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PubMed2005

Effect of inter-phase gap on the sensitivity of cochlear implant users to electrical stimulation.

Human behavioral thresholds for trains of biphasic pulses applied to a single channel of Nucleus CI24 and LAURA cochlear implants were measured as a function of inter-phase gap (IPG). Experiment 1 used bipolar stimulation, a 100-pps pulse rate, and a 400-ms stimulus duration. In one condition, the two phases of each pulse had opposite polarity. Thresholds continued to drop by 9-10 dB as IPG was increased from near zero to the longest value tested (2900 micros for CI24, 4900 micros for LAURA). This time course is much longer than reported for single-cell recordings from animals. In a second condition, the two phases of each pulse had the same polarity, which alternated from pulse to pulse. Thresholds were independent of IPG, and similar to those in condition 1 at IPG=4900 micros. Experiment 2 used monopolar stimulation. One condition was similar to condition 1 of experiment 1, and thresholds also dropped up to the longest IPG studied (2900 micros). This also happened when the pulse rate was reduced to 20 pps, and when only a single pulse was presented on each trial. Keeping IPG constant at 8 micros and adding an extra biphasic pulse x ms into each period produced thresholds that were roughly independent of x, indicating that the effect of IPG in the other conditions was not due to a release from refractoriness at sites central to the auditory nerve. Experiment 3 measured thresholds at three IPGs, which were less than, equal to, and more than one half of the interval between successive pulses. Thresholds were lowest at the intermediate IPG. The results of all experiments could be fit by a linear model consisting of a lowpass filter based on the function relating threshold to the frequency of sinusoidal electrical stimulation. The data and model have implications for reducing the power consumption of cochlear implants.

Action Potentials↗

PubMed2005

Is there a critical period for cochlear implantation in congenitally deaf children? Analyses of hearing and speech perception performance after implantation.

A range of basic and applied studies have demonstrated that during the development of the auditory system, early experimental manipulations or clinical interventions are generally more effective than those made later. We present a short review of these studies. We investigated this age-related plasticity in relation to the timing of cochlear implantation in deaf-from-birth children. Cochlear implantation is a standard intervention for providing hearing in children with severe to profound deafness. An important practical question is whether there is a critical period or cutoff age of implantation after which hearing outcomes are significantly reduced. In this article, we present data from prelingually deaf children (mostly congenitally deaf) implanted at ages ranging from 1 to 15 years. Each child was tested with auditory and speech understanding tests before implantation, and at regular intervals up to 8 years postimplantation. We measured the improvement in performance of speech understanding tests in younger implanted children and compared it with the results of those implanted at a later age. We also used a binary partitioning algorithm to divide the data systematically at all ages at implant to determine the optimum split, i.e., to determine the age at implant which best separates performance of early implanted versus later implanted children. We observed distinct age-of-implant cutoffs, and will discuss whether these really represent critical periods during development.

Adolescent↗

PubMed1989

Auditory consonant and word recognition skills of cochlear implant users.

Auditory consonant recognition and sentence recognition tests were administered to two subjects wearing the 3M/House cochlear implant, three subjects wearing the 3M/Vienna implant, seven subjects wearing the Cochlear Corporation (Nucleus) implant and 10 subjects wearing the Symbion implant. For the 14-item consonant test, the Symbion subjects scored an average of 41% consonants correct (17-58%), the Cochlear Corporation subjects scored an average of 34% (25-48%), the 3M/Vienna subjects scored 19% (15-26%), and the 3M/House subjects scored 11% (7-14%). An information transfer analysis performed on the consonant data suggested that subjects perceive the envelope feature relatively well and the place feature relatively poorly. All of the 3M/House and 3M/Vienna subjects scored 0% words correct for the sentence test. The Symbion and Cochlear Corporation subjects scored an average of 35% (0-92%) and 32% (9-45%) words correct, respectively. To better understand the variability in word recognition skills, the scores from the sentence test were correlated with the results of the information transfer analysis. The voicing and duration features did not correlate with the sentence scores very well. Place and frication features were shown to be most predictive of auditory word recognition. This finding suggests that subjects who utilize middle and high-frequency speech information are more likely to score better on open-set word recognition tests than subjects who do not.

Cochlear Implants↗

PubMed1995

Performance of prelingually and postlingually deaf patients using single-channel or multichannel cochlear implants.

