Comparative Study of Pure-Tone, Impedance, and Otoscopic Hearing Screening Methods A
Survey of Native
Margaret
E.
Indian Children in British Columbia
Roberts, MSc
\s-b\A survey of 1,109 native Indian children in five communities in British Columbia was conducted to determine incidence of middle ear pathologic features and to compare impedance and
pure-tone audiometry as hearing screening methods. Survey teams included a public health nurse, two otologists, and two audiologists. On ear, nose, and throat (ENT) otoscopic examination, the incidence of middle ear disease requiring treatment was 12%. Disease was most prevalent in the preschool- and primary school-aged children. Pure-tone audiometry yielded 62% normal and 19% abnormal results. Nineteen
of methods has received much attention, and empha¬ sis has been placed on finding proce¬ dures that will identify both hearing loss and middle ear pathologic fea¬ tures. The opinions have been numer¬ ous and diverse.'"' Based on a study of a large population of school-aged chil¬ dren, Eagles' emphasized that pres¬ ent methods of pure-tone screening are not sensitive enough to identify the child with fluctuating mild con¬ ductive losses. In a long-range investi¬ gation of children, Brooks- showed that impedance audiometry, when used as an "identification procedure," provides a sensitive index of middle ear pathologic features and has rec¬ ommended further study of its use for this purpose. Harker and Van Wa¬ goner,' in their study of 710 southeast Alaskan children of preschool and elementary school age, showed that the
five years,
past comparison In hearing screening
Accepted for publication June 22, 1976. From the Hearing Branch, Workers' Compen-
sation Board of British Columbia, British Columbia, Canada.
Richmond,
Reprint requests to Hearing Branch, Workers' Compensation Board of British Columbia, 1055 Shellbridge Way, Richmond, British Columbia, V6X 2X1, Canada (Ms Roberts).
percent of the children could not be tested by this method. Impedance audiometry yielded 54% normal and 38% abnormal results on the stringent criteria used to define the parameters of normality. Eight percent of the children could not be tested. Since there was a high incidence of middle ear pathologic features in the preschool group of children who could not be successfully evaluated by pure\x=req-\ tone audiometry, it is suggested that further investigation of impedance audiometry be undertaken in order to define parameters that will provide the most reliable referral criteria.
(Arch Otolaryngol 102:690-694, 1976)
impedance audiometry is a successful method of assessing middle ear dis¬ ease, particularly in the preschool group of children, who cannot be tested by traditional pure-tone, dis¬ crete
frequency testing. They
recom¬
mended that impedance be used "in addition to" pure-tone screening. On the other hand, in a survey of a limited number of 71 children, Lewis et al· found impedance audiometry to be "feasible but not significantly more reliable in predicting middle ear disease than pure tone audiometry or
otoscopy."
In the fall of
1974, the Canadian
Department of National Health and Welfare sponsored an Ear Disease and Hearing Survey of five Indian
reservations on the Pacific coast of British Columbia. The aims of the survey were: (1) to determine the inci¬ dence of ear disease in children of various age groups; (2) to compare the incidence of active disease vs old disease; and (3) to determine the inci¬ dence of hearing disability. In addi¬ tion to these aims, this survey provided the opportunity to compare
pure-tone audiometry, impedance
au¬
diometry, and otoscopie examination
Downloaded From: http://archotol.jamanetwork.com/ by a University of Michigan User on 06/14/2015
hearing screening methods. The results of that comparative survey are reported herein. as
METHODS Each of the survey teams included
a
locally based public health nurse, two audiologists, and two otologists. Every
was interviewed by the nurse for a history and then underwent pure-tone audiometry, impedance audiometry, and
child
ear, nose, and throat (ENT) examination, in that order. The following procedures were used.
Pure-Tone Audiometry Pure-tone audiometry was conducted in a small office. Only the audiologist and subject were present. The child was condi¬ tioned to respond using a 1,000-Hz 45-dB tone. His response was then tested at 25 dB for the pure tones 500, 1,000, 2,000 and 4,000 Hz. If he failed to respond to 25 dB, the frequencies missed were tested at a 35-dB level. If a positive response was elicited, that frequency was retested at 25 dB. A test result was considered abnormal if no response was obtained at one or more frequencies in either ear at 25 dB.
