CLINICAL REVIEWS Hearing Impairment in the Elderly RISA J. LA VIZZO-MOUREY, MD, MBA, EUGENIA L. SIEGLER, MD ONE-FOURTH OF ADULTSover 65 years old have chronic hearing loss significant e n o u g h to diminish their quality of life. 1, 2 Although hearing loss is remediable, most hearing-impaired older adults are not treated), 4 Because of the high prevalence of hearing loss among older adults and the bewildering array of tests and devices, the primary care provider is frequently e x p e c t e d to orchestrate the management of hearing loss in these patients. The purpose of this article is to help these clinicians identify patients with significant chronic hearing loss and c o m m u n i c a t i o n impairment, select and interpret tests, and counsel patients about treatment.
CHARACTERISTICS, PREVALENCE, AND EFFECTS The h u m a n ear is capable of perceiving sound over a wide range of frequencies. Each frequency has a threshold (usually reported in decibels) b e l o w w h i c h sound is inaudible (Fig. 1). The normal ear's sensitivity is highest for frequencies between 500 and 4 , 0 0 0 Hz - - t h e approximate frequency range of h u m a n speech. Sensitivity, particularly for frequencies > 4 , 0 0 0 Hz, decreases with advancing age in the majority of Western populations. 1 Hearing is abnormal in older p e o p l e if pure tones softer than 40 dB in more than one frequency cannot be heard in one or both ears. 1, 3.6 (Because the decibel is a logarithmic unit, an increase of 20 dB represents a tenfold increase in intensity over an established standard, and an increase of 40 dB, a 1,000-fold increase.) Using this definition, cross-sectional studies indicate that 18% of w o m e n over age 65 and 25.3% of men over 65 have hearing impairmentsY Studies that have included higher frequencies or used lower thresholds, however, reveal that 50% to 80% of persons over 65 have some hearing loss. s, 9 Because it is d e p e n d e n t on high-freq u e n c y consonant sounds, speech c o m p r e h e n s i o n among older persons with typical high-frequency hear-
Received from General Internal Medicine, Philadelphia Veterans Affairs Medical Center, and Geriatrics Program, University of Pennsylvania, Philadelphia, Pennsylvania. Dr. Lavizzo-Moureyis the recipient of an Academic Award #KO8AGO036304. Dr. Siegler is a Merck/AFARFellow in Geriatric Clinical Pharmacology. Address correspondence and reprint requests to Dr. LavizzoMourey: General Internal Medicine, Philadelphia Veterans Affairs Medical Center, Universityand WoodlandAvenues, Philadelphia, PA 19104.
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110 120
125
L
250
ro k pana 500 1000 2000 Frequency (Hz)
j~t airplane ' 4000
8000
FIGURE 1. The frequencies and intensities for common sounds, including consonants. Each sound is positioned in relation to its frequency and loudness under normal conditions. The shaded area depicts the frequency and intensity of conversational speech. An older person with presbycus!s typically has difficulty hearing high-frequency sounds softer than 40 dB. ANSI = American National Standards Institute.
ing loss is lower than normal. Older persons may be unable to distinguish consonants with similar frequencies (Fig. 1 charts the frequencies of consonants). For example, the " s " sound might be interpreted as a " t h " sound in this type of hearing loss, making complex, rapid patterns of speech especially difficult for elderly persons to understand.', s The most c o m m o n cause of bilateral hearing impairment a m o n g the elderly, presbycusis, is characterized by increased thresholds for high-frequency tones, recruitment, and difficulty with speech comprehension.', 3, lo Diminished speech c o m p r e h e n s i o n and recruitment can generally be elicited in the history. Recruitment is the perception of a sudden and dramatic increase in the intensity of sound (often to the point of being painful) in response to mild or moderate increases in volume. Although five types of presbycusis have been documented, the distinctions are not clinically helpful, because they can all o c c u r simultaneously. 1, Other com191
192,
Lavizzo-Mourey. Siegler.
