Universal newborn hearing screening: a question of evidence.

The objective of this paper is to present data on the ages of diagnosis and hearing-aid fitting of children with permanent congenital or early-onset hearing loss who were identified through neonatal hearing screening (NHS) programs or medical referral. Data were collected for 709 children born between 1980 and 2003. Children who were screened were diagnosed significantly earlier (mean 6.3 months) than referred children (mean 39.5 months). For the referred children, the ages of diagnosis and amplification improved over time but remained unacceptably high. In addition, there was an inverse relationship between degree of loss and age of diagnosis, with children with lesser degrees of hearing loss identified later than those with severe to profound hearing loss. These results contribute to the evidence that NHS programs lower the ages of diagnosis and amplification and lead to earlier improved hearing. It is argued that early access to hearing should be the desired primary outcome of NHS. The numerous studies demonstrating improved ages of diagnosis resulting from NHS programs constitute adequate evidence to support these initiatives.

Randomized, controlled trial comparing long-term sulfonamide therapy to ventilation tubes for otitis media with effusion.

Several studies have indicated that either the surgical insertion of ventilation tubes (VTs) or long-term treatment with sulfonamide-based antibacterials is effective in the management of otitis media with effusion (OME; otherwise known as serous otitis media, secretory otitis media, and glue ear) when compared with a no-treatment control or placebo. This controlled trial is the first to compare directly the effectiveness of these two treatments for long-standing OME. Outcome variables are treatment success rates, hearing thresholds, recurrent acute otitis media episodes, and side effects of medication or complications of VT placement. One hundred twenty-five children (aged 2.5 to 7 years) who met the usual indications for surgery (long-standing [greater than 3 months] OME and conductive hearing loss) were randomly assigned to "medical" treatment (sulfisoxazole 75 mg/kg per day for 6 months) or "surgical" treatment (bilateral insertion of VTs). Subjects underwent pure-tone audiometry (500, 1000, 2000, 4000 Hz) and otomicroscopic examination at 2, 4, 6, 12, and 18 months. A significantly greater proportion of medical subjects (67%) than surgical subjects (48%) were treatment failures at 6, 12, or 18 months (P = .0208). Surgical subjects had significantly better hearing at 2 and 4 months (P values less than .01) but not at 6, 12, and 18 months (P values greater than .2). A significantly greater proportion of surgical subjects (50%) experienced complications of treatment than did medical subjects (9%) (P less than .001). Thirty-three percent of candidates for VT placement did not require surgery when treated with a 6-month course of sulfisoxazole.(ABSTRACT TRUNCATED AT 250 WORDS)

Auditory evoked potentials in the assessment of hearing.

The auditory evoked potentials are the best available technique for identifying infants with a hearing impairment before the age of 6 months. They are also very important in the evaluation of patients with suspected retrocochlear hearing loss. New developments may soon allow the determination of hearing thresholds at different frequencies and a more accurate assessment of patients with central auditory dysfunction.

Recording auditory brainstem responses from infants.

Auditory brainstem responses (ABRs) can be reliably recorded from infants in the first few months of life. Since they are normally recognizable down to intensities that are 30 dB above normal hearing thresholds, ABRs elicited by clicks are useful in screening for hearing-impairment in infancy. The ABRs can also provide further diagnostic information about the hearing losses that are detected by screening: the threshold for the response represents a reasonable estimate of the severity of the hearing loss; bone-conduction studies can assess the extent of a conductive loss; and frequency-specific techniques can evaluate hearing thresholds at different frequencies. At present, ABRs are mainly used for screening infants who have been treated in neonatal intensive care units. Because the majority of infants with hearing impairment are not seen in these units, it might be worthwhile to use ABRs in a more widespread screening program.

Objective evaluation of aided thresholds using auditory steady-state responses.

