Tympanoplasty Health Article

Definition

Tympanoplasty, also called eardrum repair, refers to surgery performed to reconstruct a perforated tympanic membrane (eardrum) or the small bones of the middle ear. Eardrum perforation may result from chronic infection or, less commonly, from trauma to the eardrum.

Purpose

The tympanic membrane of the ear is a three-layer structure. The outer and inner layers consist of epithelium cells. Perforations occur as a result of defects in the middle layer, which contains elastic collagen fibers. Small perforations usually heal spontaneously. However, if the defect is relatively large, or if there is a poor blood supply or an infection during the healing process, spontaneous repair may be hindered. Eardrums may also be perforated as a result of trauma, such as an object in the ear, a slap on the ear, or an explosion.

The purpose of tympanoplasty is to repair the perforated eardrum, and sometimes the middle ear bones (ossicles) that consist of the incus, malleus, and stapes. Tympanic membrane grafting may be required. If needed, grafts are usually taken from a vein or fascia (muscle sheath) tissue on the lobe of the ear. Synthetic materials may be used if patients have had previous surgeries and have limited graft availability.

Demographics

In the United States, ear disorders leading to hearing loss affect all ages. Over 60% of the population with hearing loss is under the age of 65, although nearly 25% of those above age 65 have a hearing loss that is considered significant. Causes include: birth defect (4.4%), ear infection (12.2%), ear injury (4.9%), damage due to excessive noise levels (33.7%), advanced age (28%), and other problems (16.8%).

Description

There are five basic types of tympanoplasty procedures:

• Type I tympanoplasty is called myringoplasty, and only involves the restoration of the perforated eardrum by grafting.
• Type II tympanoplasty is used for tympanic membrane perforations with erosion of the malleus. It involves grafting onto the incus or the remains of the malleus.
• Type III tympanoplasty is indicated for destruction of two ossicles, with the stapes still intact and mobile. It involves placing a graft onto the stapes, and providing protection for the assembly.
• Type IV tympanoplasty is used for ossicular destruction, which includes all or part of the stapes arch. It involves placing a graft onto or around a mobile stapes footplate.
• Type V tympanoplasty is used when the footplate of the stapes is fixed.

Depending on its type, tympanoplasty can be performed under local or general anesthesia. In small perforations of the eardrum, Type I tympanoplasty can be easily performed under local anesthesia with intravenous sedation. An incision is made into the ear canal and the remaining eardrum is elevated away from the bony ear canal, and lifted forward. The surgeon uses an operating microscope to enlarge the view of the ear structures. If the perforation is very large or the hole is far forward and away from the view of the surgeon, it may be necessary to perform an incision behind the ear. This elevates the entire outer ear forward, providing access to the perforation. Once the hole is fully exposed, the perforated remnant is rotated forward, and the bones of hearing are inspected. If scar tissue is present, it is removed either with micro hooks or laser.

Tissue is then taken either from the back of the ear, the tragus (small cartilaginous lobe of skin in front the ear), or from a vein. The tissues are thinned and dried. An absorbable gelatin sponge is placed under the eardrum to support the graft. The graft is then inserted underneath the remaining eardrum remnant, which is folded back onto the perforation to provide closure. Very thin sheeting is usually placed against the top of the graft to prevent it from sliding out of the ear when the patient sneezes.

If it was opened from behind, the ear is then stitched together. Usually, the stitches are buried in the skin and do not have to be removed later. A sterile patch is placed on the outside of the ear canal and the patient returns to the recovery room.