Otitis media is inflammation of the middle ear: the small space between the ear drum and the inner ear. It is one of the two categories of ear inflammation that can underly what is commonly called an earache, the other being otitis externa. An important fact is that many diseases can cause ear pain other than ear infections, including cancers of any structure that shares nerve supply with the ear, so unexplained ear pain calls for a complete and detailed examination by an otolaryngologist (ear, nose, and throat physician). Otitis media is very common in childhood, with the average toddler having two to three episodes a year, almost always accompanied by a viral upper respiratory infection (URI), also known as the common cold. The rhinoviruses (nose viruses) that cause the common cold infect the eustachian tube that goes from the back of the nose to the middle ear, causing swelling and compromise of pressure equalization, which is the normal function of the tube. In general, the more severe and prolonged the compromise of eustachian tube function, the more severe the consequences are to the middle ear and its delicate structures. If a person is born with poor eustachian tube function, this greatly increases the likelihood of more frequent and severe episodes of otitis media. Progression to chronic otitis media is much more common in this group of people, who often have a family history of middle ear disease.