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Factors influencing sensorineural hearing loss in chronic otitis media
Am I Otolaryngol 8:13-15, 1987
Factors Influencing Sensorineural Hearing Loss in Chronic Otitis Media EERO VARTIAINEN,
MD, AND SEPPO KARJALAINEN,M D
Sensorineural hearing loss was studied in 874 chronically infected ears and was found to occur more frequently in cases of cholesteatoma and in the presence of discharge. Sensorineura! hearing loss is not dependent on the type of causative microorganism. Older patients exhibited sensorineural hearing loss more often than did younger patients, this disorder being more common in affected ears than in control ears (the contralateral ear in unilateral cases).
MATERIALS AND METHODS
Several studies have shown that chronic otitis media can result in sensorineural hearing loss. 1-4 According to Paparella et el., 4 sensorineural hearing loss caused by chronic otitis media is the result of a cochlear biochemical change created across the membrane of the round window. The authors hypothesize that the semipermeable nature of the membrane enables the passage of toxic materials that cause biochemical changes in the perilymph and endolymph, resulting in the gradual destruction of Corti's organ. Walby et al., 3 however, found no evidence that chronic suppurative otitis media causes destruction of hair cells or cochlear neurons. They concluded that the abnormally high bone conduction thresholds frequently observed in this condition may result from changes in the mechanics of sound transmission. Dumich and Harner, 5 in their study of 200 patients with unilateral chronic otitis media, found significant loss of cochlear function in only a small group with extensive disease. They concluded that chronic otitis media had little effect on cochlear function in the majority of patients. The purpose of our study was to investigate factors that might affect sensorineural hearing loss associated with chronic otitis media.
The study sample consisted of 874 chronically infected ears treated at the Department of Otolary-ngology, University of Kuopio, between 1966 and 1979. Patients who had previously undergone otologic surgery, had suffered head injury, had taken ototoxic drugs or who had a family history of hearing loss were excluded, Patients under 10 and over 60 years old also were excluded. Air and bone conduction thresholds were determined using an audiometer calibrated according to ISO standards. Pretreatment bone conduction thresholds were analyzed. Ears were classified as exhibiting sensorineural hearing loss if they showed losses in bone conduction of 30 dB or greater at two or more frequencies of 1, 2, and 4 kHz. In unilateral cases, the contralateral (healthy) ear served as a control. The statistical significance of differences between group distributions was tested using the chi-square test.
RESULTS Table 1 shows the results obtained for various age groups. The number of chronically infected ears with sensorineural hearing loss was greater in older than in younger age groups. High-frequency hearing loss was significantly more prevalent in chronically infected ears than in controis, with the exception of the youngest age group, wherein differences were not statistically significant.
Received July 23, 1986, from the Department of Otolaryngology, Universityof Kuopio, Kuopio, Finland. Accepted for publication August 13, 1986. Address reprint requests to Dr. Vartiainen: Osasto 2551, University Central Hospital PL 21, SF-70211 Kuopio, Finland. 0196-0709/87 $0.00 + .25 13
SENSORINEURALHEARINGLOSS TABLE 1. Sensorineural Hearing Loss in Various Age Groups CONTROLEARS
CHRONICALLYINFECTED EARS
Sensorineural loss
Sensorineural l a s s No.
Age g r o u p s (years)
o f ears
No. of ears
10--19 20--29 30--39 40-49 50-59
139 152 243 185 155
2 10 35 39 73
The results in relation to bacteriologic findings are listed in Table 2. No statistically significant differences were found in relation to the various causative bacteria. The n u m b e r of discharging ears w i t h sensorineural hearing loss was significantly greater (P < 0.001) than that of dry ears with the same disorder. As indicated in Table 3, high-frequency sensorineural hearing loss was significantly more frequent in cholesteatomatous ears than in chronically infected ears without cholesteatoma (P < 0.05). The n u m b e r of ears with sensorineural hearing loss was significantly greater (P < 0.001) than the n u m b e r of control ears with sensorineural hearing loss, both in cases of cholesteatoma and of chronic infection without cholesteatoma. DISCUSSION The so-called Carhart's notch must be considered w h e n dealing w i t h bone conduction thresholds in chronically infected ears. In chronic otitis media, mechanical occlusion of the w i n d o w by granulations, chelesteatoma and pus, or stiffness of the ossicular chain m a y result in loss of bone
TABLE 2.
