Application of impedance audiometry as a screening instrument

Otitis Media and Child Development

Otitis media with effusion (OME) is the major cause of auditory dysfunction in preschool and early-grade schoolchildren. At especially high risk are children with cleft palate/lip; some groups of mentally retarded children; children from underprivileged communities and children with severe or profound sensorineural hearing loss. In neonates the major concern is to identify those with severe sensorineural hearing loss but awareness of the likelihood of OME is also vital. The hearing loss associated with OME in its early stages may be as small as 10–15 dB and in consequence conventional hearing tests employing pure tones are inadequate as screening procedures. Acoustic impedance testing has proved to be a practicable, acceptable, sensitive and efficient method of identification of OME in infants and children. Impedance measurement cannot, as yet, provide accurate assessment of hearing loss, but this is probably not a serious drawback. The primary requirement is to detect OME in order that swift and effective treatment can be instituted.

Secretory otitis media: A school health survey

The present study was carried out to find out prevalence of secretory otitis media in 200 school going children between the age group of 5-7 years by impedance audiometry besides clinical evaluation. 100 children were taken from two different schools catering to higher and lower socioeconomic strata of society. The overall prevalence of secretory otitis media came out to be 20.75%. It was 28.5% in lower socioeconomic group and, 13% in the other group. This high prevalence warrants routine screening for secretory otitis media. Further impedance audiometry was found to be very good method of screening secretory otitis media.

External ear resonance as a screening technique in children with otitis media with effusion

External ear resonance can be quickly and accurately measured using real ear insertion gain equipment. It has been previously shown that external ear resonance characteristics are often altered by the presence of middle ear fluid. The external ear resonance characteristics of 84 children with a history of chronic middle ear disorder were determined. Results were compared to other audiological data and otological findings recorded during surgery. External ear resonance peak amplitude was significantly correlated with the presence or absence of middle ear fluid. It was found that peak amplitude of > or = 24 dB was associated with only 15% of dry ears and peak amplitude of < or = 22 dB associated with 79% of ears without fluid. The use of external ear resonance measures as a potential screening procedure is discussed.

Screening for otitis media with effusion in preschool children

1439 Dutch children were included in a randomised trial to evaluate the efficacy of preschool screening for otitis media with effusion (OME) by 3-monthly tympanometry. Children with bilateral OME on two consecutive occasions were referred for further investigation and then, if parents gave their consent, allocated at random to treatment or non-treatment groups. The effect of childhood screening for OME and subsequent treatment was evaluated by assessment of language performance; no benefit was found, mainly because of the large degree of spontaneous recovery.

Tympanometric findings in patients with adenoid hyperplasia, chronic sinusitis and tonsillitis

Tympanograms were done on 120 patients with adenoid hyperplasia, chronic sinusitis and chronic tonsillitis to measure the middle-ear pressure as a parameter to eustachian tube function. The results were compared with those obtained in 50 normal subjects. The statistical significance of the mean values of middle-ear pressure is very highly significant in patients with adenoid hyperplasia, significant in chronic sinusitis group and insignificant in patients with chronic tonsillitis, as compared to the normal control group. Hence, eustachian tube dysfunction is maximum in patients with obstructing adenoids, less in chronic sinusitis and least in chronic tonsillitis.

Middle ear disease assessed by impedance in primary school children in south London

413 children aged 5 to 6 years from twelve randomly selected primary schools in SE London were screened for middle ear disease by the use of tympanography . Those with abnormal tympanograms were retested 10 weeks later. 41% had an abnormality at first test, but half had recovered by second test. Children of African origin were significantly less likely to show abnormalities and in almost none did the abnormality persist; children from poorer families were significantly more likely to have a persistent abnormality. Tympanography is a feasible screening test in children of this age-group and complements audiometry and otoscopy.

Screening of hearing disorders in schoolchildren

A program of screening hearing in schoolchildren based in part on the teacher's observations of behavioral, language, and learning problems has been initiated. Every child identified as suffering from "school pathology" is referred to the school nurse, who arranges for otolaryngologic evaluation, including a complete otologic examination and audiologic assessment with determination of pure-tone air and bone conduction thresholds. Of the 265 children identified as having "school pathology," 93, or 35 per cent, had audiographic abnormalities, and 120, or 45 per cent, had disease processes requiring otolaryngologic management.

