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PubMed2005

Electrophysiological and speech perception measures of auditory processing in experienced adult cochlear implant users.

OBJECTIVE: This study determined the relationship between auditory evoked potential measures and speech perception in experienced adult cochlear implant (CI) users and compared the CI evoked potential results to those of a group of age- and sex-matched control subjects. METHODS: CI subjects all used the Nucleus CI-22 implant. Middle latency response (MLR), obligatory cortical potentials (CAEP), mismatch negativity (MMN) and P3a auditory evoked potentials were recorded. Speech perception was evaluated using word and sentence tests. RESULTS: Duration of deafness correlated with speech scores with poor scores reflecting greater years of deafness. Na amplitude correlated negatively with duration of deafness, with small amplitudes reflecting greater duration of deafness. Overall, N1 amplitude was smaller in CI than control subjects. Earlier P2 latencies were associated with shorter durations of deafness and higher speech scores. In general, MMN was absent or degraded in CI subjects with poor speech scores. CONCLUSIONS: Auditory evoked potentials are related to speech perception ability and provide objective evidence of central auditory processing differences across experienced CI users. SIGNIFICANCE: Since auditory evoked potentials relate to CI performance, they may be a useful tool for objectively evaluating the efficacy of speech processing strategies and/or auditory training approaches in both adults and children with cochlear implants.

Acoustic Stimulation↗
PubMed2006

Speech recognition for unilateral and bilateral cochlear implant modes in the presence of uncorrelated noise sources.

OBJECTIVE: The purpose of the current investigation was to compare speech recognition in noise for bilateral and unilateral modes within postlingually deafened, adult bilateral cochlear implant recipients. In addition, it was of interest to evaluate the time course of the bilateral speech-recognition advantage and the effect of changing signal-to-noise ratio (SNR) on the magnitude of the bilateral advantage. DESIGN: In the first experiment, 16 postlingually deafened adults who were bilaterally implanted with the MED-EL C40+ cochlear device were evaluated in unilateral left, unilateral right, and bilateral conditions 4 to 7 mo after activation. Speech recognition in the presence of five spatially separated, uncorrelated noise sources was evaluated using both a single fixed SNR of +10 dB and an adaptive-SNR method. In a follow-up study, a subset of 10 participants was re-evaluated using an identical fixed-SNR method 12 to 17 mo after activation to examine the time course of speech-recognition performance in both unilateral and bilateral modes at a single SNR. A third study was performed with a subset of six participants to examine performance over a range of SNRs. In this study, speech recognition was measured 12 to 17 mo after activation in quiet and at +5, +10, +15, and +20 dB SNRs using the same five uncorrelated noise sources. RESULTS: The speech-recognition data revealed a significant bilateral advantage of 3.3 dB using the adaptive-SNR method. A significant bilateral advantage of 9% was also measured using a fixed +10 dB SNR. Results from the second study revealed that experience resulted in a significant (11 to 20%) increase in speech-recognition-in-noise performance for both unilateral and bilateral modes; however, the magnitude of the bilateral advantage was not affected by experience. Results from the third study revealed the largest bilateral advantage at the poorest SNR evaluated. In addition, performance in quiet was significantly better than that measured in the presence of noise, even at the +20 dB SNR. CONCLUSIONS: The results of these experiments support a small but significant bilateral speech-recognition-in-noise advantage for cochlear implant recipients in an environment with multiple noise sources. This advantage is presumed to be attributable to the combined effects of binaural squelch and diotic summation. Although experience generally improved speech-recognition-in-noise performance in both unilateral and bilateral modes, a consistent bilateral advantage (approximately 10%) was measured at 4 to 7 mo and at 12 to 17 mo postactivation.

Acoustic Stimulation↗
PubMed2000

Cochlear implantation: minimal hair removal technique.

This prospective study was undertaken to evaluate the safety and patient acceptance of minimal hair removal during cochlear implantation. Forty-six consecutive patients (17 adults, 29 children; age range 13 months to 84 years) received cochlear implantation with a minimal hair removal technique. A questionnaire was used to evaluate acceptance and value of this technique among the first 15 patients and parents. Postoperative examinations were completed 1 and 4 weeks after implantation. Patients were monitored for complications, which included 3 cases of transient seroma, 2 cases of transient dysequilibrium, 2 individual electrode failures, and 1 facial nerve stimulation. Importantly, no wound infections were documented. Use of a small shave technique did not increase surgical risk. This technique has proved to be cosmetically and psychologically more desirable for the patients and their families than complete hair removal in the operative field.

