Efficacy Of Cochlear Implantation Research Articles

Effectiveness of CI as an alternative to ABI for hearing loss in patients with vestibular schwannomas: A multicenter study in Japan

ObjectiveNF2-related schwannomatosis (NF2) is characterized by bilateral vestibular schwannomas (VS), often causing severe damage to the bilateral auditory function. Auditory brainstem implantation (ABI) provides hearing-impaired patients with an opportunity to reacquire auditory sensation through electrical stimulation of auditory neurons in the cochlear nucleus. However, ABI is not covered by public health insurance in Japan, leading to a large difference in financial burden compared to cochlear implantation (CI). The aim of the present study was to demonstrate the effectiveness of CI as an alternative to ABI for hearing reacquisition in patients with profound hearing loss caused by VS. MethodsTo investigate the current situation of ABI and CI for hearing reconstruction in VS patients, we conducted a questionnaire survey of 102 facilities in Japan. Based on the responses to the questionnaire, a multicenter research group consisting of otolaryngologists and neurosurgeons was established. We collected detailed data on patients with VS who underwent ABI (n = 7, all NF2) and CI (n = 14 [nine NF2, and five non-NF2]). ResultsSome sense of hearing was obtained in all patients but one with CI indicating the efficacy of CI and ABI for profound hearing loss caused by VS. The mean hearing levels were 45.4 dB HL in the ABI patients and 32.7 dB HL in the CI patients, indicating that CI was effective as an alternative to ABI. ConclusionThe results of the present study suggest the effectiveness of CI as an alternative to ABI for hearing reacquisition in patients with profound hearing loss caused by VS. Level of evidence4.

Efficacy of cochlear implantation in cochlear nerve deficiency children – A single center study

PurposesThe objective of this research was to interpret and analyze the imaging, audiological features and cochlear implantation outcomes in cochlear nerve deficiency children. Material and methodsRetrospective analysis. Results25 prelingual hearing loss children diagnosed cochlear nerve deficiency (CND), the age range from 1 to 15 (mean age, 5.04), underwent cochlear implantation at Ear Nose and Throat Hospital - Ho Chi Minh City (ENT hospital – HCMC) from 2016 to 2023. All children had sensorineural hearing loss (SNHL) from severe to profound degree. Magnetic resonance imaging (MRI) showed cochlear nerve hypoplasia in 76 % and cochlear nerve aplasia in 24 % of cases. Inner ear malformations were found in 52 % of cases. The mean Categories of Auditory Performance (CAP) score at 1 year after surgery was 4.8. At 6 months and 1 year after surgery, the mean CAP score of the aplasia group was significantly lower than that of the hypoplasia group (p < 0.05). ConclusionsIn cochlear nerve deficiency children, auditory perception and speech performance still improved after cochlear implantation. However, this progress was significantly limited in cochlear nerve aplasia group.

Models of service delivery in adult cochlear implantation and evaluation of outcomes: A scoping review of delivery arrangements.

This study aimed to describe available evidence of cochlear implantation delivery arrangements in adults and the outcomes by which these service models are measured. Scoping review of English language, primary studies conducted on adults (≥18 years) with ten or more subjects, published between January 2000 and June 2022, which assessed the effects of delivery arrangements of cochlear implantation were included. MEDLINE, EMBASE, CINAHL Plus, AMED, PsycINFO, LILACS, KoreaMed, IndMed, Cochrane CRCT, ISRCTN registry, WHO ICTRP and Web of Science were systematically searched. Included studies had to have a method section explicitly measure at least one of the Cochrane Effective Practice and Organization of Care (EPOC) outcome category. Criteria for systematic reviews and delivery arrangement category based on EPOC taxonomy was included in data extraction. Data was narratively synthesized based on EPOC categories. A total of 8135 abstracts were screened after exclusion of duplicates, of these 357 studies fulfilled the inclusion criteria. Around 40% of the studies investigated how care is delivered, focusing on quality and safety systems. New care pathways to coordinate care and the use of information and communication technology were emerging areas. There was little evidence on continuity, coordination and integration of care, how the workforce is managed, where care is provided and changes in the healthcare environment. The main outcome measure for various delivery arrangements were the health status and performance in a test. A substantial body of evidence exists about safety and efficacy of cochlear implantation in adults, predominantly focused on surgical aspects and this area is rapidly growing. There is a lack of evidence on aspects of care delivery that may have more impact on patients' experience such as continuity, coordination and integration of care and should be a focus of future research. This would lead to a better understanding of how patient's view CI experience, associated costs and the value of different care models.