Auditory steady-state responses to amplitude-modulated tones with modulation frequencies between 80 and 105 Hz can be recorded when multiple stimuli are presented simultaneously through a soundfield speaker and amplified using a hearing aid. Responses were recorded at carrier frequencies of 500, 1000, 2000, and 4000 Hz in a group of 35 hearing-impaired children using hearing aids. The physiologic responses were recorded at intensities close to the behavioral thresholds for sounds in the aided condition, with average differences between the physiologic and behavioral thresholds of 17, 13, 13, and 16 dB for carrier frequencies 500, 1000, 2000, and 4000 Hz. The technique shows great promise as a way to assess aided thresholds objectively in subjects who cannot reliably respond on behavioral testing.

Exploring factors that affect the age of cochlear implantation in children.

OBJECTIVE: Early access to sound through early cochlear implantation has been widely advocated for children who do not derive sufficient benefit from acoustic amplification. Early identification through newborn hearing screening should lead to earlier intervention including earlier cochlear implantation when appropriate. Despite earlier diagnosis and the trend towards early implantation, many children are still implanted well into their preschool years. The purpose of this study was to examine the factors that affected late cochlear implantation in children with early onset permanent sensorineural hearing loss. METHODS: Data were examined for 43 children with cochlear implants who were part of a group of 71 children with hearing loss enrolled in a Canadian outcomes study. Eighteen (41.9%) of the 43 children were identified through newborn screening and 25 (58.1%) through medical referral to audiology. Medical chart data were examined to determine age of hearing loss diagnosis, age at cochlear implant candidacy, and age at cochlear implantation. Detailed reviews were conducted to identify the factors that resulted in implantation more than 12 months after hearing loss confirmation. RESULTS: The median age of diagnosis of hearing loss for all 43 children was 9.0 (IQR: 5.1, 15.8) months and a median of 9.1 (IQR: 5.6, 26.8) months elapsed between diagnosis and unilateral cochlear implantation. The median age at identification for the screened groups was 3.3 months (IQR: 1.4, 7.1) but age at implantation (median 15.8 months: IQR: 5.6, 37.1) was highly variable. Eighteen of 43 children (41.9%) received a cochlear implant more than 12 months after initial hearing loss diagnosis. For many children, diagnosis of hearing loss was not equivalent to the determination of cochlear implant candidacy. Detailed reviews of audiologic profiles and study data indicated that late implantation could be accounted for primarily by progressive hearing loss (11 children), complex medical conditions (4 children) and other miscellaneous factors (3 children). CONCLUSIONS: This study suggests that a substantial number of children will continue to receive cochlear implants well beyond their first birthday primarily due to progressive hearing loss. In addition, other medical conditions may contribute to delayed decisions in pediatric cochlear implantation.

Comparison of auditory brainstem response and behavioral screening in neonates.

This paper reports on two studies, one in Halifax and the other in Ottawa, which compared behavioral methods and BERA in the screening of hearing loss in neonates. The Halifax study used BERA as the screening procedure for infants of a neonatal intensive care unit (NICU) and as a supplementary procedure to behavioral screening test for non-NICU but "at risk" infants. The results of this study indicate false positive rates with the behavioral test of 86.1 and 50.5% for NICU and at risk groups respectively. The Ottawa study evaluated the Crib-o-gram as a screening test for NICU infants using BERA as the standard. The results of this study indicated that approximately one third of babies with normal BERA thresholds failed Crib-o-gram screening and that Crib-o-gram could identify moderately/severe losses.

Auditory brainstem response audiometry in neonatal hydrocephalus.

Sixteen hydrocephalic NICU babies and 16 age-matched, non-hydrocephalic NICU babies were tested with BERA. The latency and amplitude of waves I and V were compared between groups. Both waves were longer in latency and smaller in amplitude in the hydrocephalic group. The I-V latency interval was within normal limits, but the V/I amplitude ratio was significantly smaller. The reduced amplitude of wave V was the most noticeable ABR abnormality. A total of 11 hydrocephalic babies showed responses that were considered abnormal in amplitude, with all but one having an elevated ABR threshold in at least one ear. These threshold elevations may reflect a neurological condition rather than a peripheral hearing loss.

The contribution of brainstem electric response audiometry (BERA) to the evaluation and management of infants with cleft palate.

