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PubMed2005

Auditory localization abilities in bilateral cochlear implant recipients.

OBJECTIVE: To quantify binaural advantage for auditory localization in the horizontal plane by bilateral cochlear implant (CI) recipients. Also, to determine whether the use of dual microphones with one implant improves localization. METHODS: Twenty subjects from the UK multicenter trial of bilateral cochlear implantation with Nucleus 24 K/M device were recruited. Sound localization was assessed in an anechoic room with an 11-loudspeaker array under four test conditions: right CI, left CI, binaural CI, and dual microphone. Two runs were undertaken for each of five stimuli (speech, tones, noise, transients, and reverberant speech). Order of conditions was counterbalanced across subjects. RESULTS: Mean localization error with bilateral implants was 24 degrees compared with 67 degrees for monaural implant and dual microphone conditions (chance performance is 65 degrees). Normal controls average 2 to 3 degrees in similar conditions. Binaural performance was significantly better than monaural performance for all subjects, for all stimulus types, and for different sound sources. Only small differences in performance with different stimuli were observed. CONCLUSIONS: Bilateral cochlear implantation with the Nucleus 24 device provides marked improvement in horizontal plane localization abilities compared with unilateral CI use for a range of stimuli having different spectral and temporal characteristics. Benefit was obtained by all subjects, for all stimulus types, and for all sound directions. However, binaural performance was still worse than that obtained by normal hearing listeners and hearing aid users with the same methodology. Monaural localization performance was at chance. There is no benefit for localization with dual microphones.

Acoustic Stimulation↗

PubMed1987

Cochlear implant: audiometric results with a single-channel device.

With the FDA approval of the first cochlear implant device in November 1984, the possibility of the perception of sound became a reality for the profoundly deaf individual. The cochlear implant group of Cincinnati was involved in the coinvestigator study before the approval of the device. This paper presents data from seven patients with cochlear implants and the resulting improvement in their hearing perception, as well as a discussion about which patients can benefit from the cochlear implant.

Adult↗

PubMedDate not supplied

The cochlear implant program: an overview.

The single-electrode cochlear implant used at the House Ear Institute is undergoing clinical trials under Food and Drug Administration regulations governing medical devices. The program involves selection and evaluation of suitable subjects, surgery, basic guidance or training in implant use, and regular follow-up. As of November 1, 1981, 199 deaf subjects have had cochlear implant surgery. They range in age from 3.5 to 75 years old. Subjects with a wide variety of etiologies have been successfully implanted. The vast majority use their device on a daily basis, and subjects as a group have received more than 800,000 hours of electrical stimulation. Fifteen other otologists in the United States have implanted one or more subjects as coinvestigators in this clinical trials program. The otologists and their implant teams are trained by the House Ear Institute. Results indicate that the implant program can be performed adequately in a variety of clinical settings.

Adolescent↗

PubMed2005

Speaker normalization for chinese vowel recognition in cochlear implants.

Because of the limited spectra-temporal resolution associated with cochlear implants, implant patients often have greater difficulty with multitalker speech recognition. The present study investigated whether multitalker speech recognition can be improved by applying speaker normalization techniques to cochlear implant speech processing. Multitalker Chinese vowel recognition was tested with normal-hearing Chinese-speaking subjects listening to a 4-channel cochlear implant simulation, with and without speaker normalization. For each subject, speaker normalization was referenced to the speaker that produced the best recognition performance under conditions without speaker normalization. To match the remaining speakers to this "optimal" output pattern, the overall frequency range of the analysis filter bank was adjusted for each speaker according to the ratio of the mean third formant frequency values between the specific speaker and the reference speaker. Results showed that speaker normalization provided a small but significant improvement in subjects' overall recognition performance. After speaker normalization, subjects' patterns of recognition performance across speakers changed, demonstrating the potential for speaker-dependent effects with the proposed normalization technique.

Artificial Intelligence↗

PubMed2004

Simple method to control a cerebrospinal fluid gusher during cochlear implant surgery.

OBJECTIVE: : Perilymph/cerebrospinal fluid gushers are reported at the time of cochleostomy during the performance of cochlear implant surgery. Anatomic conditions are discussed. Surgical methods of control with tissue seals have varied results. A simple technique using bone-waxed silk suture is described. PATIENTS: : Three patients with perilymph/cerebrospinal fluid gushers were encountered during cochlear implant surgery in the Louisiana State University Cochlear Implant Project. A simple method for control of these leaks is described using lengths of bone-waxed silk suture. CONCLUSIONS: : This safe and rapid technique is a useful addition to the armamentarium of the cochlear implant surgeon.