Impedance Audiometry were brought one at a time
Children
to
the testing room and instructed to sit very still and make no response. The probe tip was inserted into the external ear canal and adjusted until an air-tight seal was obtained. Pressure in the outer canal was then increased to positive 200 mm H.,0 and the deflection of the balance needle observed as the pressure was gradually decreased. From this observation, the examiner noted middle ear pressure and tympanogram type. Middle ear pressure was recorded at the point of minimum needle deflection. Tympanograms were typed according to the classification of Jerger et al.:' Type A shows a high, welldefined peak of maximum balance needle deflection between +100 and —100 mm H,0 pressure; type shows limited balance needle deflection and no well-defined peak; type C shows a well-defined peak at près-
Table
less than -200 mm , . The stapedius reflex contraction was then tested at 95 dB at 1,000 and 2,000 Hz using a contralateral signal. Deflection of the balance needle with simultaneous presentation of the stimulus indicated a
1.—Age
and Sex Distribution of 1,109 Children Tested in Five Communities
Haida
SkideGate
sures
positive reflex.
The entire procedure was carried out first with the probe in the left ear and then in the right. A normal test was one in which a type A tympanogram and stape¬ dius reflexes at both test frequencies were elicited from both ears. Any other result was considered abnormal. Since the described impedance screening procedure might not discover a highfrequency sensorineural loss, one further measurement was added by asking the child to respond to a pure tone of 4,000 Hz at 25 dB. This high-frequency sensori¬ neural test at 4,000 Hz was analyzed sepa¬ rately and compared with the pure-tone results. ENT Examination A was
complete ENT evaluation of each child made by the otolaryngologist and
included examination of the nose, tonsils, and adenoids as well as otoscopie observa¬ tion of the ears. The examiner was required to note whether the tympanic membrane was normal and whether any of the following were present: cerumen impaction, serous otitis, adhesive otitis, tympanic perforation (dry or wet), and cholesteatoma. The Weber and Rinné tuning fork tests were attempted on all children of suitable age. If cerumen was present, it was removed before proceeding with otoscopie and tuning fork tests. At the conclusion of the survey, it was realized that the conditions "cerumen impaction" and "adhesive otitis" had not been clearly defined and thus had not been uniformly recorded. These two diagnoses are, there¬ fore, omitted from the results reported.
RESULTS A total of 1,109 children were tested. The age and sex distribution in the five communities is shown in Table 1. In each age group, there were a number of children that could not be tested by one or more of the screening procedures due to inattention or lack of cooperation. Table 2 indicates the number of children who could not be tested in each one of the three screen¬ ing procedures. Not included in the Table as "could not test" by imped¬ ance are 46 children in whom either a seal could not be maintained (perfora-
Age Group, yr 2-4
5-8 9-13
Village
Bella
Mt
Bella
Currie
Subtotal M 49
M 12
25 31
29
66 19
40 8
147
94
18 11 17 12
Undeter¬ mined Subtotal Total
Bella Coola
241
12 14 11
23 41 13
15
19 29
13 13 36
13
14
19 31
16
38
34 19
69
64
21
16
23 1
1
122 226
118
0
1
62 47 109
104
17 27
F 40 74
86 148
231 82
127 197 72
598
511
0
116
167 132 299
334
Total 89 160 275 428 154
1
1,109
1,109 1,109
Table 2—Number of Children Who Could Not Be Tested* ENT
Age Group, yr 2
2-4 5-8 9-13 14 + Total %of Total Tested
No. Tested
89 160
Serous Otitis
Distribution of Children With Disease Who
Perforation
Perforation and Cholesteatoma
Perforation and Serous Otitis
Required
Treatment
Perforation,
% of Total in
Serous Otitis, and Cholesteatoma
Total
Age Group
¿2!
~~20~ 23
28
12
1,109
73
6.6
ranged from 7% (Haida Village) 18% (Skidegate).