Efficacy of cochlear implants in children with borderline hearing who have already achieved significant language development with hearing aids.

There are still debates about timing and effectiveness of cochlear implants (CI) in pediatric subjects with significant residual hearing who do not belong to traditional indication of CI. In this study, we aimed to investigate the outcomes of CI, specifically on improvement of pronunciation, among hearing-impaired children already with a substantial degree of language skills as evaluated by Categories of Auditory Perception (CAP) scores or sentence score. Our cohort comprised pediatric CI recipients from July 2018 through October 2020. Among them, cases with CAP scores of 5 or 6 preoperatively were defined as "borderline cases". We investigated prevalence and etiologies, and compared speech evaluation data preoperatively and postoperatively at three time points (3, 6 and 9-12 months after implantation). Among 86 pediatric CI recipients, 13 subjects (15.12%) had language development that reached CAP scores of 5 or 6 before implantation. Postoperative speech evaluation data 6 months after implantation revealed significant improvement of pronunciation (Urimal Test of Articulation and Phonation scores: UTAP), Infant-Toddler Meaningful Auditory Integration Scale (IT-MAIS) and word perception scores, but not of CAP and sentence perception scores. Notably, the significant improvement of pronunciation based on UTAP scores outstripped that of other speech parameters and this continued steadily up to one-year postoperatively. The result of the study serves as evidence for what to expect from cochlear implantation in hearing-impaired children who have already achieved a substantial degree of language development in terms of CAP scores or sentence perception scores, preoperatively.

Efficacy of Cochlear Implantation in Neurofibromatosis Type 2 Related Hearing Loss.

To investigate the results of cochlear implantation in subjects with neurofibromatosis type 2 (NF2) and bilateral vestibular schwannomas (VS). Retrospective case series. University-based tertiary referral center. Five subjects with NF2 and severe-to-profound sensorineural hearing loss. Cochlear implantation. Surgical outcomes and audiometric performance after cochlear implantation. Five subjects (3 female, 2 male) were included in the study. The mean age at the time of implantation was 54 years old (range 35-78 years). Follow-up after cochlear implantation averaged 38 months (range 21-106 months). In the 5 implanted ears, 2 had no prior treatment, 1 had undergone prior radiation therapy, 1 underwent prior microsurgical removal, and 1 underwent prior microsurgical removal with adjuvant radiation therapy. The mean ipsilateral VS dimensions at time of implantation were 14 mm × 7.2 mm × 6.1 mm (mediolateral × anteroposterior × craniocaudal). Following cochlear implant activation, all 5 subjects achieved sound awareness, open set speech recognition, and 4 continue to be daily users of the devices. Cochlear implantation is a viable hearing rehabilitation option for subjects with NF2 and severe-to-profound sensorineural hearing loss. All subjects reported benefit with their cochlear implant, including open set speech recognition, enhanced lip-reading skills and environmental awareness of sound. Four subjects continued to demonstrate improved open-set speech recognition at the time of their last evaluations.

Estimating health of the implanted cochlea using psychophysical strength-duration functions and electrode configuration

It is generally believed that the efficacy of cochlear implants is partly dependent on the condition of the stimulated neural population. Cochlear pathology is likely to affect the manner in which neurons respond to electrical stimulation, potentially resulting in differences in perception of electrical stimuli across cochlear implant recipients and across the electrode array in individual cochlear implant users. Several psychophysical and electrophysiological measures have been shown to predict cochlear health in animals and were used to assess conditions near individual stimulation sites in humans. In this study, we examined the relationship between psychophysical strength-duration functions and spiral ganglion neuron density in two groups of guinea pigs with cochlear implants who had minimally-overlapping cochlear health profiles. One group was implanted in a hearing ear (N = 10) and the other group was deafened by cochlear perfusion of neomycin, inoculated with an adeno-associated viral vector with an Ntf3-gene insert (AAV.Ntf3) and implanted (N = 14). Psychophysically measured strength-duration functions for both monopolar and tripolar electrode configurations were then compared for the two treatment groups. Results were also compared to their histological outcomes. Overall, there were considerable differences between the two treatment groups in terms of their psychophysical performance as well as the relation between their functional performance and histological data. Animals in the neomycin-deafened, neurotrophin-treated, and implanted group (NNI) exhibited steeper strength-duration function slopes; slopes were positively correlated with SGN density (steeper slopes in animals that had higher SGN densities). In comparison, the implanted hearing (IH) group had shallower slopes and there was no relation between slopes and spiral ganglion density. Across all animals, slopes were negatively correlated with ensemble spontaneous activity levels (shallower slopes with higher ensemble spontaneous activity levels). We hypothesize that differences in strength-duration function slopes between the two treatment groups were related to the condition of the inner hair cells, which generate spontaneous activity that could affect the across-fiber synchrony and/or the size of the population of neural elements responding to electrical stimulation. In addition, it is likely that spiral ganglion neuron peripheral processes were present in the IH group, which could affect membrane properties of the stimulated neurons. Results suggest that the two treatment groups exhibited distinct patterns of variation in conditions near the stimulating electrodes that altered detection thresholds. Overall, the results of this study suggest a complex relationship between psychophysical detection thresholds for cochlear implant stimulation and nerve survival in the implanted cochlea. This relationship seems to depend on the characteristics of the electrical stimulus, the electrode configuration, and other biological features of the implanted cochlea such as the condition of the inner hair cells and the peripheral processes.

