The correlation between negative middle ear pressure and the corresponding conductive hearing loss in children. A 12-month study of 352 unselected 7-year-old children

Subclinical conductive hearing loss significantly reduces otoacoustic emission amplitude: Implications for test performance

OBJECTIVES

Distortion product otoacoustic emissions (DPOAEs) are a time-efficient, non-invasive means of assessing the integrity of active inner ear mechanics. Unfortunately, the presence of even relatively minor conductive hearing loss (CHL) has been suggested to reduce the clinical utility of DPOAEs significantly. The primary aims of this study were to systematically evaluate the impact of CHL on DPOAE amplitude and to determine if ear-specific primary tone level manipulations can be used to mitigate CHL impact and recover DPOAE measurability.

METHODS

For 30 young adults (57 ears) with normal hearing, DPOAEs were obtained for f₂ = 1-6 kHz. Observed DPOAE amplitudes were used to generate ear- and frequency-specific models with the primary tone levels, L₁ and L_2, as inputs and predicted DPOAE amplitude, L_DP, as output. These models were then used to simulate the effect of CHL (0-15 dB), as well as L₁ manipulations (0-15 dB), on DPOAE measurability.

RESULTS

Mean L_DP for every CHL condition was significantly different from that for all other conditions (p = <.001), with a mean L_DP attenuation of 8.7 dB for every 5 dB increase in CHL. Mean DPOAE measurability in response to a standard clinical stimulation paradigm of L₁/L₂ = 65/55 (dB SPL) was determined to be 99%, 84%, 37%, and 9% in the presence of 0, 5, 10, and 15 dB CHL, respectively. In the presence of 10 dB CHL, altering L₁ resulted in an approximately 25% increase in DPOAE responses.

CONCLUSION

Subclinical CHL loss is sufficient to significantly impair DPOAE measurability in a meaningful proportion of otherwise healthy ears. However, through strategic alteration of primary tone levels, the clinician can mitigate CHL impact and at least partially recover DPOAE measurability.

Wideband Absorbance and 226-Hz Tympanometry in the Prediction of Optimal Distortion Product Otoacoustic Emission Primary Tone Levels

PURPOSE

Distortion product otoacoustic emission (DPOAE) amplitude is sensitive to the primary tone level separation effective within the cochlea. Despite potential for middle ear sound transmission characteristics to affect this separation, no primary tone level optimization formula accounts for its influence. This study was conducted to determine if inclusion of ear- and frequency-specific immittance features improves primary tone level optimization formula performance beyond that achieved using a univariate, L2-based formula.

METHOD

For 30 adults with normal hearing, DPOAE, wideband absorbance, and 226-Hz tympanometry measures were completed. A mixed linear modeling technique, incorporating both primary tone and acoustic immittance features, was used to generate a multivariable formula for the middle ear-specific recommendation of primary tone level separations for f2 = 1-6 kHz. The accuracy with which L1OPT, or the L1 observed to maximize DPOAE level for each given L2, could be predicted using the multivariable formula was then compared with that of a traditional, L2-based univariate formula for each individual ear.

RESULTS

Use of the multivariable formula L1 = 0.47L2 + 2.40A + f2param + 38 [dB SPL] resulted in significantly more accurate L1OPT predictions than did the univariate formula L1 = 0.49L2 + 41 [dB SPL]. Although average improvement was small, meaningful improvements were identified within individual ears, especially for f2 = 1 and 6 kHz.

CONCLUSION

Incorporation of a wideband absorbance measure into a primary tone level optimization formula resulted in a minor average improvement in L1OPT prediction accuracy when compared with a traditional univariate optimization formula. Further research is needed to identify characteristics of ears that might disproportionately benefit from the additional measure.

Prognostic and influencing factors of tinnitus in chronic otitis media after tympanoplasty

