otosclerosis

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Otosclerosis

 

Definition

Otosclerosis is an excessive growth in the bones of the middle ear which interferes with the transmission of sound.

Description

The middle ear consists of the eardrum and a chamber which contains three bones called the hammer, the anvil, and the stirrup (or stapes). Sound waves passing through the ear cause the ear drum to vibrate. This vibration is transmitted to the inner ear by the three bones. In the inner ear, the vibrations are changed into impulses which are carried by the nerves, to the brain. If excessive bone growth interferes with the stapes ability to vibrate and transmit sound waves, hearing loss will result.
Otosclerosis is classified as a conductive disorder because it involves the bones of the ear, which conduct the sound to the nerve. If a person has hearing loss classified as neural, the nerve conducting the impulses to the brain is involved.
Otosclerosis is a common hereditary condition. About 10% of the caucasion population has some form of otosclerosis, however, it is rare among other ethnic backgrounds. Women are more likely than men to suffer from otosclerosis. It is the most common cause of conductive hearing loss between the ages of 15-50, but if the bony growth affects only the hammer or anvil, there are no symptoms and the condition goes undetected. Disease affecting the stapes is also associated with progressive hearing loss.

Causes and symptoms

Otosclerosis is hereditary. Acquired illness and accidents have no relationship to its development.
The primary symptom of otosclerosis is loss of hearing. In addition, many people experience tinnitus (noice originating inside the ear). The amount of tinnitus is not necessarily related to the kind or severity of hearing loss.

Diagnosis

Hearing loss due to otosclerosis is usually first noticed in the late teens or early twenties. Hearing loss usually occurs in the low frequencies first, followed by high frequencies, then middle frequencies. Extensive hearing tests will confirm the diagnosis.

Treatment

People with otosclerosis often benefit from a properly fitted hearing aid.
The surgical replacement of the stapes has become a common procedure to improve conductive hearing problems. During this operation, called a stapedectomy, the stapes is removed and replaced with an artificial device. The operation is performed under local anesthesia and is usually an outpatient procedure. Surgery is done on only one ear at a time, with a one year wait between procedures. The degree of hearing improvement reaches its maximum about four months after the surgery. Over 80% of these procedures successfully improve or restore hearing.

Prognosis

People with otosclerosis almost never become totally deaf, and will usually be able to hear with a hearing aid or with surgery plus a hearing aid. In older people, the tendency for additional hearing loss is diminished due to the hardening of the bones.

Prevention

Otosclerosis cannot be prevented.

Key terms

Tinnitus — Tinnitus is noise originating in the ear, not in the environment. The noise can range from faint ringing to roaring.

Resources

Organizations

American Tinnitus Association. P.O. Box 5, Portland, OR 97207. (503) 248-9985. 〈tinnitus@ata.org〉.
National Association of the Deaf. 814 Thayer Ave., Silver Spring, MD, 20910. (301) 587-1788. 〈http://nad.policy.net〉.
NIDCD Hereditary Hearing Impairment Resource Registry. c/o Boys Town National Research Hospital. 555 N. 30th St., Omaha NE 68131. (800) 320-1171.
Self Help for Hard of Hearing People, Inc. 7800 Wisconsin Ave., Bethesda, MD 20814. (301) 657-2248. http://www.shhh.org.

otosclerosis

 [o″to-sklĕ-ro´sis]
the formation of spongy bone in the capsule of the labyrinth of the ear, often causing the auditory ossicles to become fixed and less able to pass on vibrations when sound enters the ear. Approximately 10 per cent of adults have otosclerosis, but in only 1 per cent does it affect the stapes, which becomes fixed to the oval window and causes symptoms. adj., adj otosclerot´ic.