In the three-year period ending December 1986, 31 infants followed by the Cleft Palate Team of our institution were evaluated with BERA one or more times. Seventy-four percent presented auditory threshold elevation on initial examination; none was observed to resolve spontaneously in the first year of life. Myringotomy and tympanostomy tube insertion normalized auditory thresholds effectively in most children with serous otitis media. In a few cases, however, recovery required several months. BERA can assist the early detection of children with sensorineural hearing loss. It may also be valuable as an additional consideration in selecting treatment of serous otitis media in these children. Precise guidelines as to the ideal time to perform tympanostomy requires further substantiation of the effects of early hearing loss on speech and language development.

Neonatal auditory brain stem responses from ipsilateral and contralateral recording montages.

Ipsilateral and contralateral auditory brain stem responses were recorded from both ears of 10 neonates between 37 and 43 weeks from conception with normal auditory brain stem function. The most prominent component of the contralateral response was a forehead positive deflection occurring 0.3 millisecond before the ipsilateral wave III followed by two forehead negative waves, the latter present at the same latency as the ipsilateral wave V. The amplitude of the contralateral response was small: at 30 dB nHL only 7 of the 20 ears showed clear responses from this montage. The morphology of the neonatal contralateral response is thus considerably different than the ipsilateral, unlike the adult. A neonate could be mistakenly diagnosed as hearing impaired or neurologically involved if the interpretation is based on the contralateral recording.

Probe tube microphone measures of loudness discomfort levels in children.

Loudness discomfort levels (LDLs) have been advocated as a means for selecting the SSPL90 setting of an individual's hearing aid. Kawell, Kopun, and Stelmachowicz (Ear Hear 1988; 9: 133-136) recently developed a procedure to measure LDLs in children. Several procedural cautions, involving the hearing aid stimulus delivery and sound field calibration, have been noted with this method. As a means of overcoming these problems, a new method utilizing insert earphone derived stimuli delivered to a child's ear-mold with probe tube microphone monitoring of real-ear sound pressure level was explored. Twenty children, aged 7 to 14 years, served as subjects. The advantage of the present method lies in the procedural conveniences and the ability to compare real-ear audiometric measures and hearing aid performance.

Critical differences in aided sound field thresholds in children.

Variability of aided sound field thresholds (ASFTs) was examined in 30 children comprising two age groups (5-9 and 10-14 years). Test-retest ASFTs were collected at six frequencies (250, 500, 1000, 2000, 3000, and 4000 Hz). No statistically significant difference was found in mean test and retest ASFTs between the two groups (p greater than .05). Test-retest difference data from both groups of children were combined and used to generate critical differences (in dB) for two ASFTs. At a 95% confidence level, two ASFTs would have to differ by more than 10 dB across signal test frequencies to attain statistical significance. In clinical decision-making, if one accepts smaller differences in ASFTs as statistically significant, larger probabilities of error must be assumed.

Bayley developmental performance at two years of age of neonates at risk for hearing loss.

Of 306 infants in a neonatal intensive care unit (NICU) screened for hearing-loss before discharge with both the 'Crib-O-Gram' (COG) and brainstem auditory evoked responses (BAER), 122 failed either or both tests. These infants were then tested on the Bayley Scales at approximately 24 months corrected age, together with 25 infants who had passed both tests and 25 non-NICU infants from a general medical follow-up clinic. Compared with BAERs, the COG was found to be inadequate in detecting mild hearing loss, but its sensitivity increased with more severe loss. On the Bayley Scales, infants who had failed the BAER had lower scores than those who had passed, but for those who had passed the BAER, there was no difference in development between those who had failed and passed the COG.

Auditory brainstem responses to clicks in neonates.

Normative data are required when interpreting brainstem electric response audiometry results. An abnormal auditory brainstem response (ABR) cannot be identified without knowledge of the normal ABR and the variability associated with technical and physiological factors. Normative data obtained from babies in a neonatal intensive care unit in response to click stimulation are presented in this paper.

Incidence of hearing loss in high risk and intensive care nursery infants.

