Alicia Huarte

Advantages of cochlear implantation in prelingual deaf children before 2 years of age when compared with later implantation

Objectives: To compare the auditory abilities and speech performance of children with a profound prelingual bilateral hearing‐impairment when subjected to a cochlear implant (CI) before or after 2 years of age. To analyze the complications that arose during, or as a result of, the implantation process in these groups.

Advantages of binaural hearing provided through bimodal stimulation via a cochlear implant and a conventional hearing aid: A 6-month comparative study

Conclusions Our study data demonstrate the additional benefit derived from continued use of a contralateral hearing aid (HA) post-cochlear implantation for speech recognition ability in quiet and in noise. Postoperative bimodal stimulation is recommended for all subjects who show some speech recognition ability in the contralateral ear as it may offer binaural listening advantages in various listening situations encountered in everyday life. Objectives To assess the benefits derived from bimodal stimulation for experienced HA users implanted with a cochlear implant (CI) (score ≥ 20% in disyllabic test). The correlation between pre- and postoperative performance on speech perception measures was examined to determine additional criteria for recommending bimodal stimulation postoperatively. Material and methods A within-subject repeated-measures design was used, with each subject acting as their own control. Assessments were carried out preoperatively in aided monaural and best-aided conditions and at 6 months postoperatively in CI-alone, contralateral HA-alone and bimodal listening conditions. Speech recognition using Spanish words and sentences materials was assessed at conversational level and for soft speech in quiet. Speech comprehension in noise was assessed using word materials at a signal:noise ratio of +10, for coincident speech in noise and for spatially separated speech in noise. Twelve adult native Spanish subjects with a severe-to-profound hearing impairment who were experienced with optimally fitted conventional amplification and who displayed suboptimal speech understanding preoperatively were enrolled in the study. Preoperatively, conventional amplification was worn by five subjects binaurally and by seven monaurally. Results Postoperatively, superior speech recognition ability in quiet and in noise for disyllabic words was achieved using bimodal stimulation in comparison to performance for either monaural aided condition. Mean improvement in speech recognition in the bimodal condition was significant over performance in the CI-alone condition for disyllabic words in quiet at 70 (p=0.006) and 55 dB SPL (p=0.028), for disyllabic words in noise at +10 dB with speech and noise spatially separated with the noise source closest to the contralateral HA (S0NHA) (p=0.0005) and when the noise source was closest to the CI ear (S0NCI) (p=0.002). When testing word recognition in noise with speech and noise sources coincident in space, word scores were superior in the bimodal condition relative to the CI-alone condition but this improvement was not significant (p=0.07). The advantages of bimodal stimulation included significant effects of binaural summation in quiet and significant binaural squelch effects in both the S0NHA and S0NCI test conditions. All subjects showed superior performance in the binaural situation postoperatively relative to the best-aided condition preoperatively for one or more test situations.

Cerebral auditory plasticity and cochlear implants.

Previous animal research and clinical experiences in humans suggest the existence of an auditory critical period in language acquisition. We review the literature and present the changes within the cochlear nuclei in bilaterally deafferentated adult non-human primates. We also present and analyse the results of 98 prelingually deaf children and teenagers who underwent a cochlear implantation at the University of Navarra. Patients received a Nucleus 22 or 24 multichannel cochlear implant (CI). They were grouped in five categories according to their age at surgery. Performance is compared with a control group of 58 postlinguals. Only early-implanted prelingual children (before 6 years of age) achieved a complete open-set speech recognition, even with better performance than postlinguals. These results clearly demonstrate the existence of a period of high neural auditory plasticity within the first 6 years of life. The introduction of auditory stimulation with a CI can not restore the loss of neural plasticity out of this period. Prelingual children under 6 years of age should receive a CI as soon as there is a reliable diagnosis of bilateral sensorineural hearing loss.

International consensus on bilateral cochlear implants and bimodal stimulation

Binaural hearing allows listeners with normal hearing to understand speech better in silence and noisy conditions and is an essential requirement for spatial hearing and sound localization. Other benefits of binaural hearing are more natural hearing, reduced listening effort and an improved quality of life. The cortical projection of the ear is fundamentally contralateral and only a small proportion of fibers in the auditory neural pathway have homolateral cortical projection. This results in insufficient homolateral neural and cortical development in cases of monaural stimulation.

Prospective long-term auditory results of cochlear implantation in prelinguistically deafened children: the importance of early implantation.

The objectives of this study were to report the long-term auditory results of prelinguistically deafened children with bilateral profound hearing impairment treated with a cochlear implant (CI); to analyze the role of auditory stimulation in the development of communicating abilities in early implanted children; and to define the limits of the auditory critical period. It was designed as a prospective cohort single-subject repeated-measures study of children with bilateral profound hearing impairment treated with a CI at a tertiary referral center with a pediatric CI program since 1991. A total of 182 children with bilateral prelinguistic hearing impairment of profound degree treated with a Nucleus CI were enrolled in the study. Eighty-six children received a Nucleus 22 CI and 74 received a Nucleus 24. For data analyses the children were categorized by ages: 0-3 years of age (n = 94); 4-6 years (n = 36); 7-10 years (n = 30); 11-14 years (n = 22). The children were evaluated with a protocol that included tests of audition and speech perception, with closed-set (Vowel Confusion test, Series of Daily Words) and open-set tests (e.g. bisyllables, CID Sentences, CID Sentences adapted for children). Pure-tone averages significantly improved for all children in all groups with the CI compared with preoperative values. Nevertheless, only children implanted before the age of 6 years developed a high ability for recognition of bisyllables and sentences in an open-set. Results show that the earlier the implantation is undertaken, the better the performance outcome. Children implanted outside of the auditory critical period demonstrated significantly poorer performance, suggesting the occurrence of irreversible changes in the central auditory system. In conclusion, eligible children should receive a CI as soon as bilateral profound hearing impairment is diagnosed. This usually permits them to achieve high-performance levels on speech and language measures and potentially integration into an oral communication environment.

