Long-term residual hearing in cochlear implanted adult patients who were candidates for electro-acoustic stimulation.

PURPOSE: To evaluate the long-term hearing outcomes in cochlear implanted adults with residual hearing at low frequencies, and the proportion of patients using electro-acoustic stimulation (EAS). METHODS: A monocentric retrospective cohort study was performed in a tertiary referral center. Population demographics, surgical approach, pre- and postoperative hearing at low frequencies, in the implanted and contralateral ear, were recorded as well as duration of EAS use. The percentage hearing preservation was calculated according to the formula S (HEARRING group). RESULTS: In total, 63 adults (81 ears) with residual hearing underwent cochlear implantation with intent to use EAS processors. Six different types of electrode array were implanted. The mean pure tone audiometry (PTA) shift after cochlear implantation was 16 ± 15 dB HL (range 0-59 dB HL). Half of the implanted ears had minimal hearing preservation or total hearing loss (HL) at 5.5 years and the cumulative risk of total HL was 50% at 7 years. During the follow-up, total HL occurred in 22 ears. The decrease in hearing levels was similar in both implanted and contralateral ear during follow-up (ns, F = 2.46 ± 3, Linear Mixed Model (LMM)). Only 44 patients found a benefit from EAS at the first fitting. At the last visit, EAS processors were fitted in 30% of the cases. The pre- and postoperative mean PTA thresholds were not predictive of EAS use (Cox's proportional hazards analysis). CONCLUSIONS: Postoperative residual hearing was observed in 93% of implanted ears, but only half of them had an initial benefit from EAS. No predictive factors were found to influence the use of EAS processors.

Assessment of the efficacy of a local steroid rescue treatment administered 2 days after a moderate noise-induced trauma in guinea pig.

OBJECTIVES: Intratympanic injection of corticosteroids membrane after noise-induced hearing loss is an accepted alternative to general administration. We investigated the effect on hearing of a hyaluronic acid gel with liposomes loaded with dexamethasone (DexP) administered into the middle ear. METHODS: An acute acoustic trauma was performed to 13 guinea pigs for a period of 1 h on Day -2. Two 2 days after the noise trauma, the animals were then assigned randomly to four experimental groups: control without gel, gel injection, gel-containing free DexP, gel-containing DexP loaded into liposomes. Auditory thresholds were measured with Auditory Brainstem Response before Day -2 and at Day 0, Day 7 and Day 30 after noise trauma. RESULTS: Seven days after, a complete hearing recovery was observed in the control group at all frequencies apart from 8 kHz, and no recovery was observed in the three groups receiving a gel injection. Thirty days after trauma, all of the animals had recovered normal hearing, apart from at the 8-kHz frequency, with similar auditory thresholds. CONCLUSIONS: Local DexP administration 48 h after a mild acoustic trauma did not improve hearing recovery, even with a sustained release in a specific gel formulation designed for inner ear therapy.

Brain voice processing with bilateral cochlear implants: a positron emission tomography study.

Most cochlear implantations are unilateral. To explore the benefits of a binaural cochlear implant, we used water-labelled oxygen-15 positron emission tomography. Relative cerebral blood flow was measured in a binaural implant group (n = 11), while the subjects were passively listening to human voice sounds, environmental sounds non-voice or silence. Binaural auditory stimulation in the cochlear implant group bilaterally activated the temporal voice areas, whereas monaural cochlear implant stimulation only activated the left temporal voice area. Direct comparison of the binaural and the monaural cochlear implant stimulation condition revealed an additional right temporal activation during voice processing in the binaural condition and the activation of a right fronto-parietal cortical network during sound processing that has been implicated in attention. These findings provide evidence that a bilateral cochlear implant stimulation enhanced the spectral cues associated with sound perception and improved brain processing of voice stimuli in the right temporal region when compared to a monaural cochlear implant stimulation. Moreover, the recruitment of sensory attention resources in a right fronto-parietal network allowed patients with bilateral cochlear implant stimulation to enhance their sound discrimination, whereas the same patients with only one cochlear implant stimulation had more auditory perception difficulties.

Registration of a validated mechanical atlas of middle ear for surgical simulation.

