Competencies: Medical Knowledge, Patient Care

Competencies: Medical Knowledge, Patient Care

Learning Objectives: After reading this information you should be able to describe the aging auditory system and mechanisms of hearing loss, counsel patients regarding hearing loss and noise exposure, identify adults with hearing disability, communicate effectively with hearing impaired individuals, and make effective referrals for audiology and otolaryngology services.

Presbycusis and the Aging Auditory System

The most common pattern of hearing loss in older adults is presbycusis, a bilateral high frequency sensorineural hearing loss that occurs with advancing age. Pure- tone threshold sensitivity diminishes with age; those under 55 years typically lose hearing at a rate of 3 dB per decade, and those over 55 at a rate of 9 dB per decade.[1] Speech discrimination is also reduced with aging.

Major Types of Hearing Loss

Disorders of the outer and middle ear cause conductive hearing loss by disrupting sound transmission via the external canal, tympanic membrane, and ossicular chain. Disorders of the inner ear cause sensorineural hearing loss by damaging the cochlea, eighth cranial nerve, or internal auditory canal. Mixed hearing loss involves conductive and sensorineural mechanisms.

Preventionof Noise-induced Hearing Loss

Noise-induced hearing loss is permanent but largely preventable. It begins at the higher frequencies (3,000 to 6,000 Hz) and develops gradually as a consequence of cumulative exposure. Counsel patients to take corrective action to protect hearing during activities that generate excessive noise exposure such as lawn mowing (90 dB), stereo headphone use (100 dB), or firearm use (140 to 170 dB). Hearing loss can develop following chronic exposures equal to an average decibel level of 85 dB or higher for an 8-hour period.[2]

Hearing Disability Morbidity

Hearing disability is a prevalent condition posing significant disease burden. The prevalence of hearing loss is estimated to double per decade, beginning with 16% at 60 years of age and proceeding to 32% at 70 years of age, and 64% at 80 years of age. The associated morbidities include diminished speech understanding, social isolation, and depression. Hearing impairment can also mimic cognitive dysfunction.

Screening for Hearing Impairment and Disability

Elicit history annually regarding difficulty hearing during challenging listening tasks such as conversing in large groups or on the telephone. Obtain collateral history from a spouse or other individuals familiar with the patient's hearing when feasible. Questionnaires are also useful in identifying persons with hearing disability. The Hearing Handicap Inventory for the Elderly - Screening Version (HHIE-S) is a quick, reliable, and valid self-assessment tool for identifying elderly persons with hearing disability (see last page). The HHIE-S has a sensitivity of 76% and a specificity of 71% (for a cutoff score above eight) when compared to pure-tone audiometry. Alternatively, a portable audiometer is another screening tool that permits the identification of adults with hearing impairment. Using a 40 dB screening level, one such device (Audioscope; Welch Allyn, Inc.) has a sensitivity ranging from 87% to 96%, and a specificity ranging from 70% to 90%.[3] Screening tests such as the whispered voice, the finger rub, and the tuning fork test have been studied with relatively few patients and examiners; inadequate data exists regarding the interobserver reliability and observer repeatability for these tests.[4]

Communicating with Hearing Impaired Persons

Simple actions can facilitate communication with hearing impaired persons. These actions include keeping the speaker’s face well lit and in full view of the listener (within 2 to 3 feet), reducing background noise, and delivering speech with adequate pauses between sentences. Avoid shouting and attempt to speak clearly at a slightly louder than normal intensity. When repetition is necessary, attempt to paraphrase the message or write key words. Additionally, warn the listener when the subject of conversation is about to change. When the above measures are inadequate, consider using a portable amplifier device with headsets (i.e., a PocketTalker).

Audiology and Otolaryngology Referrals

Patients with hearing loss not amenable to medical or surgical treatment should be referred to a clinical audiologist for aural rehabilitation services. The amount of hearing loss is less crucial than is patient awareness and acceptance of hearing loss, communication difficulties, and motivation to try amplification. The audiologist will recommend a type of hearing aid(s) based on the patient’s hearing needs and goals, provide training in the use of amplification and other selected rehabilitative approaches, review the advantages and limitations of hearing aids, and provide supportive follow-up during the trial period and after the purchase. Primary care physicians should encourage new hearing aid users not to abandon their devices prematurely since it usually takes over a month to adjust to amplification and experience its full benefits.

