Download Outline for a Lecture on Hearing Loss

Geriatric Otolaryngology
October 2007
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Rehabilitation of Hearing Loss
1. Hearing loss prevalent among the elderly, yet hearing aids are underutilized
a. Affects 40%-45% of those over 65 years of age; >80% of those over
70 years of age (Cruickshanks et al., 1998)
b. Only 20% obtain hearing aids (Kochkin & MarkeTrak, 1999)
c. 46% of those wearing hearing aids at the time of testing failed screening
(Smeeth et al., 2002)
d. Only 60% of those who own a hearing aid use it regularly (Smeeth et al.,
2002)
2. Importance of hearing aids to elderly
a. Hearing aids reduce the perceived impact of the hearing loss in daily
communication (Stark & Hickson, 2004)
b. 31% of older users report benefit from hearing aids in noise (Kochkin &
MarkeTrak, 2003)
c. 76% of older users report overall benefit with their hearing aids (Kochkin
& MarkeTrak, 2003)
d. Hearing aids not only reduce hearing disability but also reverse social,
emotional, and communication dysfunction (Vuorialho et al., 2006)
3. Factors that influence purchase and use of hearing aids (Southall et al., 2006)
a. Recognition of hearing difficulties
i. Progressive nature of presbycusis limits patient awareness of
extent of handicap being experienced
ii. 2- to 3-kHz region: if no hearing loss present in this range,
patients tend not to accept hearing aids
iii. Awareness develops as impact on valued activities (social or
leisure) becomes more evident and complaints by family and
friends increase
iv. Hearing difficulties in adverse listening conditions (e.g., noisy
and/or reverberant environments)
b. Awareness of availability of technological solutions
i. Expense can be a major prohibitive factor
ii. A single programmable hearing aid with features that optimize
function can cost about $2000
c. Seeking consultation for and acquisition of assistive devices
d. Adaptation to device
i. Positive attitude, influenced by self-esteem and confidence,
important
e. Realistic expectations
i. Hearing aids may always restore full function, but can improve
quality of life by increasing awareness of environmental sounds,
facilitating directional hearing, etc.
ii. Requires appropriate pre- and post-fitting counseling
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October 2007
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4. Characteristics of hearing aid seekers (Cox et al., 2005)
a. Pragmatic and routine-oriented
b. Feel relatively more personally powerful in dealing with life’s challenges
c. More trusting, less cynical
d. Use social support coping strategies less frequently than their non-hearingimpaired peers
e. More aware of impact of their impairment on family
5. Factors that elderly cite as reasons for not following physician recommendation to
obtain hearing aids (Garstecki & Erler, 1998)
a. Cost
b. Relatively low value placed on effective communication
c. Other factors include low self-esteem, depression, low locus of self-control
d. Primary reasons cited by elderly for not routinely using hearing aids:
poor benefit, particularly in noise, restaurants, and large groups
(Kochkin & MarkeTrak, 2000)
6. Basic research - Implications for auditory rehabilitation (Chisolm et al., 2003)
a. Complex interaction of biological aging in the peripheral and central
auditory systems with peripheral pathology
b. Plasticity — Changes in auditory input due to peripheral pathology result
in hearing loss–induced plasticity in the central auditory system (e.g.,
regions previously responsive to high-frequency sounds become tuned to
lower-frequency sounds with high-frequency hearing loss)
i. Therefore, amplification of high-frequency sounds may not
necessarily result in improved auditory function
ii. On the other hand, amplification of lower-frequency sounds may
improve function
iii. Some evidence suggests that speech understanding in new hearing
aid users improves over time (auditory acclimatization effect) —
this is particularly true of sounds that were inaudible prior to use of
amplification (Philibert et al., 2005)
c. Auditory deprivation effect
i. In monaurally aided individuals with bilateral sensorineural
hearing loss, unaided ears display degraded suprathreshold speech
recognition performance
ii. Speech recognition improves after a hearing aid is fitted to the
previously unaided ear