Intrauterine hypoxia as a cause of hearing impairment in children

Among more than 10,000 mothers giving birth during 1974-1977, there were 20 known cases of severe placental insufficiency in connection with hypertensive disease during pregnancy. Well-documented signs of intrauterine hypoxia were observed in all the cases. In 50% of the fetuses intrauterine growth retardation was found to be below the 10th percentile curve. In most cases the baby was delivered by means of a caesarean section. The hearing level of these infants was examined at the age of 2-5 years. In these 20 children there were no signs of sensorineural hearing loss; however, because of the size of the population, the conclusions drawn from this thorough work must be tentative. It seems that with good maternity care and thorough treatment hearing loss due to intrauterine hypoxia can be prevented.

Spontaneous improvement in ears with middle ear disease

The 'healthy-baby-clinics' in Göteborg, as in all Sweden, test all 4-year-olds with pure tone screening (failure criterion greater than 20 dB). Those who fail are referred to an oto-audiological health center. In an effort to prevent over-referrals of false positives as well as under-referrals of false negatives all referred children in this study have been tested with pure tone audiometry supplemented by tympanometry. At the oto-audiological health center a test program including 3 tests with intervals of 6 weeks was initiated. Failure criteria were middle ear pressure less than - 150 mm H2O and hearing loss (HL) in the frequency range 0.125-8 kHz greater than 20 dB. In Göteborg (430,000 inhabitants) 5928 4-year-olds were tested at the 'healthy-baby-clinics' during 1980. Of these 498 (8.4%) failed in pure tone screening, 248 of which are included in the present study. At the first check in our test program, which was performed 3-8 weeks after referral, only 45% of the children were abnormal. Of these 60% normalized during the test program. Thus of the ears referred following the pure tone screening at the 'healthy-baby-clinics' only 18% remained after 15-20 weeks for referral to an ENT-doctor.

Eustachian tube function in normal children and adults

Eustachian tubal function was studied in 85 otologically healthy children, 3-12 years of age. Middle ear pressure and muscular opening function was measured by tympanometry performed in a pressure chamber, and the results were compared with those obtained from 92 normal adults. Children were found to have a less good muscular opening function and more negative middle ear pressures within wider ranges, compared with adults. Improvement was also seen in children with increasing age. The results seemed to indicate a relation between muscular opening function and middle ear pressure. Even if it were possible to grade the muscular opening function by means of the test procedure, it would still not be possible to define what should be regarded as normal or abnormal tubal function. This report is the first in a series of tubal function studies in normal children.

Validity of impedance measurements and referral criteria in school hearing screening programmes

The increasing use of impedance methods in screening programmes for auditory dysfunction requires that the techniques and validity of the referral criteria be continually monitored. This research report describes one such study carried out as part of the normal school hearing test procedure. Comparative measurements were made using conventional pure tone sweep audiometry and with the 'Tympanometer' (American Electromedics 85 AR). Results are based on 423 ears from 9-year old juniors and 298 ears from 5-year old infants. Agreement between the two methods was obtained with 81% of the juniors and 74% of the infants. The majority of the disagreement resulted from the high sensitivity of the impedance system in detecting middle-ear disorders which did not result in a hearing loss detectable by a 20-dB sweep. Significantly, the Tympanometer missed two infants with moderate sensorineural losses. These false negatives relate directly to the Tympanometer reflex system which proved to be unreliable. The need for care in the selection of instrumentation is stressed.

Screening procedure for detection of middle ear and cochlear disease

Experiences from a six-year study in which 11,772 seven-year-olds have been tested with a combination of the pure tone sweep check test and impedance audiometry (tympanometry and stapedius reflex test) are presented. During the study there has been a gradual change in the screening level. The goal has been to find an ideal screening level in which the results from the screening procedure correspond as much as possible to the findings of the otologist. Analysis of the results from the stapedius reflex test demonstrated that in ears in which the middle ear pressure was within +/- 50 mm H2O the stapedius reflex test could not be elicited in 1.9% of the ears when the maximum output of the audiometer was used (110 dB SPL ipsilateral stimulation); in the ears with middle ear pressure within +/- 150 mm H2O the stapedius reflex could not be elicited in 6.1% using the maximum output of the audiometer. Based on the experiences from our studies it is therefore recommended that the stapedius reflex test be excluded from the test battery and that pure tone screening supplemented by tympanometry be used. A middle ear pressure of less than or equal to -150 mm H2O or a flat tympanogram and/or tone screening levels > 20 dB HTL at 0.5 kHz and/or 4 kHz are considered as indicative of ear pathology.

