She said it was meant to be a slap on the cheek but it caught me on the ear. And now I have blood in my ear and trouble hearing—not to mention the dizziness and crazy ringing. After removing the blood and examining me under the microscope, the doctor says there is a hole in the eardrum, a perforation that will probably heal on its own. But if it does not heal, the hole will require surgical repair called tympanoplasty. I won’t be making any more jokes about my mother-in-law’s new surgically enhanced lips.
The tympanic membrane (eardrum or TM) is a thin, round structure that is located between the external ear canal and the middle ear (see chapter 1). It plays several important roles. First, it seals off the middle ear from water, debris, and bacteria present in the outer ear canal. In concert with the middle ear bones, the tympanic membrane also amplifies the sound pressure coming into the ear by twenty-two times. When the TM is perforated, middle ear infection and hearing loss are common and all water must be kept out of the ear to prevent infection.
A perforation (or hole) in the eardrum creates a communication between the external, bacteria-filled world and the sterile middle ear cavity. This can lead to recurrent bouts of middle ear infection, especially if the ear is exposed to water, as this will carry bacteria through the perforation into the middle ear space.
Larger perforations of the eardrum can cause substantial hearing loss. There is also a risk of epithelial (skin) growth from the outer surface of the eardrum to its undersurface. This can lead to the formation of a destructive growth called cholesteatoma in which skin debris builds up into a cyst that can destroy bony structures of the middle ear.
Causes of Perforation
Infection
The most common cause of perforation is otitis media, infection of the middle ear (see chapter 4). When the infection progresses, inflammation weakens the TM and pressure builds behind it, ultimately becoming severe enough to rupture the drum and allow the fluid to drain. Patients experience this as a severe ear pain that quickly goes away when the drum ruptures and relieves the pressure.
Pressure
Barotrauma (damage caused by changing pressure) is another common cause of TM perforations. Extreme changes in atmospheric pressure—for example, when descending in an airplane or diving underwater—will cause sharp pain, and bleeding from the ear may be noted. Barotrauma can also occur following open-hand blows to the ear where a pressure wave travels down the ear canal and ruptures the drum.
Trauma
People sometimes accidentally rupture their own eardrums with cotton swabs or other objects. Another cause of perforation in children is ear tubes used for chronic or recurrent infection or hearing loss. Approximately 2.5 percent of children who receive tubes will develop perforations.
Figure 18.1
The eardrum may rupture because of an infection like otitis media, a penetrating injury (caused by a cotton swab or sharp object), or a compression injury (caused by a slap or other trauma). Most perforations are self-healing, but the larger ones may require an operation called tympanoplasty to repair.
Self-Healing Perforations
The eardrum has a strong tendency to heal itself. Even eardrums that have been perforated multiple times can still close themselves. It is reasonable to observe a new small- to medium-sized perforation for a period of time to determine if the perforation will close itself. It is critical to maintain strict water precautions during this period of observation, as infection will tend to prevent the drum from healing. There are no exact definitions of an adequate period of observation, but three to six months is commonly used. Larger perforations (greater than 50 percent of the surface area of the drum), perforations with evidence of skin ingrowth, or those which continue to drain infectious material may be considered for earlier surgical treatment.
Tympanoplasty
When holes in the eardrum do not heal on their own it is necessary to perform surgery, called tympanoplasty, to close them. By grafting new tissue onto the eardrum the surgeon is able to restore the separation between the external ear canal and the middle ear and recreate a distinct middle ear space. Doing this restores hearing to an optimal status and helps avoid the risk of forming a cholesteatoma (see chapter 20).
There are many techniques used in performing a tympanoplasty, but all of them have in common sealing the perforation with a graft. The graft usually consists of the patient’s own living tissue. Once it heals into place, skin of the outer surface of the drum grows over it to complete the repair. Determining the best approach to surgery and the ideal graft material to use is critical to success.
Surgical Techniques
A number of criteria are considered for determining the best approach. The size of the perforation is one critical factor. Tiny, non-healing perforations may be amenable to a simple office procedure in which a small graft is inserted through the perforation or a paper patch is placed over the hole. Total loss of the eardrum may require much more extensive surgery under general anesthesia. The location of the perforation may also be a consideration. For example, certain approaches address perforations in the back half of the eardrum better than perforations in the front half.
The most common technique is the underlay method (also called medial graft). In this approach the ear canal skin and eardrum are lifted up and the graft is placed under the perforated eardrum. Grafts are held in place by dissolvable packing. The incision may be limited to the inside of the ear canal if perforations are small and in the back half of the eardrum. In children or adults with small ear canals, a separate incision is necessary in the crease behind the ear. This posterior incision may also be required for larger perforations or those in the front of the eardrum. The underlay technique is fast and effective, frequently taking less than an hour.
