Relationships between bilateral auditory brainstem activity and inter-implant interval in children with cochlear implants.

PURPOSE: To investigate the effect of the interval between bilateral cochlear implantation on the development of bilateral peripheral auditory pathways as revealed by the electrically evoked auditory brainstem response (EABR). METHODS: Fifty-eight children with profound bilateral sensorineural hearing loss were recruited. Among them, 33 children received sequential bilateral cochlear implants (CIs), and 25 children received simultaneous bilateral CIs. The bilateral EABRs evoked by electrical stimulation from the CI electrode were recorded on the day of second-side CI activation. RESULTS: The latencies of wave III (eIII) and wave V (eV) were significantly shorter on the first CI side than on the second CI side in children with sequential bilateral CIs but were similar between the two sides in children with simultaneous bilateral CIs. Furthermore, the latencies were prolonged from apical to basal channels along the cochlea in the two groups. In children with sequential CIs, the inter-implant interval was negatively correlated with the eV latency on the first CI side and was positively correlated with bilateral differences in the eIII and eV latencies. CONCLUSIONS: Unilateral CI use promotes the maturation of ipsilateral auditory conduction function. However, a longer inter-implant interval results in more unbalanced development of bilateral auditory brainstem pathways. Bilateral cochlear implantation with no or a short interval is recommended.

The relationship of inter-implant time and hearing outcomes for bilateral cochlear implants.

PURPOSE: Determine the relationship between time elapsed between sequential bilateral cochlear implantation (BiCI) and speech intelligibility scores in post-lingually deafened adults. MATERIALS AND METHODS: Retrospective review of post-lingually deafened adults who received bilateral cochlear implants from January 1, 2011 to January 1, 2018 at an ambulatory tertiary referral center. RESULTS: 113 patients (226 cochlear implants) were initially reviewed, with 56 patients (112 implants) being included in the final analysis. Median inter-implant interval was 187.5 days (IQ range 54.25-346.5). Maximum interval was 1787 days. Mean age at first implant was 60.66 ± 13.37. Bilateral AzBio score in quiet and inter-implant interval showed no significant correlation (r = 0.034, p = 0.815). There was no significant difference in mean bilateral AzBio scores in quiet between the simultaneous and sequential implantation groups (p = 0.22). Similar non-significant results were seen when examining the correlation between AzBio Difference and inter-implant interval (r = -0.07, p = 0.66). No significant result between mean AzBio Difference of simultaneous and sequential implant recipients was found (p = 0.06). CONCLUSIONS: For the inter-implant intervals examined, there seems to be no significant decline in speech intelligibility scores for patients receiving sequential bilateral cochlear implants compared to simultaneously implanted patients. There was no significant correlation noted between increasing inter-implant intervals and speech intelligibility scores.

Critical Factors for Binaural Hearing in Children with Bilateral Sequential Cochlear Implantation: First Implant Performance and Inter-Implant Interval.

OBJECTIVES: This study evaluated the influence of the performance of the first cochlear implant (CI-1) on the second implant (CI-2) and the significance of inter-implant intervals in children with sequential cochlear implantation. METHOD: Thirty-four patients were included for speech perception outcome and 38 patients were included for subjective hearing satisfaction in daily life in this study. The patients were classified into 3 groups according to inter-implant interval: group I, <4 years; group II, 4-7 years; group III, >7 years. Open-set speech perception scores before and at 3, 6, 12, and 24 months after the second implantation was compared among the CI-1, CI-2, and bilateral CI conditions. Subjective hearing benefits in daily life were measured using a questionnaire of Speech, Spatial, and Qualities of Hearing Scale (SSQ) for parents of children with impaired hearing, and device use and preference were evaluated (by phone interview.) Results: The speech perception of children using the CI-2 only improved quickly within 3 months postoperatively and were similar to those using the CI-1 only. The results of monosyllabic and disyllabic word tests using CI-2 at 3 months after second implantation were not significantly different from those in patients using the CI-1 only. In the sentence test, the scores using the CI-2 only were not significantly different from those using the first implant only at 6 months after second implantation. SSQ scores were similar among groups and the worst score in each section was shown from the questions about performance under noisy conditions in each section. Device usage habits showed that 17 (44.7%) and 16 (42.1%) patients preferred bilateral and the CI-1, respectively. Only 5 (13.2%) patients wanted the CI-2 rather than the CI-1. While group I and II showed a prominent positive attitude to bilateral use, group III, for which the inter-implant interval was 7 years or more, showed a definite preference for the CI-1 (p < 0.01). CONCLUSIONS: Functional binaural benefits were achieved in patients who were good performers with the CI-1 after the second implantation irrespective of the inter-implant interval. Sequential CI should be strongly recommended for patients with unilateral CI showing a good performance.

Sequential bilateral cochlear implants in children and adolescents: Outcomes and prognostic factors.

OBJECTIVES: Cochlear implants (CI) have enabled an increasing proportion of deaf children to develop oral communication. Despite the well-known benefits of bilateral implantation, many of these children and teenagers have only a unilateral implant. The aim of this study was to evaluate the benefits of sequential bilateral CI and the influence of relevant factors on outcome. MATERIAL AND METHODS: A single-center retrospective study included 109 children and adolescents who received a second sequential CI between 2008 and 2016. Subjects were evaluated before sequential implantation and subsequently at 3, 12 and 24 months, on Speech Intelligibility Rating and speech perception tests: Categories of Auditory Performance, word and sentence recognition in silence and in noise. The influence of inter-implant interval and performance with the first CI were analyzed. RESULTS: In the majority of patients, sequential CI provided significant improvement in speech and intelligibility perception. These benefits were seen not only for short but also for long inter-implant intervals. Some subjects with poor performance with their first implant showed significant progression after sequential bilateral implantation. CONCLUSION: In view of the benefits of sequential bilateral CI, we suggest that a second CI should be proposed to all unilaterally implanted children and adolescents, regardless of inter-implant interval and initial performance with the first CI. Further studies need to be conducted to identify prognostic factors for success in sequential contralateral implantation.