Speech evoked potentials in cochlear implant recipients with auditory neuropathy spectrum disorder

Purpose Cochlear implantation (CI) is now recognised as the most possible approach to help ANSD patients in improving their capability in hearing and speech communication. Because there are no reliable methods in clinical practice to identify the exact lesion site and mechanisms for a certain ANSD patient, the efficacy of CI is difficult to predict before surgery. This study was done to study speech ABR and CAEP P1 in ANSD subjects fitted with CIs and to compare results of both tests in ANSD versus SNHL subjects fitted with unilateral CIs, then correlate between both tests in both types of hearing loss. Method The current study was a case-control study, conducted on a total number of 45 subjects who were classified into three groups (one control and two study groups). The control group comprised 16 subjects with normal peripheral hearing sensitivity (NH group) who were age matched to both study groups. The study group comprised 29 children who underwent cochlear implantation. The study group were subdivided according to preoperative diagnosis of the type of their hearing loss into two groups (a group of children with sensorineural hearing loss; SNHL-CI) and (a group of children with Auditory neuropathy spectrum disorder; ANSD-CI). Both study groups were subjected to detailed history taking, aided warble-tone sound field audiometry, Speech-evoked potentials (P1 & ABR) and Questionnaire. Results There were statistically significant differences between the control group and both study subgroups regarding the P1 latencies. While; there were no statistically significant differences between {SNHL-CI group &ANSD-CI}. S-ABR waves were detected in 100% of control group, 75% of SNHL-CI group and 53.8% of ANSD-CI group. Sound-field S-ABR measured in the CI recipients indicated statistically significant delayed latencies than in the NH group. In addition, these results demonstrated that the frequency following response peak amplitude was significantly higher in CI recipients, than in the NH counterparts. Finally, the neural phase locking was significantly higher in CI recipients. Conclusion The findings of sound-field S-ABR demonstrated that CI recipients have neural encoding deficits in temporal and spectral domains at the brainstem level; therefore, the sound-field S-ABR can be considered an efficient clinical procedure to assess the speech processing in CI recipients.

Lipid nanoparticles-encapsulated brain-derived neurotrophic factor mRNA delivered through the round window niche in the cochleae of guinea pigs

The treatment of sensorineural hearing loss (SNHL) may be achieved via the application of a cochlear implant (CI) that allows the electrical stimulation of spiral ganglion neurons (SGNs). Nevertheless, the efficacy of CIs is limited by the degeneration of SGNs following SNHL. Although the application of exogenous neurotrophic factors has been reported to decrease SGN degeneration, non-invasive targeted drug delivery systems are required to achieve effective results. In this study, an SS-cleavable proton-activated lipid-like material [ssPalm; a neutral lipid nanoparticle (LNP)], was loaded with mRNA, and the efficacy of this material as a delivery system was investigated. Our results showed that LNPssPalm carrying brain-derived neurotrophic factor (BDNF) mRNA was suitable for the treatment of inner ear diseases, preventing the degeneration of SGNs. In conclusion, this modern nanotechnology-based bioconjugation system, LNPssPalm, is a potential non-invasive targeted therapy allowing the delivering biomaterials to specific structures within the inner ear for the treatment of SHNL.

