The value of impedance testing in diagnosis of middle ear effusion

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.

How to improve the accuracy of diagnosing otitis media with effusion in a pediatric population

OBJECTIVE

To determine the accuracy of pneumatic otoscopy, a tympanogram and otomicroscopy for diagnosing otitis media with effusion (OME) in a pediatric population.

STUDY DESIGN

Prospective blinded clinical and IRB-approved study at a secondary referral hospital. SUBJECTIVE AND METHODS: Eighty-one children (155 ears) were recruited for this study, who were referred to my secondary referral hospital after OME was diagnosed at other primary clinics. The examiner was blinded for the findings of the diagnostic tools. Myringotomy under local anesthesia was used as the diagnostic reference standard. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of the three diagnostic tools were calculated.

RESULTS

Otomicroscopy was the most sensitive and specific tool among the three diagnostic tools. Otomicroscopy showed the best agreement with myringotomy (kappa=0.784).

CONCLUSION

Otomicroscopy can make a more accurate diagnosis even for children who are seen at an outpatient clinic. The much higher specificity of otomicroscopy makes it the best confirmative test and its much higher positive predictive value can prevent a late diagnosis of OME, which can result in severe sequelae.

An assessment of the validity of tympanometry compared to myringotomy performed under a nitrous oxide-free general anaesthetic

To assess the validity of tympanometry as a test for the presence of middle ear effusion using a 'gold-standard' of myringotomy performed after a nitrous oxide-free general anaesthetic, we performed a prospective validity study comparing tympanometry traces obtained immediately pre-operatively from patients undergoing grommet insertion, with the otomicroscopic findings at myringotomy. Nitrous oxide was omitted from the anaesthetic gaseous mixture as it has been reported to displace middle ear effusions. One hundred and seventy-two patients (aged 1.5-15 years) with a clinically assessed 3 month history of middle ear effusion were included in the study. Sensitivity and specificity of a Jerger classification Type B tympanometric trace for the presence of middle ear effusion were 0.73 and 0.84, respectively. We conclude that tympanometry is a valid test in assessing the presence of middle ear effusion compared to a 'gold standard' of myringotomy performed after a nitrous oxide-free general anaesthetic.

Effects of desflurane on middle ear pressure

OBJECTIVE

To evaluate the effects of desflurane on middle ear pressure.

STUDY DESIGN

A prospective clinical study.

METHODS

In this study, 38 ears of 19 male children that were scheduled for circumcision were included. Baseline tympanometry reading was performed on each ear just before anesthesia. After induction anesthesia with propofol a laryngeal mask was applied and desflurane administration was started. The next tympanometry reading was taken at 5th, 10th and 15th minute after administration and at the 10th minute after the cessation of desflurane. Data were analysed using Wilcoxon test.

RESULTS

Mean MEP values before anesthesia in 38 ears of 19 boys were -10.32+/-33.14. After starting the administration of desflurane 5th minute mean value was 71.15+/-60.42, at the 10 th minute 111.56+/-59.03 and at the 15th minute it increased to 120.50+/-54.14, and these measurements were significantly higher than the starting value (p<0.001). After cessation of desflurane mean MEP value dropped to 57.56+/-79.06, but compared with the starting value this was also significantly higher (p<0.001).

CONCLUSION

Desflurane may increase the middle ear pressure and it may be unsuitable for certain middle ear surgeries.

Effects of sevoflurane and TIVA with propofol on middle ear pressure

OBJECTIVE

To evaluate the effects of sevoflurane and TIVA with propofol on middle ear pressure and to show the importance of anesthesia without using any inhalational agents during middle ear surgery.

STUDY DESIGN

A prospective, randomized controlled clinical study.

METHODS

In this study, 25 male children that were scheduled for circumcision were randomised into two groups. Group I (n=13) received TIVA with propofol and group II (n=12) received sevoflurane. Baseline tympanometry reading was performed on each ear just before anesthesia. The next tympanometry reading was taken 10min after applying the laryngeal mask. Data were analysed by Mann-Whitney U (between groups) and Wilcoxon tests (within groups).