The Optimal inter-implant interval in pediatric sequential bilateral implantation.

An increasing number of children receive bilateral cochlear implants (CIs) sequentially. Outcomes of bilateral implantation show high variability. This retrospective analysis investigates the optimal inter-implant interval. For this purpose, speech comprehension results of 250 children who underwent sequential bilateral cochlear implantation were evaluated. All individuals underwent periodic speech perception testing in quiet and noise. The most recent unilateral data for each side were statistically analyzed. Speech test outcomes were evaluated with reference to age at first implantation and interval between implantations. A statistically significant difference for speech test performance was obtained between the first-implanted ear and the second-implanted ear for all children (expressed as a mean). These outcomes were dependent on the inter-implant interval. There was a significant correlation (r = - 0.497; p = 0.000) between speech test results and the inter-implant interval. Nevertheless, one subgroup of 27 children had the same or better results for the second side as compared with the first. In conclusion, the evaluation of the inter-implant interval and age groups at first implantation showed a preferred interval of up to four years in children under the age of 4 at first implantation. The older the children were at first implantation, the shorter the inter-implant interval had to be. It is as a direct consequence of this interval that children for whom it was longer were also older.

Sequential pediatric bilateral cochlear implantation: The effect of time interval between implants.

OBJECTIVE: To examine speech intelligibility in children subjected to sequential bilateral cochlear implants (CI) surgery and to assess the influence of the inter-stage interval duration. INTRODUCTION: Binaural hearing recovery can have additional benefits, especially in speech and language development in patients with congenital profound sensorineural hearing loss; so recently there has been an increase in the number of children receiving bilateral CI. METHODS: Twenty-seven children who underwent sequential bilateral cochlear implant (SBCI) with a short (1-3 yrs), medium (4-6 yrs) and long (7-12 yrs) range interval between both implantations, respectively, were evaluated. All patients underwent periodic speech perception test in quiet and noise after second implant activation in three conditions: with the first or second implant alone and with both implants. Results were examined according to the inter-stage interval. RESULTS: Speech intelligibility in noise was significantly better under bilateral conditions than either ear alone, in all three groups. Small improvements were seen in quiet, especially in the third group (6-12 yrs). CONCLUSION: Benefits of second implant in the early-implanted children and after a short inter-implant delay are more evident. However our study support that, even after a long period of deafness and despite a prolonged inter-stage interval, sequential bilateral cochlear implantation should be considered. LEVEL OF EVIDENCE: Level 4.

Speech recognition in bilaterally cochlear implanted adults in Tokyo, Japan.

INTRODUCTION: The clinical effects of bilateral cochlear implantation (BCI) include binaural summation and better hearing under noise conditions. This study retrospectively examined the utility of BCI compared to unilateral cochlear implantation (CI) in adults. PATIENTS AND METHODS: We investigated 34 adults who underwent BCI, comparing speech recognition between BCI and first CI under silent and noise conditions. We assessed correlations between speech recognition after first and second CIs, and between the interval from first to second CI surgery and speech recognition of second CI. RESULTS: Word recognition score (WRS) and sentence recognition score (SRS) were significantly better after BCI than after first CI under conditions of silence and noise. No significant correlation was found between speech recognition after first CI and that after second CI, or between inter-implant interval and speech recognition of second CI for either WRS or SRS. CONCLUSIONS: The utility of BCI in Japanese patients was shown. Patients have no need to be pessimistic about hearing after the second implantation even if speech recognition after the first implantation is poor. A long interval from first CI does not necessarily contraindicate contralateral implantation in adults.

Bilateral cochlear implantation in children and the impact of the inter-implant interval.

OBJECTIVES/HYPOTHESIS: To determine the effectiveness of simultaneous versus sequential bilateral cochlear implantation on postoperative outcomes in children with bilateral deafness and to evaluate the impact of the inter-implant interval and age at second implantation on postoperative outcomes in children who already received their first cochlear implant. DATA SOURCES: PubMed, Embase, and Web of Science. REVIEW METHODS: All studies comparing the effects of simultaneous with sequential bilateral cochlear implantation on postoperative outcomes and those evaluating the impact of the inter-implant interval and age at second implantation were retrieved. RESULTS: Four studies compared the effects of simultaneous with sequential bilateral cochlear implantation. All studies lacked randomization. Of these, three reported better speech perception and expressive language development at one year of bilateral experience for simultaneous cochlear implantation. Of the nineteen publications on the impact of the inter-implant interval on postoperative outcomes, the risk of bias was low-moderate for seven studies which were derived from five different study populations. In two of these populations no impact of the inter-implant interval was found, while in three a longer inter-implant interval was associated with poorer speech and language development. CONCLUSION: Observational studies suggest that simultaneous implantation in children may be associated with improved speech and language development, and that a prolonged inter-implant interval between both implantations may have a negative impact on these postoperative outcomes. Randomized trials are, however, needed to demonstrate whether simultaneous implantation indeed is superior to sequential bilateral implantation in children with bilateral deafness. LEVEL OF EVIDENCE: NA.