HEARINGIMPAIRMENTIN ELDERLY
•/
100
HHIE-S
Points
Does a hearing problem cause you to feel embarrassed when meeting new people?
8O
Does a hearing problem cause you to feel frustrated when talking to a stranger?
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I
I
I
I
I
I
0
20
40
60
80
100
1-Specificity (%)
DO you feel handicapped by a hearing problem? Does a hearing problem cause you difficulty when visiting friends, relatives, or neighbors? Does a hearing problem cause you to attend religious services less often than you would like?
Does a hearing problem cause you to have arguments with family members?
FIGURE 2. The Hearing Handicap Inventory for the Elderly-Does a hearing problem cause you difficulty when listening to TV or Screening Version (HHIE-S) (right) is a self-administered instrument. radio? Patients are instructed to answer each question "no," "'sometimes," or "yes." The maximum score is 40 and the responses are scored as Do you feel that any difficulty with your hearing limits or hampers follows: no = O, sometimes = 2, and yes = 4. The left side of the your personal or social life? figure depicts the receiver operating characteristic (ROC) curve for HHIE-S scores of 2, 8, 16, and 24 (shown in parentheses) compared Does a hearing problem cause you difficulty when in a restaurant with those of three other tests. Thus, a score of 24 has similar sensiwith relatives and friends? tivity and specificity to those of the three tests shown in the box. Scores of 24 or more are an indication for a referral for further testing. Reprinted with permission from: Lichtenstein MJ, Bess FH, Logan SA. Diagnostic performance of the Hearing Handicap Inventory for the Elderly (screening version) against differing definitions of hearing loss. Ear Hear. 9(4):208-11. © by Williams & Wilkins, 1988.
m o n causes of chronic hearing loss in elderly persons are s h o w n in Table 1. Infrequently, chronic hearing i m p a i r m e n t a m o n g older adults is caused b y inner-ear malformations, syphilis, inner-ear m e m b r a n e rupture, or idiopathic hearing loss. 1, s Studies of elderly persons with hearing impairm e n t s h o w that m a n y have c o m m u n i c a t i o n dysfunction, cognitive loss, depression, social isolation, or psychosis. 12-23 Some studies reporting these associations have used hearing-specific measures of quality of life to assess the effect o f hearing impairment. 4, 2o Hearing loss causes a statistically significant i m p a i r m e n t in c o m m u n i c a t i o n and diminution in emotional and social functioning. 2, is, 24, 25 Although not all of these functional and psychologic p r o b l e m s are directly correlated with the severity of the pure-tone hearing impairment, they are sometimes partly alleviated after hearing loss is treated w i t h a hearing aid. 4. 25, 26 Conversely, studies of elderly persons with depression, psychoses, cognitive impairment, and dementia show that m a n y of these elders have hearing impairment. 13-z6 Although m a n y of these studies involved small sample sizes or lacked control groups, two larger studies, one from the Hearing and Speech Clinic at Johns Hopkins, 17 and the other a population-based study from London, 2° revealed significant associations b e t w e e n hearing loss and depression. In addition, Uhlm a n n et al. 's c a s e - control study demonstrated not o n l y
a higher prevalence of hearing i m p a i r m e n t a m o n g elderly persons w i t h d e m e n t i a than that a m o n g nondem e n t e d elders, but also a direct relationship b e t w e e n the severity of hearing loss and the severity of the cognitive loss. is In short, a growing literature supports the clinical w i s d o m that hearing loss has a negative effect on the quality o f life. In light of the high prevalence o f hearing loss and its effect on quality of life, case-finding efforts by p r i m a r y care providers are worthwhile.
