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PubMed2000

[Cochlear implants].

A cochlear implant is a technologically advanced medical device that simulates sound in the cochlea by electrically stimulating the hearing nerve. Cochlear implants are designed to help severely or totally deaf individuals who gain little or no benefit from hearing aids. Hearing aids and assistive listening devices amplify sounds. The sounds produced by even the most sophisticated hearing aids may not offer much benefit to people with a severe-to-profound or profound hearing loss in both ears. A cochlear implant is an electronic device that provides the function of the damaged or absent hair cells by providing electrical stimulation to the remaining nerve fibers. The implant provides useful hearing and improved communication abilities to the implant user.

Adult↗

PubMed2003

Cochlear implantation update.

Cochlear implantation is recognized as a valuable intervention with important implications for the acquisition of speech perception and verbal language in children with severe to profound hearing impairment. Auditory rehabilitation, language intervention, and close coordination between parents, schools, and the implant center are necessary to maximize efficacy. Early identification of hearing loss, early hearing aid use and language intervention, and cochlear implantation by 2 years of age are positive predictors for language acquisition that can approach the levels of normal-hearing children. There are early indications that increased access to mainstream education and gains in quality of life are long-term benefits that render cochlear implantation a cost-effective intervention.

Auditory Pathways↗

PubMed2005

[The influence of insertion depth on the preservation of residual hearing after cochlear implantation].

BACKGROUND: Cochlear implantation may be indicated in patients with bilateral severe sensory hearing loss. Patients with minimal residual hearing have more benefit from cochlear implantation than from optimal fitted hearing aids. However, it has to be considered that inner ear structures might be damaged during electrode insertion. METHODS: We analysed the influence of insertion depth on the preservation of residual hearing in 47 cochlear implant patients (type of implant: Nucleus 22 M or 24 M) by using the pure tone audiometry. Frequency-specific analyses of pre- and postoperative audiograms on the implanted side were performed, evaluating only frequencies above 500 Hz. The insertion depth was documented by stiffening rings outside the cochlea. RESULTS: Residual hearing was more obtained in cases with complete insertion of the electrode array than in those cases with incomplete insertion. In the frequencies 1000 and 4000 Hz these results are significant. CONCLUSION: In our opinion, the perceived resistance producing intracochlear damages and preventing the complete electrode-insertion at the same time is an explanation for the significantly poorer results of the patients with incomplete insertion.

Audiometry, Pure-Tone↗

PubMed2005

Cochlear wall erosion after cochlear implantation.

OBJECTIVES: Cochlear implantation is a clinically satisfactory procedure, but it is associated with a variable degree of histologic intracochlear trauma. We report a new histologic finding in a cochlear implant specimen from the House Ear Institute collection. METHODS: An analysis of 34 temporal bones with single-channel (n = 23) or multichannel (n = 11) cochlear implants was performed. All temporal bones had been fixed for a month in 10% buffered formalin, progressively decalcified in ethylenediaminetetraacetic acid, and embedded in celloidin. After electrode removal, the bones were cut into 20-microm sections and stained. RESULTS: In 1 specimen, the implanted electrode had caused erosion of the bone through the endosteum into the marrow spaces, at the superior-anterior portion of the basal turn. This area showed an intense lymphocytic infiltration surrounded by some new bone formation. CONCLUSIONS: Trauma may provoke an inflammatory reaction due to the presence of the foreign body after violation of the endosteum.

Aged↗

PubMed1999

Osteomyelitis, lateral sinus thrombosis, and temporal lobe infarction caused by infection of a percutaneous cochlear implant.

OBJECTIVE: Cochlear implantation has become a routine operation in the last 10 years. The most common soft tissue complications with transcutaneous cochlear implants include infection or necrosis of the flap and extrusion of the implant and device failure. The most common complication reported with percutaneous devices include minor skin irritations at the pedestal site, retraction of skin from the pedestal site, and loosening of screws that retain the pedestal. We describe one case of lateral sinus thrombosis and secondary temporal lobe infarction caused by infection of a screw anchoring the percutaneous pedestal of an Ineraid implant. STUDY DESIGN: Case report. SETTING: Tertiary referral center. CONCLUSIONS: Intracranial complications of a percutaneous bone-anchored pedestal may occur with little prodrome. Computed tomography (CT) scan of the pedestal and bone anchoring screws may be indicated if local evidence of infection persists.

