Etiology and Diagnosis
A patient with a perforated tympanic membrane can develop chronic otitis media. This is defined as a chronic ear infection with drainage out the ear canal (otorrhea). The long-standing infection slowly erodes the middle ear ossicles, causing ossicular chain discontinuity. Occasionally, the infection can spread to the inner ear causing permanent sensorineural hearing loss, to the facial nerve causing facial nerve paralysis, or to the brain causing meningitis or a brain abscess.
Chronic otitis media can also lead to a cholesteatoma. A cholesteatoma is a skin growth that occurs behind the eardrum. It is usually caused by repeated ear infections associated with poor Eustachian tube function. Over time, the cholesteatoma increases in size and destroys the delicate middle ear bones. Eventually, it may erode into the inner ear and cause permanent hearing loss or dizziness. It may grow to involve the facial nerve causing facial paralysis. In some instances, cholesteatomas can expand up into the brain.
Chronic otitis median and/or cholesteatoma are a serious conditions that requires prompt treatment. Initially, this involves careful cleaning of the ear, antibiotics, and eardrops. Often, computed tomography (CT scan) is helpful to define the extent of the disease. This also can act as a road map for surgery.
Most patients with chronic otitis media and nearly all patients with cholesteatoma require surgery to cure the disease. This involves making an incision behind the ear, drilling out the infection from the mastoid bone behind the ear, and removing cholesteatoma from the middle ear space or mastoid air cells. Also, the eardrum is rebuilt. The surgery is called a tympanoplasty with mastoidectomy. There are two types of mastoidectomies: canal-wall-up and canal-wall-down.
A canal-wall-up procedure means that the ear canal is maintained and the location of the eardrum is in its normal location. Thus, when a physician not specialized in ear surgery looks in your ear canal, he may not know that you have had surgery. The downside to having a canal-wall-up tympanoplasty with mastoidectomy is that residual cholesteatoma within the middle ear or mastoid space may grow asymptomatically, until it reaches an extremely large and dangerous size. So, most physicians who perform canal-wall-up procedures recommend a "second-look" procedure 6-12 months after the first surgery. This is basically the same as the first surgery but since most of the work has been done, it is usually a somewhat shorter procedure.
A canal-wall-down procedure means that the ear canal is removed and opened up into the mastoid cavity behind the ear. This is called a mastoid bowl. In most cases, it is quite obvious to any physician who looks in the ear that surgery has been performed because the ear canal is no longer a tube, it is a large cavity. A standard part of this procedure is a meatoplasty. This means that the ear canal is surgically enlarged, in order to permit proper aeration of the mastoid bowl and reduce the chances of infection. Most patients need to have their mastoid bowl cleaned out by an otolaryngologist every 6-12 months. This is because the normal process of the ear canal to extrude earwax and debris has been disrupted. A second look operation is usually not needed after a canal-wall-down tympanoplasty with mastoidectomy, because any residual cholesteatoma can be easily seen and removed in clinic.
With either a canal-wall-up or canal-wall-down, an ossicular chain reconstruction to rebuild the middle ear bones may be considered. This can be done at the time of the first surgery or at a second surgery 6-12 months later. This length of time is preferred because it gives time after the first surgery for the ear to heal. If a second surgery for ossicular chain reconstruction is planned, many surgeons will place a piece of Silastic into the middle ear space. This is a thin sheet of rubbery plastic that prevents scar tissue from forming between the eardrum and the inner ear, simplifying the second surgery.
Results of Surgery
The primary goal of surgery for chronic otitis media and cholesteatoma is to remove all infection and cholesteatoma. Hopefully, this will stop the ear from draining, and prevent further complications later on in life. A good result may be expected in 80 to 90 percent of the cases. The secondary goal is to improve your hearing. Failure to improve hearing is not a complication. Success depends almost as much on the ability of the body to heal and preserve the reconstruction as it does on the surgeon's skill. Fortunately, even those cases that fail may be revised. For more information, see Information on Surgical Risks and Postoperative Instructions.