Contralateral hearing aid use in cochlear implanted patients: Multicenter study of bimodal benefit

Abstract Conclusion: The use of a hearing aid (HA) in combination with a cochlear implant (CI) significantly improved performance for speech perception in quiet, in noise, and for localization compared with monaural conditions. No significant differences in functional performance were observed following optimization of HA fitting. Objectives: To evaluate the binaural benefits derived from using a contralateral HA in conjunction with a CI in subjects with significant functional hearing in the nonimplanted ear and the effects of HA fitting optimization. Methods: Fifteen adult CI users, intra-subject controls, were enrolled in a prospective repeated-measure multicenter study. Evaluation of performance for speech understanding, localization, and subjective impressions was conducted before and following HA fitting optimization for CI alone, HA alone, and CI + HA. Results: For speech testing in quiet, bimodal scores were significantly better than for HA alone and CI alone conditions (p < 0.01). For speech and noise (S0N0) at 0° azimuth the scores were significantly better in the bimodal condition than for CI alone (p = 0.01), indicating binaural summation. When noise was presented to the HA side (S0NHA) bimodal scores were significantly better than for CI alone (p < 0.01 and p < 0.05, respectively), suggesting a significant binaural squelch effect. Sound localization ability was significantly improved in the bimodal condition compared with the CI alone condition (p = 0.002).

Development of speech in 2-year-old children with cochlear implant

Auditory deprivation in children causes important adverse effects in speech development, acquisition of knowledge, and the affective area. The use of multichannel cochlear implants permits to restore the auditory capacity and therefore affects directly the children’s language and speech development. The aim of this study is to evaluate the speech development in a group of children treated with early cochlear implantation.

Bilateral sequential implantation in children

Cochlear implants provide an electrical signal that may assist in the development of the central auditory system. In order to capitalize on the developmental processes associated with a maturing auditory system, many authors suggest cochlear implantation should be performed at very young ages. In order to examine the contributions associated with one versus two cochlear implants in young children, we examined performance over three years post-implantation in children who received sequential cochlear implants. Twenty-nine children sequentially implanted were studied. All children were implanted with Cochlear Corporation multichannel cochlear implants. Mean age at the first implantation was 2.31 years (range 1–9 years) and 7.55 years at the second implantation (range 3–15 years). Children were evaluated annually with audiometric thresholds and open-set speech perception testing. Data were examined in two ways. First, data acquired annually for the first three years post-implant were compared between the first and second ears implanted (chronological option A). Secondly, performances for both ears were examined for a three-year follow-up period after the second implantation (chronological option B). Thresholds were significantly higher in the second implanted ear relative to the thresholds obtained in the first implanted ear during the first two years post-implantation. Comparisons of thresholds for the two ears following the second implant also confirmed significantly higher thresholds for the second implanted ear relative to the first implanted ear over a three-year evaluation period. Analyses of speech perception performance revealed that performance with disyllable words and sentences were significantly lower in the second implanted ear at 12, 24 and 36 months after activation relative to the first ear implanted in its initial three years of use and during the three-year period following the second implantation. There is at least a five-year window to carry out a second implantation in the contralateral ear for children suffering from a congenital bilateral hearing loss, who have been unilaterally stimulated from an early age with a cochlear implant. However, the results of this work do not apply to other situations including late initial implantations or wider windows between the implantation in the first and second ears.

Clinical evaluation of cochlear implant sound coding taking into account conjectural masking functions, MP3000™

Abstract Efficacy of the SPEAK and ACE coding strategies was compared with that of a new strategy, MP3000™, by 37 European implant centers including 221 subjects. The SPEAK and ACE strategies are based on selection of 8–10 spectral components with the highest levels, while MP3000 is based on the selection of only 4–6 components, with the highest levels relative to an estimate of the spread of masking. The pulse rate per component was fixed. No significant difference was found for the speech scores and for coding preference between the SPEAK/ACE and MP3000 strategies. Battery life was 24% longer for the MP3000 strategy. With MP3000 the best results were found for a selection of six components. In addition, the best results were found for a masking function with a low-frequency slope of 50 dB/Bark and a high-frequency slope of 37 dB/Bark (50/37) as compared to the other combinations examined of 40/30 and 20/15 dB/Bark. The best results found for the steepest slopes do not seem to agree with current estimates of the spread of masking in electrical stimulation. Future research might reveal if performance with respect to SPEAK/ACE can be enhanced by increasing the number of channels in MP3000 beyond 4–6 and it should shed more light on the optimum steepness of the slopes of the masking functions applied in MP3000.

Quality of life outcomes for cochlear implantation in the elderly.

Objectives: To determine whether individuals older than 60 years of age suffering from profound, bilateral, sensorineural hearing loss and unable to use hearing aids can benefit from a cochlear implant in order to improve hearing performance. Additionally, to evaluate how they manage the external components of their implanted system. Materials and Methods: The records of 68 cochlear implant users over 60 years of age were reviewed. They had undergone tonal and speech audiometry evaluations of hearing before and after implantation. A subset of 27 elderly patients were asked to respond to a specially designed questionnaire regarding the use of the external components of the implanted system. Results: Patients over 60 years of age benefit from cochlear implants. The earlier the implantation, the better the results tend to be. Certain limitations when using the external components of the implanted system were evident among the elderly. Conclusions: People >60 years of age suffering from profound, bilateral, sensorineural hearing loss show improved hearing performance following cochlear implantation. Using the implanted system includes some limitations that should be studied and overcome.