RESULTS

Mean MEP values in 26 ears of 13 boys in group I did not show any significant difference before and after the anesthesia with propofol (p>0.05). In group II mean MEP values in 24 ears of 12 boys showed a significant increase after the anesthesia with sevoflurane (p<0.001). No significant difference was found between the MEP values of the two groups before the anesthesia (p>0.05), and MEP values measured during the anesthesia were significantly higher in group II (p=0.007).

CONCLUSION

Sevoflurane may increase the middle ear pressure and TIVA with propofol may be used in middle ear operations more safely than sevoflurane.

Evidence assessment of the accuracy of methods of diagnosing middle ear effusion in children with otitis media with effusion

OBJECTIVES

We report the findings of an evidence assessment on the accuracy of methods of diagnosing middle ear effusion in children with otitis media with effusion (OME).

METHODS

We searched Medline (1966-January 2000), the Cochrane Library (through January 2000), and Embase (1980-January 2000) and identified additional articles from reference lists in proceedings, published articles, reports, and guidelines. Excluded were nonhuman studies; case reports; editorials; letters; reviews; practice guidelines; non-English-language publications; and studies on patients with immunodeficiencies, craniofacial anomalies (including cleft palate), primary mucosal disorders, or genetic conditions. From each eligible study, we calculated the sensitivity, specificity, positive predictive value, negative predictive value, accuracy, and prevalence of OME in the cohort. We determined the number of studies for each comparison of a diagnostic method and a reference standard listed within the scope of our assessment. For comparisons with 3 or more studies, we derived random effects estimates of sensitivity, specificity, and prevalence rate. Using the pooled estimates, we plotted the performance of each diagnostic test in terms of sensitivity and (1 - specificity) and identified the best performer among the tests included in the comparison.

RESULTS

Among 8 diagnostic methods, pneumatic otoscopy had the best apparent performance with a sensitivity of 94% (95% confidence interval: 92%-96%) and a specificity of 80% (95% confidence interval: 75%-86%). However, examiner qualifications were reported inconsistently, and training was not specified.

CONCLUSIONS

The finding that pneumatic otoscopy can do as well as or better than tympanometry and acoustic reflectometry has significant practical implications. For the typical clinician, pneumatic otoscopy should be easier to use than other diagnostic methods. The important question may be what degree of training will be needed for the clinician to be as effective with pneumatic otoscopy as were the examiners in the studies reviewed in this report.

General anesthesia with and without nitrous oxide (N2O) and the weight of middle ear effusion in children undergoing adenoidectomy and tympanostomy

This study was designed to explore the effect of nitrous oxide (N2O) on the amount of middle ear effusion. Seventy-six children referred for adenoidectomy or tympanostomy tube placement were divided into two groups in the basis of the method of anesthesia. One group of 39 children was ventilated with a mixture of 30% oxygen and 70% nitrous oxide, while the other group of 37 patients was ventilated with a mixture of oxygen and air. The amounts of middle ear effusion obtained in myringotomy were weighed and compared between these groups. Preoperative and perioperative tympanograms were performed. Ventilation with nitrous oxide caused a distinct rise in middle ear pressure. The amount of the middle ear effusion, however, remained the same in the two groups. It is concluded that the operating surgeon can rely on the myringotomy finding even when nitrous oxide anesthesia is used.

Validity of tympanometry in the diagnosis of middle ear effusion

A group of 266 children (515 ears), ranging in age from 5 months to 11 years, was studied. These children were candidates for the insertion of ventilation tubes, or adenoidectomy and/or tonsillectomy with myringotomy. Before surgery, tympanometry was performed. The surgical and tympanometric findings were compared afterwards. Two different tympanometers were used (GSI-27A and TYMP-85TT). This study showed a comparable validity of these two tympanometers. The sensitivity and specificity of tympanometry in the age group of 5 months to 2 years did not show a significant difference from that in the age group of 2-12 years. Otoscopy has limited value for the diagnosis of middle ear effusion in this age group.