This paper is centered on the development of a new training and rehearsal simulation system for middle ear surgery. First, we have developed and validated a mechanical atlas based on finite element method of the human middle ear. The atlas is based on a microMRI. Its mechanical behavior computed in real-time has been successfully validated. In addition, we propose a method for the registration of the mechanical atlas on patient imagery. The simulation can be used for a rehearsal surgery with the geometrical anatomy of a given patient and with mechanical data that are validated. Moreover, this process does not necessitate a complete re-built of the model.

Interaction between electric and acoustic cues in diotic condition for speech perception in quiet and noise by cochlear implantees.

OBJECTIVE: This study aimed to evaluate the interaction of electric and acoustic cues in diotic condition in cochlear implantees. MATERIALS AND METHODS: Five adult cochlear implantees with residual contralateral hearing were prospectively evaluated in hearing aid only (HA), cochlear implant only (CI), and HA + CI modes by audiometry (pure tone, dissyllabic words, and sentences), and sound quality questionnaires. CI electrodes corresponding to preserved frequencies in the contralateral ear (free-field aided thresholds, <50 dB) were then deactivated, and patients were retested after 20 to 30 days. RESULTS: Sentences in silence showed a benefit of CI and the additive effect of HA + CI. As expected, performances with CI alone decreased after apical electrode deactivation. In contrast, speech performances (Marginal Benefit from Acoustic Amplification sentences) in HA + CI mode were not altered by electrode deactivation in silence (90 ± 5.9% before versus 81 ± 10.1% after deactivation, not significant, 2-way analysis of variance) or in noise (78 ± 4.8% before versus 66 ± 11.9% after deactivation, not significant, 2-way analysis of variance). Performances for dissyllabic words confirmed these results. Questionnaires showed a significant compensation of partial electrode deactivation by the contralateral hearing. Moreover, the human voice was reported to be significantly less metallic. CONCLUSION: These results suggested a significant complementarity of acoustic and electric diotic cues but also some redundancy affecting the sound quality.

Cochlear implant benefits in deafness rehabilitation: PET study of temporal voice activations.

UNLABELLED: Cochlear implants may improve the medical and social prognosis of profound deafness. Nevertheless, some patients have experienced poor results without any clear explanations. One correlate may be an alteration in cortical voice processing. To test this hypothesis, we studied the activation of human temporal voice areas (TVA) using a well-standardized PET paradigm adapted from previous functional MRI (fMRI) studies. METHODS: A PET H(2)(15)O activation study was performed on 3 groups of adult volunteers: normal-hearing control subjects (n = 6) and cochlear-implanted postlingually deaf patients with >2 y of cochlear implant experience, with intelligibility scores in the "Lafon monosyllabic task" >80% (GOOD group; n = 6) or <20% (POOR group; n = 6). Relative cerebral blood flow was measured in 3 conditions: rest, passive listening to human voice, and nonvoice stimuli. RESULTS: Compared with silence, the activations induced by nonvoice stimuli were bilaterally located in the superior temporal regions in all groups. However these activations were significantly and similarly reduced in both cochlear implant groups, whereas control subjects showed supplementary activations. Compared with nonvoice, the voice stimuli induced bilateral activation of the TVA along the superior temporal sulcus (STS) in both the control and the GOOD groups. In contrast, these activations were not detected in the POOR group, which showed only left unilateral middle STS activation. CONCLUSION: These results suggest that PET is an adequate method to explore cochlear implant benefits and that this benefit could be linked to the activation of the TVA.

Combined electroacoustic stimulation in conventional candidates for cochlear implantation.

OBJECTIVE: To report on combined ipsilateral electrical and acoustic stimulation in a subset of conventional candidates for cochlear implantation where preoperative pure tone thresholds were 85-110 dB HL, 250-500 Hz). In the remaining 7 cases, residual hearing was maintained up to at least 6 months after operation with minor changes. Insertion depth angles in these cases ranged from 285 to 420 degrees . For these subjects, the mean preoperative score for words presented at 65 dB SPL was 22%. Mean postoperative scores were 56% for CI alone, and 68% for CI plus ipsilateral hearing aid (p < 0.05, paired t). For sentences presented in multitalker babble noise at 5 dB SNR, mean scores were 61% CI alone, and 75% CI+IpsiHA (p < 0.01, paired t). CONCLUSIONS: Hearing was conserved during surgery and over time in 70% of conventional candidates implanted with the Nucleus 24 Contour Advance CI who had significant levels of preoperative low-frequency residual hearing (

Residual hearing conservation and electroacoustic stimulation with the nucleus 24 contour advance cochlear implant.