^¡2
17.5 15.3 7.0 7.8
132
11.9
~~42
21
275 428 154
100.0
7.—Age
15
30
51
0.2
4.6
0.4
to
The age distribution of children found to have pathologic features is shown in Table 7. Serous otitis was the most prevalent condition. It was found in 73 children, or 7% of the total population. In 35 cases, the condition was bilateral. It was more prevalent among preschool and primary school children than among secondary school-aged children. Perforated tympanic membranes were found in 58 children (5%). In ten of these children, the condition was bilateral. This pathologic feature was most prevalent in the 5- to 8-year-old age bracket; only six such cases were found in the preschool age group. Four cholesteatomas were found. In one case, a perforation was also found in the same ear. In three cases, active disease was found in the opposite ear: one had a perforation in the opposite ear; one had a perforation in the same ear and serous otitis in the opposite ear; and one had serous otitis in the same ear and a perforation in the
opposite one.
Pure-tone and impedance results for the ears diagnosed to have patho¬ logic features by ENT otoscopie exam¬ ination are summarized in Table 8. Of 185 diseased ears, 24 (13%) had normal pure-tone results and 14 (8%) had normal impedance results. Seventyeight (42%) of the 185 ears could not be tested by pure-tone audiometry and 26 (14%) could not be tested by imped¬ ance.
COMMENT
The results of the present survey among Indian children of different ages emphasizes the need for contin¬ ued study of hearing screening pro¬ grams aimed at detecting both senso-
0.2
11.9
Table 8.—Results of Pure-Tone and Impedance on Ears With Pathologic Features
Audiometry Combined
Screening Test Total pathologic features by otoscopy Left
Serous Otitis
29
ear
Bilateral
ears
Total children
Total ears Pure-tone audiometry Normal Abnormal CNT
Tympanometry Type A Type Type C
Features
17 24
ear
Right
Pathology Perforation
36 73 109
26 53
10
53
51
132 185
61
15
17
24
30 61
10
15
82 78 24
33 42
30
72 52 11
No Seal CNT
Stapedius
Total
25 reflex 14
Present Absent
78 20
CÑT rineural and tive losses.
fluctuating mild conduc¬
Ninety-nine percent of the children otoscopie examination. ear pathologic features were diagnosed in 12% of 1,109 chil¬ underwent Mild middle
dren. This incidence of disease is slightly higher than that reported for urban community children (5% to 8%), but lower than that reported for native and other low socioeconomic populations (16% to 18%).J The age distribution of the children requiring treatment is of particular importance: 15% were under 2 years old; 21% were 2 to 4 years old; and 32% were of primary school age. These data em¬ phasize the point that a screening program for detection of middle ear pathologic features must include this very young population. results Pure-tone audiometrie showed that 19% of the children did
52
15
145 26
not pass this
screening test. Although possible that some diseased ears may have been missed at otoscopie inspection, the 19% pure-tone failure rate quite likely indicates a high overreferral rate when compared with the 12% incidence of pathologic features found by otoscopy. Of greater impor¬ tance, however, is the fact that 19% of the total population could not be tested by pure-tone audiometry and, it is
of these, 96% were under 4 years of age. That is, 100% of the under 2-year and 68% of the 2- to 4-year-old chil¬ dren could not be evaluated by this method (Table 2). These figures dem¬ onstrate that a substantial proportion of children in the apparent high-risk age groups cannot be tested by pure-
audiometry. Impedance audiometrie
tone
results showed that 8% of the children could not be tested, as compared with 19%
Downloaded From: http://archotol.jamanetwork.com/ by a University of Michigan User on 06/14/2015
by pure-tone audiometry. Sixty-six
percent of those who could not be tested were under 2 years of age. Nineteen percent of the children from 2 to 4 years of age could not be evaluated by this method, as com¬ pared with 68% by pure-tone audiome¬
try.
