Aim: Evidence suggests that cochlear implants are beneficial for language development, but there is no consensus about the ideal age for surgery. We investigated how language development and surgical safety were affected by patients’ ages.Methods: This study comprised 103 children (52 boys) aged 4.3‐16 years who received cochlear implants at 5‐29 months at the Karolinska University Hospital, Stockholm, Sweden, between 2002 and 2013. All showed typical development and were from monolingual homes. Bilateral implants were common (95%). The children were regularly assessed on language understanding, vocabulary and speech recognition by a multi‐disciplinary team for 10.0 ± 3.7 (4.7‐16.0) years.Results: There were no associations between complications after surgery and the age when children had their first implant. Children implanted at 5‐11 months reached an age‐equivalent level of language understanding and better vocabulary outcome sooner than subgroups implanted later. Children who had surgery at 12‐29 months demonstrated more atypical and delayed language abilities over time. Early implantation, preferably before 9 months, may lead to a more typical trajectory of spoken language development.Conclusion: Our findings showed that cochlear implantation before 9 months was safe. Early implantation may reduce the negative effects of auditory deprivation and promotes more natural and synchronised language development.

Objective: To compare bilateral and unilateral speech recognition in quiet and in multi-source noise, and horizontal sound localization of low and high frequency sounds in children with bilateral cochlear implants. Design: Bilateral performance was compared to performance of the implanted side with the best monaural speech recognition in quiet result. Parental reports were collected in a questionnaire. Results from the CI children were compared to binaural and monaural performance of normal-hearing peers. Study sample: Sixty-four children aged 5.1–11.9 years who were daily users of bilateral cochlear implants. Thirty normal-hearing children aged 4.8–9.0 years were recruited as controls. Results and Conclusions: Group data showed a statistically significant bilateral speech recognition and sound localization benefit, both behaviorally and in parental reports. The bilateral speech recognition benefit was smaller in quiet than in noise. The majority of subjects localized high and low frequency sounds significantly better than chance using bilateral implants, while localization accuracy was close to chance using unilateral implants. Binaural normal-hearing performance was better than bilateral performance in implanted children across tests, while bilaterally implanted children showed better localization than normal-hearing children under acute monaural conditions.

To study the development of the bilateral benefit in children using bilateral cochlear implants by measurements of speech recognition and sound localization. Bilateral and unilateral speech recognition in quiet, in multi-source noise, and horizontal sound localization was measured at three occasions during a two-year period, without controlling for age or implant experience. Longitudinal and cross-sectional analyses were performed. Results were compared to cross-sectional data from children with normal hearing. Seventy-eight children aged 5.1-11.9 years, with a mean bilateral cochlear implant experience of 3.3 years and a mean age of 7.8 years, at inclusion in the study. Thirty children with normal hearing aged 4.8-9.0 years provided normative data. For children with cochlear implants, bilateral and unilateral speech recognition in quiet was comparable whereas a bilateral benefit for speech recognition in noise and sound localization was found at all three test occasions. Absolute performance was lower than in children with normal hearing. Early bilateral implantation facilitated sound localization. A bilateral benefit for speech recognition in noise and sound localization continues to exist over time for children with bilateral cochlear implants, but no relative improvement is found after three years of bilateral cochlear implant experience.

Objective: To evaluate if cochlear implantation is safe and constitutes an option for hearing rehabilitation of children with x-linked inner ear malformation. Study Design: Retrospective patient review in combination with a multidisciplinary follow-up. Setting: Tertiary referral hospital and cochlear implant program. Patients: Ten children with severe-profound mixed hearing loss and radiological findings consistent with Incomplete Partition type 3 cochlear malformation received cochlear implants during the years 2007 to 2015. Nine of the children had a mutation affecting the gene POU3F4 on Xq21. Intervention: Cochlear implantation. Main Outcome Measures: Surgical events, intraoperative measures and electrical stimulation levels, hearing and spoken language abilities. Results: In all, 15 cochlear implantations were performed. In three cases the electrode was found to be in the internal auditory canal on intraoperative x-ray and repositioned successfully. One child had a postoperative rhinorrhea confirmed to be cerebrospinal fluid but this resolved on conservative treatment. No severe complications occurred. Postoperative electrical stimulation levels were higher in 9 of 10 children, as compared with typically reported average levels in patients with a normal cochlea. Eight patients developed spoken language to various degrees while two were still at precommunication level. However, speech recognition scores were lower than average pediatric cases. Conclusion: Cochlear implantation is a safe procedure for children with severe-profound mixed hearing loss related to POU3F4 mutation inner ear malformation. The children develop hearing and spoken language but outcome is below average for pediatric CI recipients.

To study sound localization performance in relation to auditory experience and age at implantation in children with bilateral cochlear implants. Clinical study. University hospital. Sixty-two sequentially and 4 simultaneously bilaterally implanted children participated in this clinical sound localization study, at a median age of 5.6 years. They underwent sequential implantations at median ages of 1.9 and 4.2 years, respectively. Simultaneous implantations were performed at a median age of 2.0 years. Localization performance was measured with pink noise presented in random order from 5 loudspeakers in the frontal horizontal plane. Twenty-one subjects participated in repeated testing. Sound localization performance as quantified with an Error Index. On group level, bilaterally implanted children pinpointed the sounding loudspeaker in the frontal horizontal plane. Sound localization performance improved significantly with increasing bilateral cochlear implant experience, as observed in the entire study group and intraindividually, albeit large interindividual variability existed. Regression analyses in the entire study group and in the sequentially implanted children did not reveal any relationship between sound localization performance and ages at first and second implantation, interimplant interval, or age. However, second implantation before 4 years of age contributed to faster sound localization improvement with increasing bilateral cochlear implant experience. Median perceived azimuths coincided with presented azimuths. We suggest that listening experience after bilateral cochlear implantation affects sound localization performance, possibly owing to the ongoing stimulus-driven maturation of the central auditory system. The amount of time listening with bilateral implants has methodologic implications on sound localization assessment in bilaterally implanted children.

Unilateral hearing loss (UHL) occurs in 25% of cases of congenital sensorineural hearing loss. Due to the unilaterally reduced audibility associated with UHL, everyday demanding listening situations may be disrupted despite normal hearing in one ear. The aim of this study was to quantify acute changes in recognition of speech in spatially separate competing speech and sound localization accuracy, and relate those changes to two levels of temporary induced UHL (UHL30 and UHL43; suffixes denote the average hearing threshold across 0.5, 1, 2, and 4 kHz) for 8 normal-hearing adults. A within-subject repeated-measures design was used (normal binaural conditions, UHL30 and UHL43). The main outcome measures were the threshold for 40% correct speech recognition and the overall variance in sound localization accuracy quantified by an Error Index (0 = perfect performance, 1.0 = random performance). Distinct and statistically significant deterioration in speech recognition (2.0 dB increase in threshold, p < 0.01) and sound localization (Error Index increase of 0.16, p < 0.001) occurred in the UHL30 condition. Speech recognition did not significantly deteriorate further in the UHL43 condition (1.0 dB increase in speech recognition threshold, p > 0.05), while sound localization was additionally impaired (Error Index increase of 0.33, p < 0.01) with an associated large increase in individual variability. Qualitative analyses on a subject-by-subject basis showed that high-frequency audibility was important for speech recognition, while low-frequency audibility was important for horizontal sound localization accuracy. While the data might not be entirely applicable to individuals with long-standing UHL, the results suggest a need for intervention for mild-to-moderate UHL.