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Ruptured or Perforated Eardrum
ALTERNATIVE NAMES: None
DEFINITION: A hole in the eardrum.
WHAT IS GOING ON IN MY BODY? The eardrum is the dividing line between the external and middle ears. The external ear is formed by the auricle (pinna) and the external ear canal, whereas the middle ear is the air-filled space behind the eardrum which contains the three small bones for hearing (the ossicles). The eardrum is thus an important barrier between the environment and the middle ear. The tympanic membrane is a three-layered structure. On its outer layer is a very thin layer of skin. Its inner layer is a thin layer of mucous membrane. The middle or fibrous layer is what provides most of the eardrum strength and rigidity. In its protective capacity it prevents high pressure either in the form of air or water from exerting a direct effect on the delicate membranes covering the oval and round windows. If these oval and round window membranes rupture from excessive application of pressure, then temporary or permanent deafness or vertigo can result. The eardrum also is an effective barrier against contamination of the middle ear and mastoid by non-sterile material, such as contaminated water. The eardrum also has an important purpose in hearing. It is approximately 17 times greater in size than the oval window in which the foot plate of the stapes sits. This ratio provides approximately 20 decibels of amplification of sound. This difference in surface area coupled with lever action of the ossicles provides approximately 25 decibels of total sound amplification by the eardrum and ossicles.
A perforation in the tympanic membrane can occur via a variety of mechanisms. Severe infections that compromise its blood supply will cause a portion of it to die and break down. If the perforation occurs from an infection, often infected material will drain into the ear canal. Chronic infections cause perforations in the tympanic membrane. Tuberculosis is particularly notable for multiple small perforations. PE tube placement can cause a perforation in approximately 3% of the children in whom they are placed. Trauma is probably the most common cause of eardrum perforation. Water skiers who fall directly on their ear often suffer tympanic membrane perforations. Traumatic perforations are often associated with blood in the ear canal.
WHAT ARE THE SIGNS AND SYMPTOMS? In the individual suffering from traumatic perforation, they will often complain of immediate decline in hearing and some tinnitus along with bloody ear drainage. Those whose perforations develop from infection will often have symptoms consequent to the acute infection (see acute otitis media) superimposed upon which is infected, bloody material draining from the ear canal. Once the drum perforates, pain lessens. In cases of tuberculosis perforations, the drainage is mostly watery and clear along with the hearing loss. The degree of the hearing loss depends very much upon the size and location of the perforation. Because of the amplification provided by the surface area ratio between the eardrum and oval window, any reduction in eardrum size will affect this ratio, with a subsequent decline in amplification. Location is also critical in determining the severity of the hearing loss. The inner ear has two fluid-filled compartments, one of which is inside the other. The stapes sits in the membrane-covered oval window. As the stapes moves inward caused by application of sound pressure upon the eardrum, the round window moves outward. Conversely, if the eardrum moves outward, the stapes will move outward, and the round window will move inward. Anything that obstructs flow of fluid between the oval and round windows will affect hearing. Normally the intact eardrum prevents sound waves from impacting directly on the round window. If sound happens to hit the round window and the eardrum at the same time, the sound will move the stapes inward, but that same sound going through the perforation will hit the round window and also force it inward. Therefore, the round and oval windows will move in the same direction, thus blocking the fluid wave from moving through the inner ear, with failure to vibrate the membranes in the inner ear responsible for generating the nerve response. In this particular case, there may be up to a 40-decibel loss of hearing, whereas a similar-sized perforation in a different part of the eardrum would cause a much less severe degree of hearing impairment.
Upon examination a hole in the eardrum can be visualized. If it is a result of acute infection, there will be pulsating, infected-looking fluid. If it is from tuberculosis, there will be multiple small perforations with watery drainage. If the perforation is from trauma, there will usually be blood in the middle ear, around the edges of the perforation, and also in the external canal. Some holes are quite difficult to see. With a hole in the eardrum, application of air into the ear canal during observation (pneumatoscopy) will not make the eardrum move. That is a very important observation, particularly if the perforation is not immediately visible. In a perforated eardrum there will be no eardrum movement, and conversely if the eardrum is intact, it will move to the application of positive and negative pressure. A hearing test is often useful to quantify the degree of the hearing loss. If there is associated vertigo, it is important to get a hearing test to see if there has been damage to the nerve portion of hearing.