The incidence of hearing impairment in high risk infants is summarized for five programs which use brainstem electric response audiometry (BERA) to detect hearing loss in this population. Programs are compared with respect to the following variables which may affect reported incidence figures: population characteristics, stimulus and recording parameters, criteria for failure on the initial BERA test, and follow-up protocols. Between 10-30% of these infants fail an initial BERA test, with initial failure rate largely dependent on the failure criteria used. Approximately 10% will continue to show some degree of hearing impairment on follow-up tests at 2-5 months of age. Between 2-4% will have a moderate to profound bilateral sensorineural hearing loss requiring amplification and habilitation.

The Crib-O-Gram in the NICU: an evaluation based on brain stem electric response audiometry.

This study evaluated the Crib-O-Gram as a screening test for hearing loss in NICU infants using Brain Stem Electric Response Audiometry (BERA) as the standard. Two Crib-O-Gram tests were administered to 280 babies within 48 hours of BERA testing. An additional 26 babies received BERA and one Crib-O-Gram test. Correlation coefficients for the two Crib-O-Gram scalar scores were calculated separately for a group of preterm (31 to 37 weeks) and a group of full term and older (38 to 54 weeks) infants, with values of 0.36 and 0.52, respectively. This indicates that the Crib-O-Gram has poor reliability for a screening test, particularly for preterm babies. Approximately one-third of babies with normal BERA thresholds failed Crib-O-Gram screening. The identification of hearing loss by Crib-O-Gram increased with the severity of the loss. Crib-O-Gram was able to identify moderately severe hearing losses in full term and older babies.

Brainstem electric-response audiometry in infants of a neonatal intensive care unit.

Brainstem electric-response audiometry was used to assess the auditory function of 600 infants from a neonatal intensive care unit. Two groups of children were tested, one group as inpatients prior to discharge with a mean age at test of 39.4 weeks and one group as outpatients with a mean age at test of 55.4 weeks. Our results indicate that testing infants when they are older will reduce the incidence of failure on the initial evaluation and will reduce the identification of transient hearing losses which resolve spontaneously. Our results also indicate that a threshold of 30 dB nHL or less is probably normal and that some infants with a threshold of 40 dB nHL at first test require otological or audiological management.

Prognostic validity of brainstem electric response audiometry in infants of a neonatal intensive care unit.

This study compared the results of brainstem electric response audiometry (BERA) in infants of a neonatal intensive care unit to those obtained on the same children with pure-tone audiometry at 3 years of age. Six hundred children were initially tested in infancy, and complete follow-up information was obtained on 333. In 297 (89%) the BERA results accurately predicted the hearing status at the age of 3 years. Twenty-nine (9%) of the discrepancies were related to conductive hearing losses: 17 patients with a conductive hearing loss in the first few months of life had normal hearing at 3 years, and 12 patients normal in infancy had a conductive loss at 3 years. Two patients evaluated as a sensorineural hearing loss by BERA had normal hearing. These may have been due to a conductive loss. Six patients assessed as normal by BERA had significant hearing losses at the age of 3 years. Five of these had normal hearing at one frequency between 1,000 and 4,000 Hz. The sixth may have developed a sensorineural hearing loss after birth.

Thresholds for short-latency auditory-evoked potentials to tones in notched noise in normal-hearing and hearing-impaired subjects.

The thresholds for the short-latency auditory evoked potentials (SLAEPs) to short-duration tones presented in notched-noise masking were evaluated in 20 normal-hearing and 20 hearing-impaired subjects. The differences (dB) between these thresholds (dB nHL) and the pure-tone behavioral thresholds (dB HL) across all 40 subjects were 11.6, 6.1, 6.3 and 0.8 dB for 500, 1,000, 2,000 and 4,000 Hz, respectively. These differences were significantly smaller for the hearing-impaired subjects than for the normal-hearing subjects. Ninety-eight percent of the SLAEP threshold estimations were within 30 dB of the subjects' pure-tone behavioral thresholds and 91% were within 20 dB.