| Hearing loss (deafness, hearing impairment) refers to the partial or complete inability to hear sounds in one or both ears. There are several types of hearing loss: conductive, sensorineural (including noise-induced hearing loss and presbycusis), mixed, and functional hearing loss.
Conductive hearing loss is the poor transmission of sound waves through the external ear canal to the bones (ossicles) of the middle ear. It may be caused by obstruction (impacted earwax, or cerumen), accumulation of fluid in the middle ear (middle ear effusion), or disturbances affecting the continuity of the ossicles of the middle ear (otosclerosis). Temporary conductive hearing loss usually results from impacted earwax and acute middle ear infection (acute otitis media) with effusion. Persistent conductive loss may be caused by chronic otitis media, trauma, or otosclerosis.
Sensorineural hearing loss (sensory organ or nerve-related hearing loss) is the poor transmission of sound waves as a result of damage to the essential organ of hearing (cochlea) within the inner ear and/or damage to the eighth cranial nerve (vestibulocochlear nerve). Sensorineural hearing loss can be caused by drugs that harm some part of the hearing mechanism (ototoxic drugs), endolymphatic hydrops (Ménière's syndrome), brain tumors, and head trauma. Sensorineural hearing loss can also result from problems affecting the eighth cranial nerve (vestibulocochlear nerve) such as acoustic neuroma; systemic diseases like multiple sclerosis, diabetes, Paget's disease, and cerebrovascular disease; and immunosuppressive diseases. Because the balance centers within the inner ear are associated with the vestibulocochlear nerve, sensorineural hearing loss may be associated with vertigo and balance disorders.
In addition, sensorineural hearing loss may be caused by noise trauma or by the aging process. Noise-induced hearing loss results from extended overexposure to hazardous noise that permanently damages the cochlear hair cells. The most common types of noise that can produce a high-frequency hearing loss include industrial noise, gunshots, and loud music. Aging can also result in progressive age-related hearing loss (presbycusis), which occurs as degenerative changes manifest within the cochlea.
Mixed hearing loss refers to a combination of conductive and sensorineural hearing loss. In individuals with mixed hearing loss, it is important to note that although the conductive portion of the hearing loss may be helped by medical or surgical treatment, the sensorineural hearing loss is permanent.
Functional hearing loss is caused by emotional or psychological factors. The individual does not seem to hear, but there is no organic cause or history of deafness in the family.
Hearing loss has many causes. It may be genetic. It may arise in the aftermath of an infectious process or disease (such as Lyme disease, AIDS, mumps, meningitis, tuberculosis, kidney disease, cancer, diabetes, syphilis, glaucoma, sickle cell disease, and dizziness). Trauma, toxins, a history of ear infections in childhood, allergies, high blood pressure, brain abscess, bone infection (osteomyelitis), and tumors may all lead to hearing loss. Frequently, the first symptom of hearing loss is tinnitus, which refers to ringing in the ears and can range from a low hiss to a high-pitched ringing sound.Risk: The elderly and smokers are at greater risk of hearing loss. Those who experience damage from excessive noise and vibration, such as occurs in certain occupations or forms of entertainment, are also at greater risk. Incidence and Prevalence: More than 28 million people in the US suffer from some degree of hearing loss (Issacson). Of this number, 80% have irreversible hearing loss. An estimated 4.6% of individuals between the ages of 18 and 44 have hearing loss; about 14% of individuals between the ages of 45 and 64 have hearing loss; and approximately 54% of the over-65 population suffer from hearing loss ("Prevalence"). |
Source: Medical Disability Advisor
| History: Individuals with hearing loss are often unaware of their problem. They frequently agree to see a physician at the urging of family members, friends, or co-workers who have had trouble communicating with them.
Individuals with conductive hearing loss may simply report that sounds are more quiet and distant than before. Their own voices sound loud to themselves, and, consequently, they tend to speak softly. Because of this, they may be frequently asked to repeat things they say.
The individual with sensorineural hearing loss may report that sounds are not only quieter than before but also distorted and less clear. High-pitched tones are harder to hear (less audible) than low ones, words are difficult to distinguish, and sounds are muffled. The sounds "s," "f," and "z" are not heard, but consonants such as "c" come through more clearly. These individuals may tend to speak loudly because they have difficulty hearing their own voices and consequently cannot modulate them.
