Tympanoplasty

Markus Fichtl is a freelance writer in the medical department.

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In ENT medicine, tympanoplasty is a restorative intervention on the sound conduction apparatus of the ear to improve hearing. Reasons for this can be a perforation (perforation) of the eardrum or a break in the ossicular chain, i.e. the connection between the hammer, anvil and stapes. Read all about this surgical procedure, when it is performed, and the risks involved.

Physiology of sound conduction

The sound that enters the ear through the ear canal is transmitted from the eardrum to the small bones in the middle ear. These are connected to one another via joints and form a movable chain from the eardrum to the oval window, another structure between the middle and inner ear.

Due to the larger area of ​​the eardrum compared to that of the oval window and the leverage of the ossicles, the sound in the middle ear is amplified. The oval window transmits the vibration to the fluid in the cochlea in the inner ear. After the vibrations are perceived by the sensory cells, they finally fade out in the round window.

What is a tympanoplasty?

If part of the sound conduction chain in the middle ear is broken, hearing deteriorates. This can occur either through perforation of the eardrum or through displacement or destruction of one or more of the three small ossicles. In tympanoplasty, which roughly translates as "surgical repair of the tympanic cavity", this damage is treated surgically. "Tympanic cavity" here means the same as the inner ear.

Depending on which part of this sound conduction chain is affected, a distinction is made between the different variants of tympanoplasty in five types according to Wullstein. However, only types 1, 2 and 3 of these are of practical importance today.

When to do a tympanoplasty

Tympanoplasty is performed for:

• chronic otitis media, where the ossicles or eardrum have been damaged.
• Removal of a cholesteatoma - uncontrollably growing mucosal tissue from the ear canal or eardrum into the middle ear, which can cause inflammation.
• traumatic damage following external violence that damage or displace the eardrum and / or ossicles.
• other inflammatory, age-related or congenital damage to the sound conduction system.

A tympanoplasty usually eliminates the underlying problem directly, quickly and without major complications and improves hearing.

What do you do with a tympanoplasty?

Tympanoplasty is performed under the surgical microscope with very delicate instruments such as drills or milling machines. As a preventive measure, the patient is given antibiotics. Depending on the type of structures affected, five different basic types of tympanoplasty can be divided according to Wullstein:

Tympanoplasty type 1

The so-called myringoplasty corresponds to an exclusive reconstruction of the eardrum, the ossicles are undamaged and fully functional. Here, the hole in the eardrum can be covered with the body's own pieces of tissue made of connective tissue or cartilage.

Tympanoplasty type 2

The so-called ossiculoplasty (ossiculum = bones) corresponds to the restoration of the interrupted ossicular chain in the case of an anvil or hammer head defect and an intact stapes. This damage can be bridged with the eardrum or the remaining remnants of the ossicles. To do this, the eardrum is attached to the anvil after removing the hammer handle.

Tympanoplasty type 3

It is used for the direct transmission of sound pressure from the eardrum to the inner ear in the event of a defective ossicular chain. Here the hammer and anvil are defective, the stapes can, but need not, be affected. To bridge this defect, either part of the remaining anvil residue can be changed in its position or a ceramic or metal prosthesis (usually made of titanium) can be used. Once the stapes have been preserved, the prosthesis is inserted between it and the eardrum (stapes elevation or PORP (Partial Ossicular Chain Reconstructive Prosthesis)). If the stapes are also defective, the prosthesis is inserted between the eardrum and the stapes footplate (Columella effect or TORP (Total Ossicular Chain Reconstructive Prosthesis)). To bridge the defect in the middle ear, the eardrum is attached directly to the obtained stapes without an intermediate piece. The eardrum is shifted inwards a little and the tympanic cavity is reduced in size.

Type 4 tympanoplasty

It is performed when the ossicles are completely defective or missing. The sound pressure then falls from the eardrum directly onto the oval window (the “entrance” to the cochlea) and the round window (the “exit” of the cochlea). The simultaneous incoming sound causes turbulence in the liquid of the snail, which affects the hearing ability. To protect the round window from sound, the eardrum is separated in front of the oval window so that it lies directly in the sound and a new, smaller tympanic cavity is constructed above the round window.

Tympanoplasty type 5

It stands for a window arrangement to the oval semicircular canal with missing auditory ossicles and a scarred oval window. This technology has now been replaced by the so-called cochlear implant, an electronic inner ear prosthesis.

What are the risks of a tympanoplasty?

After a tympanoplasty, damage to the structures in the outer, middle or inner ear can result in various complications, such as:

• Renewed perforation of the eardrum
• Renewed displacement or damage to the ossicles or their replacement
• Changes in the sense of taste due to damage to the chorda tympani (taste nerve that partially runs through the middle ear)
• Unilateral paralysis of facial muscles due to damage to the facial nerve (nerve responsible for moving the facial muscles) - in this case, immediate restoration is necessary.
• Ringing in the ears (tinnitus)
• dizziness
• pains
• Prosthesis incompatibility with eardrum replacement
• No hearing improvement or even hearing deterioration or even deafness. For this reason, no tympanoplasty is performed in the case of deafness in the opposite ear or in the case of inner ear hearing loss, and no tympanoplasty in both ears at the same time.

What do I have to consider after a tympanoplasty?

Since the hearing-enhancing structures of the middle ear are largely restored with tympanoplasty type 1 to 3, the hearing ability mostly normalizes after the operation. This is not the case with tympanoplasty type 4 and 5, which is why noticeable hearing loss persists after the operation. In general, you should protect the ear after the operation and not expose it to strong external pressure changes. Avoid air travel, diving, mountaineering or loud music after a tympanoplasty. If your hearing does not improve, your doctor will recommend a hearing aid.

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