Intraoperative EABR Testing Predicts Strength of Cochlear Implant Stimulation Optimized After Long-Term Use in Pediatric Malformation Ears.

OBJECTIVE: This study focused on the intensities of cochlear implant (CI) stimulation in pediatric CI users with inner ear malformation or cochlear nerve deficiency (CND). In this population, CI programming is difficult because a large intensity of CI stimulation is required to achieve sufficient hearing, but the excess CI stimuli often induce facial nerve stimulation. We aimed to assess whether the results of intraoperative electrically evoked auditory brainstem responses (EABRs) testing predict maximum current levels of CI stimuli (cC levels) optimized by a behavioral-based method after long-term CI use. STUDY DESIGN: A retrospective case review. SETTING: A tertiary referral CI center. PATIENTS: A total of 116 ears with malformations (malformation group) and 63 control ears (control group) from patients younger than 18 years who received CI. The malformation group comprised 23 ears with a common cavity (CC), 26 with incomplete partition type 1 (IP-1), 26 with incomplete partition type 2 (IP-2), and 41 with CND. INTERVENTIONS: Diagnostic. MAIN OUTCOME MEASURES: Correlation between intraoperative EABR results and cC levels determined by the behavioral-based CI programming after long-term CI use. RESULTS: The CC, IP-1, and CND ears required significantly larger cC levels than the IP-2 ears and control groups. However, the cC levels increased to reach the plateau 1 year after surgery in all groups. Among the malformation group, 79 ears underwent intraoperative EABR testing. Greater than 80% of the CC, IP-1, and IP-2 ears and 54.8% of the CND ears exhibited evoked wave V (eV) and were included in the eV-positive category. Myogenic responses but no eV were observed in 18.2, 15.0, and 35.5% of the CC, IP-1, and CND ears, defined as the myogenic category. No eV or myogenic response was elicited in 9.7% of the CND ears. We focused on minimum current levels that elicited eV (eV levels) in the eV-positive category and maximum current levels that did not elicit any myogenic responses (myogenic levels) in the myogenic category. A significant relationship was detected between the eV levels and the cC levels. When analyzed in each malformation type, the eV levels significantly correlate with the cC levels in the CC and CND ears but not in the IP-1 and IP-2 ears, probably because of slight variation within the IP-1 group and the small number of the IP-2 group. The myogenic category did not show a significant relationship between the myogenic levels and cC levels, but the cC levels were similar to or smaller than the myogenic levels in most ears. CONCLUSIONS: This study confirmed that intraoperative EABR testing helps predict the optimal cC levels in malformation ears. EABR-based CI programming immediately after cochlear implantation, followed by behavioral-based CI programming, may allow us to achieve early postoperative optimization of CI maps even in young children with severe malformations.

First Implant-Induced Changes in Rostral Brainstem Impair Second Implant Outcomes in Sequential Bilateral Cochlear Implant Children With Long Inter-Implant Delay.

HYPOTHESIS: Long-term unilateral use of a cochlear implant (CI) induces abnormal maturation of the rostral brainstem innervating the contralateral ear. BACKGROUND: In sequential bilateral CI children with long inter-implant delay, both sides of auditory cortices were dominantly activated by the first CI, but mechanisms of this abnormal development of the auditory system remain unclear. METHODS: Fifteen sequential bilateral CI children with long delay (mean ±â€ŠSD, 28.7 ±â€Š12.1 mo) underwent electrically evoked auditory brainstem response (EABR) testing using each of the first and second CI (CI1 and CI2, respectively), immediately after the second implantation. CI1 and CI2 were implanted at age of 23.7 ±â€Š9.6 and 53.1 ±â€Š12.1 months (mean ±â€ŠSD), respectively. Apical-to-basal difference in electrically evoked interwave III-V latencies (eIII-eV slope) which decreases with implant use was compared between the CI1 and CI2 sides. Their speech perception scores were evaluated 3 years after the second implantation. RESULTS: eIII-eV slopes evoked by the CI2 showed less mature pattern than those by the CI1. This CI2 versus CI1 difference in eIII-eV slopes, however, reduced as the inter-implant delay was prolonged, suggesting CI1-induced maturation of the rostral brainstem innervating the second ear before the second implantation. The smaller CI2 versus CI1 difference in eIII-eV slopes at the second implantation was correlated to poorer outcomes using the CI2 than the CI1. CONCLUSIONS: In this population, long-term unilateral CI use induced re-organization of the rostral brainstem innervating the second ear, which affected hearing outcomes using the CI2. Evaluation of eIII-eV slopes at the second implantation may be useful to predict hearing outcomes with CI2.