Successful cochlear implantation in a patient with Epstein syndrome during long-term follow-up

Epstein syndrome is a rare disease characterized by macrothrombocytopenia, nephritis and progressive sensorineural hearing loss (SNHL). This syndrome is presently recognized as an autosomal dominant disease caused by mutations of non-muscle myosin heavy chain 9 (MYH9). Little information is available about the progress of SNHL, the efficacy of cochlear implants (CI) or the perioperative management of thrombocytopenia in patients with Epstein syndrome. We herein report a case of a patient with Epstein syndrome with the MYH9:c.2105G>A:p.R702H variant who underwent cochlear implantation after 27 years of follow-up for her progressive SNHL. The deterioration rates of hearing were 3.48 dB/year on the right ear and 2.46 dB/year on the left ear. The patient derived benefits from CI and had a speech recognition test result (for sentences) of 93% at 6-months postoperatively. Thrombocytopenia was successfully managed without any bleeding complications by using eltrombopag, an oral thrombopoietic agent, making transfusion of platelets unnecessary. The accurate diagnosis of Epstein syndrome was made only after long-term follow-up as the thrombocytopenia was initially diagnosed as idiopathic thrombocytopenic purpura. This case report highlights the perioperative management of thrombocytopenia, the progress of SNHL and the potential pitfalls of diagnosis.

Cochlear implantation in the elderly: Outcomes

Objective: This review examines the various outcome measures utilized in assessing the safety and efficacy of cochlear implantation (CI) in the elderly population. Findings: Though CI is typically performed under general anesthesia, the surgery is safe for elderly patients. Similar minor and major complications rates have been reported in elderly and young patient populations. One complication specific to elderly patients is flap dehiscence due to age-related reduced vascularization and thinner skin. Speech perception, cognition, and quality of life have all been shown to improve subsequent to CI placement. However, efficacy directly correlates with duration of hearing loss with the best outcomes reported closest to when hearing loss begins. Conclusions: Cochlear Implant surgery has been demonstrated to help patients suffering from sensorineural hearing loss improve measures of speech perception, communication, cognition, and quality of life.

Long-term delivery of brain-derived neurotrophic factor (BDNF) from nanoporous silica nanoparticles improves the survival of spiral ganglion neurons in vitro.

Sensorineural hearing loss (SNHL) can be overcome by electrical stimulation of spiral ganglion neurons (SGNs) via a cochlear implant (CI). Restricted CI performance results from the spatial gap between the SGNs and the electrode, but the efficacy of CI is also limited by the degeneration of SGNs as one consequence of SHNL. In the healthy cochlea, the survival of SGNs is assured by endogenous neurotrophic support. Several applications of exogenous neurotrophic supply have been shown to reduce SGN degeneration in vitro and in vivo. In the present study, nanoporous silica nanoparticles (NPSNPs), with an approximate diameter of <100 nm, were loaded with the brain-derived neurotrophic factor (BDNF) to test their efficacy as long-term delivery system for neurotrophins. The neurotrophic factor was released constantly from the NPSNPs over a release period of 80 days when the surface of the nanoparticles had been modified with amino groups. Cell culture investigations with NIH3T3 fibroblasts attest a good general cytocompatibility of the NPSNPs. In vitro experiments with SGNs indicate a significantly higher survival rate of SGNs in cell cultures that contained BDNF-loaded nanoparticles compared to the control culture with unloaded NPSNPs (p<0.001). Importantly, also the amounts of BDNF released up to a time period of 39 days increased the survival rate of SGNs. Thus, NPSNPs carrying BDNF are suitable for the treatment of inner ear disease and for the protection and the support of SGNs. Their nanoscale nature and the fact that a direct contact of the nanoparticles and the SGNs is not necessary for neuroprotective effects, should allow for the facile preparation of nanocomposites, e.g., with biocompatible polymers, to install coatings on implants for the realization of implant-based growth factor delivery systems.

The outcome of cochlear implantation among children with genetic syndromes.