WHAT ARE THE CAUSES AND RISKS? As previously mentioned, the main cause is trauma. Other less frequent causes of eardrum perforation are tube placement, acute otitis, chronic otitis media, tuberculosis, and slag burns from welding. It is worth mentioning also that barometric pressure changes either with rapid changes in pressure, such as with aircraft flying or scuba diving (see ear barotrauma), can create a tympanic membrane perforation. Individuals who have had previous perforations or chronic eustachian tube dysfunction which has caused the eardrum to thin are more susceptible. If the eardrum perforates and spontaneously heals, it heals without its middle fibrous layer which gives its tensile strength and instead heals with the two thinner inner and outer skin and mucous membrane layers respectively. As a result, the healed tympanic membrane perforation is weaker than the native eardrum and thus is more susceptible to perforation by barometric pressure trauma or infection.
HOW TO PREVENT THE DISEASE: Appropriate antibiotic therapy in an individual with an acute infection usually resolves the infection in a short period of time. The sooner an acute ear infection is treated, the less likely the eardrum will perforate. Avoiding self-induced trauma, such as with Q-tips, will clearly prevent this form of traumatic drum perforation. The other traumatic forms would be much less preventable. For those individuals who are scuba diving and have an upper respiratory tract infection or active allergies, avoiding this activity is the only way to prevent ear barotrauma.
HOW IS IT DIAGNOSED? It is diagnosed based upon physical examination. Examination of the eardrum will demonstrate the perforation. When air pressure is increased or decreased in the ear canal using an air bulb attached to the otoscope, the drum will not move as it normally would if it were intact. For very small perforations a tympanogram may be useful. A tympanogram not only measures eardrum movement but also ear canal volume. If there is a perforation in the eardrum, the normal upside down V-shaped curve will be flat, and the volume measurement will be dramatically increased because not only is the volume of the ear canal being measured, but because the ear canal communicates to the middle ear and mastoid via the perforation, then the total ear canal, middle ear, and mastoid volume will be measured. A hearing test can also be useful to quantify the degree of the hearing deficit.
WHAT ARE THE LONG-TERM EFFECTS? An unrepaired tympanic membrane puts the middle and inner ear at risk for additional barometric pressure injury or damage from infections. Therefore, the main reason to repair an eardrum is to provide a safe ear. Eardrum perforations, as mentioned above, can affect the hearing.
AM I PUTTING OTHERS AT RISK? No.
WHAT ARE THE TREATMENTS? When an eardrum perforation is immediately confirmed, it is important to instruct the patient to keep contaminated or soapy water out of the ear canal and to avoid blowing the nose and elevation changes, all of which can serve to either create an infection or maintain an open perforation. Most traumatic and infectious perforations will heal spontaneously. Perforations following extrusion of the pressure equalization tube will often heal, but up to 3% do not. For the acute traumatic perforation where the edges of the eardrum are blown inward, spontaneous closure can be facilitated by lifting the imploded edges outward and placing a paper patch. For small perforations resulting from PE tubes or other causes, removing the mature edge of the perforation followed by placement of a small piece of fat is an effective way of repair. For larger perforations, tissue is usually harvested from the temporalis muscle (the chewing muscle located in the temple), and this is then placed either under the eardrum or on its outside surface to act as a scaffold for the drum to heal over. On the horizon are use of growth factors which may facilitate non-surgical closure.
WHAT ARE THE SIDE EFFECTS TO THE TREATMENTS? There are no side effects to observing the perforation to see if it will spontaneously close. For those individuals requiring surgical repair, the main side effects would be taste disturbance, failure of the repair to work, or hearing loss. Those individuals with perforations in both tympanic membranes have a higher failure rate of repair.
WHAT HAPPENS AFTER TREATMENT? After successful treatment, the protective barrier effect of the eardrum is restored, and hearing in most cases recovers to a completely normal state.
HOW DO I MONITOR THE DISEASE? In those individuals with traumatic perforations, as the perforation closes the hearing should improve. If the hearing loss fails to recover, that suggests that a residual perforation exists. For an individual with a known perforation who gets water in the middle ear, antibiotic ear drops should be placed to prevent ear infection from occurring. Continued or recurrent episodes of drainage must prompt medical attention to ensure that chronic otitis media is not occurring.
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