Evaluation of residual hearing in cochlear implants candidates using auditory steady-state response

Effects of Residual Hearing on the Auditory Steady State Response for Cochlear Implantation in Children

Background and Objectives

We aim to explore the effects of residual auditory steady state response (ASSR) on cochlear implantation (CI) outcomes in children lacking auditory brainstem responses (ABRs).

Subjects and Methods

We retrospectively reviewed the data of child CI recipients lacking ABRs. All ears were divided into two groups: with residual ASSR and without ASSR. For each frequency, the T- and C-levels and the electrical dynamic ranges of postoperative 3-month and 1-year mappings were compared between the groups. To evaluate speech perception, patients who received simultaneous bilateral CIs were divided into two groups: group 1 exhibited responses at all frequencies in both ears; in group 2, at least one ear evidenced no response. The Categories of Auditory Perception (CAP) and Infant-Toddler Meaningful Auditory Integration Scale (IT-MAIS) scores were compared between the groups.

Results

We enrolled 16 patients. At 2 kHz, the postoperative 3-month and 1-year T-levels of patients with residual hearing were lower than those of hearing loss group (p=0.001, p=0.035). In residual hearing group, the ASSR threshold correlated positively with the postoperative 1-year T-level (p=0.012, R² =0.276) and C-level (p=0.002, R² =0.374). Of 10 simultaneous bilateral CI recipients, 5 exhibited ASSRs at all frequencies and the other 5 showed no response at ≥1 frequency. The latter had higher CAP scores at the postoperative 1-year (p=0.018).

Conclusions

In children exhibiting hearing loss in ABR testing, residual hearing at 2 kHz ASSR correlated positively with the post-CI T-level. Those with ASSRs at all frequencies had significantly lower CAP scores at the postoperative 1year. CI should not be delayed when marginal residual hearing is evident in ASSR.

Are Auditory Steady-State Responses Useful to Evaluate Severe-to-Profound Hearing Loss in Children?

Objective. To evaluate Auditory Steady-State Responses (ASSR) at high intensities in pediatric cochlear implant candidates and to compare the results to behavioral tests responses. Methods. This prospective study evaluated 42 children with suspected severe-to-profound hearing loss, aged from 3 to 72 months. All had absent ABR and OAE responses. ASSR were evoked using binaural single frequency stimuli at 110 dB HL with a 10 dB down-seeking procedure. ASSR and behavioral test results were compared. Results. Forty-two subjects completed both ASSR and behavioral evaluation. Eleven children (26.2%) had bilateral responses. Four (9.5%) showed unilateral responses in at least two frequencies, all confirmed by behavioral results. Overall 61 ASSR responses were obtained, most (37.7%) in 500 Hz. Mean thresholds were between 101.3 and 104.2 dB HL. Among 27 subjects with absent ASSR, fifteen had no behavioral responses. Seven subjects showed behavioral responses with absent ASSR responses. No spurious ASSR responses were observed at 100 or 110 dB HL. Conclusion. ASSR is a valuable tool to detect residual hearing. No false-positive ASSR results were observed among 42 children, but in seven cases with absent ASSR, the test underestimated residual hearing as compared to the behavioral responses.

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.