There are two types of chronic middle ear infection; a chronic perforation eardrum (tubotympanic type) and entrapment of skin in the middle ear (cholesteatoma).
- Tubotympanic type
In some patients with acute middle ear infection (acute otitis media), build-up of pus and pressure cause rupture of the eardrum with ear discharge into the external ear canal. The ruptured or perforated eardrum will heal spontaneously if treatment is instituted adequately and promptly. However, if the perforated eardrum does not heal and close after 3 months, it is considered a chronic perforation. These perforations will not heal and close without surgical intervention.
Symptoms include hearing loss and discharge when infected. Pain is not common because this is a chronic infection.
Treatment – control infection with toilet and antibiotic eardrops. Once infection is controlled, surgery is required to patch the perforated eardrum (myringoplasty).
- Cholesteatoma
When there is persistent Eustachian tube dysfunction, the air in the middle ear becomes absorbed and not replaced. Over time, the relative negative pressure in the middle ear sucks the eardrum inwards. The more flaccid top part of the eardrum is first to retract and a pocket forms. Skin, dirt, wax gets trapped in this pocket forming a cholesteatoma (). Cholesteatomas enlarge as the trapped contents cannot discharge itself and erodes surrounding structures like the bone, ossicles, and facial nerve.
Symptoms include hearing loss, discharge, and occasional ear discomfort. In later stages, permanent hearing loss with dizziness and unilateral (one-sided) facial weakness can occur. End stage symptoms will involve the brain causing headache, fever, neck stiffness, visual impairment.
Treatment
Surgery to excise the cholesteatoma is needed. This procedure is called mastoidectomy. The aim is to remove the whole infected cholesteatoma with the contents of skin, debris, wax etc. At the same time, if possible, to repair any damage to the ossicles (ossiculoplasty) and restore hearing.