without long-term complications. In some cases, however, people develop a chronic infection of the outer ear that extends to inflammation of the surrounding skin. A few people, most often those with diabetes or a weakened immune system, may develop a severe infection of the bone and cartilage near the outer ear that can cause severe pain and spread to the brain. This rare but potentially life-threatening complication requires treatment with intravenous antibiotics and sometimes surgery.
In addition to these a large irregular cavity is situated at the upper and front part of the bone. It is called the tympanic antrum , and must be distinguished from the mastoid cells, though it communicates with them. Like the mastoid cells it is filled with air and lined by a prolongation of the mucous membrane of the tympanic cavity, with which it communicates. The tympanic antrum is bounded above by a thin plate of bone, the tegmen tympani , which separates it from the middle fossa of the base of the skull ; below by the mastoid process; laterally by the squama just below the temporal line , and medially by the lateral semicircular canal of the internal ear which projects into its cavity. It opens in front into that portion of the tympanic cavity which is known as the attic or epitympanic recess . The tympanic antrum is a cavity of some considerable size at the time of birth; the mastoid air cells may be regarded as diverticula from the antrum, and begin to appear at or before birth; by the fifth year they are well-marked, but their development is not completed until toward puberty .