Adolescent↗
PubMed1997

Cochlear implantation in common cavity malformations using a transmastoid labyrinthotomy approach.

The transmastoid facial recess approach has become the standard technique for cochlear implantation. Although this approach has been used for implantation in patients with common cavity deformities, it is not without increased risk to the facial nerve. Using a direct approach to the common cavity that circumvents the facial recess, we have successfully implanted four patients with common cavity deformities. An aberrant facial nerve in one patient would have precluded placement of the electrode array using standard cochlear implant techniques. As demonstrated in these four patients, the direct approach to the common cavity is an effective approach for placement of the electrode array, minimizes risk to the facial nerve, and may decrease the likelihood of postoperative cerebrospinal fluid leaks. Intraoperative video footage demonstrates the feasibility and facility of this approach in patients with common cavity deformities.

Child↗
PubMed1997

Results of speech processor upgrade in a population of Veterans Affairs cochlear implant recipients.

OBJECTIVE: This study aimed to evaluate the change in performance when the Speak processing strategy replaced the Mpeak strategy. SUBJECTS: Twenty-one veterans who participated in the original Department of Veterans Affairs Multicenter Cochlear Implant Study, received the Nucleus F0F1F2 processor (Cochlear Corp., Englewood, CO, U.S.A.) (WSP) and were subsequently upgraded to the Mpeak (MSP) processing strategy. METHODS: Closed- and open-set speech recognition in quiet and in noise in auditory only conditions at the phoneme, word, and sentence levels were evaluated. RESULTS: Changes in audiologic parameters were evaluated using a paired t-test for related samples. Statistically significant improvements in mean scores were found for all tests and were greatest for the speech-in-noise conditions. An examination of individual data revealed that 61% of the subjects improved for tests administered in quiet, whereas up to 69% of the subjects had improved performance in noise. Subjects with no open set speech discrimination using the Mpeak strategy showed no improvement with the Speak strategy. CONCLUSIONS: Cochlear implants can provide improved performance using modifications to external speech processor hardware and software without changing the internal implant.

Cochlear Implants↗
PubMed1999

Development of the Midland adult cochlear implant programme.

This paper describes the development of adult cochlear implantation in Birmingham over its first six years, from 1990 to 1996. During this time 366 patients were referred to the implant programme, female referrals outnumbered males 1.2:1. Eight per cent of referrals were over the age of 70. The annual rate of referral suggests a fairly steady demand for the service. Approximately one third of patients referred each year were subsequently implanted. The centre is currently performing an average of 2 implants per month. The average time from referral to implant is approximately 19 months. The greatest number of referrals originated from health districts closest to the implant centre. An examination of patients implanted suggested an imbalance in the uptake of the service amongst the different socio-economic groups.

Aged↗
PubMed1991

[Cochlear implants, which one to choose?].

The choice of a cochlear implant is a difficult one. A given type of implant does not yet correspond to a given type of patient. Our indications have to be refined by acquired experience and through the improvement of tests prior to implanting. The implants available present different features, but they all improve the communication of the profoundly deaf to different degrees, by attenuating their tinnitus.

Cochlear Implants↗
PubMed1995

Cortical activation during sound stimulation in cochlear implant users demonstrated by positron emission tomography.

Three patients with prelingual deafness and six patients with postlingual deafness using multichannel cochlear implants were examined by positron emission tomography using 15O-labeled water. Changes in regional cerebral blood flow (rCBF) were measured during three different sound stimuli: 1) with no sound stimulation, with the speech processor of the cochlear implant system switched off, 2) hearing white noise, and 3) hearing sequential Japanese sentences. In postlingually deaf patients, speech stimulation caused a significantly greater rCBF increase compared with noise stimulation in the left immediate auditory association area and the bilateral auditory association areas. In these patients, speech sound is thought to be processed by means of auditory cortices analogous to those in normal subjects. In contrast, in prelingually deaf patients, speech sound induced much less rCBF increase in auditory association cortices; this finding suggested underdevelopment of the neural network for complex sound analysis and speech sound recognition.

Acoustic Stimulation↗
PubMed1993

Speech discrimination via cochlear implants with two different digital speech processing strategies: preliminary results for 7 patients.

