Standard Cochlear Implantation of Adults With Residual Low-Frequency Hearing

Nucleus Hybrid S12: Multicenter Clinical Trial Results

OBJECTIVES/HYPOTHESIS

The use of a short 10-mm/10-electrode cochlear implant to preserve low-frequency residual hearing was investigated. This report describes the 12-month outcomes of this multicenter clinical trial.

STUDY DESIGN

Single-subject design.

METHODS

Twenty-eight subjects with low-frequency hearing at or better than 60 dB HL at 500 Hz and severe high-frequency hearing loss were implanted with a Nucleus Hybrid S12 implant in their poorer ear. Speech perception in quiet using Consonant-Nucleus-Consonant (CNC) words and sentences in noise using AzBio sentences was collected pre- and postoperatively at 3, 6, and 12 months. Subjective reporting using the Speech, Spatial, and Qualities of Hearing Scale (SSQ) questionnaire was also collected pre- and postoperatively.

RESULTS

Functional hearing preservation was accomplished in 96% of subjects. At 3 and 6 months, 86% of the 28 subjects had maintained functional hearing. By 12 months, 23 out of 27 subjects (85%) had maintained functional hearing (one subject with functional hearing at 6 months withdrew from the study prior to the 12-month visit). Speech perception results demonstrated that 81% of the participants on CNC words and 77% with AzBio sentences in noise had significant improvements using their everyday listening condition at 12 months compared to preoperative performance with bilateral hearing aids. Furthermore, preoperative to 12 months postoperative subjective ratings showed significant improvements for the SSQ.

CONCLUSIONS

This study demonstrates that a high degree of hearing preservation enabling acoustic-electric hearing and improvement in speech understanding in quiet and in noise can be accomplished using a short-electrode 10-mm cochlear implant.

LEVEL OF EVIDENCE

2c Laryngoscope, 130:E548-E558, 2020.

Acoustic plus electric speech processing: Long-term results

OBJECTIVE

Few studies have investigated the stability of residual hearing and speech perception outcomes in individuals who were implanted with a shorter electrode device.

STUDY DESIGN

Longitudinal, single-subject design.

METHODS

Fifty subjects who received a Nucleus Hybrid (Cochlear, Sydney, Australia) short electrode cochlear implant (CI) and had a minimum of 2 years (and up to 15 years) of postoperative longitudinal experience were included in this study. Twenty-three subjects received a Nucleus Hybrid S8 (S8); 14 subjects received a Nucleus Hybrid L24 (L24); and 13 received a Nucleus Hybrid S12 (S12). Audiometric thresholds and consonant-nucleus-consonant (CNC) words were collected pre- and postoperatively for up to 15 years for the S8 subjects and for up to 7 years for the S12 and L24 subjects. AzBio Sentences in multi-talker babble was collected for up to 7 years on the S12 and L24 subjects.

RESULTS

Longitudinally, 83% of the S8 subjects, 92% of the S12 subjects, and 86% of the L24 subjects maintained a functional hearing pure-tone average (PTA) (125-500 Hz). Predicted change using a piecewise linear mixed model in PTA over time showed a postoperative linear decrease in hearing for each group until 0.5 years, after which the PTA stabilizes and is maintained. The averaged individual data for CNC and AzBio sentences show a significant improvement in scores by 0.25 to 0.5 years postimplantation, after which scores start to reach their maximum.

CONCLUSION

This long-term study demonstrates that acoustic-electric processing hearing and improvement in speech understanding in quiet and in noise can be accomplished and sustained for many years with a short electrode CI.

LEVEL OF EVIDENCE

2C. Laryngoscope, 128:473-481, 2018.

Outcomes of Adolescents With a Short Electrode Cochlear Implant With Preserved Residual Hearing

OBJECTIVE

The purpose of this study was to determine if adolescents with preserved residual low-frequency hearing can develop improved speech perception and maintain localization abilities by combining their acoustic hearing with electrical processing from a short electrode cochlear implant.

STUDY DESIGN

Repeated-measure, single-subject experiment.

SETTING

Research hospital.

PATIENTS

Adolescents with sensorineural hearing loss with a pure-tone average (PTA) between 60 and 90 dB HL between 125 and 1500 Hz and profound loss at higher frequencies.

INTERVENTION(S)

rehabilitative.

MAIN OUTCOME MEASURE(S)

Five adolescents received a short electrode cochlear implant in their poorer ear. Audiometric, speech perception in quiet (CNC words), localization, speech production, and language outcomes were collected pre- and postoperatively at 4, 8, 12, and 24 months.

RESULTS

Functional hearing preservation was accomplished in all subjects at initial activation and was maintained through 24 months. In the Combined and Hybrid conditions, all subjects showed significant improvements by 4 months postimplantation, with exception of Subject 2 in the Combined condition, who showed a significant improvement by 8 months postimplantation. Results also indicated that all subjects continue to have localization abilities postimplantation.

