DEFINITIONS AND NATURAL HISTORY
Tympanic membrane perforations are holes in the eardrum that most commonly occur as a consequence of either ear infections, chronic eustachian tube dysfunction or trauma to the ear.
Acute middle ear infection (acute otitis media) is a common condition occurring at least once in 80% of children. Most acute otitis media resolves with spontaneous discharge of infected secretions through the eustachian tube into the nasopharynx.
Occasionally when the infections are frequent, there is extensive scarring (tympanosclerosis and myringosclerosis) of the ear drum and middle ear . This scarring compromises blood supply to the healing ear drum and occasionally stops the hole from healing.
Traumatically induced holes occur from a rapid compression of the air column in the external ear canal, most commonly from a blow to the side of the head. (Figure 2) In the Australian population this occurs most frequently either with water skiing and surfing accidents.
Cholesteatoma is an epidermal inclusion cyst within the middle ear, temporal or tympanic bone with a propensity for expansion, recurrent infection and destruction of surrounding structures. This condition typically presents as a perforation in the a!ic or margins of the ear drum.
The condition has an incidence of approximately one in 10,000 in adults and one in 30,000 in children.
The vast majority of cholesteatoma is acquired and is thought to evolve when negative pressure in the middle ear space, from long-term eustachian tube dysfunction, causes development of a collapsed eardrum known as a “retraction pocket “in the tympanic membrane. Accumulation of debris within the retraction pocket leads to gradual expansion and recurrent infection.