Sensorineural Hearing in Relation to Bacteriologic Findings SENSORINEIJRAL HEARING LOSS
Pseu d o m o n a s aeruginosa Staphylococcus
American
aureus Proteus strains O t h e r bacteria or
polyinfection Journal No growth of Discharging ears Otolaryngology Dry ears 14
No. of ears
No, of ears
(%)
65
17
(31)
68
18
(26)
20 118
10 22
(50) (19)
75 336 538
20 87 72
(27) (26) (13)
(%)
No. of ears
No. of ears
(%)
(1.41 (6.6) (14) (21) (47)
108 124 156 122 99
0 0 1 2 7
--(0.6) (1.6) (7.0)
conduction. The effect of Carhart's notch on the bone conduction threshold is greatest at 4 kHz (15 dB) and less (5-10 dB) at lower frequencies2 Owing to extremely strict criteria for sensorineural hearing loss (bone conduction losses of 30 dB or greater at two or more frequencies of 1, 2, and 4 kHz), we believe that any middle ear mechanical interference has been eliminated in the results. Loss of cochlear function in chronically infected ears may be due to the use of topical atetoxic drugs. Several patients had received conservative treatment at some stage of their diseases before coming to us for treatment. Since some of these patients could not remember the names of drugs taken, the possibility that they had been treated with ototoxic ear drops cannot be excluded. According to the results, sensorineural hearing loss in chronic otitis media is particularly significant in older patients. This suggests that sensorineural hearing loss in chronically infected ears depends on the duration of the disease. In older patients, chronic otitis media had usually been present for longer periods of time than in younger patients. The influence of presbycusis was minimized by using the healthy ears in unilateral cases as controls. TABLE 3. Sensorineural Hearing Loss in Cholesteatomatous Ears and in Ears without Cholesteatoma SENSORINEURAL HEARING LOSS
Cholesteatomatous ears Ears w i t h o u t chalesteatoma Chronically infected ears Control ears
No.
No. of
of ears
ears
(%)
322
72
(22)
552
87
(16)
874
159
(18)
609
10
(1,6)
VARTIAINENAND KARJALAINEN The a s s u m p t i o n might be m a d e that sensorineural hearing loss in c h o l e s t e a t o m a t o u s ears, particularly w h e n the disease is confined to the attic region, is insignificant. Our study reveals, however, that ears with cholesteatomatous chronic otitis m e d i a exhibit s e n s o r i n e u r a l hearing loss significantly m o r e often t h a n other chronically infected ears. A possible e x p l a n a t i o n is that m o s t cholesteatomatous ears studied had suffered from prolonged periods of discharge, m o s t of t h e m revealing extensive disease u p o n operation. Pseudomonas aeruginosa m a y cause, u n d e r suitable host conditions, an e x t r e m e l y resistant, invasive t y p e of infection. 7'a This bacterium is one of the m o s t c o m m o n etiologic agents in chronic otitis media. No significant differences were found b e t w e e n c a u s a t i v e bacteria in relation to the i n c i d e n c e of sensorineural hearing loss. The i n c i d e n c e of c o c h l e a r damage does not s e e m to be a n y higher with P. a e r u g i n o s a t h a n w i t h any other bacteria. In general, s e n s o r i n e u r a l h e a r i n g loss a p p e a r s to be a frequent c o m p l i c a t i o n of chronic otitis media. H i g h - f r e q u e n c y hearing loss was found in 18% of c h r o n i c a l l y infected ears but in only 1.6% of control ears. Our findings indicate that
sensorineural hearing loss is m o s t c o m m o n in chronically infected ears with c h o l e s t e a t o m a s and in ears that h a v e suffered f r o m p r o l o n g e d p e r i o d s of discharge. T h e results also i n d i c a t e that the degree of s e n s o r i n e u r a l h e a r i n g l o s s is not d e p e n d e n t on the t y p e of c a u s a t i v e m i c r o o r ganism.
References 1. Paparella MM, Brady DR, Heel R: Sensorinaural hearing loss in chronic otltis media and mastoiditis. Trans Am Acad Ophthalmol Otolaryngol 1970;74:108-115 2. English GM, Northern [L, Fria TJ: Chronic atitis media as a cause of sensorineurai hearing loss. Arch Otalaryngol 1973',98:18-22 3. Walby AP, Barrera A, Schuknecht HF: Cochlear pathology in chronic suppurative otitis media. Ann Otal Rhino/ Laryngol 1983;92(suppl 103} 4. Paparella MM, Morizono T, Le CT, et al: Sensarineural hearing loss in otitis media. Ann Otol Rhinol Laryngol 1984;93:623-629 5. Dumich PS, Homer SG: Cochlear function in chronic otitis media. Laryngoscope 1983;93:583-586 6. Beickert P: Otosclerase, in Berendes J, Link R, Z611ner F (eds]: Hals-Nasen-Ohren Heilkunde. Stuttgart, Georg Thieme Verlag, 1979, pp 19.23-19.24 7. Chandler JR: Malignant exlernal otitis, Laryngoscope 1968;78:1257-1294 8. Wilson DF, Pulec JL, Linthicum FH: Malignant external otitis. Arch Otolaryngol 1971;93:419-422
Volume 8 Number 1 Janua W 1987 15
Factors Influencing Sensorineural Hearing Loss in Chronic Otitis Media EERO VARTIAINEN,
MD, AND SEPPO KARJALAINEN,M D
Sensorineural hearing loss was studied in 874 chronically infected ears and was found to occur more frequently in cases of cholesteatoma and in the presence of discharge. Sensorineura! hearing loss is not dependent on the type of causative microorganism. Older patients exhibited sensorineural hearing loss more often than did younger patients, this disorder being more common in affected ears than in control ears (the contralateral ear in unilateral cases).