To assess the outcome and efficacy of cochlear implantation in children with genetic syndromes. Study design: case-control study. A cochlear implantation tertiary referral center. All pediatric cochlear implantation recipients with Waardenburg syndrome, Usher syndrome, Dandy-Walker syndrome, or albinism. A control group was appropriately matched to the syndromic group with regard to age at implantation and duration of device use. Cochlear implantation. Subjects' auditory abilities, speech intelligibility, and pure tone thresholds were compared between the syndromic and non-syndromic group. A total of 25 subjects (13 syndromic and 12 non-syndromic) participated in the study. Neither auditory ability nor speech intelligibility scores differed significantly by group. The final PTA of both the groups showed normal-to-mild hearing loss: 26dB HL in the syndromic group and 23dB HL for the control group. Cochlear implant recipients with genetic syndromes achieved similar levels auditory perception and speech intelligibility as their peers with a genetic syndrome. The presence of any of the genetic syndromes described herein should not be a contraindication to cochlear implant provision, as it would have a positive impact on the patients' sensory perception and lifestyle.

Towards a Unified Testing Framework for Single-Sided Deafness Studies: A Consensus Paper

Background: While hearing aids for a contralateral routing of signals (CROS-HA) and bone conduction devices have been the traditional treatment for single-sided deafness (SSD) and asymmetric hearing loss (AHL), in recent years, cochlear implants (CIs) have increasingly become a viable treatment choice, particularly in countries where regulatory approval and reimbursement schemes are in place. Part of the reason for this shift is that the CI is the only device capable of restoring bilateral input to the auditory system and hence of possibly reinstating binaural hearing. Although several studies have independently shown that the CI is a safe and effective treatment for SSD and AHL, clinical outcome measures in those studies and across CI centers vary greatly. Only with a consistent use of defined and agreed-upon outcome measures across centers can high-level evidence be generated to assess the safety and efficacy of CIs and alternative treatments in recipients with SSD and AHL. Methods: This paper presents a comparative study design and minimum outcome measures for the assessment of current treatment options in patients with SSD/AHL. The protocol was developed, discussed, and eventually agreed upon by expert panels that convened at the 2015 APSCI conference in Beijing, China, and at the CI 2016 conference in Toronto, Canada. Results: A longitudinal study design comparing CROS-HA, BCD, and CI treatments is proposed. The recommended outcome measures include (1) speech in noise testing, using the same set of 3 spatial configurations to compare binaural benefits such as summation, squelch, and head shadow across devices; (2) localization testing, using stimuli that rove in both level and spectral content; (3) questionnaires to collect quality of life measures and the frequency of device use; and (4) questionnaires for assessing the impact of tinnitus before and after treatment, if applicable. Conclusion: A protocol for the assessment of treatment options and outcomes in recipients with SSD and AHL is presented. The proposed set of minimum outcome measures aims at harmonizing assessment methods across centers and thus at generating a growing body of high-level evidence for those treatment options.

Dendrogenin A and B two new steroidal alkaloids increasing neural responsiveness in the deafened guinea pig.

Aim: To investigate the therapeutic potential for treating inner ear damage of two new steroidal alkaloid compounds, Dendrogenin A and Dendrogenin B, previously shown to be potent inductors of cell differentiation.Methods: Guinea pigs, unilaterally deafened by neomycin infusion, received a cochlear implant followed by immediate or a 2-week delayed treatment with Dendrogenin A, Dendrogenin B, and, as comparison artificial perilymph and glial cell-line derived neurotrophic factor. After a 4-week treatment period the animals were sacrificed and the cochleae processed for morphological analysis. Electrically-evoked auditory brainstem responses (eABRs) were measured weekly throughout the experiment.Results: Following immediate or delayed Dendrogenin treatment the electrical responsiveness was significantly maintained, in a similar extent as has been shown using neurotrophic factors. Histological analysis showed that the spiral ganglion neurons density was only slightly higher than the untreated group.Conclusions: Our results suggest that Dendrogenins constitute a new class of drugs with strong potential to improve cochlear implant efficacy and to treat neuropathy/synaptopathy related hearing loss. That electrical responsiveness was maintained despite a significantly reduced neural population suggests that the efficacy of cochlear implants is more related to the functional state of the spiral ganglion neurons than merely their number.