The purpose of this study is to investigate what characteristics of tinnitus in patients with chronic otitis media was reduced after tympanoplasty and to assess the relationship between post-operative tinnitus reduction and pre-operative tinnitus tone, tinnitus duration, post-operative hearing recovery, and tympanogram. Medical records were prospective between March 2013 and May 2016. Audiologic evaluation by pure tone audiometry and acoustic impedance and tinnitus assessment using scores on the Tinnitus Handicap Inventory (THI) was conducted preoperatively and 6 months post-operatively. The data were analyzed using the Wilcoxon test, Student's and paired t test, and ANOVA. The pre-operative incidence of tinnitus in patients with COM was 47%. There was a very significant difference between pre-operative and post-operative mean THI scores (p < 0.05). Tinnitus was reduced or alleviated in 83% of tinnitus patients. Pre-operative low-tone tinnitus was significantly reduced 6 months after surgery. After surgery, air-conducted hearing improvement at 250, 500, and 1000 Hz in the tinnitus significant recovery group was greater than the tinnitus non-significant recovery group (p < 0.05). Tinnitus reduction in tympanogram A was significantly greater than in tympanograms B or C (p < 0.05). There was no statistically significant correlation between tinnitus duration and tinnitus reduction (p > 0.05). There was no significant effect of presence cholesteatoma and dry period on the gain THI (p > 0.05). The types of tympanoplasty had no effect on tinnitus improvement (p > 0.05). No patients experienced new tinnitus after surgery. Following tympanoplasty, most patients experienced a reduction in tinnitus. Pre-operative low-tone tinnitus is easier to reduce after tympanoplasty. Post-operative normal tympanogram and improved low-frequency AC hearing were important to tinnitus reduction.

Use of tympanometry in general practice in Denmark

OBJECTIVES

Otitis media has been a serious disease and can be that even today. The diagnosis of otitis media is often difficult. Pneumatic otoscopy, otomicroscopy, and tympanometry can improve the diagnostic quality by indication of fluid in the middle ear and thereby improve the quality of treatment. The aim of this ongoing study is to analyze the use of tympanometry in Denmark after reimbursement for doing tympanometry (November 2006) when clinically indicated. Our research questions were: How many clinics were using tympanometry? How frequent was it used? Is the use increasing? Has the number of GPs in the clinic any relation to the use of tympanometry?

METHOD

We used information in The Danish National Health Service in three Regions to analyze the use of tympanometry in general practice during the years 2007-2009. The coverage of the GPs is 100% in the regions.

RESULTS

The three regions counted about half of Danish population. In 2009 the material was 902 different clinics with more than 1700 GPs. In 2007 55% of the clinics did tympanometry, in 2009 the figure was 60%. In the clinics doing tympanometry the median value was 28 tympanometries per year (inter-quartile range 13-53) per GP. The variation in the use of tympanometry was surprisingly high, from none or a few per GP per year to a maximum of more than 500 tympanometric examinations per GP a year. This huge variation has to be discussed.

DISCUSSION

Many answers can be given. Some of the explanation was problems in doing correct tympanometry, and problems understand the clinical implications of curves and the figures.

Wideband energy reflectance measurements: effects of negative middle ear pressure and application of a pressure compensation procedure

The wideband energy reflectance (ER) technique has become popular as a tool for evaluating middle ear function. Negative middle ear pressure (MEP) is a prevalent form of middle ear dysfunction, which may impact application of ER measurements in differential diagnosis. A negative MEP may be countervailed by application of an equivalent negative ear canal pressure. The present study examined ER in the same ears under normal and experimentally induced negative MEP conditions. Thirty-five subjects produced at least one negative MEP each (-40 to -225 daPa). Negative MEP significantly altered ER in a frequency-specific manner that varied with MEP magnitude. ER increased for low- to mid-frequencies with the largest change (~0.20 to 0.40) occurring between 1 and 1.5 kHz. ER decreased for frequencies above 3 kHz with the largest change (~-0.10 to -0.25) observed between 4.5 and 5.5 kHz. Magnitude of changes increased as MEP became more negative, as did the frequencies at which maximum changes occurred, and the frequency at which enhancement transitioned to reduction. Ear canal pressure compensation restored ER to near baseline values. This suggests that the compensation procedure adequately mitigates the effects of negative MEP on ER. Theoretical issues and clinical implications are discussed.

Wideband aural acoustic absorbance predicts conductive hearing loss in children

OBJECTIVE

This study tested the hypothesis that wideband aural absorbance predicts conductive hearing loss (CHL) in children medically classified as having otitis media with effusion.

DESIGN

Absorbance was measured in the ear canal over frequencies from 0.25 to 8 kHz at ambient pressure or as a swept tympanogram. CHL was defined using criterion air-bone gaps of 20, 25, and 30 dB at octaves from 0.25 to 4 kHz. A likelihood-ratio predictor of CHL was constructed across frequency for ambient absorbance, and across frequency and pressure for absorbance tympanometry. Performance was evaluated at individual frequencies and for any frequency at which a CHL was present.

STUDY SAMPLE

Absorbance and conventional 0.226-kHz tympanograms were measured in children of age three to eight years with CHL and with normal hearing.

RESULTS

Absorbance was smaller at frequencies above 0.7 kHz in the CHL group than the control group. Based on the area under the receiver operating characteristic curve, wideband absorbance in ambient and tympanometric tests were significantly better predictors of CHL than tympanometric width, the best 0.226-kHz predictor. Accuracies of ambient and tympanometric wideband absorbance did not differ.