The cause is still unknown; it may be hereditary or related to vitamin deficiency or otitis media. An early symptom is ringing in the ears, but the most noticeable symptom is progressive loss of hearing. It usually begins in the teens or early twenties, strikes women about twice as often as men, and may be worsened by pregnancy. Although no cure is known, surgical techniques can often restore hearing by freeing the stapes or replacing it with other tissue. In this operation (stapedectomy), the stapes is removed and replaced with grafted tissue attached to a stainless steel wire or plastic tube. Patients who do not desire surgery may have their hearing loss relieved by the use of a hearing aid. Large but uncontrolled research studies have suggested that sodium fluoride may decrease the rate of hearing loss; this dietary supplement along with vitamin D is used to slow the disease in selected patients.
Common sites of otosclerosis. Otosclerosis can cause fixation of the stapes by spongy growth of bone around the anterior footplate or at the junction of the incus and stapes. From Ignatavicius et al., 1995.

o·to·scle·ro·sis

(ō'tō-sklĕ-rō'sis), [MIM*166800]
A disease of the otic capsule (bony labyrinth) characterized by formation of soft, vascular bone and resulting in progressive conductive hearing loss because of fixation of the stapes and sensory hearing loss because of involvement of the cochlear duct.
[oto- + G. sklērōsis, hardening]

otosclerosis

/oto·scle·ro·sis/ (-sklĕ-ro´sis) a condition in which otospongiosis may cause bony ankylosis of the stapes, resulting in conductive hearing loss.otosclerot´ic

otosclerosis

(ō′tō-sklə-rō′sĭs)
n.
A disease of the ear in which the movement of the stapes within the oval window becomes impeded by abnormal deposits of spongy bone, leading to a progressive loss of hearing.

o′to·scle·rot′ic (-rŏt′ĭk) adj.

otosclerosis

[ō′tōsklərō′sis]
Etymology: Gk, ous + skleros, hard, osis, condition
a hereditary condition of unknown cause in which irregular ossification occurs in the ossicles of the middle ear, especially of the stapes, causing hearing loss. It is usually first noticed between 11 and 30 years of age. Women are affected twice as often as men. The condition may worsen during pregnancy. Stapedectomy or stapedotomy is usually successful in restoring hearing.

otosclerosis

ENT Abnormal growth of bone in inner ear, blocking normal function of ear bones with gradual loss of hearing Clinical Slow, progressive; hearing may be better in noisy environments, tinnitus Diagnosis Ear examination may exclude other causes of hearing loss; audiometry/audiology may determine extent of hearing loss; CT, MRI, PET of head

o·to·scle·ro·sis

(ō'tō-skle-rō'sis)
A new formation of spongy bone about the stapes and fenestra vestibuli (ovalis), resulting in progressively increasing deafness, without signs of disease in the auditory tube or tympanic membrane.
[oto- + G. sklērōsis, hardening]

otosclerosis

A hereditary bone disease affecting the freedom of vibration of the footplate of the inner auditory OSSICLE (the stapes) in the oval window in the wall of the inner ear. Progressive immobilization of the bone interferes with the transmission of vibrations from the ear drum and leads to progressive deafness. The condition can usually be effectively treated by a microsurgical operation.

otosclerosis (ō´tōsklərō´sis),

n a disorder of the middle ear that generally results in hardening and fusion of the ossicles of the ear, with resultant immobilization so that sound waves cannot be conducted along their paths.

otosclerosis

the formation of spongy bone in the capsule of the labyrinth of the ear, often causing the auditory ossicles to become fixed and less able to pass on vibrations when sound enters the ear. May be an inherited condition in humans.
References in periodicals archive ?
Thus far, attempts to detect measles virus in otosclerotic bone by tissue culturing or localizing the virus by in situ hybridization have failed.
Because the otosclerotic focus usually is in close contact with inner ear fluids, an immunologic reaction of the inner ear immune system, presumably in the endolymphatic sac, should be observed.
Detection of measles virus RNA in otosclerotic bone
30] McKenna's technique offers the advantage that the specimen can be morphologically examined for otosclerotic foci in the sample.
Another might be that the infected cells were lost during the final stages of otosclerotic eburnation.
In clinical otosclerosis, the otosclerotic focus is in close contact with the inner ear fluids.
Incidence, location and extent of otosclerotic lesions.