The auditory and aided lipreading performance of 8 prelingually and 11 postlingually deaf patients who had received a single-channel or multichannel cochlear implant was evaluated during 2 years of follow-up. Although all the patients improved on both closed-set pattern recognition and speech discrimination tests and on a Continuous Discourse Tracking task, the most significant improvement was observed in the postlingually deaf patients who were using a multichannel implant. These patients were the only ones to achieve open-set speech recognition in the auditory-only condition. Only small differences were found between prelingually deaf patients who were using a single-channel system and those who were using a multichannel system. The users' evaluations, obtained by means of a questionnaire, were generally positive in all patients. Based on the study results, the authors concluded that it is feasible to use cochlear implants in highly motivated prelingually deaf patients who have learned to use oral-aural communication.

Adult↗

PubMed1996

Place pitch discrimination and speech recognition in cochlear implant users.

The considerable variability in speech perception performance among cochlear implant patients makes it difficult to compare the effectiveness of different speech processing strategies. One result is that optimal individualized processor parameter setting is not always achieved. This paper investigates the relationship between place pitch discrimination ability and speech perception to establish whether pitch ranking could be used as an aid in better patient-specific fitting of processors. Three subjects participated in this study. Place pitch discrimination ability was measured and this information was used to design new channel to electrode allocations for each subject. Several allocations were evaluated with speech tests with consonant, vowel and sentence material. It is shown that there is correlation between the perceptual pitch distance between electrodes and speech perception performance. The results indicate that pitch ranking ability might be used both as an indicator of the speech perception potential of an implant user and in the choice of better electrode configurations.

Adult↗

PubMed2000

New approach for cochlear implantation: cochleostomy through the middle fossa.

The middle fossa approach was used in 11 patients with profound bilateral hearing loss for insertion of a cochlear implant. Fibroadhesive otitis media (n = 1), bilateral cavity radical mastoidectomy (n = 1), autoimmune inner ear disease (n = 2), previous cranial trauma (n = 1), genetic prelingual deafness (n = 5), and otosclerosis (n = 1) were the causes of deafness. A cochleostomy was performed on the most superficial part of the basal turn, and the electrode array was inserted up to the cochlear apex. Speech perception tests (1-9 months after cochlear implant activation) yielded better results in these patients compared with a homogeneous group of postlingually deaf patients operated on through the traditional transmastoid route. Insertion of the implant through the middle fossa cochleostomy furnishes the possibility of stimulating areas of the cochlea (ie, the middle and apical turns) where a greater survival rate of spiral ganglion cells is known to occur, with improvement of information regarding the formants relevant for speech perception.

Adolescent↗

PubMed1997

Open-set speech perception in congenitally deaf children using cochlear implants.

OBJECTIVE: To assess and document the development of open-set speech recognition in congenitally deaf children implanted with the Nucleus multichannel cochlear prosthesis at < 5 years of age. STUDY DESIGN: The study group consisted of 38 consecutively chosen children in whom the decision to proceed with implantation had already been made. PATIENTS AND SETTING: Congenitally profoundly deaf children were implanted with the Nucleus multichannel cochlear implant at < 5 years of age and followed at NYU Medical Center for a period of 1-5 years. MAIN OUTCOME MEASURES: Open-set speech perception was evaluated preoperatively and postoperatively using the following: the Glendonald Auditory Screening Procedure (GASP) word subset, the GASP sentence subtest, Phonetically Balanced Kindergarten monosyllabic word lists, Common Phrases test, Multisyllabic Lexical Neighborhood test, and Lexical Neighborhood test. RESULTS: Correlation coefficients were calculated between scores at each interval and age at implantation; one-way analyses of variance were performed independently. Results showed that all subjects had significant open-set speech recognition at the time of the last postoperative evaluation. Thirty-seven of the children use oral language as their sole means of communication. CONCLUSIONS: Multichannel cochlear implants provide significant and usable open-set speech perception in congenitally deaf children given implants at < 5 years of age.

Auditory Threshold↗

PubMed1983

[Current stage of rehabilitation of totally deaf persons using cochlear implantation].

Up to now the results obtained with the "Vienna Cochlear Implant" have been encouraging. All our patients achieved acoustic orientation, the majority improved in lipreading ability and many patients achieved a good standard of open speech understanding. Furthermore, our results show that implants can be worn over a long time without causing any side effects.

Acoustic Stimulation↗

PubMed1997

Pitch and loudness estimation for single and multiple pulse per period electric pulse rates by cochlear implant patients.