MATERIALS AND METHODS
Several studies have shown that chronic otitis media can result in sensorineural hearing loss. 1-4 According to Paparella et el., 4 sensorineural hearing loss caused by chronic otitis media is the result of a cochlear biochemical change created across the membrane of the round window. The authors hypothesize that the semipermeable nature of the membrane enables the passage of toxic materials that cause biochemical changes in the perilymph and endolymph, resulting in the gradual destruction of Corti's organ. Walby et al., 3 however, found no evidence that chronic suppurative otitis media causes destruction of hair cells or cochlear neurons. They concluded that the abnormally high bone conduction thresholds frequently observed in this condition may result from changes in the mechanics of sound transmission. Dumich and Harner, 5 in their study of 200 patients with unilateral chronic otitis media, found significant loss of cochlear function in only a small group with extensive disease. They concluded that chronic otitis media had little effect on cochlear function in the majority of patients. The purpose of our study was to investigate factors that might affect sensorineural hearing loss associated with chronic otitis media.
The study sample consisted of 874 chronically infected ears treated at the Department of Otolary-ngology, University of Kuopio, between 1966 and 1979. Patients who had previously undergone otologic surgery, had suffered head injury, had taken ototoxic drugs or who had a family history of hearing loss were excluded, Patients under 10 and over 60 years old also were excluded. Air and bone conduction thresholds were determined using an audiometer calibrated according to ISO standards. Pretreatment bone conduction thresholds were analyzed. Ears were classified as exhibiting sensorineural hearing loss if they showed losses in bone conduction of 30 dB or greater at two or more frequencies of 1, 2, and 4 kHz. In unilateral cases, the contralateral (healthy) ear served as a control. The statistical significance of differences between group distributions was tested using the chi-square test.
RESULTS Table 1 shows the results obtained for various age groups. The number of chronically infected ears with sensorineural hearing loss was greater in older than in younger age groups. High-frequency hearing loss was significantly more prevalent in chronically infected ears than in controis, with the exception of the youngest age group, wherein differences were not statistically significant.
Received July 23, 1986, from the Department of Otolaryngology, Universityof Kuopio, Kuopio, Finland. Accepted for publication August 13, 1986. Address reprint requests to Dr. Vartiainen: Osasto 2551, University Central Hospital PL 21, SF-70211 Kuopio, Finland. 0196-0709/87 $0.00 + .25 13
SENSORINEURALHEARINGLOSS TABLE 1. Sensorineural Hearing Loss in Various Age Groups CONTROLEARS
CHRONICALLYINFECTED EARS
Sensorineural loss
Sensorineural l a s s No.
Age g r o u p s (years)
o f ears
No. of ears
10--19 20--29 30--39 40-49 50-59
139 152 243 185 155
2 10 35 39 73
The results in relation to bacteriologic findings are listed in Table 2. No statistically significant differences were found in relation to the various causative bacteria. The n u m b e r of discharging ears w i t h sensorineural hearing loss was significantly greater (P < 0.001) than that of dry ears with the same disorder. As indicated in Table 3, high-frequency sensorineural hearing loss was significantly more frequent in cholesteatomatous ears than in chronically infected ears without cholesteatoma (P < 0.05). The n u m b e r of ears with sensorineural hearing loss was significantly greater (P < 0.001) than the n u m b e r of control ears with sensorineural hearing loss, both in cases of cholesteatoma and of chronic infection without cholesteatoma. DISCUSSION The so-called Carhart's notch must be considered w h e n dealing w i t h bone conduction thresholds in chronically infected ears. In chronic otitis media, mechanical occlusion of the w i n d o w by granulations, chelesteatoma and pus, or stiffness of the ossicular chain m a y result in loss of bone
TABLE 2.