Audio-visual speech perception in prelingually deafened Japanese children following sequential bilateral cochlear implantation.

OBJECTIVES: An effect of audio-visual (AV) integration is observed when the auditory and visual stimuli are incongruent (the McGurk effect). In general, AV integration is helpful especially in subjects wearing hearing aids or cochlear implants (CIs). However, the influence of AV integration on spoken word recognition in individuals with bilateral CIs (Bi-CIs) has not been fully investigated so far. In this study, we investigated AV integration in children with Bi-CIs. METHODS: The study sample included thirty one prelingually deafened children who underwent sequential bilateral cochlear implantation. We assessed their responses to congruent and incongruent AV stimuli with three CI-listening modes: only the 1st CI, only the 2nd CI, and Bi-CIs. The responses were assessed in the whole group as well as in two sub-groups: a proficient group (syllable intelligibility ≥80% with the 1st CI) and a non-proficient group (syllable intelligibility < 80% with the 1st CI). RESULTS: We found evidence of the McGurk effect in each of the three CI-listening modes. AV integration responses were observed in a subset of incongruent AV stimuli, and the patterns observed with the 1st CI and with Bi-CIs were similar. In the proficient group, the responses with the 2nd CI were not significantly different from those with the 1st CI whereas in the non-proficient group the responses with the 2nd CI were driven by visual stimuli more than those with the 1st CI. CONCLUSION: Our results suggested that prelingually deafened Japanese children who underwent sequential bilateral cochlear implantation exhibit AV integration abilities, both in monaural listening as well as in binaural listening. We also observed a higher influence of visual stimuli on speech perception with the 2nd CI in the non-proficient group, suggesting that Bi-CIs listeners with poorer speech recognition rely on visual information more compared to the proficient subjects to compensate for poorer auditory input. Nevertheless, poorer quality auditory input with the 2nd CI did not interfere with AV integration with binaural listening (with Bi-CIs). Overall, the findings of this study might be used to inform future research to identify the best strategies for speech training using AV integration effectively in prelingually deafened children.

Audio-visual integration during speech perception in prelingually deafened Japanese children revealed by the McGurk effect.

OBJECTIVE: To investigate the McGurk effect in profoundly deafened Japanese children with cochlear implants (CI) and in normal-hearing children. This was done to identify how children with profound deafness using CI established audiovisual integration during the speech acquisition period. METHODS: Twenty-four prelingually deafened children with CI and 12 age-matched normal-hearing children participated in this study. Responses to audiovisual stimuli were compared between deafened and normal-hearing controls. Additionally, responses of the children with CI younger than 6 years of age were compared with those of the children with CI at least 6 years of age at the time of the test. RESULTS: Responses to stimuli combining auditory labials and visual non-labials were significantly different between deafened children with CI and normal-hearing controls (p<0.05). Additionally, the McGurk effect tended to be more induced in deafened children older than 6 years of age than in their younger counterparts. CONCLUSIONS: The McGurk effect was more significantly induced in prelingually deafened Japanese children with CI than in normal-hearing, age-matched Japanese children. Despite having good speech-perception skills and auditory input through their CI, from early childhood, deafened children may use more visual information in speech perception than normal-hearing children. As children using CI need to communicate based on insufficient speech signals coded by CI, additional activities of higher-order brain function may be necessary to compensate for the incomplete auditory input. This study provided information on the influence of deafness on the development of audiovisual integration related to speech, which could contribute to our further understanding of the strategies used in spoken language communication by prelingually deafened children.

Bilateral duplication of the internal auditory canal: a case with successful cochlear implantation.

We report a case of bilateral duplication of the internal auditory canal (IAC). An 11-month-old girl with congenital profound hearing loss was referred to our hospital. Imaging evaluations revealed bilateral IAC duplication, which contained the facial and cochleovestibular nerves in one canal, but no nerves in the other. She underwent cochlear implantation. At 5 months after surgery her hearing thresholds with the cochlear implant are 40 and 45dB at 2000 and 4000Hz, respectively. Bilateral duplicated IAC is extremely rare, with seven cases reported in the literature. This case represents a previously unreported type of IAC duplication, and is the first case in which cochlear implantation was successfully performed.