CONCLUSIONS

Absorbance accurately predicted CHL in children and was more accurate than conventional 0.226-kHz tympanometry.

In vivo measurement of O(2) and CO(2) gas exchange across the human tympanic membrane

CONCLUSION

The hypothesis that the human tympanic membrane (TM) is permeable to CO(2) and O(2) at physiologic pressure gradients is supported but additional experiments need to be done to validate this methodology.

OBJECTIVE

Gas exchange between the middle ear and adjacent compartments determines the trajectory of middle ear pressure change. Little information is available regarding the permeability of the TM to physiological gases. This study aimed to determine in vivo if the human TM is permeable to O(2) and CO(2) at physiologic transTM pressure gradients.

SUBJECTS AND METHODS

An ear canal (EC) probe (ECP) constructed from a custom-fitted acrylic body, a glass capillary tube enclosing an oil meniscus to maintain ambient ECP + EC pressure and a silica glass microtube linked to a mass spectrometer (MS) for measuring gas composition was hermetically sealed within one EC in each of 15 adults. ECP + EC volume was measured and gas samples were taken at 10 min intervals for 1 h. Epinephrine (1:100 000) was applied topically to the ipsilateral TM to decrease blood flow and the experiment was repeated. The ECP + EC pressures of O(2) (32 AMU) and CO(2) (44 AMU) were regressed on time and the slope divided by the predicted transTM partial-pressure gradients to yield estimates of transTM O(2) and CO(2) conductance.

RESULTS

Consistent with expectations for transTM gas exchange, ECP + EC O(2) decreased and CO(2) increased during the experiments. CO(2) increase was faster after application of epinephrine to the TM. The ratio of O(2)/CO(2) conductances was not consistent with the gas exchange through a primarily water or lipid diffusion barrier.

Air-conduction estimated from tympanometry (ACET) 1: relationship to measured hearing in OME

OBJECTIVE

In otitis media with effusion (OME), the accuracy of predicting air-conduction hearing-level (HLs) from tympanometry has generally been seen as too poor for use in clinical practice. Previous studies of the relationship have mostly concerned single ears, many using samples with predominantly mild cases of OM and weak statistical approaches. A better understanding of the interrelations between these tests might improve efficiency in testing and decision-making for individuals.

METHOD

Binaural average HL was adopted as the measure to be predicted most relevant to auditory disability. Multiple regression from modified Jerger tympanogram categories B, C2, C1 and A tympanogram types on 3085 children aged 3(1/4)-6(3/4) years gave formulae which we tested for replication, stability and generalization across distributions differing in severity.

RESULTS

Age-adjusted formulae explained up to 49% of the variance in binaural HL (i.e. a multiple correlation of 0.70), and were robust across phase of disease. Best predictions were seen in a severe sample permitting exploitation of the strong conditioning effect by a B tympanogram in one ear upon the tympanometry/HL relationship in the other. This permits a trichotomous approximation (0, 1, or 2 B-tympanograms) to also perform well.

CONCLUSIONS

We name the HL prediction formula "ACET" - Air Conduction Estimated from Tympanometry. We do not recommend replacing audiometry with tympanometry, particularly not at first assessment. However, where the diagnosis is, or likely from history to be, OME (even if fluid is absent on test day), the informativeness of further air-conduction audiometry on the same or later occasion may not always be worth the further effort or cost. It is therefore clinically useful to have a dB measure, from an evidence-based formula justifying a principled estimate. Non-clinical uses include imputation when research data are missing, and non-intensive applications where audiometry is impracticable, e.g. field clinics and large scale or longitudinal research. A companion paper shows how the part of the air-conduction HL variance that is not explicable by ACET, also offers a surrogate, but for bone-conduction HL (BC), where BC testing may be problematic, as in the very young. This surrogate can also define cases needing true BC testing.

Otitis media and reading achievement: a review

Nineteen studies on the relationship between otitis media (OM) or otitis media with effusion (OME) (secretory otitis media (SOM)) and reading achievement were reviewed. The result is that the children catch up in cognitive development when their ears and hearing become normal at about school age. The correlations that have been found between SOM and reading achievement are so small that they have no practical importance for the average child. At the present time we have no knowledge that justifies intervention against SOM as a general preventive task to ensure the cognitive development, or reading achievement. The absent or very small correlation between SOM and reading in the reviewed studies, 'explaining' only 2-4% of the variance, has no implications in comparison with other important factors. Reading achievement was more closely correlated with cognitive, language, and linguistic factors, and to a series of socioenvironmental and classroom related factors. The high frequency of SOM, with resulting hearing loss, and the long duration and high rate of occurrence of OM in 'otitis-prone' children, and clinical observations underlines the need for further research.