Relation of infant feeding practices, cigarette smoke exposure, and group child care to the onset and duration of otitis media with effusion in the first two years of life

The relation of infant feeding practices, cigarette smoke exposure, and group child care to the onset and duration of otitis media with effusion (OME) was evaluated in a cohort of 698 healthy infants prospectively monitored by tympanometry in the home every 2 to 4 weeks until 2 years of age. Except for an experimental group of children who were offered early tube placement, the study children received conventional care from their personal physician or clinic. We used LISREL, a structural equation modeling procedure (computer software), to explore associations between environmental variables and OME onset and duration while controlling for interrelations among the variables. Supine feeding position and early initiation of group child care were associated with earlier onset of OME. Shorter duration of breast-feeding, increased packs of cigarettes smoked per day in the home, and increased hours per week in group child care were associated with an increase in the amount of time with OME during one or more of the age blocks studied (birth to 6, 6 to 12, 12 to 18, and 12 to 24 months). For a decrease in the amount of time with OME during the first 2 years of life, prolonged breast-feeding and upright feeding position should be encouraged, and cigarette smoke exposure should be minimized. Limiting early child care in large groups might also be advisable.

The Welch Allyn Audioscope and Microtymp: their accuracy and that of pneumatic otoscopy, tympanometry and pure tone audiometry as predictors of otitis media with effusion

Results of standard audiometry and tympanometry were compared with the Welch Allyn 'Audioscope' and 'Microtymp', in the diagnosis of secretory otitis media, in 100 children. Standard pure tone audiometry had a specificity of 92 per cent and sensitivity of 51.6 per cent. The Welch Allyn 'Audioscope' a specificity of 84.2 per cent and sensivity of 57.5 per cent; standard tympanometry a specificity of 71 per cent and sensitivity of 88 per cent; the Welch Allyn 'Microtymp' a specificity of 63 per cent and sensitivity of 90 per cent. In view of cost, portability, and speed of testing the Welch Allyn instruments would be particularly suitable for community screening. Pure tone audiometry with a pass threshold of 25 dB, at 2 and 4 kHz is a poor indicator of effusion.

The effect of anaesthesia on tympanograms of children undergoing grommet insertion

A prospective study was designed to assess the effect of anaesthesia, including nitrous oxide, on tympanometric results of children undergoing myringotomy and possible grommet insertion. 155 patients (310 ears) were examined with a pneumatic otoscope and had tympanograms performed within 1 hour of operation. The patients were then anaesthetized by a combination of intravenous and gaseous anaesthetic. Immediately before myringotomy, a tympanogram was repeated. In 13% of patients predicted to have fluid at admission, there was a change in their tympanogram after induction of anaesthesia, suggesting clearance of fluid. At myringotomy, these ears were dry. We surmise that there was displacement of fluid from the middle ear by nitrous oxide during the early stages of anaesthesia. Thus we feel that, if an otologist confidently expects to find an effusion at myringotomy, the presence of a dry tap should not change his management plan.

Normal tympanometric gradient: a comparison of three methods

Tympanograms were obtained from 166 ears of 83 college students with normal middle ear function. Three measures of gradient were determined for each tympanogram: Gdif, Gratio, and GdP. Each gradient measure was evaluated for its potential usefulness in discriminating between ears with and without effusion. Gdif was found to be a fairly poor choice for gradient. Because it correlated so highly with static admittance, little additional information would be gained about tympanogram shape. The two other measures, Gratio and GdP, appeared to be roughly equivalent and would be preferred over Gdif as measures of tympanogram shape.

Malleus handle probe: a middle ear diagnostic procedure

Manual probing of the malleus handle (MH) of 477 patients suggests a protective middle ear reflex with a variable tonic contraction of the tensor tympani muscle (TTM). The degree and type of MH retraction suggests three stages of progressive middle ear inflammation. Prediction accuracy of 250 myringotomy findings was 60% with impedance audiometry and 92% with MH probing. Mechanical pressure gauge readings (grams) of 202 ears correlated with finger pressure estimations. The TTM tendons were sectioned in ten children with persisting otitis media with effusion (OME) and seven obtained benefit. The three diagnostic methods, pneumatic otoscopy, impedance audiometry and MH probing, assess similar and separate perimeters and are complementary. Malleus handle probing alone detects attic loculation of OME, 54 of 954 ears (5.6%). it extends the diagnostic range to the TTM activities.

