Tympanic Membrane Perforation
A tympanic membrane perforation can be caused by many different things. Traumatic tympanic membrane perforations are quite common. Sticking things in the ear (like a Q-tip, bobby pin, or pencil) or getting slapped on the ear are common causes of a hole in the eardrum. Occasionally, welders may have a hot metal slag fly down the ear canal. Tympanic membrane perforations caused by a hot slag are notoriously difficult to heal presumably because the heat traumatizes the surrounding tissue, preventing normal healing. Also, a large pressure wave caused by a slap to the ear or being close to an explosion can cause a perforation.
Ear infections are another common cause of tympanic membrane perforations. Even one really bad ear infection may lead to a perforation if the pressure of the pus behind the eardrum causes the eardrum to rupture. Repeated mild ear infections can also cause a perforation of the eardrum.
In most cases cases, patients usually complain of hearing loss. They may also notice that if they blow their nose forcefully, they can hear air coming out of their ear. In some situations, the sound may be audible to other people as well. This surprising symptom occurs because nose blowing forces air up the Eustachian tube and into the middle ear space. If the eardrum is intact, it balloons outward: If the eardrum is perforated, the air rushes out the perforation and may be audible.
Patients with tympanic membrane perforations may have episodic ear infections. While the normal middle ear space is sterile, a perforated eardrum permits the bacteria and fungus that reside within the ear canal to enter the middle ear. An infection can then develop, causing pus to drain out through the perforation into the ear canal. Although patients usually do not have pain, they typically notice that there is a wet spot on their pillow under the infected ear. The drainage typically occurs for a few days to weeks at a time, and then stops. It may come back periodically, possibly related to activities in which water gets into the ear. Seasons with high humidity levels also predispose patients with tympanic membrane perforations to getting an ear infection.
Tympanic membrane perforations can usually be diagnosed by routine examination of the ear with an otoscope. Occasionally, wax or drainage may occlude the ear canal so that the eardrum can not be seen. In this situation, the physician should either clean the ear canal, prescribe eardrops for a few weeks to help remove the debris, or refer the patient to an otolaryngologist. When a tympanic membrane perforation is identified, it is important to note how much of the tympanic membrane is involved. A central perforation does not involve the edge of the eardrum (the annulus), whereas a marginal perforation does. This is important because central perforations heal better than marginal perforations.
A hearing test is important to obtain in patients with a tympanic membrane perforation. Usually, a conductive hearing loss is found. The degree of conductive hearing loss is variable. Small perforations away from the ossicles (the middle ear bones), may cause only a slight hearing loss that is barely noticeable to the patient. Larger perforations or those that are around the ossicles cause larger degrees of hearing loss. It is uncommon for the inner ear to be affected in patients with a tympanic membrane perforation and so typically no sensorineural hearing loss is found. However, if sensorineural hearing loss is found in the affected ear, inner ear involvement must be considered. In the case of traumatic tympanic membrane perforation, this may suggest injury to the connection of the third ossicle (the stapes) with the inner ear. In the case of tympanic membrane perforation secondary to infection, the possibility of cholesteatoma should be considered.
Most patients with a traumatic tympanic membrane perforation do not require any specific treatment they have an excellent chance of healing spontaneously. This is especially true for central perforations. Data show that within one month 6 percent are healed, and within three months 94 percent are healed. However, strict dry ear precautions are best followed to prevent water from getting into the ear. Instructions to the patient include no swimming and the use of a Vaseline-soaked cotton ball in the affected ear during bathing. A hearing test should be performed after 2-3 months to verify that hearing has returned to normal. If not, it is possible that an ossicular chain injury is present.
Patients with a tympanic membrane due to repeated ear infections are a different story. The underlying problem for these patients is Eustachian tube dysfunction. The Eustachian tube connects the middle ear to the back of the nose (the nasopharynx), and functions to equalize the middle ear pressure. If this tube does not function properly, middle ear fluid and/or repeated ear infections can result. If a perforation occurs, it will probably not heal spontaneously.
Surgery to patch a hole in the tympanic membrane is indicated for non-healing perforations. Either a paper patch myringoplasty in the office (for a small, dry, central perforation caused by trauma) or a formal tympanoplasty in the operating room can be performed (for a large central perforation, a marginal perforation, or a perforation caused by an ear infection).
Tympanoplasty involves rebuilding the eardrum and the middle ear bones, if needed. This is an outpatient surgery that usually takes about two hours. An incision is made behind the ear and the ear canal is entered from behind. The tympanic membrane is elevated and the middle ear space inspected. If there is no evidence of cholesteatoma (see below) or other complication of chronic ear disease, the edges of the perforation are cleaned and a tissue graft is placed under the perforation. Usually, the tissue graft is the outer layer of the temporalis muscle (the muscle used for chewing that you can feel in the side of your head). This causes no injury to the muscle itself, and does not have side effects. Absorbable gelfoam packing is placed into the middle ear space to support the patch in place, pressing it up against the tympanic membrane. Further packing is placed on top of the tympanic membrane, so as to sandwich the patch and the tympanic membrane together. The incision behind the ear is then closed with sutures and a mastoid dressing applied. The mastoid dressing consists of a large gauze wrap around the head, to compress the ear against the side of the head.
The rate of successful repair of a tympanic membrane perforation is about 90 to 95 percent. The chance of a successful repair is improved if the ear is dry and uninfected. Also, if a patient has had a previous tympanoplasty that was unsuccessful, the success rate of revision surgery is somewhat reduced. Some patients have such poor Eustachian tube function that complete repair of their perforation is impossible. Tympanoplasty will patch most of the perforation, but a small residual hole persists. This hole acts like a pressure equalization tube, to equalize middle ear and atmospheric pressures when the Eustachian tube does not work like it should.
See Tympanic Membrane, Middle Ear and Mastoid Disease for additional information.