EVALUATION Screening
The clinician must identify patients w h o s e hearing losses impair c o m m u n i c a t i o n or quality of life. Although an audiogram is required to make an accurate diagnosis, a u d i o m e t r y is too c o m p l i c a t e d to administer routinely as a screening test. Instead, two types of screening tests are used: those measuring actual hearing loss and those measuring the disability associated with hearing loss. 26-32 Because tests for hearing thresholds do not measure disability, and tests for disability do not assess i m p a i r m e n t s at specific frequencies, the two types of tests are best used together. 31, 32 An example of a disability screen is the Hearing Handicap Inventory for the E l d e r l y - - S c r e e n i n g Version (HHIE-S), a ten-item self-administered disability test that is m o r e
JOURNALOFGENERALiNTERNALMEDICINE, Volume 7 (March/April). 1992
specific (70% to 84%) than sensitive (53% to 72%) w h e n audiometric definitions of hearing impairment are used as the "gold standard" (Fig. 2).28, 29 In addition, among elderly hearing aid owners, it has been shown that scores on the HHIE-S improve after the initiation of hearing aid use. 33 An instrument increasingly used to evaluate hearing thresholds is the Audioscope (Welch Allyn, Inc., Skaneateles Falls, NY). Audioscopes are portable instruments similar to otoscopes that are capable of emitting pure tones, They test for hearing loss at the 25- and 40-dB levels over four frequencies (500, 1,000, 2,000, and 4,000 Hz).29 When audiometry results are used as the gold standard, and failure to detect an Audioscope tone at two or more frequencies defines an abnormal result, the sensitivity and specificity in elderly persons w h o do not have dementia are 1.00 and 0.70, respectively. 29 Together the HHIE-S and audioscopy yield a test with impressive sensitivity, specificity, and an overall accuracy of 83%. 31 The major advantage the Audioscope has over traditional portable audiometers with earphones (used to screen for hearing loss in many settings) is convenience. This hand-held instrument can screen for hearing loss in conjunction with a routine otoscopic examination, and the c o m b i n e d audioscopic and otoscopic examination should take less than five minutes. The sensitivities and specificities of other screening tests, such as tuning fork, finger rub, or whisp e r e d voice, are inferior to those of audioscopy. 3o However, of these, the widespread voice test is the next best alternative. 34 TM
Diagnostic Tests
Once the screening examination has identified a patient likely to have significant hearing loss, definitive testing is necessary to confirm the presence of the impairment and diagnose the underlying pathologic factor (if any). Differential diagnosis of hearing loss is extensive, and a n u m b e r of reviews discuss these diagnoses in great detail. 32, 35, 36 Table 1 lists the causes of hearing loss found most c o m m o n l y in elderly persons. Most of these types of loss can be diagnosed using a combination of history taking, physical examination, and audiometry. Audiometry is essential in the diagnostic evaluation of hearing impairment. Approximately an hour in length, the p r o c e d u r e usually consists of four parts: pure-tone audiometry, speech audiometry, tympanometry, and acoustic reflex threshold measurement (which is rarely useful in age-related hearing loss).
Pure-tone Audiometry.
In pure-tone audiometry, tones are presented to the ear in a systematic fashion to determine the threshold for hearing at each o f a series of frequencies one octave apart. Norms for the threshold of audibility have been established for
193
each frequency. These are standardized to a reference level of 0 dB on the audiogram. A negative n u m b e r on the audiogram denotes better than normal hearing for that tone, and a n u m b e r higher than 20 dB, abnormal hearing. Both the degree and the pattern of abnormalities are important. Differences in thresholds between ears, between air and bone conduction, and among the specific frequencies are all helpful in making a diagnosis. As an example of the diagnostic value of the audiogram, diseases that spare the inner ear and affect only the middle or outer ear, such as otosclerosis, will result in audiograms with normal values for bone c o n d u c t i o n and abnormal values for air conduction. This is known as a i r - bone gap. Sounds transmitted by air c o n d u c t i o n must pass through outer, middle, and inner ears. When transmitted by b o n e conduction, however, sounds bypass the outer and middle ears. Table 1 summarizes the results of pure-tone audiometry for the c o m m o n causes of hearing impairment in the elderly. TABLE 1 Common Causesof Hearing Loss in the Elderly