Anti-Bacterial Agents↗

PubMed2004

Multichannel place pitch sensitivity in cochlear implant recipients.

Cochlear implant recipients perceive a rise in pitch when the site of stimulation is moved from the apex toward the base. The place pitch sensitivity is typically measured using the stimulation of single channels. However, all current cochlear implant devices stimulate multiple channels simultaneously or with pulses temporally interleaved. The primary goal of the present study is to test whether the sensitivity of a cochlear implant recipient to changes in perceived pitch associated with changes of place of excitation improves or deteriorates when the number of active channels is increased, compared with stimulation with only one active channel. Place pitch sensitivity was recorded in four Nucleus CI24 subjects as a function of number of active channels (from 1 to 8). Just noticeable differences were estimated from a constant stimuli 2AFC pitch-ranking experiment with roving loudness. Reference and comparison stimuli contained the same number of active channels but were shifted one or two electrodes toward the base or toward the apex. The place pitch sensitivity was measured using monopolar stimulation at two locations along the electrode array. To minimize cues related to loudness, the multichannel stimuli were loudness balanced relative to the single-channel stimuli presented at C-level. The number of active channels did not affect place pitch sensitivity. This is consistent with a model that compares the edges of the excitation pattern irrespective of the overlap between excitation patterns. There was a significant difference in sensitivity to place pitch among subjects. The average just noticeable differences of place pitch, extrapolated from a fitting procedure, for the subjects ranged from 0.25 mm to 0.46 mm.

Acoustic Stimulation↗

PubMed2006

The development of the Nucleus Freedom Cochlear implant system.

Cochlear Limited (Cochlear) released the fourth-generation cochlear implant system, Nucleus Freedom, in 2005. Freedom is based on 25 years of experience in cochlear implant research and development and incorporates advances in medicine, implantable materials, electronic technology, and sound coding. This article presents the development of Cochlear's implant systems, with an overview of the first 3 generations, and details of the Freedom system: the CI24RE receiver-stimulator, the Contour Advance electrode, the modular Freedom processor, the available speech coding strategies, the input processing options of Smart Sound to improve the signal before coding as electrical signals, and the programming software. Preliminary results from multicenter studies with the Freedom system are reported, demonstrating better levels of performance compared with the previous systems. The final section presents the most recent implant reliability data, with the early findings at 18 months showing improved reliability of the Freedom implant compared with the earlier Nucleus 3 System. Also reported are some of the findings of Cochlear's collaborative research programs to improve recipient outcomes. Included are studies showing the benefits from bilateral implants, electroacoustic stimulation using an ipsilateral and/or contralateral hearing aid, advanced speech coding, and streamlined speech processor programming.

Acoustic Stimulation↗

PubMed2006

Preliminary results on correlation between neural response imaging and 'most comfortable levels' in cochlear implantation.

During cochlear implantation, precise placement of the cochlear electrodes against the cochlear nerve is one of the most important steps, necessary to enable the patient to be aware of the stimulus from the implanted device. Neural response imaging (NRI) is a new tool which measures the evoked compound action potential generated as a result of electrical stimulation of the cochlea by properly placed electrodes during surgery. The aim of this study was to examine the correlation between intra-operative NRI recordings and 'most comfortable levels' (M levels) measured during standard fitting with the SoundWave fitting software, in cochlear implantation patients. Seven adult subjects were included in the study. The average duration of profound bilateral deafness was seven years (range = 19 years) and the mean age at implantation was 24 years (range = 17-34 years). All subjects underwent implantation and reached the one-month fitting session; one patient reached the two-month fitting session. The intra-operative NRI threshold (tNRI) was observed to be much higher than the first fitting M levels. The tNRI was 203 per cent of the sequential M value and 246 per cent of the paired M value. All but one intra-operative tNRI values were greater than 150 clinical units (CU), and all first fitting M levels were on average below 100 CU. No obvious correlation was found between individual intra-operative tNRI and first fitting M levels. The M levels at one month were much higher than the first fitting M levels, with much more dispersion.