iii. These findings are consistent with plasticity in the central auditory
system
iv. Implication: When possible, fit both ears with hearing aids
d. Age-related sensorineural pathology may be modulated by use of
amplification
i. Animal studies suggest that an augmented acoustic environment
can slow (not reverse) progressive sensorineural hearing loss
ii. Implication: Start use of hearing aids earlier rather than later
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October 2007
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7. Advantages of binaural hearing aids
a. Provide binaural summation — hearing threshold improvement that
occurs when listening with two ears as opposed to one ear
b. Provide binaural squelch — ability to “tune out” unwanted noise
c. Auditory deprivation effect — lack of amplification leads to decline
in word recognition (Silverman et al., 2006; also see above)
8. Factors influencing hearing aid choice — complex and multifactorial; this
section will highlight some key factors; see Johnson et al., 2001 and Hanratty &
Lawlor, 2000 for more complete overviews. In general, individual factors have
to be taken into account to determine the right type of hearing aid for that
individual (not “one size fits all”):
a. Patient factors
i. Hearing
1. Pure tone audiogram
2. Dynamic range
3. Loudness levels — most comfortable and uncomfortable
4. Speech recognition threshold
5. Word recognition
ii. Physical
1. Manual dexterity, fine motor skills, ability to raise arm to
level of ears (i.e., consider severity of arthritis), and
visual status
2. Outer ear: shape, external canal length, mobility in outer
1/3 of canal, TMJ problems, exostoses/osteomas, mastoid
bowl, canal eczema/otitis external, cerumen impaction
iii. Psychosocial
1. Attitude, motivation, cognitive impairment, depression,
social support and demands
9. Prescriptive rules (e.g., half-gain rule)
a. Techniques used by audiologist in decision making
b. Use loudness levels that are most comfortable/uncomfortable to calculate
amplification needed
c. Optimize understanding of conversational speech by using amplification
levels that can be tolerated by the patient
10. Hearing aid types
a. Vary from adjustable analog to programmable multi-microphone digital
i. In general, the programmable digital aid offers greater flexibility
and improved patient satisfaction; however, cost is
significantly higher
1. Particularly suitable for patients with unusual audiometric
configuration (take advantage of multiple frequency bands
for matching targets and manipulating compression
parameters) and also patients residing in reverberant, noisy
environments
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October 2007
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b. Behind-the-ear (BTE), in-the ear (ITE), and completely-in-canal (CIC)
i. BTE — for mild to profound losses, versatile (newer models
are miniaturized, can be combined with open-fit molds)
ii. ITE — for mild to severe losses
1. Feedback (sound leaking out of hearing aid getting
amplified again, due to proximity of receiver and
microphone) a problem for severe losses
2. “Occlusion effect” (good low-frequency hearing results in
plugged-up effect and may make patient’s voice resonate)
a. Reduced by use of vent hole
iii. CIC — popular largely due to cosmetic appeal
1. Appropriate for hearing losses up to 60 dB HL in the low
frequencies and up to 80 dB HL in middle to high
frequencies
2. Special considerations for three types of hearing losses
a. Flat or reverse-slope losses (out of CIC may not
reach low-frequency targets); consider using twochannel digital programmable CIC aid
b. Normal thresholds up to 2000 Hz followed by
sharply sloping losses
i. “Occlusion effect” — consider “step
microphones” that eliminate gain below
1500 Hz in a two-channel digital
programmable CIC aid
c. CIC aids do not offer adequate gain required for
severe to profound hearing losses
11. Hearing aid features — e.g., Siemens Centra hearing aids
a. SoundSmoothing™ technology — recognizes and reduces annoying
noises like rustling paper, clanging dishes, and breaking glass, while
preserving the sound of voices and conversations
b. DataLearning™ — learns based on patient volume changes,
and automatically adjusts itself to match patient preferences
c. e2e wireless™ communication — keeps patient instruments properly