Individuals with conductive, sensorineural, or mixed hearing loss may report ringing in the ear (tinnitus) and balance disturbances (vertigo), sometimes accompanied by nausea, vomiting, and a rhythmic jerking of the eyes (nystagmus). Physical exam: In the office, an otoscopic examination is performed. Hearing loss may be estimated by having the individual repeat out loud words that are presented by the physician in a soft whisper, a normal spoken voice, or a shout. The Weber test, in which a tuning fork is placed in the middle of the forehead, helps to determine the range of hearing loss in individuals with asymmetrical hearing loss. The Rinne test, in which the tuning fork is placed on the bony area behind the ear and then moved to the opening of the ear, also helps to determine the scope of hearing loss.
In conductive hearing loss, external ear or middle ear abnormalities may be found, including earwax (cerumen) obstruction, an inflamed eardrum (tympanic membrane) with evidence of fluid buildup behind it, or a ruptured eardrum (tympanum perforation). A balance disorder accompanied by nystagmus may be observed in the individual with conductive or sensorineural hearing loss, depending on the nature of the hearing problem and the degree to which the vestibulocochlear nerve has been affected. Tests: Audiometric studies are performed in a soundproof room. Based on the results of the audiogram, conductive hearing loss can be classified by the decibel level, with a range of 0 to 15 decibels (dB) being normal hearing. This is equivalent to hearing a soft whisper. A mild hearing loss is 16 to 25 dB, the equivalent of hearing a soft-spoken voice. Moderate hearing loss ranges from 41 to 55 dB, the equivalent of hearing a normally spoken voice. A moderately severe hearing loss ranges from 56 to 70 dB. A severe loss falls in the range of 71 to 90 dB, the equivalent of hearing only a loud-spoken voice. Profound hearing loss is a reading above 91 dB, the equivalent of hearing only a loud shout.
Sensorineural hearing loss is evaluated by speech discrimination (testing of the individual's ability to distinguish certain sounds and words). Results are reported as the percentage of correct answers (90% to 100% correct is normal). An electrophysiologic test (auditory brain stem evoked potential) can determine whether the problem affects the cochlea or the central nervous system.
Electronystagmography (ENG), a test in which warm or cold water is used to stimulate the inner ear (caloric test), may be ordered if balance disorders are suspected. Skull x-rays, a CT scan, or an MRI of the ear or head help rule out head trauma and diseases of the central nervous system. Electromyography (EMG) may be ordered to rule out diseases of the neurological system. Sound energy flow (tympanometry) provides an indirect measurement of the mobility of the tympanic membrane and ossicles. |
Source: Medical Disability Advisor
| Some hearing loss may not be correctable, so treatment is aimed at improving residual hearing and developing coping skills. Treatment of conductive hearing loss targets the specific underlying cause within the ear. Temporary conductive hearing loss is correctable, either medically or surgically. Cerumen impaction can be mechanically removed in the physician's office or flushed from the ear with warm water. To treat middle ear infections, fluid in the middle ear can be drained (myringotomy) and the individual treated with antibiotics. If the infection is chronic and has spread to the mastoid bone, a mastoidectomy can be performed, with or without the removal of a cyst-like mass in the middle ear or mastoid (cholesteatoma), in conjunction with antibiotic therapy.
A perforated eardrum usually heals by itself or can be surgically repaired (tympanoplasty, myringoplasty). Hearing loss from otosclerosis is usually treated by a surgical procedure in which the stapes (a middle ear bone) is replaced with a prosthesis (stapedectomy). A hearing aid (amplification) may be useful for some conductive hearing loss, depending on the cause.
Most sensorineural hearing losses cannot be corrected with medical or surgical therapy but often may be stabilized. Sensorineural hearing losses are generally treated by providing hearing aids (amplification) specifically fitted to the individual's hearing loss by an audiologist or speech and hearing specialist. The volume of sound will be increased through amplification, but sounds will remain muffled. Digitally programmable aids are now available that can be tuned to deal with difficult listening circumstances. Other assistive devices that attach to the television set, radio, or telephone may be recommended.