Impedance results were normal in 54% of the children and abnormal in 38%. The large number of children failing the impedance audiometrie test indicates that this screening procedure is not as selective as puretone audiometry, even though it can be successfully applied to the very young populations. Closer examina¬ tion of the impedance results, how¬ ever, suggests that the concept of "abnormality" may have been too stringent. The 302 cases judged nor¬ mal by otoscopy but abnormal by impedance can be divided into distinct groups when viewed according to degree of impedance abnormality and when compared with otoscopie obser¬ vations other than those diagnosed as "requiring treatment." For example, 135 (45%) had type A tympanograms with one or more absent stapedius reflexes. Since the lack of reflexes with type A tympanograms most likely reflects old rather than current pathologic features, this result could be considered normal in the planning of a more selective screening pro¬ gram. Furthermore, 28 (9%) of the 302 children labelled abnormal by imped¬ ance had normal tympanic mem¬ branes by otoscopy, once impacted wax was
removed. Since impedance
done before the ENT examina¬ tion, the and C tympanograms and lack of stapedius reflexes accurately reflect the condition of these chilwas
dren's ears. In 27 (9%) additional cases or C tympanograms in which type and no reflexes were found, the otologist indicated "abnormal" tym¬ panic membranes. In these cases, the impedance results also correlate with otoscopie observations. There were 12 (4%) further cases judged abnormal by impedance that had or C tympano¬ grams with reflexes present. When reflexes occur with either type or C tympanograms (although very rare in type C), early serous otitis or abnor¬ mal Eustachian tube function can be suspected and these cases should, perhaps, be referred to the otologist as
preventive measure. Thirty-eight (13%) additional children had type C
a
tympanograms and
possible
that these
no
reflexes. It is
are
false-negative
results by otoscopy, since some chil¬ dren with mild middle ear conditions may not have been correctly diag¬ nosed by this method. If the impedance criteria for "ab¬ normal" were revised to exclude the children with absent reflexes with type A tympanograms, the break¬ down of normal and abnormal results on the present survey would be 66% and 26%, respectively. FINAL REMARKS The incidence of middle ear disease in the Indian population studied was lower than has been reported for other native and low socioeconomic groups. A high incidence of middle ear disease was found in the preschool age group. Thirty-seven percent of the children found to have pathologic features were 4 years old or younger. Results of the ENT otoscopie exam¬ ination showed that 88% of the chil¬ dren were normal and 12% were
abnormal.
Pure-tone
audiometry
yielded 62% normal and 19% abnormal
was not successful in the evaluating very young group: 100% of the children under 2 years old and 68% of the 2- to 4-year-olds could not be tested. Using stringent criteria for abnor¬ mality, impedance was normal in 54% of the population tested and was abnormal in 38%. Impedance was used successfully to evaluate a number of the young children: 69% of the chil¬ dren under 2 years old and 19% of the 2- to 4-year-olds could not be tested. The design of an adequate hearing screening program should include con¬ sideration of the age group of children who are to be examined. When chil¬ dren are able to perform the task required for pure-tone audiometry in a screening environment, this method has a good correlation with ENT oto¬ scopie results. However, for the pre¬ school and primary school group, in which behavioral responses are unre¬ liable and the incidence of fluctuating mild conductive losses is high, imped¬ ance audiometry accurately reflects the condition of the middle ear. Further investigation of impedance is required in order to define parame¬ ters that will provide the most reliable referral rate. The parameters used in this study may have been too strin¬ gent, and it is suggested that on a screening program the absence of reflexes in the presence of a type A tympanogram not be included in the criteria of abnormality.
results.
It
This study was supported by the Pacific Region Medical Services Branch, Department of
National Health and Welfare, Canada. R. Patrick
Gannon, MB, CHB, provided support anc guidance. Hernando Tutassaura, MD, FRCS(C) provided editorial assistance.
References
Eagles EL: Selected findings from the Pittsburgh study. Trans Am Acad Ophthalmol Otolaryngol 76:343-348, 1972. 2. Brooks DN: Hearing screening: A comparative study of impedance method and pure tone screening. Scand Audiol 2:67-72, 1973. 3. Harker LA, Van Wagoner R: Application of impedance audiometry as a screening instrument. Acta Otolaryngol 77:198-201, 1974. 4. Lewis AN, Barry M, Stuart JE: Screening and procedures for the identification of hearing ear disorders in Australian aboriginal children. Laryngol Otol 88:335-347, 1974. 5. Jerger J, Jerger S, Mauldin L: Studies in impedance audiometry. Arch Otolaryngol 96:513\x=req-\ 1.
J
523, 1972.