Adolescent↗

PubMed1998

Speech perception performance in experienced cochlear-implant patients receiving the SPEAK processing strategy in the Nucleus Spectra-22 cochlear implant.

Sixteen experienced cochlear implant patients with a wide range of speech-perception abilities received the SPEAK processing strategy in the Nucleus Spectra-22 cochlear implant. Speech perception was assessed in quiet and in noise with SPEAK and with the patients' previous strategies (for most, Multipeak) at the study onset, as well as after using SPEAK for 6 months. Comparisons were made within and across the two test sessions to elucidate possible learning effects. Patients were also asked to rate the strategies on seven speech recognition and sound quality scales. After 6 months' experience with SPEAK, patients showed significantly improved mean performance on a range of speech recognition measures in quiet and noise. When mean subjective ratings were compared over time there were no significant differences noted between strategies. However, many individuals rated the SPEAK strategy better for two or more of the seven subjective measures. Ratings for "appreciation of music" and "quality of my own voice" in particular were generally higher for SPEAK. Improvements were realized by patients with a wide range of speech perception abilities, including those with little or no open-set speech recognition.

Adult↗

PubMed1999

Multichannel cochlear implantation in children with cochlear ossification.

OBJECTIVE: To compare results of post-meningitic children who had cochlear implantation with partial or complete drill-out to those who had no drill-out. STUDY DESIGN: This study is a retrospective case review. SETTING: The Atlanta Cochlear Implant Group is a private, tertiary, outpatient clinic. PATIENTS: Eligibility included all our post-meningitic patients, 2-17 years, having a cochlear implant between June 1990 and July 1997. INTERVENTIONS: All subjects had a Nucleus 22 cochlear implant surgically implanted, speech processor programming and follow-up testing in our center, and aural rehabilitation in a variety of therapy settings. MAIN OUTCOME MEASURE: Open and closed set speech discrimination tests. RESULTS: Test performance for speech understanding was highest in the non-ossified group and lowest, but above chance, in the ossified group with complete drill-out. CONCLUSIONS: While children with non-ossified cochleas performed best, even children with extensive ossification requiring complete drill-out benefited from cochlear implantation.

Adolescent↗

PubMed2004

Late failure of cochlear implantation resulting from advanced cochlear otosclerosis: surgical and programming challenges.

OBJECTIVE: The objective of this study was to discuss cochlear implantation in the setting of severe cochlear otosclerosis and review programming challenges in a patient whose performance is deteriorating as a result of advancing disease. STUDY DESIGN: We conducted a case report and literature review. SETTING: Tertiary care medical center. PATIENTS, INTERVENTION, AND RESULTS: A case is presented of a 66-year-old man with otosclerosis who initially had good benefit from a cochlear implant but gradually lost benefit even with reimplantation. Imaging studies demonstrated severely distorted otic capsule anatomy from cochlear otosclerosis. CONCLUSIONS: Advancing cochlear otosclerosis can result in a severely thinned and distorted otic capsule. Although cochlear implantation is generally beneficial in cochlear otosclerosis, implantation in certain severe cases may be complicated as a result of difficulties with cerebrospinal fluid leak, programming challenges, and other potential hazards that can occur with a distorted anatomy.

Aged↗

PubMed2007

Using evoked potentials to match interaural electrode pairs with bilateral cochlear implants.

Bilateral cochlear implantation seeks to restore the advantages of binaural hearing to the profoundly deaf by providing binaural cues normally important for accurate sound localization and speech reception in noise. Psychophysical observations suggest that a key issue for the implementation of a successful binaural prosthesis is the ability to match the cochlear positions of stimulation channels in each ear. We used a cat model of bilateral cochlear implants with eight-electrode arrays implanted in each cochlea to develop and test a noninvasive method based on evoked potentials for matching interaural electrodes. The arrays allowed the cochlear location of stimulation to be independently varied in each ear. The binaural interaction component (BIC) of the electrically evoked auditory brainstem response (EABR) was used as an assay of binaural processing. BIC amplitude peaked for interaural electrode pairs at the same relative cochlear position and dropped with increasing cochlear separation in either direction. To test the hypothesis that BIC amplitude peaks when electrodes from the two sides activate maximally overlapping neural populations, we measured multiunit neural activity along the tonotopic gradient of the inferior colliculus (IC) with 16-channel recording probes and determined the spatial pattern of IC activation for each stimulating electrode. We found that the interaural electrode pairings that produced the best aligned IC activation patterns were also those that yielded maximum BIC amplitude. These results suggest that EABR measurements may provide a method for assigning frequency-channel mappings in bilateral implant recipients, such as pediatric patients, for which psychophysical measures of pitch ranking or binaural fusion are unavailable.