The following processing strategies have been implemented on an experimental laboratory system of a cochlear implant digital speech processor (CIDSP) for the Nucleus 22-channel cochlear prosthesis. The first approach (PES, Pitch Excited Sampler) is based on the classical channel vocoder concept whereby the time-averaged spectral energy of a number of logarithmically spaced frequency bands is transformed into appropriate electrical stimulation parameters for up to 22 electrodes. The pulse rate at any electrode is controlled by the voice pitch of the input speech signal. The pitch extraction algorithm calculates the autocorrelation function of a lowpass-filtered segment of the speech signal and searches for a peak within a specified time window. A random pulse rate of about 150 to 250 Hz is used for unvoiced speech portions. The second approach (CIS, Continuous Interleaved Sampler) uses a stimulation pulse rate which is independent of the input signal. The algorithm scans continuously all specified frequency bands (typically between 4 and 22) and samples their energy levels. Evaluation experiments with 7 experienced cochlear implant users showed significantly better performance in consonant identification tests with the new processing strategies than with the subjects' own wearable speech processors whereas improvements in vowel identification tasks were rarely observed. Modifications of the basic PES- and CIS-strategies resulted in large variations of identification scores. Information transmission analysis of confusion matrices revealed a rather complex pattern across conditions and speech features. No final conclusions can yet be drawn. Optimization and fine-tuning of processing parameters for these coding strategies require more data both from speech identification and discrimination as well as psychophysical experiments.

Acoustic Stimulation↗
PubMed2003

[Cochlear implants in adults: indications and realizations. Part I: Diagnosis, operation techniques and results].

From the technical point of view, cochlear implant (CI) surgery in adults is a well established procedure. Pre- and postoperative evaluation, surgical approach and rehabilitation programs are standardized, presenting CI as a low risk procedure with rare complications similar to those of middle ear surgery. Modern advanced CI devices offer technical reliability and multiple speech encoding strategies and recently, even small processors which are worn behind the ear. Further technical advances are continuously available, even for implanted patients. Upgrading is usually easy because the outer parts of the implant are exchangeable and software upgrades can be transmitted transcutaneously to the implant. Assuming that medical and rehabilitation requirements are available, there are only very few indications against CI in adults. Candidate patients should therefore be transferred to CI-centres where a decision can be taken depending on presurgical evaluation results.

Adult↗
PubMed1994

Cochlear implantation in young children: histological studies on head growth, leadwire design, and electrode fixation in the monkey model.

For safe cochlear implantation in children under 2 years of age, the implant assembly must not adversely affect adjacent tissues or compromise head growth. Furthermore, growth changes and tissue responses should not impair the function of the device. Dummy receiver-stimulators, interconnect plugs, and leadwire-lengthening systems were implanted for periods of 36 months in the young monkey to effectively model the implantation of the young child. The results show that implanting a receiver-stimulator package has no adverse effects on skull growth or the underlying central nervous system. The system for fixing the electrode at the fossa incudis proved effective. There was marked osteoneogenesis in the mastoid cavity, resulting in the fixation of the leadwire outside the cochlea. This study provides evidence for the safety of cochlear implantation in young subjects.

Animals↗
PubMed1998

Performance with the 20 + 2L lateral wall cochlear implant.

OBJECTIVE: The purpose of this study was to investigate the operating characteristics of the Nucleus 20 + 2L lateral wall cochlear implant including speech recognition results. STUDY DESIGN: This was a prospective randomized study involving five different modes of stimulation. SETTING: This study was carried out in an academic, tertiary referral center. PATIENTS: The patients included in this study were adult cochlear implant candidates ages 44-74 years. Length of deafness ranged from 1 to 58 years with a variety of etiologies. INTERVENTIONS: All patients were implanted with a 20 + 2L implant, which includes an intrascalar electrode array and an apically placed extracochlear, titanium encased ball electrode in contact with the endosteum of the apical turn. All patients underwent psychophysical and speech recognition testing in five different modes of electrode configuration. MAIN OUTCOME MEASURE(S): The main outcome measures included thresholds, comfort levels, dynamic ranges, and speech recognition results obtained in five electrode configuration modes. RESULTS: Thresholds were significantly lower (repeated measures ANOVA) in both monopolar conditions when compared to bipolar mode of stimulation. A binomial statistical analysis indicated that in five of nine patients activated in all five modes of stimulation, the monopolar modes of stimulation resulted in improved speech recognition scores. CONCLUSIONS: The results of the study demonstrate the feasibility of the use of an apical lateral cochlear wall electrode in conjunction with an intrascalar electrode array. It further demonstrated the superiority of monopolar stimulation in selected patients.

Adult↗
PubMed1983

Impact of FDA regulations on the cochlear implant field.