6. Baxter JD,
Ling D: Ear disease and hearing
loss among the Eskimo population of the Baffin zone. Can J Otolaryngol 3:110-122, 1974. 7. Brooks DN: The use of the electro-acoustic impedance bridge in the assessment of middle ear function. Int Audiol 8:563-569, 1969. 8. Brooks DN: The role of the acoustic impedance bridge in paediatric screening. Scand Audiol 3:99-104, 1974. 9. Cooper JC, Gates GA, Owen JH, et al: An abbreviated impedance bridge technique for school screening. J Speech Hear Disord 40:260\x=req-\ 269, 1975. 10. Feldman AS: Acoustic measurement. Hear Inst 2:16, 1974. 11. Keith RW: Applications of impedance audiometry with children. Hear Inst 2:18-19, 1974.
Downloaded From: http://archotol.jamanetwork.com/ by a University of Michigan User on 06/14/2015
12. Libby ER (ed): New advances in screening for auditory disorders in children with emphasis on impedance audiometry. Hear Inst (sympo-
sium) 9:1974.
13. McCandles GA, Thomas GK: Impedance audiometry as a screening procedure for middle
disease. Trans Am Acad Ophthalmol Oto1974. 14. Renvall U, Liden G, Jungert S, et al: Impedance audiometry as screening method in school children. Scand Audiol 2:133-137, 1973. 15. Sanders W: Impedance measurement Otolaryngol Clin North Am 8:109, 1975. 16. Van Wagoner RS, Chun TH: Hearing loss in southeast Alaska. Alaska Med 16:61, 1974.
ear
laryngol 78:98-102,
Survey of Native
Margaret
E.
Indian Children in British Columbia
Roberts, MSc
\s-b\A survey of 1,109 native Indian children in five communities in British Columbia was conducted to determine incidence of middle ear pathologic features and to compare impedance and
pure-tone audiometry as hearing screening methods. Survey teams included a public health nurse, two otologists, and two audiologists. On ear, nose, and throat (ENT) otoscopic examination, the incidence of middle ear disease requiring treatment was 12%. Disease was most prevalent in the preschool- and primary school-aged children. Pure-tone audiometry yielded 62% normal and 19% abnormal results. Nineteen
of methods has received much attention, and empha¬ sis has been placed on finding proce¬ dures that will identify both hearing loss and middle ear pathologic fea¬ tures. The opinions have been numer¬ ous and diverse.'"' Based on a study of a large population of school-aged chil¬ dren, Eagles' emphasized that pres¬ ent methods of pure-tone screening are not sensitive enough to identify the child with fluctuating mild con¬ ductive losses. In a long-range investi¬ gation of children, Brooks- showed that impedance audiometry, when used as an "identification procedure," provides a sensitive index of middle ear pathologic features and has rec¬ ommended further study of its use for this purpose. Harker and Van Wa¬ goner,' in their study of 710 southeast Alaskan children of preschool and elementary school age, showed that the
five years,
past comparison In hearing screening
Accepted for publication June 22, 1976. From the Hearing Branch, Workers' Compen-
sation Board of British Columbia, British Columbia, Canada.
Richmond,
Reprint requests to Hearing Branch, Workers' Compensation Board of British Columbia, 1055 Shellbridge Way, Richmond, British Columbia, V6X 2X1, Canada (Ms Roberts).
percent of the children could not be tested by this method. Impedance audiometry yielded 54% normal and 38% abnormal results on the stringent criteria used to define the parameters of normality. Eight percent of the children could not be tested. Since there was a high incidence of middle ear pathologic features in the preschool group of children who could not be successfully evaluated by pure\x=req-\ tone audiometry, it is suggested that further investigation of impedance audiometry be undertaken in order to define parameters that will provide the most reliable referral criteria.
(Arch Otolaryngol 102:690-694, 1976)
impedance audiometry is a successful method of assessing middle ear dis¬ ease, particularly in the preschool group of children, who cannot be tested by traditional pure-tone, dis¬ crete
frequency testing. They
recom¬
mended that impedance be used "in addition to" pure-tone screening. On the other hand, in a survey of a limited number of 71 children, Lewis et al· found impedance audiometry to be "feasible but not significantly more reliable in predicting middle ear disease than pure tone audiometry or
otoscopy."
