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Auditory screening in high risk neonates: selection of a test protocol
1Department of Medical Physics and Clinical Engineering, Royal Hallamshire Hospital, Sheffield, UK.
Insights
Evoked oto-acoustic emissions (EOAE) offer a cost-effective initial hearing screen for neonatal intensive care unit graduates. Auditory brain-stem response (ABR) is recommended for follow-up and for smaller patient groups.
Area of Science:
- Neonatal audiology
- Hearing screening technologies
- Clinical audiology protocols
Background:
- Neonatal intensive care unit (NICU) graduates are at higher risk for hearing impairment.
- Early detection of hearing loss is crucial for developmental outcomes.
- Evaluating the efficacy of different audiological tests is essential for optimizing screening programs.
Purpose of the Study:
- To determine the optimal test protocol for screening hearing impairment in NICU graduates.
- To compare the effectiveness and efficiency of evoked oto-acoustic emissions (EOAE) and auditory brain-stem response (ABR) tests.
- To assess the feasibility of bone conduction ABR for differentiating hearing loss types.
Main Methods:
- A study involving 250 infants, graduates of a neonatal intensive care unit.
- Administration of evoked oto-acoustic emissions (EOAE) and air conduction auditory brain-stem response (ABR) to all infants.
- Bone conduction ABR performed on infants who failed the air conduction ABR test.
Main Results:
- Screening failure rates were not dependent on age at testing but were influenced by gestational age if tested before discharge.
- Infant hearing screening coverage was 98% before discharge and 81% for out-patients tested later.
- Bone conduction ABR proved feasible for routine use, differentiating conductive and sensorineural hearing losses.
Conclusions:
- For large cohorts, initial screening with EOAE followed by ABR for failures is the most cost-effective approach.
- For smaller groups, auditory brain-stem response (ABR) alone is recommended.
- Auditory brain-stem response (ABR) is preferred for follow-up due to lower failure rates and threshold measurement capabilities.
Abstract:
As part of a programme evaluating evoked oto-acoustic emissions (EOAE) as a screen for hearing impairment in graduates of a neonatal intensive care unit (NICU), a detailed study has been carried out on 250 infants to determine the best test protocol. EOAE and air conduction auditory brain-stem response (ABR) tests have been carried out on all infants and bone conduction ABR on air conduction ABR failures. Screen failure rates were not dependent on age when tested but were affected by gestational age if the infant was tested before discharge. Coverage was 98% for infants tested before discharge but was 81% for infants tested as out-patients at a mean age of 47 weeks (post-conception). Consideration of different test protocols and the shorter test time for the EOAE test led to the conclusion that, where large numbers are involved, the most cost-effective method is to screen initially by EOAE. Failures would then be re-tested before discharge by ABR. Where numbers are small then ABR alone would be used. Follow up would be by ABR rather than EOAE as this gave a lower failure rate and threshold can be measured. Bone conduction ABR was found to be a feasible test in routine use allowing differentiation between conductive and sensorineural losses.