Adult↗

PubMed2000

Cochlear implantation and change in quality of life.

The aim of this study was to assess the benefits of cochlear implantation (CI) in adults and to evaluate the average implant usage per day. Ten profoundly deaf adults were implanted during the period April 1994 to September 1997. The patients answered questionnaires 1 year or more after receiving their cochlear implants. All of the patients used their implant daily. The average implant usage per day was 16 h. The patients stated that, given the choice, they would again opt for a cochlear implant and would recommend a cochlear implant for a deaf friend. A paired comparison showed that the implants led to significant improvements in a number of factors: self-perceived communication skills, frequency of conversation with others, telephone usage, self-confidence and the impact of hearing impairments on family life. CI dramatically changed the quality of life for all patients. No surgical complications were observed.

Adult↗

PubMed2002

Auditory brain stem and midbrain development after cochlear implantation in children.

Input to the central auditory system through a cochlear implant promotes psychophysical improvement of auditory skills. However, the developmental changes along the pathways have never been characterized in children with hearing loss who use implants. We aimed to measure auditory development in such children by using the electrically evoked auditory brain stem response (EABR). We made repeated measures of the EABR in 41 nonsedated children with implants before chronic stimulation and after 2, 6, and 12 months of consistent implant use. The results show that EABRs were present in all of the children even before chronic auditory stimulation, and that EABR wave latencies decreased from the time of initial activation throughout the first year of cochlear implant use. These findings reflect auditory development to the level of the midbrain as a result of the cochlear implant. The decreasing latencies likely reflect decreased neural conduction times at this level, in part because of increased synaptic efficacy.

Adolescent↗

PubMed2006

Effects of stimulus level on the speech perception abilities of children using cochlear implants or digital hearing aids.

OBJECTIVE: The present investigation was designed to provide information to facilitate the decision of whether a child should continue using digital signal processing (DSP) hearing aids with wide dynamic range compression (WDRC) or be recommended for a cochlear implant, based on the unaided pure-tone average (PTA at 500, 1000, and 2000 Hz). DESIGN: Fifty-two children (ages 5 to 15 yr) with unaided PTAs in the moderately severe to profound range, wearing (DSP) hearing aids with (WDRC) or a Nucleus 24, Clarion 1.2, or CII cochlear implant system, participated: 26 with unaided PTAs from 60 to 98 dB HL using DSP hearing aids and 26 with pre-implant unaided PTAs from 93 to 120 dB HL, using cochlear implants. An open-set speech perception test, the Lexical Neighborhood Test (LNT; ), was administered at intensity levels representative of raised (70 dB SPL) and soft (50 dB SPL) speech at two different times approximately 1 mo apart. Minimum audibility of soft sounds was determined for the children with implants and with DSP hearing aids using warble-tone thresholds at octave intervals between 250 and 4000 Hz. RESULT: Regression analyses and significance testing were used to determine the unaided PTA values at which the performance of the DSP Hearing Aid group (DSP HA group) and Cochlear Implant group on the LNT test were statistically different at the 0.05 significance level. For the 70 dB SPL presentation level, the statistically different PTAs were 113 and 97 dB HL at Time 1 and Time 2, respectively, and 96 and 88 dB HL at 50 dB SPL for Time 1 and Time 2, respectively. CONCLUSIONS: The Unaided PTA at which children in the cochlear implant group would be expected to score significantly better than the children in the DSP HA group was lowest (96 and 88 dB HL) for the lower signal level (50 dB SPL). Assuming that LNT scores at 50 dB SPL are representative of long-term hearing of soft incidental speech that is essential for language learning and fluent communication, the children with PTA values greater than the range from 88 to 96 dB HL would be expected to have significantly better LNT scores with a cochlear implant. These results should be further examined with research efforts focusing on early intervention with optimally fitted DSP hearing aids and cochlear implants.

Acoustic Stimulation↗

PubMed2005

A prospective randomized controlled trial evaluating alcohol on loudness perception in cochlear implant users.

