Description

• The tympanic membrane (TM), or “eardrum,” is a thin, three-layered barrier that separates the external auditory canal (EAC) from the middle ear space and hearing bones (ossicles). Along with the ossicles, the TM helps transmit and amplify sound vibrations to the inner ear/cochlea.
• The TM consists of an outer squamous layer, contiguous with the EAC skin; the middle fibrous layer with both peripheral fibers and central radial fibers that provide support; and the inner mucosal layer, contiguous with the middle ear lining.
• Rupture of the TM can disrupt hearing and also can allow pathogens access to the middle ear space from the EAC.
• Perforations may be classified by location:
  • Central: does not involve the annulus and is more likely to heal spontaneously
  • Marginal: lies in the periphery, involves the annulus; may be associated with cholesteatoma; is less likely to heal and harder to repair
  • Involvement of the malleus decreases chance of spontaneous healing.
  • Perforations of the posterior-superior quadrant overlie the ossicles and are often associated with more extensive damage.
  • When a TM perforation heals, the mucosal and squamous layers reepithelialize, but the fibrous layer won’t reform, resulting in a thinner two-layer membrane (paradoxically termed “monomeric”).
• Classification of perforations by etiology:
  • Infectious: acute/chronic suppurative otitis media
  • Traumatic: barotrauma (e.g., diving), acoustic trauma (e.g., explosion), self-inflicted/penetrating (Q-tips, bobby pins)
  • Middle ear mass: cholesteatoma or neoplasm
  • Iatrogenic: persistent perforation after myringotomy tube placement or secondary acquired cholesteatoma
• The TM possesses the ability for spontaneous closure resulting in formation of a dimeric membrane (outer squamous and inner mucosal). However, if this does not occur, a persistent perforation will result.

Epidemiology

Incidence in the general population is unknown because many perforations heal spontaneously.

Genetics
Genetic susceptibility has been reported for recurrent acute otitis media (AOM) and chronic otitis media with effusion (COME), two etiologies that may lead to the complication of TM perforation (1)[C].

General Prevention

Preservation of eustachian tube function, avoiding insertion of foreign bodies and objects into the EAC, and prompt treatment of significant infection and inflammation of the ear reduces the chances of perforation.

Risk Factors

• Eustachian tube dysfunction and inability to equalize middle ear pressures
• Rapid changes in ambient pressures (air flight or deep-water diving)
• Insertion of objects into ears, frequent cotton tip use
• Head trauma, exposure to explosions

Etiology and Pathophysiology

• Barotrauma: sudden or large changes in the pressure differential across the TM (such as in air flight, proximity to explosions, or diving underwater)
• Direct penetration of the TM by a foreign object
• Otitis media: Purulent, inflammatory process leads to ischemia and necrosis of the TM.
• Inflammation and erosion results from neoplasm, cholesteatoma, and localized infection.

Commonly Associated Conditions

• Chronic eustachian tube dysfunction (craniofacial abnormalities, such as cleft, may predispose)
• Otitis media with effusion (OME)
• Recurrent AOM
• Cholesteatoma
• Tympanosclerosis
• Ossicular chain damage (from traumatic perforation)