Animals↗

PubMed2000

[Preoperative imaging of the inner ear prior to the implantation of a multichannel cochlear implant using computed and MR technology].

CT and MRT are now standard examinations prior to insertion of a cochlear implant. Both methods have advantages and disadvantages in terms of discovering potentially pathological structures in the inner ear. The aim of this study was to evaluate the pros and cons of using CT and MRT before cochlear implantation. CT is usually performed using axial planigraphic planes. Like MRT, bone-specific CT is helpful in the diagnosis of congenital and acquired changes within the inner ear. Congenital defects in the meatus acusticus internus, the endolymphatic duct and sac, the cochlea and the vestibulum can be diagnosed and also quantified. Infectious morphologic changes can be seen on CT images in their terminal residual state (sclerotic tissue). However, acute inflammation and fibrotic tissue is not visible on CT. T2-specific MRT images are very fluid sensitive and play a major role in preoperative cochlear implant diagnosis. This examination demonstrates fluid within the peri- and enolymphatic cave and permits the diagnostician to determine whether congenital or acquired diseases have destroyed such fluid-filled cavities. In order to demonstrate pathological changes in the temporal bone and neural structures in the inner ear, MRT is the preferred method. Displaying the modiolus and the cochlear nerve is extremely important because, in their absence, a cochlear implantation may be contra-indicated. MRT also demonstrates other neural structures such as the facial nerve. This information may be important for the surgeon, e.g. the state of the pneumatic system in the mastoid cavity (which is best visualised by bone-specific CT).

Cochlear Implantation↗

PubMed1987

Technical development of an implantable cochlear prosthesis in Canada.

A new cochlear implant device is currently being developed by a group of research teams in Canada. This is an update on the progress of this development, including a brief description of the cochlear electrode array, the implantable stimulator, and the software development for the speech processor.

Cochlear Implants↗

PubMed1980

Neurophysiological requirements for implanted cochlear prostheses.

In a few introductory remarks the technological, neurophysiological and clinical assessments of new developments in modern, highly sophisticated hearing aids are reviewed. The necessity of preprocessing auditory information is discussed as well as the problems related to the choice of suitable electrodes, and, in particular, how much auditory information for speech communication, given by the product of number of just noticeable differences in intensity, number of just noticeable differences in frequency, number of channels for conveying neurophysiologically processable signals would be required as a minimum for cochlear implants to enable patients to communicate with one another. Finally, the fact that a number of different sensory modalities converge in to man's cortical association area might possibly be used for some special application of a multimodal input in a completely deaf patient with the aim of enabling him to understand human speech.

Animals↗

PubMed2001

The influence of age at implantation on performance with a cochlear implant in children.

OBJECTIVE: This study involved the assessment of speech recognition abilities as a function of age at implantation and length of cochlear implant use in children who received the Nucleus CI22M cochlear implant. STUDY DESIGN: Two separate analyses were performed. The first analysis involved the assessment of speech recognition performance as a function of length of time with a cochlear implant in 48 patients evaluated at 7 years of age. The second analysis involved the assessment of speech recognition performance as a function of age at implantation in 53 patients evaluated 36 months after implantation. Patients were divided into four groups based on length of implant use or age at implantation, and the results were analyzed by a repeated-measures analysis of variance. SETTING: This study was carried out at a tertiary academic medical center. PATIENTS: Patients consisted of children implanted with a Nucleus Multi Channel cochlear implant programmed with the SPEAK encoding strategy. Their ages at the time of evaluation ranged from 5.5 to 7.8 years. Their ages at implantation ranged from 2.4 to 14.5 years. INTERVENTIONS: All patients received a Nucleus Multi Channel cochlear implant programmed with the SPEAK encoding strategy. Word and sentence recognition tests were administered at various ages and at several postimplantation intervals. MAIN OUTCOME MEASURES: Performance as a function of length of cochlear implant use and as a function of age at implantation. RESULTS: Patients performed significantly better as length of cochlear implant use increased and age at implantation decreased. When patients were tested at a fixed postimplantation time interval (36 months), there was an overall trend for patients who received the implant at a younger age to perform better in spite of being younger at the time of evaluation. However, these effects were not statistically significant for all speech recognition tests that were administered. CONCLUSIONS: These results confirm previous findings indicating continued improvement of speech recognition with time in implanted children. Furthermore, the results support the concept of the advantage of a younger age at implantation.

