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The effects of stimulus rate on detectability of the auditory brain stem response in infants
A J Klein1, E D Alvarez, C A Cowburn
1Department of Otolaryngology and Communicative Sciences, Medical University of South Carolina, Charleston.
Insights
Fast stimulus rates for auditory brain stem response (ABR) hearing screening are feasible for infants over 42 weeks postconceptional age (PCA). For younger infants, slower rates are necessary to ensure accurate ABR detection and avoid false positives.
Area of Science:
- Audiology
- Neonatal screening
- Neuroscience
Background:
- Auditory brain stem response (ABR) is crucial for infant hearing screening.
- Optimizing ABR testing parameters, like stimulus rate, can improve efficiency and accuracy.
- Determining appropriate stimulus rates for different postconceptional ages (PCA) is essential for reliable screening.
Purpose of the Study:
- To evaluate the feasibility of using a fast stimulus rate (90/sec) for ABR hearing screening in infants.
- To compare ABR detectability at different stimulus rates and intensities in younger infants.
- To establish practical ABR screening protocols for diverse infant populations.
Main Methods:
- Eighty-four infants (30-78 weeks PCA) with clear ABRs at 40/sec were retested at 90/sec.
- ABR detectability was assessed at 40 dB clicks and 70/sec versus 40/sec in 20 infants (33-42 weeks PCA).
Main Results:
- Infants > 42 weeks PCA (92%) had identifiable ABRs at 90/sec.
- Infants between 37-42 weeks PCA (71%) and < 37 weeks PCA (50%) showed reduced ABR identifiability at 90/sec.
- A 70/sec rate with 40 dB clicks showed 85% ABR detectability in infants aged 33-42 weeks PCA.
Conclusions:
- A 90/sec stimulus rate is practical for ABR hearing screening in infants > 42 weeks PCA and children.
- A faster stimulus rate is not practical for infants < 43 weeks PCA.
- Infants failing fast-rate screening require repeat testing at a slower rate to confirm results and prevent false positives.
Abstract:
This study was undertaken to determine the feasibility of using a fast stimulus rate for auditory brain stem response (ABR) hearing screening in infants. Eighty-four neonates and infants with postconceptional ages (PCA) from 30 to 78 weeks with clear ABRs to click rate of 40/sec at 30 dB HL were retested at 90/sec. Ninety-two percent of infants with PCA > 42 weeks had a clearly identifiable ABR at the 90/sec rate. In contrast, 71% of the infants with PCA between 37 and 42 weeks, and only 50% of the infants with PCA < 37 weeks, had clearly identifiable ABRs at 90/sec. Thus, a 90/sec stimulus rate was not practical on infants < 43 weeks PCA. Accordingly, ABR detectability was assessed to 40 dB clicks at 70/sec compared to the 40/sec rate on 20 infants between 33 and 42 weeks PCA. ABRs were detectable on 85% of this group, which suggests that these parameters may be more reasonable, but further data are needed. ABR measures for hearing screening on infants > 42 weeks and children can be satisfactorily performed at stimulus rates up to 90/sec; however, infants who fail the screening when using a fast stimulus rate should have a repeated measurement at a slower rate to rule out a false positive result.