Asia Pacific Journal of Speech, Language and Hearing, 8,179-1842003 ... of Speech Pathology and Audiology, The University of Queensland, Australia;.
Asia Pacific Journal of Speech, Language and Hearing, 8,179-1842003
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Hearing screening for children in cOIDlllunity settings using transient evoked otoacoustic eDlissions Carlie Driscoll1, Joseph Kei1 and Bradley McPherson2 1Department of Speech Pathology and Audiology, The University of Queensland, Australia; 2Department of Speech and Hearing Sciences, The University of Hong Kong, Hong Kong
Abstract
Despite widespread investigation and utilization of transient evoked otoacoustic emission (TEOAE) hearing screening programmes in the neonatal population, limited research has occurred into the applicability and particulars of TEOAE testing of other paediatric ages. Further consideration must be afforded to screening beyond the neonatal stage. Later, community-based options for hearing screening include the infant period and/or upon entry to primary school, or special education settings. The present researchers have conducted TEOAE screening and analyses for 627 subjects in the two-month-old age group, 940 children of school-entry age and 489 subjects studying in special schools. In particular, TEOAE normative data were provided for specific groups and environments, and non-pathological effects on the results were described. The technical findings of this paper lend themselves to a vast array of immediate clinical applications to improve hearing screening of two-month-old infants, six-year-old schoolchildren and children in special education settings.
Introduction
Consensus exists that the earlier the diagnosis of hearing impairment, the greater the potential for rehabilitative success. For instance, a child diagnosed with moderate hearing impairment and provided with access to effective rehabilitation services within the critical first six months of life may develop normal speech and language skills by approximately five years of age (Yoshinaga-Itano et aI., 1998; Yoshinaga-Itano, 2000). Early detection is achievable for many cases through universal hearing screening programmes and transient evoked otoacoustic emission (TEOAE) technology is considered to be an appropriate tool for this (White et aI., 1993; De Ceulaur et aI., 1999; Norton et aI., 2000). Universal neonatal TEOAE programmes have, indeed, become widespread. However, they are not infallible in the capturing of all children. Potential shortcomings include the· inability to screen all cases because of early hospital discharge, home births, medical contraindications
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and lack of parental consent. Further, universal screening of neonates does not address the important issue of fluctuating or late-onset hearing pathologies. To improve on the detection of hearing impairment that begins in the neonatal period, screening throughout childhood is obviously desirable. Yet, a paucity is apparent in respect of the literature regarding TEOAE screening for paediatric populations other than neonates. Little information is available concerning the use of TEOAEs in the community-based screening of infants (a group that are easily accessible on presentation for their first immunizations), entry-level schoolchildren (a group for whom high screening coverage is anticipated due to essentially compulsory attendance in many developed countries) or children with special needs (a high-risk population for which traditional screening batteries may be unsuitable). In particular, prior to the utilization of TEOAE hearing screening for these groups, it is necessary to determine the feasibility of the technique in community settings, establish normative data, and investigate the effects of pathological and non-pathological factors. Further, estimation of associated costs and exploration of test accuracy must occur. Whilst all such requirements have been satisfied for universal neonatal hearing screening programmes, very few have been fulfilled for programmes aimed at children beyond the neonatal stage. In view of the above-mentioned motivations, the current researchers conducted several investigations of TEOAE screening in community-based paediatric populations. Among the various objectives of their studies were the following aims: (1) to establish TEOAE normative data for two-month-old infants in a community setting, as well as describe non-pathological effects (i.e. gender, ear asymmetry, activity state) on the results and examine test/retest variability, (2) establish TEOAE normative data for six-year-old schoolchildren, as well as describe nonpathological effects (i.e. gender, ear asymmetry, history of ear infections) on the results and examine test/retest variability, (3) investigate the test performance of TEOAE as a screening system for six-year-old schoolchildren, and (4) explore the feasibility of TEOAE screening of children in special schools. Methods