Numerical estimates of loudness and pitch for electric pulse rates were obtained from 14 patients using the 22 electrode cochlear implant manufactured by Cochlear Limited. Six patients were postlinguistically deafened adults, and eight patients were adults and children who became deaf very early in life. Comparisons were made between two types of pulse rate patterns. The SPP pulse pattern presented a single pulse every period, the inverse of the pulse rate. The MPP pulse pattern presented multiple pulses in the first half of the period, using a rate of 1000 pulses/s, with no stimulation in the second half of the period. The pulse rates used for the SPP and MPP pulse patterns were 71.4-500 pulses/s, which corresponded to periods of 14-2 ms. For the SPP pulse pattern, the total number of pulses over the duration of the stimulus increased with increases in pulse rate, while for the MPP pulse pattern, the total number of pulses remained constant. Pitch and loudness estimates were obtained from the postlinguistically deafened patients for the SPP and MPP pulse patterns, and from the early-deafened patients for the MPP pulse pattern. Loudness estimates for the SPP pulse pattern increased with increases in pulse rate for all postlinguistically deafened patients. Loudness estimates for the MPP pulse pattern decreased with increases in pulse rate for three of the six postlinguistically deafened patients and for six of the eight early-deafened patients. For the other patients (three postlinguistically deafened and two early-deafened), loudness estimates marginally increased with increases in pulse rate. Pitch estimates for the SPP and MPP pulse patterns increased with increases in pulse rate for the six postlinguistically deafened patients. For the early-deafened patients, pitch estimates for the MPP pulse patterns increased with increases in pulse rate for only five of the eight patients. For the other three early-deafened patients, pitch estimates were similar to the loudness estimates and decreased with increases in pulse rate.

Adolescent↗

PubMed1997

Computed tomography data based rapid prototyping model of the temporal bone before cochlear implant surgery.

Rapid prototyping (RP) technique allows automatic fabrication of 3D model parts. This method was applied to make a temporal bone model before cochlear implant surgery. A helical CT scan is used to acquire high resolution data from the middle and the inner ear of the patient. From the scanning data bone structures and soft tissues can be separated because their different grayscale pixel values. By using a guided image processing tool the desired parts of the anatomy can be extracted and 3D data created. The segmented data are processed to the form suitable for creating a high accuracy RP model. The RP model is made in the stereolithography (SLA) process by means of a computer guided HeCd laser beam inducing polymerisation of acrylic solution as it passes layer by layer over the surface of the polymer solution. In this prototype model the anatomy of the temporal bone can be clearly visualised, including, e.g., mastoid cells, tympanic cavity, bony canal of facial nerve, and round and oval windows. The inner ear spaces including vestibule, semicircular canals and cochlear turn are also shaped. The transparent acrylic material allows bonelike mechanical handling. The RP model can be dissected and used in individual surgical planning and simulation prior to cochlear implantation.

Cochlear Implants↗

PubMed1996

Maturation of human cortical auditory function: differences between normal-hearing children and children with cochlear implants.

OBJECTIVE: We investigated maturation of cortical auditory function in normal-hearing children and in children who receive stimulation of their auditory system through a cochlear implant. DESIGN: As a measure of cortical auditory function, auditory evoked responses (AERs) were recorded from normal-hearing children and adults as well as from children and adults fitted with a cochlear implant. Morphological and latency changes for evoked responses recorded at electrode Cz are reported. RESULTS: For normal-hearing children, there is a gradual evolution of AER features that extends through adolescence, with P1 latency becoming adult-like in the late teens. Latency changes for P1 occur at the same rate for implanted children, but the overall maturation sequence is delayed. By extrapolation from the existing data, the age at which P1 latency becomes adult-like is delayed by approximately 5 yr for the implanted population. Other typical features of the AER, namely N1 and P2, are either delayed in developing or absent in the implanted children. CONCLUSIONS: These preliminary findings suggest both similarities and differences in cortical auditory maturation for normal-hearing and implanted children. For implanted children, the 5 yr delay for maturation of P1 latency roughly corresponds to the average 4.5 yr interval between the onset of deafness and the time of implantation. These findings suggest that during the period of deafness, maturation of cortical auditory function does not progress. However, some, if not all, maturational processes resume after stimulation is reintroduced.

Adult↗

PubMed1994

[Test of electrical stimulation of the round window. Diagnostic and prognostic value of the rehabilitation of total deafness by cochlear implant].