Cochlear implantation for single-sided deafness: the outcomes. An evidence-based approach

The aim of the present paper is to critically review the current evidence on the efficacy of cochlear implantation as a treatment modality for single-sided deafness (SSD), and/or unilateral tinnitus. Systematic literature review in Medline and other database sources was conducted along with critical analysis of pooled data. The study selection includes prospective and retrospective comparative studies, case series and case reports. The total number of analyzed studies was 17. A total of 108 patients with SSD have been implanted; 66 patients due to problems associated with SSD, and 42 primarily because of debilitating tinnitus. Cochlear implantation in SSD leads to improved sound localization performance and speech perception in noise from the ipsilateral side with an angle of coverage up to (but not including) 90(°) to the front, when noise is present in the contralateral quartile (Strength of recommendation B). Speech and spatial hearing also subjectively improve following the insertion of a cochlear implant (Strength of recommendation B); this was not the case regarding the quality of hearing. Tinnitus improvement was also reported following implant placement (Strength of recommendation B); however, patients need to be advised that the suppression is mainly successful when the implant is activated. The overall quality of the available evidence supports a wider use of cochlear implantation in SSD following appropriate selection and counseling (overall strength of recommendation B). It remains to be seen if the long-term follow-up of large number of patients in well conducted high quality studies will confirm the above mentioned results.

An improved cochlear implant electrode array for use in experimental studies

Experimental studies play an important role in establishing the safety and efficacy of cochlear implants and they continue to provide insight into a new generation of electrode arrays and stimulation strategies. One drawback has been the limited depth of insertion of an electrode array in experimental animals. We compared the insertion depth and trauma associated with the insertion of Cochlear Ltd’s Hybrid-L (HL) array with a standard 8 ring array in cat cochleae. Both arrays were inserted into cadaver cochleae and an X-ray recorded their anatomical location. The implanted cochlea was serially sectioned and photographed at 300 μm intervals for evidence of electrode insertion trauma. Subsequently two cats were chronically implanted with HL arrays and electrically-evoked potentials recorded over a three month period. Mean insertion depth for the HL arrays was 334.8° (SD = 21°; n = 4) versus 175.5° (SD = 6°; n = 2) for the standard array. This relates to ∼10.5 mm and 6 mm respectively. A similar insertion depth was measured in a chronically implanted animal with an HL array. Histology from each cadaver cochleae showed that the electrode array was always located in the scala tympani; there was no evidence of electrode insertion trauma to the basilar membrane, the osseous spiral lamina or the spiral ligament. Finally, evoked potential data from the chronically implanted animals exhibited significantly lower thresholds compared with animals implanted with a standard 8 ring array, with electrical thresholds remaining stable over a three-month observation period. Cochlear Ltd’s HL electrode array can be safely inserted ∼50% of the length of the cat scala tympani, placing the tip of the array close to the 4 kHz place. This insertion depth is considerably greater than is routinely achieved using a standard 8-ring electrode array (∼12 kHz place). The HL array evokes low thresholds that remain stable over three months of implantation. This electrode array has potential application in a broad area of cochlear implant related research.

Preliminary clinical research of cochlear implantation in elderly and pre-elderly patients with profound hearing loss

To explore the safety and efficacy of cochlear implantation among elderly patients with severe to profound hearing loss. Eight pre-elderly and elderly patients with an medium age of 58 years who suffered from bilateral severe to profound sensorineural hearing loss received cochlear implantation between November 2008 and November 2009. The patients' tolerance to implant surgery and the occurrence of complications were observed. Three months after switch-on, aided threshold and speech performance were measured. The surgery was uneventful in all cases with normal intraoperative neural response telemetry elicited. Three months after switch-on, average aided threshold across speech frequencies was 35 - 50 dB HL measured in sound field with warble tone. The results of speech audiometry showed large variation between individuals. Some patients achieved good performance in monosyllable recognition test, disyllables threshold test and sentences recognition test under both bubble noise and quiet conditions. Pre-elderly and elderly patients can endure a state of general anesthesia for cochlear surgery without complications. Cochlear implant can provide reconstruction of speech recognition capabilities for elderly patients suffering from severe to profound hearing loss. Cochlear implantation can improve the quality of life of elderly patients with hearing loss.

Survival-enhancing of spiral ganglion cells under influence of olfactory ensheathing cells by direct cellular contact