Three subject groups of interest were targeted for hearing screening and were included: infants, schoolchildren and students in special schools. The infant group comprised 627 subjects (289 male, 338 female), with a mean age of 2.0 months (SD = 0.2), who 'were tested in non-sound-treated health clinics prior to immunization. The schoolchildren group included 940 subjects (495 male, 445 female), with a mean age of 6.2 years (SD = 0.4, range = 5.2-7.9 yrs), who were recruited from Year 1 classes in 22 schools. These subjects were tested in quiet, non-sound-treated rooms within each school. The final group consisted of 489 subjects (308 male, 181 female), with a mean age of 9.6 years (SD = 4.6, range = 1.9-19.9 yrs), who were recruited from 15 special education schools. Again, testing was conducted within quiet rooms at each school. All participation was voluntary. Full procedural details for the studies conducted for each subject group may be viewed in the corresponding references (Driscoll et aI., 1999,2000,2001,2002). In essence, TEOAE screening was performed for all subject groups using the IL088 or IL0292 Otodynamics Analyzer (connected to a laptop/desktop computer) in Quickscreen mode. The criterion of Kei et al. (1997) was applied to delineate
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passing from failing results. Specifically, results were considered a 'pass' if the TEOAE spectrum was recorded at least 3 dB above the noise floor (i.e. SNR ~ 3 dB) at 2.4, 3.2 and 4.0 kHz. A 'fail' was otherwise indicated. Such a criterion is virtually identical to the commonly utilized Rhode Island Hearing Assessment Project (RIHAP) version, with the exception of the former's exclusion of 1.0-2.0 kHz. Ambient noise levels recorded for each subject group were: 34-51 dB A (infants), 35-47 dB A (schoolchildren) and 31-61 dB A (special schools). In the event that background noise exceeded 50 dB A, TEOAE testing was temporarily paused, in accordance with upper noise limits suggested by Rhoades et al. (1998). The schoolchildren were also assessed using pure tone screening and tympanometry for comparative purposes. Pure tone screening utilized the Madsen Micromate 304 portable audiometer. Tones of frequencies 0.5, 1.0, 2.0 and 4.0 kHz were presented to each ear at an intensity level of 20 dB HL. If the subject failed to respond twice to three consecutive presentations at any frequency at 20 dB HL, the threshold for that frequency was determined. Thresholds greater than 25 dB HL for any frequency were considered to indicate failure of pure tone screening. Tympanometry was performed for schoolchildren using the Madsen Zodiac 901 Middle Ear Analyzer. Failure was defined as any result that could be classified as a type B or C2 tympanogram (refer to Jerger [1970] for further detail). Major findings
For the two-month-old infants in health clinics, results revealed a significant influence of subject gender on the TEOAE values obtained. In particular, females displayed higher whole-wave reproducibility (REPRWH), response (RESPON), band reproducibility (REPRO) and signal-to-noise ratio (SNR) mean values than males, with no significant gender difference in AB difference (AB DIFF) and NOISE values evident. Therefore, it was possible to conclude that females did indeed produce stronger and more robust emissions than males. A significant ear asymmetry was also displayed in the TEOAE results of the infant group. Specifically, higher REPRWH, RESPON, REPRO and SNR mean values were obtained for right ears, with no notable difference between ears found for AB DIFF and NOISE. Thus, right ear TEOAE robustness was confirmed. Further, examination of results detected the fact that activity status of subjects had a significant bearing on TEOAE results, with inferior mean values recorded for REPRWH, RESPON, REPRO and SNR when infants were assessed in a 'noisy' activity state (restless, sucking a pacifier, or being fed). Higher AB DIFF and NOISE values were also observed for these children. Hence, it was confirmed that 'quiet' activity states (awake and calm, or asleep) were superior for TEOAE screening of two-month-old infants in community settings. A substantial amount of variability in scores was revealed by investigation of gender, ear and activity state specific normative data for the infant group (refer to Driscoll et al. [1999] for complete normative data). It was shown, for example, that 8% separated minimum from maximum mean REPRO scores across the eight possible combinations (of male/female, left/right, quiet/noisy). A 6 dB separation between extreme values was displayed for SNR. Notably, females generally displayed greater variance in REPRO and SNR scores than males.
