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Tympanoplasty

 

By

Dr. T. Balasubramanian M.S. D.L.O.

Definition:

Tympanoplasty is defined as the surgical procedure which enables reconstruction of middle ear cavity and the conducting ossicular system (tympano- ossicular system).

The following surgical procedures are components of tympanoplasty:

1. Canal plasty

2. Meatoplasty

3. Myringoplasty

4. Ossiculoplasty

Canalplasty: Is widening of the external auditory canal. It should be considered to be an integral part of myringoplasty. This procedure should be performed before grafting anterior perforations of tympanic membrane as it gives necessary surgical access for repair. This procedure facilitates healing, cleansing and if needed a second stage ossiculoplasty.

Meatoplasty: Is used to enlarge the opening of lateral cartilagenous portion of external auditory canal. This enlargement should be in proportion to the size of the medial bony external auditory canal.

Ossiculoplasty: This procedure is used to reconstruct the damaged middle ear sound conducting ossicular system.

 

Aims of this surgical procedure:

a. Disease eradication

b. Restoration of middle ear aeration

c. Reconstruction of sound transmission mechanism

d. Creation of self cleansing dry cavity

 

Desired Preoperative investigations:

Tubal function tests

Tubal funtion tests is very important for proper surgical planning and to assess the chance of a possible hearing improvement. If tubal function tests are negative, blockage if any at the tympanic end of the eustachean tube. If any scar tissue is present in that area it should be meticulously removed to pave way for better ventilation of the middle ear cavity.

Radiological investigation:

Xray of temporal bones / CT scan temporal bones will be a reliable indicator for pneumatization of temporal bone. A well pneumatized temporal bone indicates a normally functioning eustachean tube. Sclerosed mastoid indicates supressed due to infantile otitis media or blocked eustachean tube.

Temporary closure of perforation with wet gelfoam: This helps to assess the condition of ossicular chain / status of round and oval windows. If hearing improves when the perforation is temporarily occluded with a gelfoam plug then it indicates normally functioning middle ear sound conduction mechanism.

Fistula test: Should always be performed before surgery. If it is positive then surgery should be deferred as this would lead to dead ear.

Pre op preparation:
1. Surgery should be ideally performed in a dry ear. The ear must be cleaned before surgery. Systemic / topical antibiotics should be administered to reduce the likelihood of infection.

2. A persistently draining ear is a problem. If the secretion is purulent then it should be swabbed and sent for culture and sensitivity. This will help in prescription of drugs to which the microbes are sensitive to. A predominantly clear mucoid secretion from the ear is definitely related to hyperplastic changes of middle ear mucosa, hence ear swab for culture sensitivity is not necessary.

3. Hair is shaved above and behind the ear about 2 cms. The ear canal is plugged with sterile cotton when the area of surgery is disinfected with povidone iodine. The external auditory canal is not disinfected.

Anesthesia:

Local / General

Position: Supine. The head should be positioned slightly lower than the plane of the table. The angle between the head and shoulder should be between 100 - 130 degrees to allow adequate working space for the surgeon's hands.

Surgical approach:

Transcanal approach:

In this approach surgery is performed through the ear speculum inserted into the external auditory canal. This approach is indicated in:

a. Patients with wide external auditory canal

b. There is no overhanging bony wall obscuring the rim of the perforation

Figure showing transcanal approach

Figure showing transcanal view of ear drum

 

Endaural approach: In this approach the incision is made between the tragus and helix. An endaural speculum is introduced to widen the entrance into the external auditory canal. If posterior overhang is persent it can be easily burred out. If this approach is used better anterior visualization of the ear drum is possible.

 

 

Figure showing endaural approach

Figure showing endaural view of ear drum

 

Post aural approach:

Mastoid bone and the external auditory canal is approached via a post aural incision of William Wilde.

This approach is useful in cases of:

1. Narrow external auditory canal as it would improve exposure and facilitate canalplasty

2. In perforations involving the anterior portion of the ear drum

 

 

Figure showing post aural approach

 

 

 

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