CONCLUSIONS

All of the subjects have benefitted from the combined electric and acoustic processing for speech perception abilities. The results from this study suggest that it could be worthwhile to consider acoustic and electric hearing in the adolescent population that have some low-frequency residual hearing and are struggling with hearing aids.

Results with cochlear implantation in adults with speech recognition scores exceeding current criteria

OBJECTIVES

The primary purpose of this study was to evaluate a group of postlingually deafened adults, whose aided speech recognition exceeded commonly accepted candidacy criteria for implantation. The study aimed to define performance and qualitative outcomes of cochlear implants in these individuals compared with their optimally fitted hearing aid(s).

STUDY DESIGN

Retrospective case series.

SETTING

Tertiary referral center.

PATIENTS

All postlingually deafened subjects (N = 27), who were unsuccessful hearing aid users implanted between 2000 and 2010 with a preimplantation Hearing in Noise Test (HINT) score of 60% or more were included.

INTERVENTION

We compared patients' preoperative performance (HINT score) with hearing aids to postoperative performance with the cochlear implant after 12 months of device use. In addition, the Hearing Handicap Inventory questionnaire was used to quantify the hearing-related handicap change perceived after the implantation.

RESULTS

The study group demonstrated significant postoperative improvement on all outcome measures; most notably, the mean HINT score improved from 68.4% (standard deviation, 8.3) to 91.9% (standard deviation, 9.7). Additionally, there was a significant improvement in hearing-related handicap perceived by all patients.

CONCLUSION

The envelope of implantation candidacy criteria continues to expand as shown by this study's cohort. Patient satisfaction and speech recognition results are very encouraging in support of treating those who currently perform at a level above the conventional candidacy threshold but struggle with optimally fitted hearing aids.

Suppression of the acoustically evoked auditory-nerve response by electrical stimulation in the cochlea of the guinea pig

There is increasing interest in the use of electro-acoustical stimulation in people with a cochlear implant that have residual low-frequency hearing in the implanted ear. This raises the issue of how electrical and acoustical stimulation interact in the cochlea. We have investigated the effect of electrical stimulation on the acoustically evoked compound action potential (CAP) in normal-hearing guinea pigs. CAPs were evoked by tone bursts, and electric stimuli were delivered at the base of the cochlea using extracochlear electrodes. CAPs could be suppressed by electrical stimulation under various conditions. The dependence of CAP suppression on several parameters was investigated, including frequency and level of the acoustic stimulus, current level of the electric stimulus and the interval between electric and acoustic stimulus (EAI). Most pronounced suppression was observed when CAPs were evoked with high-frequency tones of low level. Suppression increased with current level and at high currents low-frequency evoked CAPs could also be suppressed. Suppression was typically absent several milliseconds after the electric stimulus. Suppression mediated by direct neural responses and hair cell mediated (electrophonic) responses is discussed. We conclude that the high-frequency part of the cochlea can be stimulated electrically with little detrimental effects on CAPs evoked by low-frequency tones.

Combined electro-acoustic stimulation: a beneficial union?

BACKGROUND

The most pressing problem facing cochlear implant research is no longer making artificial hearing a reality. Instead, it is to develop devices that can more clearly reflect the capabilities of the human auditory system. Current cochlear implants rarely provide adequate pitch perception. As hearing loss commonly affects higher, more than lower frequencies, a possible solution is to preserve acoustic hearing at low frequencies by inserting a short electrode array and thus deliver combined electro-acoustic stimulation (EAS).

OBJECTIVE OF REVIEW

To determine whether individuals with severe-to-profound high-frequency hearing loss have realised this predicted benefit of combined EAS, over conventional cochlear implants, with respect to pitch.

TYPE OF REVIEW

A systematic review of publications pertaining to the benefits of combined EAS over conventional cochlear implantation, with specific reference to pitch perception.

SEARCH STRATEGY

A systematic literature search was conducted across multiple databases and supplemented by searching the reference lists of relevant trials and identified reviews.

RESULTS

The included studies suggest an overall benefit of combined EAS, over conventional cochlear implants, with respect to pitch. In addition, (i) 13% sustained a total loss of low-frequency hearing post-implantation of the short electrode array and, (ii) 24% had >20 dB hearing loss across all frequencies and/or total hearing loss.

CONCLUSIONS

For patients with severe-to-profound high-frequency hearing loss combined EAS appears to offer a significant, everyday, long-term benefit. However, further clinical trials with larger numbers of candidates are necessary to confirm this finding. The risks involved cannot be ignored, but there is potential for a variety of strategies to improve the safety margin.