Patients with hearing loss that appears possibly amenable to medical or surgical treatment should be referred to an otolaryngologist (ENT). Hearing loss patterns that should prompt consideration for ENT referral include: unexplained unilateral, sudden onset, loss associated with ear pain, tinnitus, or drainage, or loss associated with middle ear diseases such as cholesteatoma or tympanic membrane perforation. Causes of sudden hearing loss include viral cochleitis, vascular ischemic events, acoustic neuroma, Ménière’s disease, multiple sclerosis, and perilymph fistulas. ENT referral is generally appropriate for patients who have hearing loss that deviates from the pattern characteristic for presbycusis (bilateral, symmetric, high frequency hearing loss). An example is Ménière’s disease that causes hearing loss that is almost always low frequency and is typically episodic with periods of vertigo, hearing loss, tinnitus, and aural fullness.

NOTE: we have a portable audiometer in Hoxworth – it is kept in the Medicine Pediatrics practice. To use it, please contact XXXXXXXXXXXXXXXX
Hearing Handicap Inventory For the Elderly – Screening Version

Total Score:______(Ranges 0 to 40). Score >8 indicates hearing disability.

References:

1.Jennings, C.R. and N.S. Jones, Presbyacusis. J Laryngol Otol, 2001. 115(3): p. 171-8.

2.Rabinowitz, P.M., Noise-induced hearing loss. Am Fam Physician, 2000. 61(9): p. 2749-56, 2759-60.

3.Lichtenstein, M.J., F.H. Bess, and S.A. Logan, Validation of screening tools for identifying hearing-impaired elderly in primary care. Jama, 1988. 259(19): p. 2875-8.

4.Mulrow, C.D. and M.J. Lichtenstein, Screening for hearing impairment in the elderly: rationale and strategy. J Gen Intern Med, 1991. 6(3): p. 249-58.

5.Weinstein, B.E., Geriatric Audiology. 2000, New York: Thieme Medical Publishers. 332.

6.Mulrow, C.D., et al., Quality-of-life changes and hearing impairment. A randomized trial. Ann Intern Med, 1990. 113(3): p. 188-94.

7.Yueh, B., et al., Randomized trial of amplification strategies. Arch Otolaryngol Head Neck Surg, 2001. 127(10): p. 1197-204.

Discussion Questions:

True or False:

1.When hearing loss is identified by air conduction and bone conduction, a conductive hearing loss is present.

2.When air-conduction results suggest hearing loss, but bone-conduction results are normal, a conductive hearing loss is present.

Discussion: An audiogram measures hearing levels for air-conduction and bone conduction of pure tones at specified frequencies in each ear. Air-conduction testing measures the function of the entire auditory system from the ear canal through the middle ear to the cochlea and its afferent neural pathways to the brain. Therefore, loss in air-conduction can be due to a disorder anywhere in the auditory system. To better locate the anatomic site of the hearing disorder, pure-tone bone-conduction is also performed. Sound transmitted via bone-conduction bypasses the outer and middle ear. When air and bone conduction is impaired, sensorineural hearing loss is present. Therefore statement 1 is false, and 2 is true.

1. A jet air plane at take off generates about 150 dB of noise, whereas light traffic generates about 50 dB. Which is a true comparison of the sound intensities for these two events?
2. A jet plane’s sound intensity is 1 billion times louder than light traffic.
3. A jet plane’s sound intensity is 1000 times louder than light traffic.
4. A jet plane’s sound intensity is 100 times louder than light traffic.
5. A jet plane’s sound intensity is 3 times louder than light traffic.

Discussion: Because dB units comprise a logarithmic scale, 150 dB is actually 1 billion times louder than 50 dB.

1. For how many continuous hours would a person have to operate a lawn mower to require the wearing of hearing protection by OSHA standards (1910.95)?
2. 2 hours
3. 4 hours
4. 6 hours
5. 8 hours
6. 10 hours

Discussion: A lawnmower generates about 90 dB. Hearing loss can develop following chronic exposures equal to an average decibel level of 85 dB or higher for an 8-hour period.

1. Each of the following statements expresses a myth about hearing aids except:
2. Hearing aids restore hearing to normal.
3. Hearing aids eliminate all communication problems.
4. All hearing aid users can achieve adequate speech recognition with hearing aids alone.
5. Most people with hearing aids do not like how they sound.
6. Randomized controlled clinical trials have demonstrated significant improvements in social and emotional function, communication function, and depression among hearing aid recipients.

Discussion: A-D are all myths.[5] Hearing aids improve hearing but do not return it to normal, nor do they eliminate all communication problems. Speech recognition sometimes requires more than a hearing aid; for instance, a patient may have to learn lip reading techniques to augment amplification. Growing evidence is showing that hearing aids improve quality of life among adults with hearing impairment.[6, 7]