Diagnosis
Otoscopic and Audiometric Findings
External canal obstruction
Cerumen plug, collapsed canal, or foreign body on otoscopic examination
Otosderosis
Normal otoscopic findings Low frequency, bilateral conductive loss on pure-tone audiometry that progresses to include all frequencies Shallow but normally placed curve on tympanometry (Fig. 3)
Ototoxicity
Normal otoscopic findings Pure-tone audiometry shows bilateral sensorineural loss that may fluctuate or be progressive; usually confined to high frequencies but can occur occasionally throughout spectrum. Some recovery can occur after offending drugs are discontinued
Presbycusis
Normal otoscopic findings High-frequency loss on pure-tone audiometry, followed by loss of middle frequencies, decreasedword recognition, and other changes shown in Figure 3
Noise-induced impairment
Normal otoscopic findings Exposure to loud noise (may be chronic exposure or a single intense exposure) Notching high-frequency loss on pure-tone audiometry ( 3 - 6 KHz are most affected)
Meniere's disease
Normal otoscopic findings Unilateral low-frequency loss initially Normal tympanometric findings
Acoustic neuroma
Normal otoscopic findings Unilateral loss (various frequencies are affected) Normal tympanometric findings Often word discrimination in affected ear is poor
Lavizzo-Mourey, Siegler,
194
HEARING
Speech Audiometry. Pure-tone audiometry does
Tympanometry. Tympanometry can help identify causes for hearing loss other than presbycusis. The technique measures the mobility of the tympanic membrane under different degrees of positive and negative air pressure. Changes in compliance are charted graphically as a function of air pressure. Deviations from the normal pattern include excessive compliance (consistent with ossicular discontinuity), r e d u c e d compliance ( c o m m o n with middle-ear fluid), or left shifts on the graph (indicative of negative middle-ear pressure, w h i c h occurs with eustachian tube dysfunction). Although not a part of standard audiometry, auditory brain-stem response testing uses electrodes to measure neural activity in response to a series of "clicks." Computerized signal averaging allows dis-
Left E a r
R i g h t Ear 250
500
0 ...........
~0
CHARACTERISTICS, PREVALENCE, AND EFFECTS The h u m a n ear is capable of perceiving sound over a wide range of frequencies. Each frequency has a threshold (usually reported in decibels) b e l o w w h i c h sound is inaudible (Fig. 1). The normal ear's sensitivity is highest for frequencies between 500 and 4 , 0 0 0 Hz - - t h e approximate frequency range of h u m a n speech. Sensitivity, particularly for frequencies > 4 , 0 0 0 Hz, decreases with advancing age in the majority of Western populations. 1 Hearing is abnormal in older p e o p l e if pure tones softer than 40 dB in more than one frequency cannot be heard in one or both ears. 1, 3.6 (Because the decibel is a logarithmic unit, an increase of 20 dB represents a tenfold increase in intensity over an established standard, and an increase of 40 dB, a 1,000-fold increase.) Using this definition, cross-sectional studies indicate that 18% of w o m e n over age 65 and 25.3% of men over 65 have hearing impairmentsY Studies that have included higher frequencies or used lower thresholds, however, reveal that 50% to 80% of persons over 65 have some hearing loss. s, 9 Because it is d e p e n d e n t on high-freq u e n c y consonant sounds, speech c o m p r e h e n s i o n among older persons with typical high-frequency hear-
Received from General Internal Medicine, Philadelphia Veterans Affairs Medical Center, and Geriatrics Program, University of Pennsylvania, Philadelphia, Pennsylvania. Dr. Lavizzo-Moureyis the recipient of an Academic Award #KO8AGO036304. Dr. Siegler is a Merck/AFARFellow in Geriatric Clinical Pharmacology. Address correspondence and reprint requests to Dr. LavizzoMourey: General Internal Medicine, Philadelphia Veterans Affairs Medical Center, Universityand WoodlandAvenues, Philadelphia, PA 19104.
