This editorial illustration was created for a September 2013 cover of American Family Physician. The image summarizes Otitis Media, infection of the middle ear. Although several subtypes of otitis media are distinguished, the term is often used synonymously with acute otitis media. It is very common in childhood. An integral symptom of acute otitis media is ear pain; other possible symptoms include fever, and irritability (in infants). Since an acute otitis media is usually precipitated by an upper respiratory tract infection, there often are accompanying symptoms like cough and nasal discharge.
The common cause of all forms of otitis media is blockage of the Eustachian tube. This is usually due to swelling of the mucous membranes in the nasopharynx, which in turn can be caused by a viral upper respiratory infection or by allergies. Because of the blockage of the Eustachian tube, the air volume in the middle ear is trapped and parts of it are slowly absorbed by the surrounding tissues, leading to a mild vacuum in the middle ear. Eventually the vacuum can reach a point where fluid from the surrounding tissues is sucked in to the middle ear’s cavity (also called tympanic cavity), causing middle ear effusion.
Acute otitis media (AOM) is usually developing on the basis of a (viral) upper respiratory infection with blockage of the Eustachian tube and effusion in the middle ear, when the fluid in the middle ear gets additionally infected with bacteria. The most common bacteria found in this case are Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis.
As its typical symptoms overlap with other conditions, clinical history alone is not sufficient to predict whether acute otitis media is present; it has to be complemented by visualization of the tympanic membrane as shown in this illustration.