Clinical Experience of Using Cortical Auditory Evoked Potentials in the Treatment of Infant Hearing Loss in Australia

Abstract

This article presents the clinical protocol that is currently being used within Australian Hearing for infant hearing aid evaluation using cortical auditory evoked potentials (CAEPs). CAEP testing is performed in the free field at two stimulus levels (65 dB sound pressure level [SPL], followed by 55 or 75 dB SPL) using three brief frequency-distinct speech sounds /m/, /ɡ/, and /t/, within a standard audiological appointment of up to 90 minutes. CAEP results are used to check or guide modifications of hearing aid fittings or to confirm unaided hearing capability. A retrospective review of 83 client files evaluated whether clinical practice aligned with the clinical protocol. It showed that most children could be assessed as part of their initial fitting program when they were identified as a priority for CAEP testing. Aided CAEPs were most commonly assessed within 8 weeks of the fitting. A survey of 32 pediatric audiologists provided information about their perception of cortical testing at Australian Hearing. The results indicated that clinical CAEP testing influenced audiologists' approach to rehabilitation and was well received by parents and that they were satisfied with the technique. Three case studies were selected to illustrate how CAEP testing can be used in a clinical environment. Overall, CAEP testing has been effectively integrated into the infant fitting program.

Keywords: Cortical auditory evoked potential; hearing; hearing aid; infant.

Figures

Figure 1

Clinical pathway for aided CAEP assessment within Australian Hearing pediatric program. Abbreviations: ABR, auditory brainstem response; ANSD, auditory neuropathy spectrum disorder; ASSR, auditory steady-state response; CAEP, cortical auditory evoked potential; PEACH, Parents' Evaluation of Aural/Oral Performance of Children.

Figure 2

Aid adjustment per speech stimulus. Abbreviations: CI, cochlear implant; HA, hearing aid; PEACH, Parents' Evaluation of Aural/Oral Performance of Children; SD, standard deviation; SPL, sound pressure level; TEACH, Teachers' Evaluation of Aural/Oral Performance of Children.

Figure 3

Interval between fitting and first cortical auditory evoked potential assessment.

Figure 4

How often cortical auditory evoked potentials were used in infant fitting programs.

Figure 5

Reasons why cortical auditory evoked potential assessment was not performed in the infant fitting program (n = 28). Abbreviations: DNA, did not attend; OME, otitis media effusion.

Figure 6

Client groups/patients assessed using the HEARLab system, Frye Electronics, Tigard, Oregon.

Figure 7

Case study 1: CI candidacy. Absent responses to speech stimuli /m/, /ɡ/, and /t/ at 65 and 75 dB sound pressure level (SPL) via a loudspeaker when bilaterally aided. Statistical p values for every speech sound are provided (p ≤ 0.05 indicates a high likelihood of a cortical auditory evoked potential being present).

Figure 8

Case study 2: first visit. Present responses to speech stimuli /m/, /ɡ/, and /t/ at 65 dB sound pressure level (SPL) and to the /t/ stimulus at 55 dB SPL via a loudspeaker when bilaterally aided. Statistical p values for every speech sound are provided (p ≤ 0.05 indicates a high likelihood of a cortical auditory evoked potential being present).

Figure 9

Case study 2: Expected audibility for 50 and 65 dB sound pressure level speech as indicated by NAL-NL2 speech-o-gram.

Figure 10

Case study 2: second visit. Present responses to speech stimuli /m/, /ɡ/, and /t/ at 65 dB sound pressure level (SPL) and to the /ɡ/ and /t/ stimuli at 55 dB SPL via a loudspeaker when bilaterally aided. Statistical p values for every speech sound are provided (p ≤ 0.05 indicates a high likelihood of a cortical auditory evoked potential being present).

Figure 11

Case study 3: first visit. Present responses to speech stimuli /m/, /ɡ/, and /t/ at 65 dB sound pressure level (SPL) and to the /ɡ/ and /t/ stimuli at 55 dB SPL via a loudspeaker when bilaterally aided. Statistical p values for every speech sound are provided (p ≤ 0.05 indicates a high likelihood of a cortical auditory evoked potential being present).

Figure 12

Case study 3: second visit. Present response at 55 dB sound pressure level (SPL) when testing /m/ only (p  ≤ 0.05).

Figure 13

Case study 3: Latest audiogram obtained using play audiometry at the age of 2 years and 10 months. It is incomplete as testing had to be discontinued due to child's inattention.