SLC26A4 p.Thr410Met homozygous mutation in a patient with a cystic cochlea and an enlarged vestibular aqueduct showing characteristic features of incomplete partition type I and II.

Mutations of SLC26A4 are associated with incomplete partition type II (IP-II) and isolated enlargement of the vestibular aqueduct (EVA). We experienced a congenitally deaf 6-year-old boy with a rare p.Thr410Met homozygous mutation in SLC26A4 who underwent bilateral cochlear implantation. He had bilateral inner ear malformation, in which the dilated vestibule and EVA were identical to those in IP-II, but the cochlea lacking a bony modiolus resembled that in incomplete partition type I. These results suggest that homozygous mutations in SLC26A4 are always associated with EVA, while the severity of cochlear malformation may vary depending on the type of SLC26A4 mutation.

Electrically evoked auditory brainstem response-based evaluation of the spatial distribution of auditory neuronal tissue in common cavity deformities.

OBJECTIVE: In a common cavity (CC) deformity, the cochlea and vestibule are confluent to form a single cavity without internal architecture, and distribution of auditory neuronal tissue is unclear. The purposes of this study are to reveal the spatial distribution of auditory neuronal tissue in CC deformity using electrically evoked auditory brainstem response (EABR) during cochlear implantation. STUDY DESIGN: Retrospective case review. SETTING: Cochlear implant (CI) center at a tertiary referral hospital. PATIENTS: Five patients with CC deformity who underwent cochlear implantation and intraoperative EABR testing. MAIN OUTCOME MEASURES: Spatial distribution of electrodes that elicited an evoked wave V (eV) in EABR testing was evaluated in each CC deformity. RESULTS: Electrically evoked auditory brainstem response testing demonstrated that electrodes attached on the inner wall of the anteroinferior cavity of the CC deformity successfully elicited a reproducible eV in all cases, and the latency of each eV was an approximately 4 ms, which is similar to those reported in patients without an inner ear malformation. Interestingly, in Case 1 with the lowest percentage of eV-positive electrodes (31.8%), CI-aided audiometric thresholds were changed, depending on the frequency allocation to eV-positive electrodes in the programming. Cochlear implant-mediated facial nerve stimulation was observed in 3 of 5 cases, and results of EABR testing were useful for optimizing the device program to decrease facial nerve stimulation without sacrificing CI-mediated auditory performance. CONCLUSION: The results of EABR testing suggested that auditory neuronal elements are distributed to the anteroinferior part of CC deformity, mainly around or near the inner wall of the cavity. In cases with CC deformity, EABR testing is useful to achieve the optimal electrode array placement and to adjust programming parameters of the implanted device, which might be essential to maximize CI outcomes and to decrease facial nerve stimulation.

Cochlear implantation in children with congenital cytomegalovirus infection accompanied by psycho-neurological disorders.

CONCLUSION: Cochlear implantation was effective for deaf children with congenital cytomegalovirus (CMV) infection, but their cochlear implant (CI) outcomes were often impaired, depending on the types of CMV-associated psycho-neurological disorders. Evaluation of cognitive development and autistic tendency of implantees might be useful to predict their CI outcomes. OBJECTIVES: To reveal the influence of CMV-associated psycho-neurological disorders on CI outcomes. METHODS: This was a retrospective evaluation of 11 implantees with congenital CMV infection (CMV-CIs) and 14 implantees with autosomal recessive hearing loss (genetic-CIs). RESULTS: Nine of 11 CMV-CIs suffered from psycho-neurological disorders; one from attention deficit hyperactivity disorder, two from pervasive developmental disorder, and six from mental retardation. Aided hearing thresholds with CIs in the two groups did not differ, but two autistic and two mentally retarded CMV-CIs showed significantly low scores in speech discrimination tests. Language-Social (L-S) developmental quotients (DQs) evaluated by the Kyoto Scale of Psychological development were improved after the implantation in both groups, but the postoperative increase of L-S DQs was significantly smaller in the CMV-CIs than that of genetic-CIs. Interestingly, the postoperative L-S and Cognitive-Adaptive (C-A) DQs showed statistically significant correlation in all cases except for two autistic CMV-CIs whose L-S DQs were much lower than those expected from their C-A DQs.