Screening tympanometry in infants and two-year-old children

In 150 newborn children tympanometry was repeated each third month until the age of one year. In 222 two-year-old children repetitive tympanometric screenings were performed in November, February, May and August, and the alterations in the tympanogram types were analyzed. There was found a very low stability of the tympanogram types and about 50% of the ears changed type between the investigations. The type A tympanogram (0 to -99 mm H2O) was the most stable type, only 52% of the ears changed tye. All ears with type C1 (-100 to -199 mm H2O), 97% of ears with type C2 (-200 to -350 mm H2O), and 84% of the ears with type B (flat curve) changed tympanogram type at least once at the four evaluations. This large variability in the tympanometric conditions, most often caused by a change in the frequency and severity of catarrhalia, makes the prognostic value of the screening tympanometry very small.

Impedance screening for preschool children. State of the art

As a test for detecting middle ear disease among preschool children, tympanometry -- as opposed to audiometry -- has three advantageous attributes: a high degree of sensitivity, minimal need for subject cooperation, and total objectivity. For these reasons interest has arisen in tympanometry as a method for screening, i.e., identifying children with previously undetected middle ear disease. However, uncertainty persists concerning the importance of detecting apparently asymptomatic middle ear effusions, and concerning optimal methods, or even the advisability, of treating them. Further, the sensitivity and specificity of tympanometry depend on how the pass-fail cutoff point is defined. Defining this cutoff point so as to achieve high sensitivity may result in excessively low specificity, with the production of large numbers of false-positives who then become overreferrals. Data are presented to show how the validity of the test may be increased to some extent by attention to the gradient of "negative-pressure" tympanograms. At the present time, given the various aforementioned uncertainties, and with adequate validation as to the presence or absence of disease often lacking in reported studies of impedance screening in preschool populations, the cumulative results of these studies do not warrant embarking on large-scale screening programs. What is needed instead is additional research to explore the issue further.

Brain stem electric response audiometry and middle ear effusion

Brain stem electric response audiometry has been performed in a group of 41 difficult-to-test children under the age of 8 years. All ears were examined with the pneumatic otomicroscope prior to determination of response thresholds, and middle ear effusion found in 24 (29.3%). Seven of the 14 children requiring hearing aid amplification had fluid in 12 ears (42.9%). The importance of early recognition and treatment of middle ear pathology in children with sensori-neural hearing loss is stressed, and routine otomicroscopy by the attending otologist is recommended.

Long-term observation of ears with reduced middle ear pressure

335 ears from 210 childred in which tympanometry initially indicated middle ear pressure less than or equal to -100 mm H2O or a flat tympanogram have been reinvestigated 3 years later. When the inital investigation was performed all children were 7 years old. The present study reveals that 25% of these ears still have middle ear pressure less than or equal to -100 mm H2O and 16% middle ear pressure less than or equal to -150 mm H2O. In normal material of the same age group 9% have middle ear pressure less than or equal to -100 mm H2O and 4% middle ear pressure less than or equal to -150 mm H2O. The study also reveals effusion in 10% of ears with normal screening audiograms. In ears with normal screening audiograms and middle ear pressure greater than or equal to -145 mm H2O effusion was found in 5% and in ears with abnormal screening audiograms and middle ear pressure less than or equal to -150 mm H2O effusion was found in 81%. As tympanometric criterion for otologist referral, middle ear pressure less than or equal to -150 mm H2O or a flat tympanogram is suggested. The inclusion of tympanometry in routine screening for middle ear pathology in children is recommended.

Screening tympanometry in newborn infants and during the first six months of life

Tympanometry was performed in 151 healthy children at birth and at 3 and 6 months of age. At birth 10.5% of the ears had a pressure of -100 mmH2O, and 0.3% a pressure of -125 mmH20. The pressure in most of these ears later became normalized. At 3 months of age 17.9% had a pressure of -100 mmH2O or less, and at 6 months of age 39.2%. At 6 months of age 1.3% of the ears had flat curves and middle ear effusion, and 9.6% had a pressure between -200 and -300 mmH2O. The pressure changes and their cause were analysed. Catarrhalia occurred in 23% of the infants before 3 months of age and in 60% in the 3-6 month period. This is an important though not the only etiological factor for the reduced ventilation in the middle ear, which probably occurs via oedema of the tubal mucosa and mild internal tubal occlusion. Ventilation was significantly reduced at 3 months of age in catarrhal girls, and in catarrhal boys at 6 months of age.

Middle-ear impedance measurements in screening

Middle-ear disorders are the major cause of hearing loss in the young school child, the majority of sensorineural disorders already having been detected. Mild conductive deafness may lead to educational retardation, psychological and social problems as well as to more severe middle-ear problems. It is consequently important to detect persistent middle-ear conditions as early as possible. Pure-tone audiometry has been shown to be a poor method of identifying middle-ear effusions. Impedance measurement is considerably more efficient, and different approaches are reviewed in the light of long-term studies of middle-ear effusion.

