The diagnosis of otoclerosis has been established as the cause of your hearing impairment. Otosclerosis means hardening of one of the bones of the ear. Approximately one-third of all persons with impaired hearing have this condition. Since otosclerosis is hereditary, someone in your family had this condition and passed it down to you. You may not be aware of the presence of the hearing loss in your family because it may date back many generations. The fact that you have otosclerosis does not necessarily mean that your children will be affected. Because otosclerosis is hereditary, diseases such as scarlet fever, ear infections, measles, influenza, etc., have no relationship to its development.
In your case, even before you knew you had a hearing impairment, had we been able to examine your inner ear under a microscope, we would have seen minute areas of hardening (sclerosis). When this hardening process spreads to involve the stapes bone, a conductive (mechanical) hearing loss results, due to impairment of its vibrations.
Appropriately identified adults as well as profoundly deaf children (starting at age 12 months) can be implanted. Research demonstrates that the earlier a deaf child is implanted, the better the long term result will be with respect to speech and language development. Following surgery, rehabilitation is necessary, as the child must learn to associate the sound signals with normal sounds. Regarding deaf adults, research suggests that adults who receive cochlear implants are less lonely, have less social anxiety, are more independent, have increased social and interpersonal skills, and of course, they hear better with the cochlear implant!
FUNCTION OF THE NORMAL EAR
The ear is divided into three parts: the external ear (the outer ear canal), the middle ear and the inner ear. Sound vibrations enter the external ear canal and cause the ear drum membrane (tympanic membrane) to vibrate. Movements of the tympanic membrane are transmitted across the three middle ear bones (hammer or malleus, anvil or incus and stirrup or stapes). These middle ear bones act as a transformer, changing sound vibrations in air into fluid waves in the inner ear. The fluid waves bend delicate nerve endings (hair cells) in the cochlea and electrical impulses occur. These electrical impulses then are transmitted by the hearing nerve (cochlear nerve) to the brain, where they are interpreted as understandable sounds.
CAUSES OF HEARING IMPAIRMENT
If there is some difficulty in the external (outer) or middle ear, a conductive hearing impairment occurs. If the hearing loss is secondary to problems in the inner ear, a sensorineural hearing impairment occurs (as a result of the loss of hair cells). When there is difficulty in both the middle and inner ear, a mixed or combined impairment exists. Mixed impairments are common in otosclerosis because of stapes fixation and also because of the bony changes which occur in the cochlea.
HEARING IMPAIRMENT FROM OTOSCLEROSIS
Usually otosclerosis spreads to the stapes or stirrup bone. This stapes bone is positioned in a small groove called the oval window and is in intimate contact with the inner ear fluids. As a result of the inability of the stapes bone to vibrate the inner ear fluid, a conductive hearing impairment occurs. This type of impairment is called stapedial otosclerosis and is usually correctable by surgery.
The amount of hearing loss due to involvement of the stapes (stapedial otosclerosis), and the degree of hair cell loss (cochlear otosclerosis) present, can be determined only by a careful hearing test.
When otosclerosis spreads to the inner ear, a sensorineural hearing impairment (hair cell loss) may result due to interference with the inner ear function. This hearing impairment is called cochlear otosclerosis and once it develops it is permanent. This otosclerosis disease process affects the cochlea because the disease releases enzymes which are toxic to the hair cells and leads to cochlear deterioration. In addition, there are some other connective tissue changes which result in bone destruction. This process, however, is limited to the ear and involves no other organs. When one has otosclerosis it may affect only the stapes, the inner ear or both areas. In selected cases, medication may be prescribed in an attempt to prevent further hair cell loss and subsequently prevent further inner ear damage. This medication is sodium fluoride. On occasion the otosclerosis may spread to the balance canals and may cause episodes of unsteadiness or dizziness.
SYMPTOMS OF OTOSCLEROSIS
Progressive hearing loss is the most typical symptom of the stapedial type of otosclerosis. In pure cochlear otosclerosis a sensorineural hearing loss is the main finding. The hearing loss appears to be accelerated by pregnancy. In addition to a hearing loss, some patients experience dizziness or unsteadiness. It is more like dysequilibrium and not usually vertigo. Often the dizziness or dysequilibrium disappears after a stapes operation. Most patients with otosclerosis notice tinnitus (ear noise) to some degree. Tinnitus develops due to changes in the hearing pathway. It is usually more apparent when the patient is fatigued, nervous, or in a quiet environment. The amount of tinnitus is not necessarily related to the degree of hearing impairment. Following successful stapes surgery, the tinnitus is often decreased.
TREATMENT OF OTOSCLEROSIS
There is no local treatment to the ear itself or any medication that will improve the hearing in persons with otosclerosis. In some cases medication (sodium fluoride) is used to prevent further loss of hearing. This is given to those patients who have evidence of having hair cell loss, as a result of involvement of the cochlea.
The stapes operations are recommended for patients with otosclerosis who are candidates for surgery. This operation is performed under local or general anesthesia and requires a short period of hospitalization and convalescence. Over 90 percent of these operations are successful in restoring hearing permanently.
For the stapes operation to be successful in restoring hearing in otosclerosis, the hearing nerve must be able to receive and transmit sound to the brain. Careful and thorough hearing tests are necessary to determine the hearing nerve function.
Whenever an ear is operated upon, there is a chance that the hearing could be made worse or lost altogether. The possibility of this happening differs from one operation to another and may occur even if the surgery goes well and there are no complications.
If you are a suitable candidate for surgery, you are also suitable to benefit from a properly fitted hearing aid. If you have otosclerosis and are not suitable for stapes surgery, you still may benefit from a properly fitted hearing aid.
If you are suitable candidate for surgery, and do not wish to have the stapes operation at this time, it is advisable to have a careful hearing test repeated at least once a year.
Fortunately, patients with otosclerosis very seldom go “totally deaf.” Some will be able to hear with an electronic aid.