The overlay approach (also known as the lateral graft approach) is more complex. It involves reconstructing the entire ear canal and eardrum. It is sometimes necessary to use this technique to repair large perforations as well as in revision cases. It typically has the highest success rate in difficult cases, but is technically more challenging and takes longer to perform. Healing time is also longer, typically two to three months as opposed to the one-month period average for the underlay tympanoplasty.
The approach involves an incision behind the ear, but then all of the skin of the ear canal and the eardrum is removed. The bony ear canal is then widened using a drill. A graft is placed over the remaining elements of the eardrum and the skin of the ear canal replaced in such a way that it overlays the edges of the graft. Dissolving packing is placed to hold the graft and skin in place.
Graft Material
A number of different materials, from the patient’s own veins to cadaver eardrums, have been used over the years to close eardrum perforations. Fat grafts, cigarette paper, and other man-made substances are still used to repair tiny perforations. But at the present time, the majority of grafts come from the lining of muscle (fascia) behind the ear and are about the size of a postage stamp.
After Surgery
Following surgery, mild pain can be expected. Because the ear is full of packing, a temporary blockage of hearing is likely. After a week or so, patients are usually placed on antibiotic ear drops to dissolve the packing. It is crucial to keep water out of the ear canal when bathing. Swimming is not allowed for six to eight weeks or more. Any remaining packing is removed one month after surgery.
Success Rate
The success rate of tympanoplasty is in the range of 80 to 90 percent. Larger perforations and abnormal findings in the opposite ear are associated with poorer results. Success in adult patients may be slightly better than in children.
Complications of tympanoplasty include:
• bleeding (rare)
• infection (uncommon)
• additional hearing loss (rare)
• facial nerve injury (rare)
Middle Ear Reconstruction for Conductive Hearing Loss
Tympanoplasty for more advanced cases must often be combined with reconstruction of the middle ear bones in order to restore hearing. This is necessary when the bones of hearing do not function properly, a condition that may occur for several reasons outlined below.
Infection
Chronic infection is the most common cause of damage to the middle ear bones. Collapse of the eardrum in the setting of chronic ear infections frequently leads to erosion of the hearing bones, especially at the joint between the incus and the stapes. Infection may also lead to tympanosclerosis or cholesteatoma.
Although commonly seen as a white plaque in the eardrum, tympanosclerosis does not cause hearing loss unless the plaque enlarges and fuses the hearing bones in the middle ear. Patients with this condition usually complain of a progressive hearing loss. Upon examination, the physician will see a white discoloration through the eardrum. Surgical repair has inconsistent results and, if the stapes is involved, there is a risk of sensorineural hearing loss.
Cholesteatoma is discussed in chapter 20. It is a benign, expanding growth that usually occurs in people who have had chronic ear infections. Cholesteatomas are capable of resorbing bone that they come in contact with, often the incus and stapes.
Hearing loss is treated with hearing aids or surgical reconstruction. The surgical procedure consists of microsurgical replacement of the damaged bone. When the malleus or incus has been damaged, various biocompatible prosthetics can be used.
In an outpatient procedure under local or general anesthesia, the connection from the eardrum to the cochlea is restored. The surgery may be combined with tympanoplasty when there is a perforation of the eardrum. When there is no perforation, the surgical approach is similar to tympanoplasty, but without repair of the eardrum.
If the malleus or incus have been damaged, a partial ossicular replacement prosthesis (PORP) is used. Usually made of artificial bone (hydroxyapatite) or titanium, these prostheses connect the eardrum to the stapes. When the stapes is also fractured or eroded, a total ossicular prosthesis (TORP) is necessary to connect the eardrum directly to the cochlea. A cartilage graft is often used between the prosthesis and eardrum. Success rates for hearing improvement are about 80 percent for PORPs and 70 percent for TORPs.
Traumatic Dislocation
Dislocation of the hearing bones can occur with head trauma or injury of the eardrum with cotton swabs. The most common injury is dislocation of the joint between the incus and the stapes. Repair of this is usually delayed for at least three months after the injury to permit blood and fluid to clear from behind the eardrum. Repair can be accomplished by re-approximating the incus and stapes with a small prosthesis or by performing a stapedectomy if this is not possible.
Congenital Fixation
Fixation of the malleus occurs in about 1 percent of people and causes a mild to moderate conductive hearing loss. Less commonly the incus may be involved. To remedy this the skin of the ear canal and eardrum are lifted as in tympanoplasty and small bridges of bone that fuse the malleus to the surrounding bone are removed. Sometimes a spacer is placed to prevent regrowth in children. This is a highly effective outpatient procedure with a low complication rate.
Congenital anomalies of the stapes represent approximately 40 percent of all congenital ossicular lesions. Although many stapes abnormalities are possible, footplate fixation is the most common. Treatment is identical to that for otosclerosis (see chapter 19).