Are auditory steady-state responses a good tool prior to pediatric cochlear implantation?

INTRODUCTION

ASSR allow frequency-specific evaluation in intensities up to 120dB HL and detection of residual hearing in patients with severe-to-profound hearing loss.

AIM: to compare ASSR thresholds and behavioral test results in children with suspected severe-to-profound hearing loss.

METHODS

Cross sectional study to compare ASSR and behavioral responses (VRA or audiometry) in 63 pediatric cochlear implant candidates (126 ears) aged between 6 and 72 months. We included children with normal otomicroscopy, absent responses to click-ABR and otoaccoustic emissions. We excluded children with inner ear malformations, auditory neuropathy spectrum disorder or who did not complete VRA or achieve EEG noise<30nV during the ASSR test. Air-conduction ASSR stimuli were continuous sinusoidal tones presented at 0.5, 1, 2 and 4kHz starting at 110dB HL. Behavioral thresholds were acquired with warble tones presented at 0.5, 1, 2 and 4kHz in each ear through insert or head phones at maximum presentation level of 120dB HL.

RESULTS

Behavioral thresholds were obtained in 36.7% (185/504) of all frequencies in all subjects, 9% in intensities >110dB HL. Among 504 ASSR measurements, 53 thresholds were obtained (10.5%). Overall 89.5% of the tested frequencies did not show any response at 110dB HL. Most responses were at 500Hz. Mean differences between behavioral and ASSR thresholds varied from 0.09 to 8.94dB. Twenty-seven comparisons of behavioral and ASSR thresholds were obtained: 12 at 0.5kHz, 9 at 1kHz, 5 at 2kHz and 1 at 4kHz. Absent responses were observed in both tests in 38.1% at 0.5kHz, 52.4% at 1kHz, 74.6% at 2kHz and 81.0% at 4kHz. Specificity was>90% at 1, 2 and 4kHz. In ears with no behavioral response at 120dB HL all ASSR thresholds were in the profound hearing loss range, 90% of them were ≥110dB HL.

CONCLUSION

Among 63 pediatric CI candidates, absent responses to high-intensity ASSR was the major finding (specificity>90%) predicting behavioral thresholds in the profound hearing loss range. These findings can be helpful to confirm the decision for cochlear implantation.