balanced at all times, so patient can tell where sounds are coming from;
also makes instruments easier to use by enabling patient to control the
volume and program of both instruments at the same time
d. Advanced Adaptive Feedback Cancellation — reduces or eliminates
the high-pitched whistling common with many other hearing
instruments
e. eWindScreen — an electronic system that detects wind conditions and
adapts automatically to reduce annoying wind noise
f. Directional Microphone System — automatically adapts to patient listening
environment and can reduce multiple noise sources, making it easier to
focus on speech and conversations
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October 2007
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g. BTE housings are gold-plated from the inside to ensure disturbance-free
operation with mobile phones
h. AutoPhone feature — telecoils that are automatically engaged when
the wearer uses a hearing instrument–compatible phone
i. Of note: integration of frequency modulation (FM) systems into BTE
systems can further improve listening in reverberant environments
(Chisholm et al., 2004)
12. Cochlear implants
a. Criteria
i. Bilateral, severe to profound sensorineural hearing loss (i.e., 70 dB
or greater pure-tone average at 500, 1000, and 2000 Hz)
ii. Limited benefit from an adequately fitted binaural hearing aid
iii. Sentence recognition score of 50% or less in the ear to be
implanted and 60% or less in contralateral ear in best-aided
conditions
b. Patients over 60 years of age with cochlear implants demonstrate
similar speech perception gains as younger patients with cochlear
implants (Herzog et al., 2003; Monsier et al., 2004)
i. However, older patients need more time to reach the same level of
performance as that of younger patients after implantation (up to 3
years, or 4 years when signal-to-noise ratio was 15%)
Recommended Reading
Gordon-Salant S. Hearing loss and aging: new research findings and clinical
implications. J Rehab Res Devel. 2005;42:9-24.
References
Chisolm TH, Willott JF, Lister JJ. The aging auditory system: anatomic and physiologic
changes and implications for rehabilitation. Int J Audiol. 2003;42:2S3-2S10.
Chisolm TH, McArdle R, Abrams H, Noe CM. Goals and outcomes of FM use by adults.
Hear J. 2004;57:28-35.
Cox RM, Alexander GC, Gray GA. Who wants a hearing aid? Personality profiles of
hearing aid seekers. Ear Hear. 2005;26:12-26.
Cruickshanks KJ, Wiley TL, Tweed TS, et al. Prevalence of hearing loss in older adults in
Beaver Dam, Wisconsin: the Epidemiology of Hearing Loss Study. Am J Epidemiol.
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Hanratty B, Lawlor, D. Effective management of the elderly hearing impaired: a
review. J Public Health Med. 2000; 22:512-517.
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October 2007
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Herzog M, Schön F, Müller J, Knaus C, Scholtz L, Helms J. Long term results after
cochlear implantation in elderly patients. Laryngorhinootologie. 2003;82:490-493.
Johnson CE, Danhauer JL, Krishnamurti S. A holistic model for matching high-tech
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Kochkin S, MarkeTrak V. "Baby Boomers" spur growth in potential market, but
penetration rate declines. Hear J. 1999; 52:33-48.
Kochkin S, MarkeTrak VI. On the issue of value: hearing aid benefit, price, satisfaction,
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Kochkin S, MarkeTrak V. "Why my hearing aids are in the drawer": the consumers’
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Mosnier I, Bouccara D, Ambert-Dahan E, et al. Beneficial effect of cochlear implants in
the elderly. Ann Otolaryngol Chir Cervicofac. 2004;121:41-46.
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Silverman CA, Silman S, Emmer MB, Schoepflin JR, Lutolf JJ. Auditory deprivation
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Smeeth L, Fletcher AE, Ng ES, et al. Reduced hearing, ownership, and use of hearing
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Southall K, Gagne J-P, Leroux T. Factors that influence the use of assistance
technologies by older adults who have a hearing loss. Int J Audiol. 2006;45:252-259.
Stark P, Hickson L. Outcomes of hearing aid fitting for older people with hearing
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