In favorable listening conditions, cochlear-implant (CI) users can reach high speech recognition scores with as little as seven active electrodes. Here, we hypothesized that even when speech recognition is high, additional spectral channels may still benefit other aspects of speech perception, such as comprehension and listening effort. Twenty-five adult, postlingually deafened CI users, selected from two Dutch implant centers for high clinical word identification scores, participated in two experiments. Experimental conditions were created by varying the number of active electrodes of the CIs between 7 and 15. In Experiment 1, response times (RTs) on the secondary task in a dual-task paradigm were used as an indirect measure of listening effort, and in Experiment 2, sentence verification task (SVT) accuracy and RTs were used to measure speech comprehension and listening effort, respectively. Speech recognition was near ceiling for all conditions tested, as intended by the design. However, the dual-task paradigm failed to show the hypothesized decrease in RTs with increasing spectral channels. The SVT did show a systematic improvement in both speech comprehension and response speed across all conditions. In conclusion, the SVT revealed additional benefits in both speech comprehension and listening effort for conditions in which high speech recognition was already achieved. Hence, adding spectral channels may provide benefits for CI listeners that may not be reflected by traditional speech tests. The SVT is a relatively simple task that is easy to implement and may therefore be a good candidate for identifying such additional benefits in research or clinical settings.

Objective To assess the effect of sequential bilateral cochlear implantation on auditory, cortical maturation after various periods of unilateral cochlear implant use. Study Design Prospective cohort study. Setting Tertiary academic referral center. Patients Thirty prelingually deaf children, who received their first implant at a mean age of 1.8 years and their second implant at a mean age of 5.3 years. Intervention Sequential bilateral cochlear implantation. Main Outcomes Measure The electrically evoked auditory cortical response (EACR) was evoked by the 2 implants separately after 12 and 24 months of bilateral cochlear implant use. P1 and N2 latencies and RMS amplitudes were compared between both implant sides and were compared with those of a group of 27 age-matched children with normal hearing. Results EACR latencies diminished over time for both implant sides. RMS amplitudes and P1 latencies elicited by the second implant were still significantly different from that of the first implant after 24 month. After 24 months, the difference in N2 latencies between both implant sides was no longer significant, although still apparent. Interimplant delay had an adverse effect on RMS amplitudes and waveform morphology. EACR latencies were age appropriate, although RMS amplitudes evoked by the second implant were smaller than those of the children with normal hearing. Conclusion Auditory cortical maturation is possible after extended unilateral cochlear implant use, although responses evoked by the second implant still lack behind that of the experienced first implant. It is not clear if the auditory cortical response will become similar on both implant sides over time, especially for the children with longer interimplant delays.

Pathogenic missense variants in COCH are associated with DFNA9, an autosomal dominantly inherited type of progressive sensorineural hearing loss with or without vestibular dysfunction. This study is a comprehensive overview of genotype-phenotype correlations using the PRISMA and HuGENet guidelines. Study characteristics, risk of bias, genotyping and data on the self-reported age of onset, symptoms of vestibular dysfunction, normative test results for vestibular function, and results of audiovestibular examinations were extracted for each underlying pathogenic COCH variant. The literature search yielded 48 studies describing the audiovestibular phenotypes of 27 DFNA9-associated variants in COCH. Subsequently, meta-analysis of audiometric data was performed by constructing age-related typical audiograms and by performing non-linear regression analyses on the age of onset and progression of hearing loss. Significant differences were found between the calculated ages of onset and progression of the audiovestibular phenotypes of subjects with pathogenic variants affecting either the LCCL domain of cochlin or the vWFA2 and Ivd1 domains. We conclude that the audiovestibular phenotypes associated with DFNA9 are highly variable. Variants affecting the LCCL domain of cochlin generally lead to more progression of hearing loss when compared to variants affecting the other domains. This review serves as a reference for prospective natural history studies in anticipation of mutation-specific therapeutic interventions.

To assess the effect of cochlear implantation on the function of the semicircular canals (SCC) and on experienced vestibular symptoms. Second, to determine the relation between vestibular test resu...

This study determined electrocochleography (ECochG) parameter settings to obtain cochlear microphonics (CM) with less invasive flexible extra-tympanic membrane electrodes. In 24 adult normal-hearing subjects, CMs were elicited by presenting click stimuli at 100 dBnHL, tone bursts (2 kHz) and broadband (BB) CE-chirps^® LS (Interacoustics, Middelfart, Denmark), both at 80 dBnHL. Different high-pass filters (HPFs) (3.3 Hz and 100 Hz, respectively) were used to investigate response quality of the CM. CMs were successfully obtained in 92–100% with click-, 75–83% with 2 kHz tone burst- and 58–63% with CE-chirp^®-LS stimuli. Click stimuli elicited significantly larger CM amplitudes compared to 2 kHz tone bursts and BB CE-chirp^® LS (Interacoustics, Middelfart, Denmark). No significant differences were found between the two different high-pass filter (HPF) settings. The present study shows that it is possible to obtain clear CMs with the flexible extra-tympanic membrane electrodes using click stimuli. In contrast to 2 kHz tone bursts and CE-chirp^® (Interacoustics, Middelfart, Denmark) LS, clicks show a significantly higher success rate and are the preferred stimuli to confirm the presence or absence of CMs.

Some pathogenic variants in mtDNA and nuclear DNA, affecting mitochondrial function, are associated with hearing loss. Behavioral and electrophysiological auditory performance are obtained from 62 patients, clinically diagnosed with different mitochondrial diseases (MD) using tone/speech audiometry and Auditory Brainstem Responses (ABR). Audiological variables (hearing loss type, pure tone average (PTA), interaural asymmetry, speech perception and brainstem neural conductivity) were analyzed and related to Newcastle Mitochondrial Disease Scale for Adults (NMDAS). In 35% of MDs, a mild to severe symmetrical sensorineural hearing loss (SNHL) was found. Patients with Maternally Inherited Diabetes and Deafness (MIDD) show significantly higher PTAs compared to other MDs. For all MDs, speech recognition scores were in accordance with their individual age- and gender-corrected tone audiometry, but ABR peak latencies were prolonged in patients with MIDD, Mitochondrial Encephalopathy Lactate acidosis and Stroke-like episodes (MELAS), Chronic Progressive External Ophthalmoplegia (CPEO) and Subacute necrotizing encephalopathy (Leigh). Correlations between NMDAS and audiological variables were low.