The middle ear is an important space for the hearing, being involved, just like the tympanic membrane and the auditory ossicles, in the transport of the sound waves from the ear canal to the sensory organ, the inner ear (cochlea), where the vibrations are transformed into electric impulses which the auditory nerve carries to the brain where they are finally “decoded”. Since the sound transfer in the middle ear is a mechanical process, impairments affecting this part of the ear can generally be repaired by anatomic surgical interventions, hence operations of the middle ear.
Hearing Impairments Due to Disorders Affecting the Eardrum and the Auditory Ossicles
The most frequent reason for middle ear surgery, aimed at improving the hearing, is damage caused by a chronic inflammation or the so-called otosclerosis.
Chronic Middle Ear Infections (Otitis Media Chronica)
Chronic inflammations of the middle ear are typically characterized by a perforation of the eardrum. There are two different types: a defect in the central part of the tympanic membrane (mesotympanic eardrum perforation) and a marginal defect of the eardrum (bone suppuration, cholesteatoma, epitympanic middle ear infection).
The mesotympanic otitis media, involving a central defect of the tympanic membrane is the less harmful variant of the chronic middle ear infection. Although there is a perforation of the tympanic membrane, the hearing impairment may only be slight and the typical symptoms, such as ear discharge or ear pain are only very mild or even absent. The disorder can be treated by a middle ear surgery (tympanoplasty), which consists of the repair of the eardrum with a tissue graft taken from the patient‘s body and the reconstruction of the ossicular chain (hammer, anvil and stirrup), if it is damaged. Generally, titanium implants are used to replace the auditory ossicles.
If the patient suffers from a suppurative otitis media with eardrum defect, a tympanoplasty has to be performed prior to the use of a hearing aid.
In the case of a chronic epitympanic otitis media with marginal defects of the eardrum the bone is usually damaged. There is a progressive accumulation of horny scales in the middle ear which continuously grow and may destroy the bone walls and the auditory ossicles (cholesteatoma). Such a cholesteatoma is frequently accompanied by a bacterial infection which aggravates the existing disorders affecting the middle ear and causes a fool-smelling secretion and sometimes pain. Given the risk of a propagation of the bacterial infection to vital structures, such as the meninges and even the brain, the cholesteatoma, once diagnosed, requires an urgent surgical treatment!
Surgical Treatment of Chronic Middle Ear Infections
A tympanoplasty, including the reconstruction of the auditory ossicles and the repair of the eardrum to improve the hearing, is generally a short operative procedure which can be performed under local or general anaesthesia. For the restoration of the ossicular chain (malleus, incus, stapes) Prof. Dr. Alexander Berghaus uses either the auditory ossicles of the affected patient and rearranges them or an artificial ossicle replacement prosthesis, generally made from titanium. The eardrum is repaired with fascia or periosteum and cartilage.
Under favourable circumstances the surgery can be carried out on an outpatient basis. Otherwise, a stay in hospital is required, which is, however, not longer than 3 days.
If the patient suffers from a cholesteatoma, the primary goal of the surgery is the removal of the cyst. Afterwards, it may be necessary, depending on the case, to remove the alterations in the middle ear caused by the inflammation either by an endaural approach through the ear canal or by a postauricular approach through the mastoid process (2-way operation). The cholesteatoma removal surgery may require a stay in hospital of several days.
The surgery is primarily aimed at the complete removal of the cholesteatoma. The secondary goal is the restoration of a good hearing. Therefore, the cholesteatoma removal is generally combined with a surgery to improve the hearing, which may, however, also be performed later as a separate surgical procedure. In most cholesteatoma cases a second surgery (the so-called “Second Look”) is anyway recommended about one year after the initial surgery to check whether a new cholesteatoma has developed in the meantime. Within a period from 9 to 12 months such a recurring cyst is usually still very small and can be completely removed by a microscopic surgery. Frequently, the “Second Look” is combined with a surgery to improve the hearing, if necessary.
Further useful information about related issues
- Hearing impairment treatment