In the fall of
1974, the Canadian
Department of National Health and Welfare sponsored an Ear Disease and Hearing Survey of five Indian
reservations on the Pacific coast of British Columbia. The aims of the survey were: (1) to determine the inci¬ dence of ear disease in children of various age groups; (2) to compare the incidence of active disease vs old disease; and (3) to determine the inci¬ dence of hearing disability. In addi¬ tion to these aims, this survey provided the opportunity to compare
pure-tone audiometry, impedance
au¬
diometry, and otoscopie examination
Downloaded From: http://archotol.jamanetwork.com/ by a University of Michigan User on 06/14/2015
hearing screening methods. The results of that comparative survey are reported herein. as
METHODS Each of the survey teams included
a
locally based public health nurse, two audiologists, and two otologists. Every
was interviewed by the nurse for a history and then underwent pure-tone audiometry, impedance audiometry, and
child
ear, nose, and throat (ENT) examination, in that order. The following procedures were used.
Pure-Tone Audiometry Pure-tone audiometry was conducted in a small office. Only the audiologist and subject were present. The child was condi¬ tioned to respond using a 1,000-Hz 45-dB tone. His response was then tested at 25 dB for the pure tones 500, 1,000, 2,000 and 4,000 Hz. If he failed to respond to 25 dB, the frequencies missed were tested at a 35-dB level. If a positive response was elicited, that frequency was retested at 25 dB. A test result was considered abnormal if no response was obtained at one or more frequencies in either ear at 25 dB.
Impedance Audiometry were brought one at a time
Children
to
the testing room and instructed to sit very still and make no response. The probe tip was inserted into the external ear canal and adjusted until an air-tight seal was obtained. Pressure in the outer canal was then increased to positive 200 mm H.,0 and the deflection of the balance needle observed as the pressure was gradually decreased. From this observation, the examiner noted middle ear pressure and tympanogram type. Middle ear pressure was recorded at the point of minimum needle deflection. Tympanograms were typed according to the classification of Jerger et al.:' Type A shows a high, welldefined peak of maximum balance needle deflection between +100 and —100 mm H,0 pressure; type shows limited balance needle deflection and no well-defined peak; type C shows a well-defined peak at près-
Table
less than -200 mm , . The stapedius reflex contraction was then tested at 95 dB at 1,000 and 2,000 Hz using a contralateral signal. Deflection of the balance needle with simultaneous presentation of the stimulus indicated a
1.—Age
and Sex Distribution of 1,109 Children Tested in Five Communities
Haida
SkideGate
sures
positive reflex.
The entire procedure was carried out first with the probe in the left ear and then in the right. A normal test was one in which a type A tympanogram and stape¬ dius reflexes at both test frequencies were elicited from both ears. Any other result was considered abnormal. Since the described impedance screening procedure might not discover a highfrequency sensorineural loss, one further measurement was added by asking the child to respond to a pure tone of 4,000 Hz at 25 dB. This high-frequency sensori¬ neural test at 4,000 Hz was analyzed sepa¬ rately and compared with the pure-tone results. ENT Examination A was
complete ENT evaluation of each child made by the otolaryngologist and
included examination of the nose, tonsils, and adenoids as well as otoscopie observa¬ tion of the ears. The examiner was required to note whether the tympanic membrane was normal and whether any of the following were present: cerumen impaction, serous otitis, adhesive otitis, tympanic perforation (dry or wet), and cholesteatoma. The Weber and Rinné tuning fork tests were attempted on all children of suitable age. If cerumen was present, it was removed before proceeding with otoscopie and tuning fork tests. At the conclusion of the survey, it was realized that the conditions "cerumen impaction" and "adhesive otitis" had not been clearly defined and thus had not been uniformly recorded. These two diagnoses are, there¬ fore, omitted from the results reported.