AIM: The aim of this study was to determine the effects of alcohol on the psychophysical responses in patients with cochlear implants. This has not been previously studied. It was also hoped to provide information that could suggest possible sites of action of the known effects of alcohol on the auditory pathway. DESIGN: A prospective randomized placebo-controlled trial, with full ethical approval. PARTICIPANTS: Eight successful cochlear implant users were selected, of whom two had bilateral implants which were tested separately. In total 10 cochlear implants were tested. INTERVENTION: Alcohol was given in the form of vodka (50% alcohol, 1 mL/kg body weight) with 500 mL of orange and cranberry juice. The placebo control was given in the form of 500 mL of orange and cranberry juice alone. OUTCOME MEASUREMENT: The 'comfort level' (C level) was recorded before, and 1 h after alcohol or placebo ingestion for each patient's cochlear implant. Blood alcohol concentration was determined prior to alcohol or placebo consumption and then repeated after 45, 60, 90 and 180 min. RESULTS: The mean blood alcohol concentration 1 h after ingestion was 50 mg/dL. In the 'alcohol' arm the mean electrical unit increase in the C level was 19.9 with a standard deviation of 2.2. In the control arm the mean change in C level was 0.10 with a standard deviation of 0.3. CONCLUSIONS: In this first prospective randomized control study of the effect of alcohol on sound perception in cochlear implant users, alcohol significantly increased the upper end of the dynamic range (C levels) in comparison with placebo (P = <0.0001 using paired t-test analysis). This effect is likely to be the result of change in the auditory pathways proximal to the cochlea.

Adult↗

PubMed1996

Enhancement of vowel coding for cochlear implants by addition of noise.

Profoundly deaf people, who gain no benefit from conventional hearing aids, can receive speech cues by direct electrical stimulation of the cochlear nerve. This is achieved by an electronic device, a cochlear implant, which is surgically inserted into the ear. Here we show physiological results from the isolated sciatic nerve of the toad Xenopus laevis, used to predict the response of the human cochlear nerve to vowels coded by a cochlear implant. These results suggest that standard analogue cochlear implants do not evoke the patterns of neural excitation that are normally associated with acoustic stimulation. Adding noise to the stimulus, however, enhanced distinguishing features of the vowel encoded by the fine time structure of neural discharges. On the basis of these results, and those concerning stochastic resonance, we advocate a cochlear implant coding strategy in which noise is deliberately added to cochlear implant signals.

Action Potentials↗

PubMed1991

Cochlear implants: indications and technology.

Over the last decade, the field of cochlear implants has progressed to the point where many postlinguistically deaf adults can use a multichannel device to understand speech without lipreading. The remainder are able to use their devices to aid in lipreading and to discriminate environmental sounds. It is anticipated that improved processing schemes will be developed so that the cochlear implant user can expect better speech perception with these devices. Eventually, a more sophisticated cochlear implant that has the capability of permitting good speech discrimination may supplant hearing aids for severely deafened individuals. Regardless of future developments, the present-day systems effectively restore auditory function to profoundly deafened children and adults.

Cochlear Implants↗

PubMed2004

Cochlear implantation in children with congenital inner ear malformations.

OBJECTIVE/HYPOTHESIS: To assess the audiologic and surgical outcomes for pediatric cochlear implant patients with inner ear malformations. STUDY DESIGN: Retrospective review of 315 pediatric cochlear implant cases from 1994 to 2002. METHODS: Twenty-eight pediatric cochlear implant patients with known inner ear malformations determined on high-resolution computed tomography (HRCT) of the temporal bone were the subjects of review. Results of HRCT findings, intraoperative findings, postoperative complications, and objective measures of both closed- and open-set testing of speech perception were analyzed. RESULTS: Patients with the constellation of an incompletely partitioned (IP) cochlea, enlarged vestibular aqueduct (EVA), and a dilated vestibule (i.e., Mondini's malformation) as well as those with an isolated EVA or partial semicircular canal aplasia have relatively good levels of speech perception. Patients with total semicircular canal aplasia, isolated IP, cochlear hypoplasia, or common cavity demonstrated lower levels of performance. Poor performance may be related to associated developmental delays rather than labyrinthine anatomy alone. Complications of surgery were relatively limited. CONCLUSIONS: Cochlear implantation can be successfully performed in children with inner ear malformations. These children and their parents can expect significant auditory benefits from this intervention. The various types of inner ear malformations may have quite different prognoses for good auditory performance.

Adolescent↗

PubMed1997

A comparison of vowel production by children with multichannel cochlear implants or tactile aids: perceptual evidence.