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Good intra-subject (test/retest) reliability was observed for certain TEOAE test parameters for two-month-olds tested in health clinics. Namely, correlation coefficients for RESPON, SNR at 4.0 kHz and REPRO at 2.4 and 4.0 kHz were moderately high. Utilizing the criterion of Kei et al. (1997), 3.2 % of the infant group failed TEOAE screening in at least one ear. Results also revealed that subject gender exerted significant influence on the TEOAE values obtained from entry-level schoolchildren. In particular, females displayed larger REPRWH, RESPON, REPRO and SNR mean values. However, males displayed higher AB DIFF and NOISE values. Hence, it was not appropriate to suggest that the emissions of females were superior in strength and robustness. As also observed for two-month-old infants, results showed that ear asymmetry was a significant factor affecting the TEOAE values of the schoolchildren group. Superior mean values were recorded for all test parameters in the right ear, supporting the notion of right ear TEOAE robustness. TEOAEs were also affected by subject history of prior ear infection. Significantly lower mean values were exhibited for the parameters REPRWH, RESPON and REPRO, in children with a positive history of ear infections. Such children were also more likely to fail TEOAE testing. Examination of gender, ear and history-specific normative data for the school group revealed the large amount of variability inherent in TEOAE screening (see Driscoll et al. [2000] for complete normative values). It was displayed that a 140/0 difference separated minimum from maximum mean REPRO scores across the eight possible combinations (of male/female, left/right, positive/negative ear infection history). Approximately 3 dB separated the extreme values for SNR. Good intra-subject (test/retest) reliability of TEOAE test parameters was achieved for entry-level schoolchildren. Specifically, correlation coefficients were moderately high for the parameters REPRWH, REPRO at 4.0 kHz and SNR at 2.4, 3.2 and 4.0 kHz, and very high for RESPON. Further, reliability was considerably higher than displayed for the two-month-old group. TEOAE testing produced high accuracy and efficiency figures in comparison with pure tone screening for schoolchildren (see Driscoll et al. [2001] for full test performance values). Results indicated that the commonly used RIHAP (~ 3 dB SNR) criterion could be replaced with a ~ 1 dB SNR or mean ~ 6 dB SNR to improve test performance. Utilizing the ~ 3 dB SNR criterion, 20% of subjects failed TEOAE testing in at least one ear. Further, TEOAE testing resulted in inferior accuracy and efficiency test performance when compared with a pure tone screening plus tympanometry battery. TEOAEs presented as a practical tool for hearing screening of children studying in special schools. Using this technology, 800/0 of subjects could be tested and average test time was very reasonable at two minutes per ear. However, a large proportion (400/0of those able to be tested) failed TEOAE testing in at least one ear. No significant effects were found between could-not-test cases and case-history factors. A significant difference in TEOAE failure rates was found across history of neonatal special care nursery residency and history of parental concern regarding possible hearing impairment. Notably, neither type nor degree of impairment had any significant bearing on could-not-test or failure rates for tympanometry or TEOAE screening. Full findings for this group may be found in Driscoll et al. (2002).
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Discussion
Ultimately, it is hoped that, by enhancing the minimal literature available on TEOAE screening of community-based paediatric populations, a contribution will be made to the development of effective hearing screening programmes for children beyond the neonatal period. These findings should assist researchers and clinicians in devising and implementing appropriate pass/fail criteria for large-scale screening with optimal accuracy and efficiency. For instance, in community-based TEOAE screening of two-month-old infants and six-year-old children, the clinician should note that certain TEOAE test parameters have been shown to have better test/retest reliability than others. Thus, the clinician may be more confident in pass/fail criteria that utilize such variables. In addition, clinicians will now be aware that acknowledgement of non-pathological factors is essential in mass communitybased TEOAE screening of infants and entry-level school children. A large amount of variability in results has been demonstrated between genders, ears, activity states and history of ear infection. The normative data tables derived in the current studies may be utilized by any clinician to improve the accuracy of hearing screening of two-month-old infants and six-year-old schoolchildren. For example, should an infant or school-aged child not display SNR values greater than the 5th percentile but less than the 95th percentile (the common range for normative OAE data), the clinician would be alerted that further testing was necessary. The normative data tables can be employed to highlight results that are not commonly found in infants and schoolchildren. Further, the clinician responsible for screening entry-level school children may choose to disregard 'blanket' pass/fail criteria that advocate use of single parameter values to determine test outcome (e.g. 2:: 3 dB SNR), irrespective of subject gender, ear infection history, ear asymmetry, age or test environment. For those testers who prefer to utilize single-value criteria, findings of the current study have shown that whilst the commonly selected modified RIHAP criteria may be suitable for hospital-based neonatal screening, they may not be directly applicable or optimal for screening of older populations, such as six-year-old schoolchildren. In addition, in constructing the community-based screening programme for schoolchildren, the clinician may consider selectingTEOAE testing over pure tone screening, but not as a replacement for a pure tone plus tympanometry battery. In the hearing screening of children studying in special schools, TEOAE testing proved itself to be particularly advantageous. The vast majority of children (800/0) could be tested using this tool. Thus, TEOAE technology presents as a potential screening option for a population that may have considerably restricted communication skills, a high prevalence of hearing pathology, and may be difficult to test using conventional methods. In view of this, both authorities and clinicians should be alerted to the relevance of screening all children in special schools prior to, or shortly after, admission. The conception by some clinicians that children with certain types of disabilities (particularly those with severe impairments) may only be tested using electrophysiological means under sedation should be discarded. However, in view of the unknown prevalence of auditory neuropathy in special school groups, it would be unwise of the clinician to rely solely on the outcomes of TEOAE screening. In the event of positive parental or educational concern of possible hearing impairment combined with a passing TEOAE result, the clinician should proceed with further diagnostic testing.