Comparative study between the normally hearing child and the hard of hearing child, by acoustic impedance measurements of the ear

In the first part, the author makes a comparative study of the tympanometric results obtained from the normally hearing child and the hard of hearing child. The frequency of serous otitis media is statistically higher in the deaf child. The author compares such results of tympanometry as obtained from the child, considers the contribution of this technique to the field of pediatric audiology and suggests a classification of tympanograms in terms of the probe-tone frequency of the impedancemeter. The second part concerns the acoustico-facial reflex. This study compares the recording of the stapedius reflex obtained by pure tone and Narrow-Band noise acoustic stimulation, thanks to Madsen electro-acoustic bridge, in two groups of children, the one consisting of normal hearing children and the other of children suffering from severe perception hearing loss. The study of the stapedius reflex threshold makes it possible to analyse the dynamics of the field of perception in both groups. After an analysis of the results, the author outlines the importance attributable to the study of the stapedius reflex in the child as a means of objectively examining the auditive function and a means of differential diagnosis in cases of sensorineural impairment of the hearing function.

Tympanometry in three-year-old children. I. A regional prevalence study on the distribution of tympanometric results in a non-selected population of 3-year-old children

Epidemiological data on middle-ear pathology during pre-school age are lacking the striking frequency of middle-ear symptoms in this age group. To evaluate the applicability of the impedance test in the younger age groups and to make an epidemiological study of the distribution of tympanogram types in a normal group of pre-school children, an attempt was made to examine all 523 3-year-olds in a limited geographic area. 1005 ears in 504 children (96.4% of those invited) were fully investigated with tympanometry and otoscopy with Siegle's speculum within 4 weeks. 62.8% of the ears showed type A tympanometric curves, 9.8% type B and 27.4% type C. Bilateral type A tympanometric curves were found in 276 children (55.4%). The prevalence of abnormal tympanometry proved to be unexpectedly high in both sexes. This finding is discussed. Even with the use of conventional technique and standard equipment, the 3-year-old clientele presented no testing problems.

Comparative study of pure-tone, impedance, and otoscopic hearing screening methods. A survey of native Indian children in British Columbia

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 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-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.

Acoustic impedance measurement in the otological assessment of multiply handicapped children

This survey investigated the use of acoustic impedance measurement on a population of multiply handicapped children and correlated the results with otoscopy. Thirty-one children were tested with an impedance meter studying tympanometry, tympanic membrane compliance, and acoustic reflex. Otoscopic examination was also scheduled for each child. The results show that 42% of children tested had some kind of middle-ear problem, mostly unrecognized at the time of this survey. There was 100% agreement between impedance and otoscopic findings. Apparently impedance audiometry can be useful for identifying middle-ear disorders in children who cannot be tested by traditional audiometric methods.

Tympanometry revealing middle ear pathology

In order to evaluate the usefulness of impedance audiometry as a screening method for school children, two different pilot studies were performed. The results indicated that impedance audiometry (tympanometry and stapedius reflex test) was more efficient than otoscopy and pure tone screening in the detection of ears with secretory otitis media (SOM). In order to gain some more experience, an extended study of 800 7-year-olds was performed. The results from this investigation showed 6.5% pathological values with pure tone screening, 13.5% pathological values with tympanometry and 32% elevated or nonelicitable stapedius reflexes. Analysis of our observations indicates that the stapedius reflex may be too sensitive a test to be used as a screening method. Tympanometry, however, is recommended as a complement to pure tone screening in screening of children. A 6-12 months follow-up was also performed on 357 ears in which an initial study had shown a middle ear pressure of less than or equal to -100 mm H2O. At the repeated test 20% had pathological pure tone screening, 40% had a middle ear pressure of less than or equal to -100 mm H2O, 57% had elevated or nonelicitable stapedius reflexes, and 14% had middle ear effusion. The high frequency of persisting abnormal middle ear pressure and effusion in these 357 ears suggests that a middle ear pressure of less than or equal to -100 mm H2O can be a predisposing factor for SOM. In an experimental study on human temporal bones it was demonstrated that the tympanogram preserves its original appearance when the water level is low in the middle ear, while a higher level gives rise to a pathological tympanogram. It is also demonstrated that there is a discrepancy between the tympanometrically, indirectly recorded middle ear pressure and the middle ear pressure as measured manometrically, directly from the middle ear.