lO ~-water O~ flowing ¢.o o) 20 (D 30 Z ca: 4O "4 m "O
50
c-
60
• .:....... whispering th :::;!?:!if..':'-:'.. S J
md b
i conver'afio~a:~''g!~":)::::;;:.:i":ii:!i:iii~ii::i:(' ::::!. :"
nglU rba.bya
:?:'i!i:Z:::!ii!i::ii!!iiii!!il i:iiiii:
Crylng
. . . . :~ ~ :I ". '
> 70 _.1 ~ 80 e~ 90 "r" 100
:el.eph. one
ringing
110 120
125
L
250
ro k pana 500 1000 2000 Frequency (Hz)
j~t airplane ' 4000
8000
FIGURE 1. The frequencies and intensities for common sounds, including consonants. Each sound is positioned in relation to its frequency and loudness under normal conditions. The shaded area depicts the frequency and intensity of conversational speech. An older person with presbycus!s typically has difficulty hearing high-frequency sounds softer than 40 dB. ANSI = American National Standards Institute.
ing loss is lower than normal. Older persons may be unable to distinguish consonants with similar frequencies (Fig. 1 charts the frequencies of consonants). For example, the " s " sound might be interpreted as a " t h " sound in this type of hearing loss, making complex, rapid patterns of speech especially difficult for elderly persons to understand.', s The most c o m m o n cause of bilateral hearing impairment a m o n g the elderly, presbycusis, is characterized by increased thresholds for high-frequency tones, recruitment, and difficulty with speech comprehension.', 3, lo Diminished speech c o m p r e h e n s i o n and recruitment can generally be elicited in the history. Recruitment is the perception of a sudden and dramatic increase in the intensity of sound (often to the point of being painful) in response to mild or moderate increases in volume. Although five types of presbycusis have been documented, the distinctions are not clinically helpful, because they can all o c c u r simultaneously. 1, Other com191
192,
Lavizzo-Mourey. Siegler.
HEARINGIMPAIRMENTIN ELDERLY
•/
100
HHIE-S
Points
Does a hearing problem cause you to feel embarrassed when meeting new people?
8O
Does a hearing problem cause you to feel frustrated when talking to a stranger?
~, 60 >
m !-.-
40 f
f
1181 ," -J ,,"
dL7 . . . .
20
•
,t~ l(2!, "" == J," ,-" ," "
Do you have difficulty hearing when someone speaks in a whisper?. • 40dBIossat 1000 and/or 2000 Hz • > 25 dB loss at 1000, 2000 and 4000 Hz 0 SpeechReception Threshold :> 25 dB
I
I
I
I
I
I
0
20
40
60
80
100
1-Specificity (%)
DO you feel handicapped by a hearing problem? Does a hearing problem cause you difficulty when visiting friends, relatives, or neighbors? Does a hearing problem cause you to attend religious services less often than you would like?
Does a hearing problem cause you to have arguments with family members?
FIGURE 2. The Hearing Handicap Inventory for the Elderly-Does a hearing problem cause you difficulty when listening to TV or Screening Version (HHIE-S) (right) is a self-administered instrument. radio? Patients are instructed to answer each question "no," "'sometimes," or "yes." The maximum score is 40 and the responses are scored as Do you feel that any difficulty with your hearing limits or hampers follows: no = O, sometimes = 2, and yes = 4. The left side of the your personal or social life? figure depicts the receiver operating characteristic (ROC) curve for HHIE-S scores of 2, 8, 16, and 24 (shown in parentheses) compared Does a hearing problem cause you difficulty when in a restaurant with those of three other tests. Thus, a score of 24 has similar sensiwith relatives and friends? tivity and specificity to those of the three tests shown in the box. Scores of 24 or more are an indication for a referral for further testing. Reprinted with permission from: Lichtenstein MJ, Bess FH, Logan SA. Diagnostic performance of the Hearing Handicap Inventory for the Elderly (screening version) against differing definitions of hearing loss. Ear Hear. 9(4):208-11. © by Williams & Wilkins, 1988.