The efficacy of cochlear implantation is primarily associated with the quantity and health of the remaining spiral ganglion cells (SGCs). Olfactory ensheathing cells (OECs) are capable of expressing a variety of growth factors and adhesion molecules, playing an important role in enhancing cellular survival. To investigate the effect of OECs on the survival of SGCs, co-cultures of OECs and SGCs were developed in this study. In addition, OECs conditioned medium (OEC-CM) was employed to culture SGCs in contrast with the co-cultures. OECs were identified immunocytochemically by low-affinity nerve growth factor receptor p75 (P75NTR) and glial fibrillary acidic protein (GFAP), while SGCs were stained with neuron-specific markerβIII-tubulin. SGCs survival was assessed in different conditions. To explore the underlying mechanism, growth factors, adhesion molecules and their receptors were investigate using RT-PCR. Our results indicate that the co-cultures of OECs and SGCs can be successfully established and that both OECs and OEC-CM promote SGCs survival in vitro. SGCs survival was most enhanced when co-cultured with OECs. Both Olfactory bulb (OB) and OECs were proved to express BMP-4 and NCAM while BMPR-1A and a7 integrin were also detected in cochlea and SGCs. In conclusion, our results suggest that enhancement in co-cultures is in part due to direct cellular contact. Transplantation of OECs may be a cell-based therapy for the application of neurotrophic factors to the inner ear.

Long-term follow-up of infants (4–11 months) fitted with cochlear implants

Conclusion: In this study the outcomes from several indices (Category of Auditory Performance, CAP; Peabody Picture Vocabulary Test (Revised), PPVT-R; Test of Reception of Grammar, TROG; and Speech Intellegibility Rating, SIR) in three groups of children with different ages at implantation (from 4 to 36 months) with a follow-up time from 4 to 9 years demonstrate that very early cochlear implantation (<11 months) provides normalization of audio-phonologic parameters with no complications. Objectives: The aim of the present study was to investigate the efficacy of cochlear implants (CIs) in infants who were implanted at < 11 months of age versus children operated at later age (i.e. 12–36 months) and to document whether children who receive a CI below 11 months of age are able to achieve age-appropriate expected spoken language skills, at a follow-up time from 4 to 9 years. Subjects and methods: From November 1998 to November 2007, 185 children received CIs and 34 received auditory brainstem implants in our department. The present study focuses on 13 children implanted at ages younger than 12 months (4–11 months; mean, 8.2; SD = 2.4) and fitted with CIs between November 1998 and March 2004. To avoid bias these children were selected from a larger longitudinal cohort of pediatric CI recipients fitted with CIs because they all were implanted with the same cochlear device (Nucleus CI 24 M) during the same period. Postoperatively auditory abilities were evaluated at the latest follow-up, from 4 to 9 years after surgery, with CAP, PPVT-R, TROG, and SIR. The results obtained in this group of 13 children were compared with those obtained in two groups of children implanted at later ages (12–23 and 24–36 months, respectively). Results: No complication has been observed so far. The highest score of CAP function was achieved in all the three groups but at different intervals from CI activation as function of age at CI implantation. The rate of receptive language growth (PPVT-R) provides distinctive evidence that only the scores of the first group overlap the line of normal-hearing children, whereas the second and third group never reached the values of normal peers even after 9 years of CI use. TROG outcomes clearly indicate that only children from the first group (77%) are in the 76–100 percentile at 5 years follow-up. At 9 years follow-up, 100% of children in the first group, 38% in the second group, and 20% in the third group are in the 76–100 percentile. The SIR outcomes at the 5 years follow-up indicate that none of children was identified within the first two categories, only children from the third group (18%) were identified in category 3, all infants of the first group, 80% of group 2, and 63% of the third group were identified in category 5. At the 9 years follow-up, the number of children from the third group identified in category 3 was reduced to 10%, the second and third groups displayed a slightly higher percentage of children in category 5, but the difference from the values observed at the 5-year follow-up is not significant.

Threshold and channel interaction in cochlear implant users: Evaluation of the tripolar electrode configuration

The efficacy of cochlear implants is limited by spatial and temporal interactions among channels. This study explores the spatially restricted tripolar electrode configuration and compares it to bipolar and monopolar stimulation. Measures of threshold and channel interaction were obtained from nine subjects implanted with the Clarion HiFocus-I electrode array. Stimuli were biphasic pulses delivered at 1020 pulses/s. Threshold increased from monopolar to bipolar to tripolar stimulation and was most variable across channels with the tripolar configuration. Channel interaction, quantified by the shift in threshold between single- and two-channel stimulation, occurred for all three configurations but was largest for the monopolar and simultaneous conditions. The threshold shifts with simultaneous tripolar stimulation were slightly smaller than with bipolar and were not as strongly affected by the timing of the two channel stimulation as was monopolar. The subjects' performances on clinical speech tests were correlated with channel-to-channel variability in tripolar threshold, such that greater variability was related to poorer performance. The data suggest that tripolar channels with high thresholds may reveal cochlear regions of low neuron survival or poor electrode placement.