Adenoids in school-aged children

A total of 687 school children, aged six to 15 years, were examined clinically, radiologically and audiometrically. Lateral radiological examination of paranasal sinuses was carried out in 663 (96.5 per cent) children for evaluation of the size of adenoids. The size of the soft tissue shadow (adenoids) was assessed as normal or large. It was large in 133 (25 per cent) children, three times more frequently in seven-year-old than in 14-year-old children. The occurrence of adenoidal symptoms (blocked nose, mouth breathing, snoring, snuffling or rhinitis) varied from 14.3 to 30.1 per cent in children with large adenoids compared to 7 to 9.8 per cent in children with normal adenoids. Logistic regression analysis revealed that only recurrent snoring and the child's age were significantly associated with radiologically large adenoids. The hearing thresholds were 1.1 to 4.2 dB poorer and mean middle ear pressure values were 60 to 70 mmH2O lower in children with large adenoids compared to those with normal size adenoids. Large adenoids have an influence on the hearing level of a child, but probably via the negative middle ear pressure.

The middle ear as a baroreceptor

Under pressure in the middle ear is thought to be important in the pathogenesis of chronic otitis media with effusion and its sequelae, but the cause of the under pressure and the mechanisms responsible for regulation of the normal middle ear pressure are a matter of debate. Numerous studies have examined the effect of large pressure changes on the ear; however, the ear's sensitivity to smaller pressure changes has received little attention. This study examines the sensitivity of the ear to atmospheric air pressure changes induced in the external ear canal. It is concluded that the normal ear is a very sensitive pressure receptor, and that the sensation is probably registered by stretch receptors in the tympanic membrane. Pathological changes in the tympanic membrane are associated with impaired baroreceptor function. The implications of these findings in the physiology of the ear and the regulation of middle ear pressure are discussed.

Effects of acute negative middle ear pressure on hearing. New answers to old questions and a review of the literature

The magnitude of hearing loss caused by negative middle ear pressure is a controversial issue. We present a clinical, prospective and controlled study on the effect of negative middle ear pressure on hearing in human ears. Sixty-two ears of patients undergoing uvulopalatopharyngoplasty were examined pre- and postoperatively. The test group consisted of 31 ears in which negative postoperative middle ear pressure ranging between -150 and -400 mmH2O had developed. The control group consisted of 31 ears in which no middle ear pressure change was recorded after the same operation. Bone conduction hearing loss up to 20 dB (with a mean of 11 dB) at 250 Hz, up to 25 dB (with a mean of 13.1 dB) at 500 Hz and up to 10 dB (with a mean of 7.6) at 1,000 Hz was the dominant finding. An additional air-bone gap up to 15 dB (with a mean of 4.3 dB) was found only at 250 Hz. Basic theories about the acoustic response of the ear are discussed and new theories proposed.

Monitoring middle ear pressure by tympanometry. A study of middle ear pressure variation through seven hours

The aim of this investigation was to monitor fluctuations in middle ear pressure, to study tympanometric signs of Eustachian tube functioning and to assess the validity of the tympanometric readings. In 20 patients with a low initial middle ear pressure (-150 daPa or lower) and 5 normals, impedance tympanometry was performed every 3 min through 7 h. Median pressure for the patients was -150 daPa (range 100 to -400 daPa) and for the normals 0 daPa (range 50 to -50 daPa). A remarkable pressure increase was seen after changing the body position to the supine. The patients were arranged into three groups according to the lowest middle ear pressure registered. Median pressures for the groups were running at a rather constant level. However, the individual pressure fluctuations in many patients were so great that a single tympanometric reading has to be considered unreliable when selecting patients for insertion of ventilation tubes. Thirteen patients never equalized their negative middle ear pressure, indicating that their Eustachian tube did not open during the test period. In spite of this the pressure did not decrease to lower values, indicating that maintaining a relative constant middle ear pressure is independent of opening of the Eustachian tube.

Impedance audiometric study of children. Comparison of impedance tympanoscope ZS 330 with impedance audiometer ZO 73 A

In order to compare the impedance audiometer ZO 73 A with the impedance tympanoscope ZS 330 (both from Madsen Electronics), we examined 50 children who had been admitted to the ENT Department and 24 children from a kindergarten. There proved to be a good correlation between the middle ear pressure, except that ZO 330 showed a rather lower middle ear pressure. As regards compliance too there was a good correlation. The ipsilateral stapedial reflex was rather labile, and in 68% of the ears the two instruments showed conformity, while in 15% only ZO 73 A and in 17% only ZS 330 could elicit the reflex. When the middle ear pressure was lower than -100 mmH2O, the ipsilateral stapedial reflex could be elicited in only 25% of the cases, even though the middle ear pressure was equalized.

