Speech evoked potentials in cochlear implant recipients with auditory neuropathy spectrum disorder

Abstract

Purpose

Cochlear implantation (CI) is now recognised as the most possible approach to help ANSD patients in improving their capability in hearing and speech communication. Because there are no reliable methods in clinical practice to identify the exact lesion site and mechanisms for a certain ANSD patient, the efficacy of CI is difficult to predict before surgery. This study was done to study speech ABR and CAEP P1 in ANSD subjects fitted with CIs and to compare results of both tests in ANSD versus SNHL subjects fitted with unilateral CIs, then correlate between both tests in both types of hearing loss.

Method

The current study was a case-control study, conducted on a total number of 45 subjects who were classified into three groups (one control and two study groups). The control group comprised 16 subjects with normal peripheral hearing sensitivity (NH group) who were age matched to both study groups. The study group comprised 29 children who underwent cochlear implantation. The study group were subdivided according to preoperative diagnosis of the type of their hearing loss into two groups (a group of children with sensorineural hearing loss; SNHL-CI) and (a group of children with Auditory neuropathy spectrum disorder; ANSD-CI). Both study groups were subjected to detailed history taking, aided warble-tone sound field audiometry, Speech-evoked potentials (P1 & ABR) and Questionnaire.

Results

There were statistically significant differences between the control group and both study subgroups regarding the P1 latencies. While; there were no statistically significant differences between {SNHL-CI group &ANSD-CI}. S-ABR waves were detected in 100% of control group, 75% of SNHL-CI group and 53.8% of ANSD-CI group. Sound-field S-ABR measured in the CI recipients indicated statistically significant delayed latencies than in the NH group. In addition, these results demonstrated that the frequency following response peak amplitude was significantly higher in CI recipients, than in the NH counterparts. Finally, the neural phase locking was significantly higher in CI recipients.

Conclusion

The findings of sound-field S-ABR demonstrated that CI recipients have neural encoding deficits in temporal and spectral domains at the brainstem level; therefore, the sound-field S-ABR can be considered an efficient clinical procedure to assess the speech processing in CI recipients.

Keywords:

• Auditory neuropathy spectrum disorder
• sensorineural hearing loss
• Cochlear implants
• auditory brainstem evoked response

Disclosure statement

No potential conflict of interest was reported by the author(s).