m o n causes of chronic hearing loss in elderly persons are s h o w n in Table 1. Infrequently, chronic hearing i m p a i r m e n t a m o n g older adults is caused b y inner-ear malformations, syphilis, inner-ear m e m b r a n e rupture, or idiopathic hearing loss. 1, s Studies of elderly persons with hearing impairm e n t s h o w that m a n y have c o m m u n i c a t i o n dysfunction, cognitive loss, depression, social isolation, or psychosis. 12-23 Some studies reporting these associations have used hearing-specific measures of quality of life to assess the effect o f hearing impairment. 4, 2o Hearing loss causes a statistically significant i m p a i r m e n t in c o m m u n i c a t i o n and diminution in emotional and social functioning. 2, is, 24, 25 Although not all of these functional and psychologic p r o b l e m s are directly correlated with the severity of the pure-tone hearing impairment, they are sometimes partly alleviated after hearing loss is treated w i t h a hearing aid. 4. 25, 26 Conversely, studies of elderly persons with depression, psychoses, cognitive impairment, and dementia show that m a n y of these elders have hearing impairment. 13-z6 Although m a n y of these studies involved small sample sizes or lacked control groups, two larger studies, one from the Hearing and Speech Clinic at Johns Hopkins, 17 and the other a population-based study from London, 2° revealed significant associations b e t w e e n hearing loss and depression. In addition, Uhlm a n n et al. 's c a s e - control study demonstrated not o n l y
a higher prevalence of hearing i m p a i r m e n t a m o n g elderly persons w i t h d e m e n t i a than that a m o n g nondem e n t e d elders, but also a direct relationship b e t w e e n the severity of hearing loss and the severity of the cognitive loss. is In short, a growing literature supports the clinical w i s d o m that hearing loss has a negative effect on the quality o f life. In light of the high prevalence o f hearing loss and its effect on quality of life, case-finding efforts by p r i m a r y care providers are worthwhile.
EVALUATION Screening
The clinician must identify patients w h o s e hearing losses impair c o m m u n i c a t i o n or quality of life. Although an audiogram is required to make an accurate diagnosis, a u d i o m e t r y is too c o m p l i c a t e d to administer routinely as a screening test. Instead, two types of screening tests are used: those measuring actual hearing loss and those measuring the disability associated with hearing loss. 26-32 Because tests for hearing thresholds do not measure disability, and tests for disability do not assess i m p a i r m e n t s at specific frequencies, the two types of tests are best used together. 31, 32 An example of a disability screen is the Hearing Handicap Inventory for the E l d e r l y - - S c r e e n i n g Version (HHIE-S), a ten-item self-administered disability test that is m o r e
JOURNALOFGENERALiNTERNALMEDICINE, Volume 7 (March/April). 1992
specific (70% to 84%) than sensitive (53% to 72%) w h e n audiometric definitions of hearing impairment are used as the "gold standard" (Fig. 2).28, 29 In addition, among elderly hearing aid owners, it has been shown that scores on the HHIE-S improve after the initiation of hearing aid use. 33 An instrument increasingly used to evaluate hearing thresholds is the Audioscope (Welch Allyn, Inc., Skaneateles Falls, NY). Audioscopes are portable instruments similar to otoscopes that are capable of emitting pure tones, They test for hearing loss at the 25- and 40-dB levels over four frequencies (500, 1,000, 2,000, and 4,000 Hz).29 When audiometry results are used as the gold standard, and failure to detect an Audioscope tone at two or more frequencies defines an abnormal result, the sensitivity and specificity in elderly persons w h o do not have dementia are 1.00 and 0.70, respectively. 29 Together the HHIE-S and audioscopy yield a test with impressive sensitivity, specificity, and an overall accuracy of 83%. 31 The major advantage the Audioscope has over traditional portable audiometers with earphones (used to screen for hearing loss in many settings) is convenience. This hand-held instrument can screen for hearing loss in conjunction with a routine otoscopic examination, and the c o m b i n e d audioscopic and otoscopic examination should take less than five minutes. The sensitivities and specificities of other screening tests, such as tuning fork, finger rub, or whisp e r e d voice, are inferior to those of audioscopy. 3o However, of these, the widespread voice test is the next best alternative. 34 TM
Diagnostic Tests
Once the screening examination has identified a patient likely to have significant hearing loss, definitive testing is necessary to confirm the presence of the impairment and diagnose the underlying pathologic factor (if any). Differential diagnosis of hearing loss is extensive, and a n u m b e r of reviews discuss these diagnoses in great detail. 32, 35, 36 Table 1 lists the causes of hearing loss found most c o m m o n l y in elderly persons. Most of these types of loss can be diagnosed using a combination of history taking, physical examination, and audiometry. Audiometry is essential in the diagnostic evaluation of hearing impairment. Approximately an hour in length, the p r o c e d u r e usually consists of four parts: pure-tone audiometry, speech audiometry, tympanometry, and acoustic reflex threshold measurement (which is rarely useful in age-related hearing loss).