Middle ear effusions and the nitrous oxide myth

Myringotomies were performed on 75 ears suspected of having chronic or recurrent otitis media with effusion. Preanesthesia and intraoperative tympanograms with halothane, nitrous oxide, and oxygen anesthesia were compared for possible changes in middle ear pressure due to anesthesia. In addition, preanesthesia tympanograms were compared with tympanograms taken 2 weeks before hospital outpatient surgery. Tympanograms of 11 ears were found to shift from a flat type recorded at the office visit to normal range at pre and postinduction anesthesia. Middle ear fluid was not present in any of these 11 ears. The remaining 64 ears were broken down into three abnormal tympanogram configurations; flat, roll-over, and peaked negative pressure types. Comparing the tympanograms done in the office, preanesthesia and intraoperatively, only one of the 64 ears showed a change after induction of anesthesia. Three of the 64 ears revealed an unpredictable result with negative myringotomies. These results tend to support tympanometry as a means in predicting myringotomy findings, and also refute the contention that short-term nitrous oxide anesthesia changes the middle ear effusion during myringotomy.

Tympanometric configurations and middle ear findings in experimental otitis media

Relationships between ventilation of the middle ear (ME) system and pathogenic bacteria in the upper respiratory tract were explored in an animal model to better understand the etiopathogenesis of otitis media. Otitis media developed in 12 of 18 chinchillas inoculated intranasally with Streptococcus pneumoniae followed by bilateral ME deflation (negative pressure). Otitis media with effusion developed in 19 of 36 ears examined ten days after inoculation. The development of purulent effusion after ten days was highly correlated with persistent negative ME pressure for at least 48 hours after deflation, while most ears that developed serous effusion after ten days had normal ME pressure 48 hours after deflation. Tympanometric validation of the presence of absence of effusion and type of effusion was obtained ten days after inoculation. A low compliance tympanogram detected 90% of the purulent effusions and was 100% specific for this type of effusion. In contrast. three of four serous effusions were associated with normal pressure/normal compliance tracings suggesting that the physical characteristics or volume of ME effusion and/or the histopathology of the ME cleft are reflected i the tympanometric configuration.

Spontaneous improvement of secretory otitis. A long-term study

Six repetitive tympanometric screenings were performed on 184 2-year-old, otherwise healthy children (368 ears) between November 1977 and February 1980. Between each examination half of the ears changed tympanogram type; during summer and spring more ears improved than deteriorated and during winter and autumn the reverse took place. Type B representing flat curve without impedance minimum improved at each examination in more than half of the ears, but a large number of "new' ears received a type B tympanogram. In all, 39% of all ears had type B at one examination at least, 7% had type B at two examinations, 4% at three, 4% at four, and 2% at five examinations; only one ear (0.3%) had a type B tympanogram at all six examinations. The investigation revealed a very high total frequency and spontaneous improvement of secretory otitis. In this period of 2 and a half years, 70% of ears had types B or C2 at one examination at least. On account of the pronounced spontaneous improvement, the results of any method of treatment-when the indications are wide-will be good, although even studies on controlled materials, comparing two methods of treatment, are encumbered with considerable uncertainties.

The post-winter prevalence rate of middle ear effusion in four-year-old children, judged by tympanometry

Tympanometry and otologic examinations were performed in 373 four-year-old children randomly selected from the Central National Register at the end of February, 1979. A close interaural correlation of the middle ear pressures of a child was found and therefore the tympanometric results represent related as well as independent data. Consequently, the post-winter prevalence rates of type B tympanograms were calculated according to different sampling units: per all ears 13.7%; per right ears 12.9%; per left ears 14.5%; per ears selected at random 13.9%. Additionally, the prevalence rate was estimated per child at 20.4% type B in at least one ear and at 7% type B in both ears. Based upon the literature the validity of the tympanometric method in detecting middle ear effusion is described. The predictive values of positive and negative tests mostly depend on the degree of the cutoff point (pass--fail point) which has been chosen. In this study the cutoff point was the presence of a type B tympanogram. The advantage and disadvantage of applying 'one ear' or 'one child' as the sampling unit is discussed from a statistical as well as a clinical point of view. When calculating either per ear or per child no sex differences in the prevalence rates could be proved.