Sensorineural Hearing in Relation to Bacteriologic Findings SENSORINEIJRAL HEARING LOSS
Pseu d o m o n a s aeruginosa Staphylococcus
American
aureus Proteus strains O t h e r bacteria or
polyinfection Journal No growth of Discharging ears Otolaryngology Dry ears 14
No. of ears
No, of ears
(%)
65
17
(31)
68
18
(26)
20 118
10 22
(50) (19)
75 336 538
20 87 72
(27) (26) (13)
(%)
No. of ears
No. of ears
(%)
(1.41 (6.6) (14) (21) (47)
108 124 156 122 99
0 0 1 2 7
--(0.6) (1.6) (7.0)
conduction. The effect of Carhart's notch on the bone conduction threshold is greatest at 4 kHz (15 dB) and less (5-10 dB) at lower frequencies2 Owing to extremely strict criteria for sensorineural hearing loss (bone conduction losses of 30 dB or greater at two or more frequencies of 1, 2, and 4 kHz), we believe that any middle ear mechanical interference has been eliminated in the results. Loss of cochlear function in chronically infected ears may be due to the use of topical atetoxic drugs. Several patients had received conservative treatment at some stage of their diseases before coming to us for treatment. Since some of these patients could not remember the names of drugs taken, the possibility that they had been treated with ototoxic ear drops cannot be excluded. According to the results, sensorineural hearing loss in chronic otitis media is particularly significant in older patients. This suggests that sensorineural hearing loss in chronically infected ears depends on the duration of the disease. In older patients, chronic otitis media had usually been present for longer periods of time than in younger patients. The influence of presbycusis was minimized by using the healthy ears in unilateral cases as controls. TABLE 3. Sensorineural Hearing Loss in Cholesteatomatous Ears and in Ears without Cholesteatoma SENSORINEURAL HEARING LOSS
Cholesteatomatous ears Ears w i t h o u t chalesteatoma Chronically infected ears Control ears
No.
No. of
of ears
ears
(%)
322
72
(22)
552
87
(16)
874
159
(18)
609
10
(1,6)
VARTIAINENAND KARJALAINEN The a s s u m p t i o n might be m a d e that sensorineural hearing loss in c h o l e s t e a t o m a t o u s ears, particularly w h e n the disease is confined to the attic region, is insignificant. Our study reveals, however, that ears with cholesteatomatous chronic otitis m e d i a exhibit s e n s o r i n e u r a l hearing loss significantly m o r e often t h a n other chronically infected ears. A possible e x p l a n a t i o n is that m o s t cholesteatomatous ears studied had suffered from prolonged periods of discharge, m o s t of t h e m revealing extensive disease u p o n operation. Pseudomonas aeruginosa m a y cause, u n d e r suitable host conditions, an e x t r e m e l y resistant, invasive t y p e of infection. 7'a This bacterium is one of the m o s t c o m m o n etiologic agents in chronic otitis media. No significant differences were found b e t w e e n c a u s a t i v e bacteria in relation to the i n c i d e n c e of sensorineural hearing loss. The i n c i d e n c e of c o c h l e a r damage does not s e e m to be a n y higher with P. a e r u g i n o s a t h a n w i t h any other bacteria. In general, s e n s o r i n e u r a l h e a r i n g loss a p p e a r s to be a frequent c o m p l i c a t i o n of chronic otitis media. H i g h - f r e q u e n c y hearing loss was found in 18% of c h r o n i c a l l y infected ears but in only 1.6% of control ears. Our findings indicate that
sensorineural hearing loss is m o s t c o m m o n in chronically infected ears with c h o l e s t e a t o m a s and in ears that h a v e suffered f r o m p r o l o n g e d p e r i o d s of discharge. T h e results also i n d i c a t e that the degree of s e n s o r i n e u r a l h e a r i n g l o s s is not d e p e n d e n t on the t y p e of c a u s a t i v e m i c r o o r ganism.
References 1. Paparella MM, Brady DR, Heel R: Sensorinaural hearing loss in chronic otltis media and mastoiditis. Trans Am Acad Ophthalmol Otolaryngol 1970;74:108-115 2. English GM, Northern [L, Fria TJ: Chronic atitis media as a cause of sensorineurai hearing loss. Arch Otalaryngol 1973',98:18-22 3. Walby AP, Barrera A, Schuknecht HF: Cochlear pathology in chronic suppurative otitis media. Ann Otal Rhino/ Laryngol 1983;92(suppl 103} 4. Paparella MM, Morizono T, Le CT, et al: Sensarineural hearing loss in otitis media. Ann Otol Rhinol Laryngol 1984;93:623-629 5. Dumich PS, Homer SG: Cochlear function in chronic otitis media. Laryngoscope 1983;93:583-586 6. Beickert P: Otosclerase, in Berendes J, Link R, Z611ner F (eds]: Hals-Nasen-Ohren Heilkunde. Stuttgart, Georg Thieme Verlag, 1979, pp 19.23-19.24 7. Chandler JR: Malignant exlernal otitis, Laryngoscope 1968;78:1257-1294 8. Wilson DF, Pulec JL, Linthicum FH: Malignant external otitis. Arch Otolaryngol 1971;93:419-422
Volume 8 Number 1 Janua W 1987 15