RESULTS A total of 1,109 children were tested. The age and sex distribution in the five communities is shown in Table 1. In each age group, there were a number of children that could not be tested by one or more of the screening procedures due to inattention or lack of cooperation. Table 2 indicates the number of children who could not be tested in each one of the three screen¬ ing procedures. Not included in the Table as "could not test" by imped¬ ance are 46 children in whom either a seal could not be maintained (perfora-
Age Group, yr 2-4
5-8 9-13
Village
Bella
Mt
Bella
Currie
Subtotal M 49
M 12
25 31
29
66 19
40 8
147
94
18 11 17 12
Undeter¬ mined Subtotal Total
Bella Coola
241
12 14 11
23 41 13
15
19 29
13 13 36
13
14
19 31
16
38
34 19
69
64
21
16
23 1
1
122 226
118
0
1
62 47 109
104
17 27
F 40 74
86 148
231 82
127 197 72
598
511
0
116
167 132 299
334
Total 89 160 275 428 154
1
1,109
1,109 1,109
Table 2—Number of Children Who Could Not Be Tested* ENT
Age Group, yr 2
2-4 5-8 9-13 14 + Total %of Total Tested
No. Tested
89 160
Serous Otitis
Distribution of Children With Disease Who
Perforation
Perforation and Cholesteatoma
Perforation and Serous Otitis
Required
Treatment
Perforation,
% of Total in
Serous Otitis, and Cholesteatoma
Total
Age Group
¿2!
~~20~ 23
28
12
1,109
73
6.6
ranged from 7% (Haida Village) 18% (Skidegate).
^¡2
17.5 15.3 7.0 7.8
132
11.9
~~42
21
275 428 154
100.0
7.—Age
15
30
51
0.2
4.6
0.4
to
The age distribution of children found to have pathologic features is shown in Table 7. Serous otitis was the most prevalent condition. It was found in 73 children, or 7% of the total population. In 35 cases, the condition was bilateral. It was more prevalent among preschool and primary school children than among secondary school-aged children. Perforated tympanic membranes were found in 58 children (5%). In ten of these children, the condition was bilateral. This pathologic feature was most prevalent in the 5- to 8-year-old age bracket; only six such cases were found in the preschool age group. Four cholesteatomas were found. In one case, a perforation was also found in the same ear. In three cases, active disease was found in the opposite ear: one had a perforation in the opposite ear; one had a perforation in the same ear and serous otitis in the opposite ear; and one had serous otitis in the same ear and a perforation in the
opposite one.
Pure-tone and impedance results for the ears diagnosed to have patho¬ logic features by ENT otoscopie exam¬ ination are summarized in Table 8. Of 185 diseased ears, 24 (13%) had normal pure-tone results and 14 (8%) had normal impedance results. Seventyeight (42%) of the 185 ears could not be tested by pure-tone audiometry and 26 (14%) could not be tested by imped¬ ance.
COMMENT
The results of the present survey among Indian children of different ages emphasizes the need for contin¬ ued study of hearing screening pro¬ grams aimed at detecting both senso-
0.2
11.9
Table 8.—Results of Pure-Tone and Impedance on Ears With Pathologic Features
Audiometry Combined
Screening Test Total pathologic features by otoscopy Left
Serous Otitis
29
ear
Bilateral
ears
Total children
Total ears Pure-tone audiometry Normal Abnormal CNT
Tympanometry Type A Type Type C
Features
17 24
ear
Right
Pathology Perforation
36 73 109
26 53
10
53
51
132 185
61
15
17
24
30 61
10
15
82 78 24
33 42
30
72 52 11
No Seal CNT
Stapedius
Total
25 reflex 14
Present Absent
78 20
CÑT rineural and tive losses.
fluctuating mild conduc¬
Ninety-nine percent of the children otoscopie examination. ear pathologic features were diagnosed in 12% of 1,109 chil¬ underwent Mild middle
dren. This incidence of disease is slightly higher than that reported for urban community children (5% to 8%), but lower than that reported for native and other low socioeconomic populations (16% to 18%).J The age distribution of the children requiring treatment is of particular importance: 15% were under 2 years old; 21% were 2 to 4 years old; and 32% were of primary school age. These data em¬ phasize the point that a screening program for detection of middle ear pathologic features must include this very young population. results Pure-tone audiometrie showed that 19% of the children did
52
15
145 26
not pass this
screening test. Although possible that some diseased ears may have been missed at otoscopie inspection, the 19% pure-tone failure rate quite likely indicates a high overreferral rate when compared with the 12% incidence of pathologic features found by otoscopy. Of greater impor¬ tance, however, is the fact that 19% of the total population could not be tested by pure-tone audiometry and, it is
of these, 96% were under 4 years of age. That is, 100% of the under 2-year and 68% of the 2- to 4-year-old chil¬ dren could not be evaluated by this method (Table 2). These figures dem¬ onstrate that a substantial proportion of children in the apparent high-risk age groups cannot be tested by pure-
audiometry. Impedance audiometrie
tone
results showed that 8% of the children could not be tested, as compared with 19%
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by pure-tone audiometry. Sixty-six
percent of those who could not be tested were under 2 years of age. Nineteen percent of the children from 2 to 4 years of age could not be evaluated by this method, as com¬ pared with 68% by pure-tone audiome¬
try.