Identification of middle ear disease

Since impedance measurements were introduced as a mean of identifying ears affected by middle ear disease, efforts have been concentrated on the identifying of ears in which effusion is present. The shape of the tympanogram has been analysed and it has been proposed that ears producing a shallow tympanometric pattern are more likely to contain fluid in the middle ear, than are ears having a tympanogram with a large peak. In this communication and great individual variation of tympanograms is shown and it is suggested that two categories of tympanogram should be considered, namely 1) flat tympanogram, and 2) tympanograms in which the middle ear pressure can be determined.

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.

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.

Tympanometry and middle ear effusion: a cohort-study in three-year-old children

Myringotomy was done on 44 three to four-year-old children out of a total of 463 three-year-olds in a geographically defined area, because these 44 children persistently showed abnormal screening-tympanometry over 6 months. The findings were correlated to middle ear pressure, absolute compliance, absolute gradient and relative gradient parameters. As regards the state of effusion in the middle ear, all parameters showed a high predictive value. A reverse proportionality of compliance parameters and the content of fluid in the tympanic cavity, each related to the magnitude of associated hearing loss, was demonstrated. The significance of the findings in the tympanometric diagnosis of middle ear disease in young children is outlined, and a revised classification system of the tympanogram, predicting middle ear effusion with a sensitivity of 91% and a specificity of 84%, is recommended.

Tympanometry in three-year-old children. III. Correlation between tympanometry and findings at paracentesis in a prospectively followed population of otherwise healthy children aged 3--4 years

Paracentesis was performed on 46 three- to four-year-old children out of all 523 three-year-olds in a geographically defined area, because these 46 children had persistently showed abnormal tympanograms over a 6-month period. The findings were correlated to the parameters middle ear pressure, absolute compliance, absolute gradient, and relative gradient. As regards the state of effusion in the middle ear, all these parameters--except for the middle ear pressure--showed a high predictive value. The significance of the findings in the tympanometric diagnosis of middle ear disease in the younger age groups is outlined.

Frequency of secretory otitis and histology of the normal middle ear mucosa

Repetitive tympanometric screenings of healthy 1-year-old and 2-year-old children showed that 36% of all healthy children had a type B tympanogram, indicating middle ear effusion or secretory otitis, at least once during the first 2 years of life. Another 29% of children had a middle ear pressure of -200 to -350 mm H2O. It was rendered probable that at least 75% of all healthy children have secretory otitis in the course of the first 8 years of life. This high frequency of secretory otitis is correlated to the histology of the normal middle ear mucosa. The many conflicting opinions that prevail in the literature concerning the compostion of the normal middle ear mucosa, especially concerning the demonstration of mucous glands, probably arise from the fact that the middle ear mucosa of most healthy adults has been exposed to metaplastic changes in childhood but has normalized except for minor sequelae. These are often misinterpreted as constituting components of the normal mucosa.

Tympanometric diagnosis of middle ear effusions

A review of medical records of unselected children in whom the otoscopic diagnosis of middle ear effusion was uncertain, showed that tympanometry resolved the diagnostic uncertainty with an accuracy of 88 per cent for the prediction of a dry middle ear and an accuracy of 85 per cent for predicting fluid in the middle ear. Tympanometry itself gave inconclusive findings in II per cent of cases. Tympanometry can greatly reduce the need for diagnostic aspiration of the middle ear.

Middle ear ventilation in conjunction with adenotonsillectomy

If the tonsils and adenoids are causing eustachian tube dysfunction with middle ear effusion, the need for a ventilation tube at the time of the T&A and myringotomy is unresolved. Thirty-one patients with bilateral symmetrical middle ear effusion had T&A and myringotomies. In one ear, a ventilation tube was inserted; the other ear acted as a control. In addition to the clinical impressions, preoperative and serial postoperative audiograms and tympanograms are compared through a 12-month time frame. Discussion is presented regarding middle ventilation at the time of the primary operation.