Pure-tone Audiometry.
In pure-tone audiometry, tones are presented to the ear in a systematic fashion to determine the threshold for hearing at each o f a series of frequencies one octave apart. Norms for the threshold of audibility have been established for
193
each frequency. These are standardized to a reference level of 0 dB on the audiogram. A negative n u m b e r on the audiogram denotes better than normal hearing for that tone, and a n u m b e r higher than 20 dB, abnormal hearing. Both the degree and the pattern of abnormalities are important. Differences in thresholds between ears, between air and bone conduction, and among the specific frequencies are all helpful in making a diagnosis. As an example of the diagnostic value of the audiogram, diseases that spare the inner ear and affect only the middle or outer ear, such as otosclerosis, will result in audiograms with normal values for bone c o n d u c t i o n and abnormal values for air conduction. This is known as a i r - bone gap. Sounds transmitted by air c o n d u c t i o n must pass through outer, middle, and inner ears. When transmitted by b o n e conduction, however, sounds bypass the outer and middle ears. Table 1 summarizes the results of pure-tone audiometry for the c o m m o n causes of hearing impairment in the elderly. TABLE 1 Common Causesof Hearing Loss in the Elderly
Diagnosis
Otoscopic and Audiometric Findings
External canal obstruction
Cerumen plug, collapsed canal, or foreign body on otoscopic examination
Otosderosis
Normal otoscopic findings Low frequency, bilateral conductive loss on pure-tone audiometry that progresses to include all frequencies Shallow but normally placed curve on tympanometry (Fig. 3)
Ototoxicity
Normal otoscopic findings Pure-tone audiometry shows bilateral sensorineural loss that may fluctuate or be progressive; usually confined to high frequencies but can occur occasionally throughout spectrum. Some recovery can occur after offending drugs are discontinued
Presbycusis
Normal otoscopic findings High-frequency loss on pure-tone audiometry, followed by loss of middle frequencies, decreasedword recognition, and other changes shown in Figure 3
Noise-induced impairment
Normal otoscopic findings Exposure to loud noise (may be chronic exposure or a single intense exposure) Notching high-frequency loss on pure-tone audiometry ( 3 - 6 KHz are most affected)
Meniere's disease
Normal otoscopic findings Unilateral low-frequency loss initially Normal tympanometric findings
Acoustic neuroma
Normal otoscopic findings Unilateral loss (various frequencies are affected) Normal tympanometric findings Often word discrimination in affected ear is poor
Lavizzo-Mourey, Siegler,
194
HEARING
Speech Audiometry. Pure-tone audiometry does
Tympanometry. Tympanometry can help identify causes for hearing loss other than presbycusis. The technique measures the mobility of the tympanic membrane under different degrees of positive and negative air pressure. Changes in compliance are charted graphically as a function of air pressure. Deviations from the normal pattern include excessive compliance (consistent with ossicular discontinuity), r e d u c e d compliance ( c o m m o n with middle-ear fluid), or left shifts on the graph (indicative of negative middle-ear pressure, w h i c h occurs with eustachian tube dysfunction). Although not a part of standard audiometry, auditory brain-stem response testing uses electrodes to measure neural activity in response to a series of "clicks." Computerized signal averaging allows dis-
Left E a r
R i g h t Ear 250
500
0 ...........
~0
