Surgery to reconstruct the tympanic membrane (eardrum) can be performed either under local or general anesthesia. Many patients prefer to be completely asleep. In small perforations, the operation 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 operating microscope helps to enlarge the view of the ear structures, giving a more detailed image to the ear surgeon. 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, gaining access to the perforation. Once the hole is exposed fully, the perforated remnant is rotated forward, and the bones of hearing are inspected. There may be scar tissue and bands surrounding the bones of hearing. These can be removed either with micro hooks or laser.
Having identified the bones of hearing, the ossicular chain is pressed to determine if the chain is mobile and functioning. If the chain is mobile, then the remaining surgery concentrates on repairing the drum defect.
Tissue is taken either from the back of the ear or from the small cartilaginous lobe of skin in front the ear called the tragus. The tissues are thinned and dried. An absorbable gelatin sponge is placed under the drum to allow for support of the graft. The graft is then inserted underneath the remaining drum remnant and the drum remnant is folded back onto the perforation to provide closure.
Complete replacement of eardrum with cartilage graft / alternative method:
Very thin silastic sheeting is generally placed against the top of the graft to prevent it from sliding out of the ear, when the patient blows his nose or sneezes. A small amount of Gelfoam is also placed on the outside of the silastic to hold it into position in a so-called sandwich type layer (drawing).
If 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. Generally, the patient can return home within two to three hours. Antibiotics are given along with a mild pain reliever such as Tylenol or Tylenol with Codeine.
After about ten days, the packing is removed and a good evaluation can then be obtained as to whether the graft was successful. Water is kept away from the ear and blowing of the nose is discouraged. If there are allegies or a cold, further antibiotics and decongestant should be given. Most individuals can return to work after five or six days unless they perform heavy physical labor, in which case the patient can return after two or three weeks.
After three weeks, all packing is completely removed under the operating microscope in the office. It can then be determined whether the graft has fully taken. In over 90 percent of cases, the tympanoplasty procedure is successful and a hearing test is performed at four to six weeks after the operation.
Failure of tympanoplasty can occur either from an immediate infection during the healing period, from water getting into the ear, or from displacement of the graft after surgery. Most patients can expect a full “take” of the grafted eardrum and improvement in hearing. After three to four months, water can be allowed to enter the ear and the patient can even return to swimming.
If ossicular reconstruction is necessary in the tympanoplasty, then an overnight stay is often recommended. There can be imbalance and dizziness immediately after this procedure. Dizziness is uncommon in operations that only involve the eardrum itself. Besides failure of the graft, there may be further hearing loss due to unexplained factors during the healing process. This occurs in less than five percent of individuals undergoing the operation.. A total hearing loss from tympanoplasty surgery is rare. This occurs in less than one percent of operations. Postoperative dizziness and imbalance can be present for about a week after surgery and are usually very mild. If the ear becomes infected postoperatively, the risk of dizziness increases. Generally, all imbalance and dizziness will be resolved after a week or two.
Tinnitus or noises in the ear, particularly an echo-type feeling, may be present as a result of the perforation itself. Usually, with improvement in hearing and closure of the eardrum, these sensations clear up. However, tinnitus is unpredictable. In some cases, it can temporarily worsen after the operation. There is no explanation for this temporary situation, but it is rare for the tinnitus to be permanently worse after surgery.
A small nerve goes through the ear called the chorda tympany nerve. This nerve goes to the taste buds of the tongue. Should this nerve be stretched or cut during tympanoplasty surgery, there may be a transient period of one or two months after surgery where there is a slight metallic or salty taste to food. Generally, the nerve connections will regenerate and taste will return to normal. The abnormal taste sensation rarely lasts longer than six months.
Tympanoplasty with Ossicular (bone) Reconstruction
If the bones of hearing are eroded, then ossicular reconstruction (reconstruction of the bones of hearing) may be necessary at the time of tympanoplasty. In some cases, this can be determined before the surgery. In other cases, it only becomes obvious at the time that the ear is completely opened and examined under the microscope.
The ear surgeon must decide whether the bones of hearing can be reconstructed at the time of the reconstruction of the ear drum. In most cases, this is possible if the ear is dry and not infected. The most common bone erosion occurs at the tip of the incus (anvil). This bone normally connects to the stapes (stirrup bone) and the connection is normally only 1.5 mm (1/24th of an inch–lead pencil’s lead width) in thickness. With prior infections, the circulation to the bone can become obstructed. Infection can gradually wear away the connection to the point where the bone is no longer in contact with the stapes bone. This is called ossicular discontinuity, a break in the bony connection. One can think of the incus as the player arm of a phonograph and the stapes as the needle. If the player arm is not in contact with the needle, sound will not be transmitted with the same force as it would with a good connection.
Reconstruction of this type of ossicular discontinuity can be performed at the time of tympanoplasty surgery. There are several options. If the gap is small, it can be bridged by inserting a small piece of bone or cartilage taken from the patient at another site (behind the ear or from the lobe of tissue called the tragus in front of the ear). If there is a larger gap, then the incus bone is removed and modelled into a tooth-like prosthesis, using the operating microscope. This is then reinserted between the stapes and the malleus in order to reestablish continuity of the ossicular chain.
Other options include the insertion of a strut made out of an artificial bone, called hydroxy apatite. This artificial bone is porous and allows for the ingrowth of blood vessels and the complete assimilation of the artificial bone into the individual’s middle ear. With the modern day use of hydroxy apatite, there has been a marked reduction in the rejection of ossicular reconstruction prostheses.
Prior prosthetic devices were made out of porous plastics which had a much higher rejection rate.
In other less common ossicular reconstructions, the malleus (hammer) can become fixated by scar tissue or bony ingrowth to the lateral wall of the ear. In this “malleus fixation,” the bone must be separated from the canal wall and remodeled. Silastic or a plastic type of sheeting is often placed against the wall to prevent regrowth of new bone. Reconstruction in this instance often requires that the stapes and incus be separated from their connection to stop the transmission of the drill’s vibration which would damage the inner ear.