An overview of the impact of the FDA's investigational device regulation on the field of the cochlear implants has been presented. It can be seen that the regulation has been established to provide a legal framework for conducting clinical investigations with medical devices. The regulation incorporates the concepts of institutional review and the informed consent of the patient. These concepts are not new; they have existed for a long time as part of medical research in the United States. We believe that the institutional review board will serve to effectively review and monitor the clinical course of patients receiving cochlear implants. We also believe that we have developed a regulation that maximizes patient safety, while encouraging investigation of the device. We understand and appreciate that IRB monitoring is far more efficient and effective than having FDA personnel on hand at various institutions around the country to monitor investigational studies. We know full well the added complexity that a bureaucratic monitoring process can bring to a clinical investigation. We think that the IRB approach is the most direct, straightforward, protective, and cost-effective approach that can be taken. We appreciate the benefit that a patient receives in having a competent and expert investigator. The regulations were written to rely on these investigators for expertise in their particular specialty in conducting and evaluating the clinical studies. We recognize the role of the sponsor, who has made a commitment to the improvement of health care through advancement in technology, and who seeks to restore or to produce some degree of hearing for the totally deaf. Without a sponsor, these studies would not be possible. And last, but not least, we recognize the all-important role of the patient, who provides the clinical data base. The patient's welfare and safety must be considered in any clinical study. The IDE regulation has been in effect since July 1980. It provides the opportunity for the FDA and the medical and scientific communities to work together for the success of medical-device investigations. We can all pride ourselves on our high standard of medical excellence. When we can work together, this standard will rise even higher.

Cochlear Implants↗
PubMed1999

Using electrically evoked auditory reflex thresholds to fit the CLARION cochlear implant.

This paper describes a method for measuring electrically elicited auditory reflex thresholds (EARTs) in young children who use the CLARION Multi-Strategy Cochlear Implant. The EART is an objective measure that can guide the fitting of a cochlear implant in individuals who are unable to perform behavioral tasks required to program the device. Reflexes were obtained in 11 of 17 pediatric Clarion users. The EART current level indicated a point at which an auditory percept was present and the sound was loud, but not uncomfortable. The EART then was used as a basis for conditioning behavioral responses, and as a guideline for setting most comfortable loudness levels.

Cochlear Implantation↗
PubMed2004

Cochlear implantation in children under the age of two--what do the outcomes show us?

OBJECTIVES: Literature that discusses the benefits of cochlear implantation (CI) in children under the age of two is limited. Previous concerns about surgical risk have been raised and addressed; however, actual benefit in terms of outcomes needs to be clearly defined. This study evaluates outcomes of children implanted under the age of two and compares them to children implanted at a later age. METHODS: Data were reviewed from the MED-EL International Children's study database. Thirty-seven children enrolled in the study have received cochlear implants before the age of two. Outcomes were assessed using the LiP and MTP tests and the MAIS and MUSS questionnaires pre-operatively and then at initial fitting, 1, 3, 6 and 12 months after first fitting and then annually thereafter. RESULTS: Statistical analysis demonstrated that these children's scores improved significantly over time. Improvement was shown to occur at a quicker rate than for children implanted at an older age with the MTP and MUSS, but not with the LiP and the MAIS. Scores may be limited by sample size and the fact that children reached ceiling on some tests. CONCLUSIONS: Results suggest a distinct advantage early implantation may have for severe to profoundly hearing impaired children. This may be particularly the case for skills necessary for development of receptive and expressive language skills.

Age Factors↗
PubMed1999

Cochlear implants in young children: the relationship between speech perception and speech intelligibility.

OBJECTIVE: To determine the relationship between measures of speech perception and speech production after cochlear implantation of young children with profound congenital and prelingual deafness. DESIGN: A prospective study was undertaken on a consecutive group of children with profound deafness. There were 126 children at the preimplantation interval and 71, 50, 26, and 20 children, respectively, at the 2, 3, 4, and 5 yr follow-up after implantation. Speech perception and speech intelligibility were assessed using hierarchical rating scales. Spearman rank correlation coefficients were used to determine the statistical correlations. All patients were either congenitally deaf or deafened before the age of 3 yr and were implanted before age 7 yr. The patients all received the Nucleus multichannel cochlear implant system with the most appropriate speech encoding strategy. RESULTS: Speech intelligibility at 5 yr was strongly correlated with speech perception at the 2, 3, 4, and 5 yr intervals after implantation (Spearman coefficients 0.77, 0.81, 0.58, 0.58; p < or = 0.01). Speech intelligibility at the 2, 3, and 4 yr intervals also correlated in a similar manner with earlier speech perception abilities (p < or = 0.01). CONCLUSIONS: The results suggest that speech intelligibility between 2 and 5 yr after implantation in young children with congenital and prelingual profound deafness can be predicted by measures of earlier speech perception.

Age Factors↗