Adolescent↗

PubMed2006

Vestibular impairment and cochlear implantation.

CONCLUSION: Cochlear implantation (CI) may induce vestibular impairment soon after surgery as well as after implant activation. This impairment seems to be independent from the cause of deafness and can be considered a possible complication from the intra-operative trauma and, to minor degree, from the ongoing electric stimulation. It would also seem that vestibular damage occurs independently from the likelihood of post-operative hearing deterioration. In unilateral selected CI cases, vestibular examination can be proposed as additional pre-operative exam for selection of the ear to be implanted. OBJECTIVES: This study has been planned in order to get evidence of eventual impairment of the vestibular apparatus after cochlear implantation as well as to verify whether the impairment could be related to different variables, such as cause of deafness, concomitant hearing deterioration, surgical trauma and duration of electrical stimulation. METHOD: Charts from two different populations of implantees have been reviewed, 21 from a prospective, 72 from a retrospective study, respectively. All the patients were implanted with Clarion(R) devices of different generation. Vestibular testing was based on rotatory, caloric (when possible) and stabilometric measurements, which were carried out pre-operatively and at the following different times: 5 weeks after CI surgery, and 30, 60 and 90 days after CI activation. Hearing thresholds were also assessed in those patients who showed signs of vestibular impairment as well as in a group of patients without vestibular disorders (control). Patients belonging to the retrospective group were all asked to fill a questionnaire regarding their balance condition. Results. In 14.3% of the prospective study group, a grade I and II spontaneous nystagmus was evidenced pre-operatively and remained unchanged during the whole assessment period. A grade II spontaneous nystagmus was present in 3 patients (21.4%) of the same group after surgery. In the immediate post-operative period, vestibular impairment was displayed as true rotational vertigo in 21.4% and unsteadiness in 42.8% of the study group. Severe unsteadiness was present during the first 2 days after activation in 14.3% of the subjects. In 21.4% of the patients a VPPB episode occured. In the retrospective study group, 26.4% of the subjects referred pre-operative dizziness and 25 patients (34.7%) referred immediate post-operative vertigo episodes, which remained in a milder form after CI activation in 12% of them. The hearing threshold showed to deteriorate in both vestibular-impaired and control CI population without significant difference.

Adolescent↗

PubMed1993

[Auditory achievements of cochlear implantation].

The cochlear implant, which stimulates the auditory nerve electrically, is a rehabilitative solution for the severely deaf who cannot benefit from a hearing aid. The implant enables them to rejoin the world of sound from which they were disconnected. We present the process of auditory diagnosis which determines the patient's suitability for cochlear implantation, the implant's tuning program and the rehabilitation process it entails. Each of the 22 implanted electrodes is checked through a computer program, and the specifications of the electrical stimulation are established to provide the most comfortable hearing level for the implanted device. These stimulation specifications determine the number of active electrodes and the ideal stimulation model. During the 8-week hearing-training program which follows implantation, the patients acquaint themselves with the new world of sound through which they will communicate with their environment. Of the 16 implanted patients 7 heard only via the implant, without the aid of lipreading, a result which is considered excellent. These patients are able to talk on the telephone with the aid of the implant. 1 patient refused to use the implant, while the others have had good to moderate results. Noteworthy is the fact that even those with only moderate results greatly benefit from the implant, and are not willing to function without it for even a single day.

Adolescent↗