OBJECTIVE: To examine changes in perceived vowel production accuracy over time in prelingually deafened children who use a multichannel cochlear implant (Nucleus 22 channel) or a multichannel tactile aid (Tactaid 7) and to compare the levels of perceived vowel production accuracy attained by the two device groups. DESIGN: The subjects were participants in longitudinal studies of the effects of sensory aids on the development of perceptual, speech, and language skills. As part of these studies, imitative vowel productions were elicited and transcribed before each child received their sensory aid and at 6 mo intervals thereafter. Data for the current study was obtained from the predevice interval and a later interval (postdevice) that was an average of 1.8 yr after the subjects received their respective devices. The subjects' vowel productions were judged for accuracy in matching an imitative model and for correctness of vowel features (height and place). Within-group analyses were completed to determine if vowel production scores improved over the course of the study for each device group. Between group comparisons were performed to examine differences in mean scores at each interval. RESULTS: Before receiving their multichannel devices, the two groups of subjects demonstrated similar imitative vowel production skills. After an average of 1.8 yr of device use, the cochlear implant subjects demonstrated significantly improved production of diphthongs and all vowel categories except low vowels. The Tactaid 7 subjects demonstrated significant improvement only in the production of diphthongs. Thus, cochlear implant recipients' vowel production skills were found to be significantly better than those of the Tactaid 7 users after a comparable amount of device experience. CONCLUSIONS: The vowel production gains of the cochlear implant subjects were similar in amount to those noted in other studies of children who use the Nucleus multichannel cochlear implant and further confirm the potential of this device for improved speech production in prelingually deafened children. The differences between the performance of the two groups demonstrate that vowel production skills improved to a greater degree through use of a multichannel cochlear implant than through use of the Tactaid 7.

Child↗

PubMed2005

Estimating time and out-of-pocket costs incurred by families attending a pediatric cochlear implant programme.

OBJECTIVES: The objectives of this study are to estimate time and out-of-pocket costs incurred by families attending a pediatric cochlear implant programme. In addition, qualitative data examine the intangible costs faced by families. METHODS: Data was collected during semi-structured face-to-face interviews with parents of children with a cochlear implant attending a clinic visit at Nottingham Cochlear Implantation Programme (NPCIP), UK. Information supplied included socio-demographic characteristics, mode of travel, out-of-pocket expenses, time foregone, and details of companions. Quantitative data was stored and analysed in SPSS version 11.5. RESULTS: Two hundred and sixteen face-to-face interviews were conducted with parents of children implanted for between 1 month and 13 years. Time and out-of-pocket costs were significantly higher for those in the first 2 years of the programme, mean UK pound 3090 per annum compared to UK pound 2159 per annum for those in years >2-5 and UK pound 1815 per annum for those in years >5 (P<0.001). The biggest component of this was time costs, although the sensitivity analysis revealed that these were also most variable depending on the methods used to estimate them. The largest out-of-pocket cost incurred by families was travel costs which accounted for 44%, although 16% of families received some financial help with travel costs. The qualitative findings are consistent with these findings, also showing that over time the financial and intangible costs incurred as a result of cochlear implantation decline. CONCLUSIONS: This study is the first to obtain primary data on the time and out-of-pocket costs incurred by families attending a pediatric cochlear implant programme in the UK. It finds that these costs are greatest for those families in the first 2 years of the programme and/or who live furthest from the programme.

Absenteeism↗

PubMed1992

Temporal modulation transfer functions in patients with cochlear implants.

Thresholds for the detection of amplitude modulation were measured in cochlear implant patients as a function of modulation frequency. Three types of threshold measures were taken: detection of amplitude modulation, detection of low-frequency sinusoidal current waveforms, and detection of beats in two-tone complexes. The temporal modulation transfer function (TMTF), defined as the plot of modulation detection thresholds as a function of modulation frequency, show low-pass filter characteristics with similar cutoff frequencies for all three tasks. The similarity of these three measures suggests a common temporal mechanism. While modulation detection differs somewhat in normal-hearing and implanted listeners, both exhibit the same general characteristics. The TMTFs are low pass with a cutoff frequency near 70 Hz for normal-hearing listeners and near 140 Hz for implanted listeners. Patients with cochlear implants can best detect temporal modulation at modulation frequencies below 300 Hz, and are most sensitive to 80- to 100-Hz modulation. At high carrier levels many implant patients could detect smaller modulation amplitudes than normal-hearing listeners, a finding that is consistent with the smaller intensity DLs for some implanted listeners at high levels. These results demonstrate that, while implant listeners cannot discriminate steady-state, high-frequency stimuli, speech information might be conveyed by the envelope of the high-frequency components of speech.

Auditory Threshold↗

PubMedDate not supplied

Cochlear implants in China.