Audiologic screening of seven- and ten-year-old children

An audiologic screening of 1 062 ears In 7-year-old and 1 175 ears in 10-year-old children was carried out by means of pure-tone audiometry and tympanometry. New cases of sensorineural hearing loss were found in six ears (0.3%). The prevalence of protracted undiagnosed middle ear pathology was found to be 2.5 and 0.5%, in the younger vs. the older age group respectively. It is concluded that a middle ear pressure more negative than -250 mmH2O would be a suitable fail criterion for tympanometry. It is questionable, however, whether tympanometric mass screening of 7- and 10-year-olds is meaningful. It is felt that pure-tone audiometry maintains its position in the screening role.

Ventilation tubes in secretory otitis media. A randomized, controlled study of the course, the complications, and the sequelae of ventilation tubes

The purpose of this study has been to evaluate the use of ventilation tubes in the treatment of cases of primary secretory otitis media. Bilateral cases were selected and a tube inserted in one ear while the other ear was left intact. Adenoidectomy was performed on all children, tonsillectomy in 34% of the cases. A total of 150 children (mean age = 3.9 years) were included during the years 1976-1979 and check-ups performed every 3-6 months. The follow-up rate was 89.3%. The condition of each individual was assessed after a 5-year period, the mean period of observation was 3.2 years. The results of tympanometry and audiometry from the two types of ears were, on average, similar. Repeat operation was carried out in 17% of the cases and later otomicroscopy revealed a higher incidence of atrophy in these eardrums (p less than 0.01). A period of suppuration was noted in 25% of the ears with a ventilation tube, 2 months or more after operation; a higher incidence of tympanosclerosis was later found (p = 0.02). Twentythree per cent of the treated eardrums were characterized at the final check-up as "normal" by means of otomicroscopy, in contrast to 83% of the intact ears. The "end-result" of each ear was estimated using tympanometry, audiometry as well as otomicroscopy, and a difference in favour of the intact ears was found (p less than 0.01). A similar estimate for each child gave the result that 31% had one ear categorized as "pathological" while this was the case in both ears of 9% of the children. The children subjected to initial tonsillectomy showed a worse "end-result" (p less than 0.05). It is concluded that the use of ventilation tubes in children with primary secretory otitis media is not justified. Observation has shown that only a small proportion will require surgical treatment of the middle ear. A ventilation tube may be indicated in order to combat hearing loss, but it should be borne in mind that its use involves a high risk of complications and sequelae which may result in chronic middle ear disease.

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.

Negative middle ear pressure. Variations by season and sex

This study describes variations in the occurrence of negative middle ear pressures during a 12-month period in an unselected group of 352 children, all about seven years old. During the year-long study, the children were screened several times in the field to measure middle ear pressure and hearing losses greater than 20 dB. The children that failed this field screening were transported to the Hearing Clinic of Vejle Hospital and their auditory acuity was measured by audiological procedures. Calculation of the cumulated incidence of negative middle ear pressure showed that a pressure of -150 to -250 mm H2O, otherwise purported to reflect pathology, occurred in 25% to 55% of the children at different times during the year. The prevalence of these negative middle ear pressures was such as to negate the term "pathology," which is usually applied to such findings. Various negative pressures were found to occur as characteristics of the season of the year and were also found to occur more frequently bilaterally in boys. Conductive hearing losses of 10 to 20 dB were found in 7% to 44% of the children but were not found to be related to sex. The variability of middle ear pressure limits its value in predicting middle ear pathology and leads to a risk that children will be over-referred for further investigation and treatment of nonexistent middle ear problems if middle ear pressure is used as the sole prognosticator of middle ear pathology.

The diagnosis of negative middle ear pressure in children. The accuracy of symptoms and signs assessed by tympanometry

Over a period of one year, we studied 352 children at random in order to determine whether or not a diagnosis of negative middle ear pressure can be made reliably without using tympanometry. Each child was tested repeatedly by screening audiometry at 20 dB and by tympanometry, and was examined once by otoscopy. Information about upper respiratory tract infections, feelings of oppression in the ears, and the parents' opinion of the child's hearing ability were obtained from questionnaires. Otoscopy correlated poorly with the tympanometry, while screening audiometry and the parents' opinion of the child's hearing ability were more reliable measures. It is concluded that tympanometry is an absolutely necessary tool in the clinical diagnosis of negative middle ear pressure.