Sensorineural hearing losses caused by certain metabolic diseases (diabetes, hypothyroidism, hyperlipidemia, and renal failure) or autoimmune disorders (polyarteritis and lupus erythematosus) may respond to medical treatment of the underlying diseases. Some individuals with profound sensorineural hearing loss may be appropriate candidates for surgical implantation of an electronic device behind the ear to directly stimulate the auditory nerve (cochlear implant/cochlear implantation).
Depression may accompany loss of hearing, and should be treated with counseling and antidepressant medications. Consultation with a social worker may help the individual and the individual's family to identify the social issues associated with living with hearing loss and help them find supportive resources within their community. Instruction in speech reading (commonly known as lip reading) may help those committed to learning this form of communication. |
Source: Medical Disability Advisor
| The predicted outcome for conductive hearing loss is restored or improved hearing, elimination of infection, and removal of invasive masses. Individuals with earwax impactions will immediately be able to hear as well as they did before the impaction. Most individuals with acute otitis media improve after 48 hours on antibiotic therapy and may be symptom-free after several days.
In some instances, individuals with conductive hearing loss may have persistent hearing loss and balance disturbances even after the immediate cause is either medically or surgically corrected.
Outcomes for chronic otitis media follow a less predictable course, and outpatient treatment tends to be ongoing. Following a tympanoplasty, if the eardrum was successfully reconstructed, the individual's hearing should markedly improve. Following a mastoidectomy, the mastoid air cells should be clear of infection, but permanent hearing loss may result from the effects of long-term infection on the bones of the middle ear. Similarly, removal of cysts within the middle ear or mastoid (cholesteatoma) will result in marked improvement in hearing, unless the middle ear bones were destroyed by the cysts' growth and development.
Without a stapedectomy, the hearing loss of an individual with otosclerosis will progress until middle age (age 45 to 50) and then stabilize. Ninety percent of individuals who have a stapedectomy procedure to treat otosclerosis will experience significant improvement in hearing postoperatively and frequently will enjoy near-normal hearing. Improvement in hearing will often be apparent within 3 weeks following surgery, and maximum hearing may be realized in approximately 4 months. Ten percent of individuals with otosclerosis experience no improvement in hearing following a stapedectomy; only a small number of individuals will suffer persistent, profound sensorineural hearing loss ("Stapedectomy").
Individuals with profound sensorineural hearing loss may be able to hear environmental sounds after cochlear implantation.
If tinnitus is caused by an acoustic tumor, otosclerosis, or a condition of increased inner ear hydraulic pressure (Ménière's syndrome), surgery to remove the lesion or equalize the pressure may be performed. Following successful surgery, tinnitus is reduced or eliminated in about 50% of severe cases ("Tinnitus"). |
Source: Medical Disability Advisor
| Individuals with hearing loss may require consultation with a speech therapist. The frequency and duration of speech therapy is contingent upon the degree of hearing loss. Individuals with conductive hearing loss may be able to function with the use of hearing aids. Individuals with sensorineural hearing loss may require pocket amplification devices that look like a personal stereo with an external microphone.
Individuals with cochlear implants require extensive training in use of the implant and may also need speech therapy if they experience profound deafness for a long period of time.
Speech therapists also teach lip reading or sign language for communication. They provide suggestions for coping with hearing loss, such as eliminating environmental background noise through the use of carpeting, drapes, and upholstered furniture to absorb the noise. Speech therapists also assist individuals in obtaining equipment to compensate for hearing loss, such as TDD (telecommunications device for the deaf) telephones and doorbells, as well as smoke detectors that utilize flashing lights instead of sound as a signal. Occupational and vocational therapy may be needed to help individuals adapt to their environments.
Individuals with persistent balance disorders may benefit from a vestibular rehabilitation exercise program designed to take advantage of the brain's tendency to eventually adapt (habituate) to the repetition of a specific stimulus, causing a reduction in the individual's sensation of rotation or movement of him- or herself or of his or her surroundings (vertigo).