China has approximately 6 million totally deaf people according to an official survey conducted in 1990, although the actual number is probably higher. A primary cause of deafness is the use of ototoxic drugs. There does not appear to be any emergent deaf culture in China at present. As the only available medical device that can restore partial hearing to a totally deaf person, the cochlear implant has been in development in China since 1979. This paper provides an overview of cochlear implants in China and is based on a review of published materials, visits to research institutes and hospitals, and personal communication with Chinese colleagues. As of 1993, about 1,000 deaf people, including 50 children below age 12 years, have received four types of single-electrode cochlear implants that were developed and fabricated by institutions in China. These single-electrode devices have provided an aid to lip reading, but are no longer in use due to their inability to produce open-set speech recognition. Present implant research in China focuses on development of multi-electrode devices. Basic research in electrical stimulation is relatively lacking and standardized audiological evaluation for cochlear implant effectiveness needs to be developed. The present economic growth and legal system reform in China, combined with advances in implant technology, may make it possible to produce an affordable yet effective cochlear implant system. This paper discusses cochlear implants only in China, but the social and economic factors are similar in many developing countries in Asia, South America, Eastern Europe, and Africa, where a low-cost, high-performance cochlear implant system is also needed.

Child↗

PubMed1995

[Quantification of relevant measurements of the petrous bone with computerized tomography before cochlear implant operation].

In this investigation the following anatomical measurements of the petrous bone preceding cochlear implant were evaluated using computed tomography (CT): the width of the basal coil of the cochlea, the thickness of the promontory, the distance between the sigmoid sinus and the posterior wall of the external auditory canal and the thickness of the squamous part of the temporal bone in the area of operation. Initially it was necessary to ascertain how accurately CT represents the anatomical structures of the petrous bone. The procedure of CT investigation in adult patients was simulated using the base of a skull. The CT plane in which the above mentioned measurements preceding cochlear implant can be made was represented and measurements were taken. Subsequently the same plane in CT was represented macroscopically with a specially developed method. The results show that anatomical structures measured in CT are magnified by 5% in contrast to the original. This magnification is presumably attributable to the computing of connective tissue which is adjacent to bone and the incapacity of CT to image structures of different density in the same voxel. In the second part of this investigation we evaluated 66 preoperative CT's of patients who were given a cochlear implant. The results must be adjusted by 5% to allow for this error in magnification. In conclusion a preoperative radiologic evaluation of the anatomical structures relevant to cochlear implant is without doubt tenable. Also the negligible difference between CT and the anatomical original requires no operative consequences. Because cochleostomy is carried out with a diamond burr of 1 mm diameter, a tenth of a millimeter is negligible according to our experience.

Adolescent↗

PubMed2005

Ethnicity and mutations in GJB2 (connexin 26) and GJB6 (connexin 30) in a multi-cultural Canadian paediatric Cochlear Implant Program.

OBJECTIVE: To determine the relationship between ethnicity and mutations in the GJB2 and GJB6 genes in multi-cultural patients enrolled in a Canadian paediatric Cochlear Implant Program. METHODS: Blood was analyzed from 65 paediatric cochlear implant users by direct sequencing of the coding region and intron/exon boundaries of the GBJ2 gene. Individuals heterozygous for one mutation in GJB2 or in whom mutations in GJB2 were not detected were analyzed for the common 342 kb deletion mutation D13S1830 in the GJB6 gene. Information regarding ethnicity of patients' families was obtained from patient records and/or interview. RESULTS: GJB2 mutations were found in 36.9% of paediatric cochlear implant users tested. Nine different GJB2 mutations were identified among individuals from 14 different countries of origin. Seventy-eight percent of all identified pathogenic GJB2 mutations were 35delG. Biallelic GJB2 mutations were found in 16 cochlear implant users (66.7% of GJB2 mutations). Three novel GJB2 sequence changes were identified: (1) a missense mutation T107C (L36P) in an individual of African decent; (2) a missense mutation G475T (D159Y) in an individual of Caribbean decent; (3) a regulatory region change 1-34C to T in an individual of African decent. GJB6-D13S1830 mutations were not found in any of the patients tested. Individuals of African, Caribbean and East Indian decent had different GJB2 mutations than the remainder of individuals tested. Patients of Asian, Italian, Spanish, Polish and Armenian decent were not found to carry mutations in GJB2 or the common GJB6-D13S1830 mutation. CONCLUSIONS: This study represents the largest number of biallelic GJB2 mutations isolated in a group of paediatric cochlear implant users to date. Numerous and diverse GJB2 mutations were found in this multi-cultural group of children. Even though GJB2 mutations have been widely reported in the literature, this discussion represents the first report of GJB2 mutations in a multi-ethnic population (Canadian), as compared with previous studies that investigated fairly homogeneous populations. The diversity of GJB2 mutations identified reinforces the importance of testing for changes in GJB2 by direct sequencing of the entire coding region rather than testing only for common mutations.

Canada↗