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Conclusion
The findings of the current studies lend to the clinical perspective a sense of direction for community-based TEOAE screening of paediatric populations. To improve on the highly beneficial detection of hearing impairment that begins at birth, a move toward mass infant and school-age screening can now be considered. Neonatal screening alone cannot achieve total coverage of the population owing to the increasing occurrence of early hospital discharge and community births. Furthermore, it does not address the frequently overlooked issues of fluctuating and late-onset hearing pathologies. Clinicians may now express confidence in, and support of, community-based opportunities to review the hearing status of paedi,;. atric populations, with the knowledge that many of the theoretical requirements for utilizing TEOAEs as a mass-screening device have been satisfied. Acknowledgements
The current investigations were supported by research grants from the University of Queensland, Australian National Health and Medical Research Council, Sylvia and Charles Viertel Charitable Foundation, Garnette Passe and Rodney Williams Memorial Foundation, and Financial Markets Foundation for Children. The authors would also like to thank Queensland Health, Queensland Education, Queensland Catholic Education, Mater Hospital (Brisbane), Brisbane City Council Immunization Services, and participating health clinics and schools for their cooperation and assistance during the course of this study. References De Ceulaur G, Daemers K, Van Driessche K, Marien S, Somers T, Offeciers FE, Govaerts PJ. Neonatal hearing screening with transient evoked otoacoustic emissions: a learning curve. Audiology 1999; 38: 296-302. Driscoll C, Kei J, McPherson B. Transient evoked otoacoustic emissions in six-year-old school children: a normative study. Scand Audio12000; 29: 103-110. Driscoll C, Kei J, McPherson B. Outcomes of transient evoked otoacoustic emission testing in six-year-old school children: a comparison with pure tone screening and tympanometry. Int J Pediatr Otorhinolaryngol2001; 57: 67-76. Driscoll C, Kei J, Bates D, McPherson B. Hearing screening for children in special schools using transient evoked otoacoustic emissions. Int J Pediatr Otolaryngol2002; 641: 51-60. Driscoll C, Kei J, Murdoch B, Smyth V, McPherson B, Latham S, Loscher J. Transient evokedotoacoustic emissions in two-month-old infants: a normative study. Audiology 1999; 38: 181-186. Jerger JF. Clinical experience with impedance audiometry. Arch Otolaryngol1970; 92: 311-324. Kei J, McPherson B, Smyth V, Latham S, Loscher J. Transient evoked otoacoustic emissions in infants: effects of gender, ear asymmetry and activity status. Audiology 1997; 36: 61-71. Norton SJ, Gorga MP, Widen JE, Folsom RC, Sininger Y, Cone-Wesson B, Vohr BR, Fletcher KA. Identification of neonatal hearing impairment: Summary and recommendations. Ear Hearing 2000; 215:529-535. Rhoades K, McPherson B, Smyth V, Kei J, Baglioni A. Effects of background noise on click-evoked otoacoustic emissions. Ear Hearing 1998; 19: 450-462. White KR, Vohr BR, Behrens TR. Universal newborn hearing screening using transient evoked otoacoustic emissions: results of the Rhode Island Hearing Assessment Project. Semin Hearing 1993; 141: 18-29. Yoshinaga-Itano C. Development of audition and speech: Implications for early intervention with infants who are deaf or hard-of-hearing. Volta Review 2000; 1005: 213-227. Yoshinaga-Itano C, Sedey A, Coulter D, Mehl A. The language of early- and later-identified children with hearing loss. Pediatrics 1998; 1025: 115-123.