Impedance results were normal in 54% of the children and abnormal in 38%. The large number of children failing the impedance audiometrie test indicates that this screening procedure is not as selective as puretone audiometry, even though it can be successfully applied to the very young populations. Closer examina¬ tion of the impedance results, how¬ ever, suggests that the concept of "abnormality" may have been too stringent. The 302 cases judged nor¬ mal by otoscopy but abnormal by impedance can be divided into distinct groups when viewed according to degree of impedance abnormality and when compared with otoscopie obser¬ vations other than those diagnosed as "requiring treatment." For example, 135 (45%) had type A tympanograms with one or more absent stapedius reflexes. Since the lack of reflexes with type A tympanograms most likely reflects old rather than current pathologic features, this result could be considered normal in the planning of a more selective screening pro¬ gram. Furthermore, 28 (9%) of the 302 children labelled abnormal by imped¬ ance had normal tympanic mem¬ branes by otoscopy, once impacted wax was
removed. Since impedance
done before the ENT examina¬ tion, the and C tympanograms and lack of stapedius reflexes accurately reflect the condition of these chilwas
dren's ears. In 27 (9%) additional cases or C tympanograms in which type and no reflexes were found, the otologist indicated "abnormal" tym¬ panic membranes. In these cases, the impedance results also correlate with otoscopie observations. There were 12 (4%) further cases judged abnormal by impedance that had or C tympano¬ grams with reflexes present. When reflexes occur with either type or C tympanograms (although very rare in type C), early serous otitis or abnor¬ mal Eustachian tube function can be suspected and these cases should, perhaps, be referred to the otologist as
preventive measure. Thirty-eight (13%) additional children had type C
a
tympanograms and
possible
that these
no
reflexes. It is
are
false-negative
results by otoscopy, since some chil¬ dren with mild middle ear conditions may not have been correctly diag¬ nosed by this method. If the impedance criteria for "ab¬ normal" were revised to exclude the children with absent reflexes with type A tympanograms, the break¬ down of normal and abnormal results on the present survey would be 66% and 26%, respectively. FINAL REMARKS The incidence of middle ear disease in the Indian population studied was lower than has been reported for other native and low socioeconomic groups. A high incidence of middle ear disease was found in the preschool age group. Thirty-seven percent of the children found to have pathologic features were 4 years old or younger. Results of the ENT otoscopie exam¬ ination showed that 88% of the chil¬ dren were normal and 12% were
abnormal.
Pure-tone
audiometry
yielded 62% normal and 19% abnormal
was not successful in the evaluating very young group: 100% of the children under 2 years old and 68% of the 2- to 4-year-olds could not be tested. Using stringent criteria for abnor¬ mality, impedance was normal in 54% of the population tested and was abnormal in 38%. Impedance was used successfully to evaluate a number of the young children: 69% of the chil¬ dren under 2 years old and 19% of the 2- to 4-year-olds could not be tested. The design of an adequate hearing screening program should include con¬ sideration of the age group of children who are to be examined. When chil¬ dren are able to perform the task required for pure-tone audiometry in a screening environment, this method has a good correlation with ENT oto¬ scopie results. However, for the pre¬ school and primary school group, in which behavioral responses are unre¬ liable and the incidence of fluctuating mild conductive losses is high, imped¬ ance audiometry accurately reflects the condition of the middle ear. Further investigation of impedance is required in order to define parame¬ ters that will provide the most reliable referral rate. The parameters used in this study may have been too strin¬ gent, and it is suggested that on a screening program the absence of reflexes in the presence of a type A tympanogram not be included in the criteria of abnormality.
results.
It
This study was supported by the Pacific Region Medical Services Branch, Department of
National Health and Welfare, Canada. R. Patrick
Gannon, MB, CHB, provided support anc guidance. Hernando Tutassaura, MD, FRCS(C) provided editorial assistance.
References
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