OBJECTIVE: To assess the conservation of residual hearing in recipients of the Nucleus 24 Contour Advance cochlear implant (CI) and the benefits of combined electrical and acoustic stimulation. STUDY DESIGN: Prospective multicenter study. SETTING: CI clinics in Western Europe. PATIENTS: Adult candidates for conventional cochlear implantation with a minimum preoperative word recognition score of 10% in the ear to be implanted. INTERVENTION: "Soft-surgery" protocol, including a 1- to 1.2-mm anterior and inferior cochleostomy hole with the electrode array, inserted 17 mm using the "advance-off-stylet" technique. Patients with postoperative pure-tone hearing threshold levels (HTLs) of 80 dB hearing loss or less at 125 and 250 Hz and 90 dB hearing loss or less at 500 Hz were refitted with an in-the-ear hearing aid for combined ipsilateral electrical and acoustic (El-Ac) stimulation. MAIN OUTCOME MEASURES: A questionnaire to collect information regarding surgery. Pure-tone HTLs measured at intervals. Word recognition tested in quiet and sentence recognition tested in noise at 10 and 5 dB signal-to-noise ratio (SNR). HEARING CONSERVATION RESULTS: HTL data were available for 27 patients. HTLs were conserved within 20 dB of preoperative levels for 33, 26, and 19% of patients for 125, 250, and 500 Hz, respectively. However, the recommended soft-surgery protocol was strictly followed in only 12 of 27 patients. For these 12 patients, hearing thresholds were conserved within 20 dB for 50, 50, and 33% of patients. Median threshold increases were 40 dB (range, 250-500 Hz) for the whole group and 23 dB for the strict surgery group. Ten patients retained sufficient HTLs to enter the El-Ac user group. SPEECH RECOGNITION RESULTS: Group mean recognition scores for nine El-Ac users for words presented at 65 dB sound pressure level were 45% for CI alone and 55% for CI + ipsilateral hearing aid (p < 0.05, paired t). For sentences presented in noise at 5 dB SNR, mean word scores were 46% CI alone and 56% CI + ipsilateral hearing aid (p < 0.01, paired t). CONCLUSION: Hearing was conserved for conventional candidates for cochlear implantation where the recommended soft-surgery protocol was strictly adhered. Combined ipsilateral electrical and acoustic stimulation provided considerable benefits for speech recognition in noise, equivalent to between 3 and 5 dB SNR, compared with CI alone.

Results from a European clinical investigation of the Nucleus multichannel auditory brainstem implant.

OBJECTIVE: This study was designed to investigate the perceptual benefits and potential risks of implanting the Nucleus(R) multichannel auditory brainstem implant. DESIGN: Between September 1992 and October 1997 a total of 27 subjects received a Nucleus 20- or 21-channel Auditory Brainstem Implant (ABI). All subjects involved in the trial had bilateral acoustic tumour as a result of neurofibromatosis type 2 (NF2) resulting in complete dysfunction of the VIIIth nerve. The study used each subject as their own control without a preoperative baseline because residual hearing, if existing, was destroyed at surgery by tumour removal. A battery of speech tests was conducted to evaluate each patient's performance and communication abilities. Tests were conducted, where possible, in the auditory-only, visual-only, and auditory-visual conditions at 3 days postoperatively (baseline), at 3-mo intervals for the first year and every 12 mo thereafter. A subjective performance questionnaire was administered together with an extensive neurological examination at each test interval. RESULTS: 27 subjects involved in this trial were successfully implanted with a Nucleus ABI. One subject died 2 days postoperatively due to a lung embolism unrelated to the device. Twenty-six subjects underwent device activation and all but one patient received auditory sensation at initial stimulation (96.2%). On average 8.6 (+/-4.2) of the available 21 electrodes were used in the patients' MAPs. Performance evaluation measures showed that the majority of users had access to auditory information such as environmental sound awareness together with stress and rhythm cues in speech that assist with lipreading. Although most subjects did not achieve any functional auditory-alone, open-set speech understanding, two subjects from this series (7.4%) did receive sufficient benefit to be able to use the ABI in conversation without lipreading. CONCLUSIONS: Although the medical risks and surgical complexity associated with ABI device implantation are far greater than those for a cochlear implant, the clinical results from this trial show that the Nucleus multichannel ABI is capable of providing a significant patient benefit over risk ratio for subjects suffering loss of hearing due to bilateral retrocochlear lesions.