Traditional physical therapy addresses secondary symptoms associated with the inactivity accompanying persistent balance disorders. These secondary symptoms include decreased strength, loss of the range of motion, and increased tension, particularly in the cervical and shoulder region, that can lead to muscle fatigue and headaches. |
Source: Medical Disability Advisor
| Complications from cochlear implantation to correct hearing loss include infection, nerve damage, and meningitis. Individuals with vestibular dysfunction or vertigo associated with hearing loss may experience loss of balance and falls that can lead to traumatic injury. |
Source: Medical Disability Advisor
| Interference in the ability to communicate adversely affects an individual's interaction with co-workers, family, friends, and the general public and can be the source of social isolation. The loss of speech clarity that confronts the individual with sensorineural hearing loss is especially frustrating because they hear what is spoken but cannot decipher the words.
Work restrictions and accommodations may be required for individuals with balance disturbances, for their own protection as well as the safety of others. Individuals with persistent temporary or permanent hearing loss following medical or surgical treatment may require vocational or occupational therapy to help them prepare for a different job. The use of hearing aids may be necessary, depending on the severity of the hearing loss. Persistent facial paralysis may also require accommodations if the individual's job requires distinct speech and/or contact with the public. Although exposure to noise in the work place should be reduced for all workers through use of protective ear-wear, this protection is critical to the individual with a hearing loss. Various aids, such as an amplifier for the earpiece of a telephone, may be necessary for the hearing-impaired. |
Source: Medical Disability Advisor
| If an individual fails to recover within the expected maximum duration period, the reader may wish to consider the following questions to better understand the specifics of an individual's medical case. Regarding diagnosis:
- Has diagnosis for cause of hearing loss been confirmed?
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Has an MRI or CT been done to determine the presence of a middle ear tumor or skull fracture, as well as the extent of the infection in the middle ear, mastoid area, and brain?
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Have pain and fever persisted despite appropriate treatment?
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Is the ear still draining?
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Has nausea, vomiting, and vertigo persisted?
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Should diagnosis be revisited?
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Has individual experienced any complications from infection or corrective procedures?
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If healing of the perforation or recovery from surgery is slow, have tests for diabetes, HIV/AIDS, leukemia, and other immunosuppressive diseases been performed?
Regarding treatment:
- Was the ear examined by using a microscope (rather than an otoscope) for better visualization?
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Did the individual tell the physician about recent head trauma, all current medications, and the history of treatment for diseases of the neurological or cardiovascular system?
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Was the individual questioned about recent middle ear infections or ear injuries, treated or untreated?
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Was culture and sensitivity testing performed on the ear discharge?
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Was the individual treated with antibiotics based on the results of culture and sensitivity testing of the ear drainage?
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Was the individual asked about past responses to infection with regard to resistance to treatment?
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Is the individual still being treated with antibiotics?
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Has the individual been compliant with taking the prescribed dose of antibiotic at the prescribed time in the prescribed manner?
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Has the individual complied with prescribed therapy (physical therapy or vestibular rehabilitation therapy)?
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Has the individual followed recommended restrictions on activity (flying, underwater diving, insertion of objects into the ear)?
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Has the individual kept the ear dry by using earplugs during bathing?
Regarding prognosis:
- If underlying condition is not resolving, have specialists been consulted to rule out systemic diseases that can cause hearing loss?
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Has the individual been seen by specialists in infectious disease and/or hematology?
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What has been done to enhance existing hearing?
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What accommodations are necessary to enable individual to return to occupational duties?
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Source: Medical Disability Advisor
| Isaacson, Jon E., and Neil M. Vora. "Differential Diagnosis and Treatment of Hearing Loss." American Academy of Family Physicians. 15 Sep. 2003. 30 Oct. 2004 <http://www.aafp.org/afp/20030915/1125.html>. "Stapedectomy." Health A to Z. 2004. 30 Oct. 2004 <http://www.healthatoz.com/healthatoz/Atoz/ency/stapedectomy.jsp>. "The Prevalence and Incidence of Hearing Loss in Adults." ASHA. American Speech-Language-Hearing Foundation. 30 Oct. 2004 <http://www.asha.org/public/hearing/disorders/prevalence_adults.htm>. "Tinnitus." YourMedicalSource. Dec. 2003. 30 Oct. 2004 <http://yourmedicalsource.com/library/tinnitus/TIN_treatment.html#surgery>. |
Source: Medical Disability Advisor
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