The round window electrical stimulation (RWES) test has been performed in 708 cases of total deafness. Among them 244 have successfully benefited with a cochlear implant. Electrical Brain Stem Evoked (EBSE) potential elicited by this stimulation have been registrated in 283 cases, 113 of them during general anesthesia necessary in children. This test supplies the patient with a subjective sound sensation and/or EBSE in 93% of cases. The correlation between electrical data of this RWES test and clinical results of the cochlear implant is described. This test is discussed regarding the simple transtympanique promonotory stimulation test.

Adolescent↗

PubMed1990

Speech perception with a single-channel cochlear implant: a comparison with a single-channel tactile device.

Suprasegmental and segmental speech perception tasks were administered to 8 patients with single-channel cochlear implants. Suprasegmental tasks included the recognition of syllable number, syllabic stress, and intonation. Segmental tasks included the recognition of vowels and consonants in three modalities: visual only, implant only, and visual + implant. Results were compared to those obtained from artificially deafened adults using a single-channel vibrotactile device. The patterns of responses for both suprasegmental and segmental tasks were highly similar for both groups of subjects, despite differences between the characteristics of the subject samples. These results suggest that single-channel sensory devices, whether they be cochlear implants or vibrotactile aids, produce similar patterns of speech perception errors, even when differences are observed in overall performance level.

Adult↗

PubMed2005

Young deaf children with hearing aids or cochlear implants: early assessment package for monitoring progress.

BACKGROUND: Very few assessment measures exist for evaluating progress in young deaf children with hearing aids and cochlear implants. OBJECTIVE: To introduce and describe an early assessment package that covers auditory perception, communication/language development, and speech production in very young deaf children. MAIN OUTCOME MEASURES: Seven of the assessment measures (Listening Progress Profile, Categories of Auditory Performance, Tait Video Analysis, Stories-Narratives Assessment Procedure, Profile of Actual Linguistic Skills, Speech Intelligibility Rating, and the Profile of Actual Speech Skills) have been specifically developed at the Nottingham Cochlear Implant Programme, and a further one (Meaningful Auditory Integration Scale) was modified for use within the package. Moreover, two commercially available tests (Pragmatics Profile of Everyday Communication Skills and Preschool Language Scale) are included to complete the package. METHODS: The present paper describes each measure, how to use it, and its time frame. In addition, two case studies demonstrate the usefulness of the package as a whole. RESULTS AND CONCLUSIONS: The Nottingham Early Assessment Package (NEAP) offers a framework with which to assess in young deaf children the use of audition and language and communication in real-life situations. Being simple, reliable, and time effective can be used in everyday clinical practice. NEAP is innovative in design and offers a structured approach to monitor very young deaf children, both in short and long term. In addition, it allows the identification of additional problems and areas of difficulty as well as specific abilities and skills. This enables the clinician to determine appropriate intervention strategies.

Auditory Perception↗

PubMed2006

The age at which young deaf children receive cochlear implants and their vocabulary and speech-production growth: is there an added value for early implantation?

OBJECTIVE: The age at which a child receives a cochlear implant seems to be one of the more important predictors of his or her speech and language outcomes. However, understanding the association between age at implantation and child outcomes is complex because a child's age, length of device use, and age at implantation are highly related. In this study, we investigate whether there is an added value to earlier implantation or whether advantages observed in child outcomes are primarily attributable to longer device use at any given age. DESIGN: Using hierarchical linear modeling, we examined latent-growth curves for 100 children who had received their implants when they were between 1 and 10 yr of age, had used oral communication, and had used their devices for between 1 and 12 yr. Children were divided into four groups based on age at implantation: between 1 and 2.5 yr, between 2.6 and 3.5 yr, between 3.6 and 7 yr, and between 7.1 and 10 yr. RESULTS: Investigation of growth curves and rates of growth over time revealed an additional value for earlier implantation over and above advantages attributable to longer length of use at any given age. Children who had received their implants before the age of 2.5 yr had exhibited early bursts of growth in consonant-production accuracy and vocabulary and also had significantly stronger outcomes compared with age peers who had received their implants at later ages. The magnitude of the early burst diminished systematically with increasing age at implantation and was not observed for children who were older than 7 yr at implantation for consonant-production accuracy or for children who were over 3.5 yr old at implantation for vocabulary. The impact of age at implantation on children's growth curves differed for speech production and vocabulary. CONCLUSIONS: There seems to be a substantial benefit for both speech and vocabulary outcomes when children receive their implant before the age of 2.5 yr. This benefit may combine a burst of growth after implantation with the impact of increased length of use at any given age. The added advantage (i.e., burst of growth) diminishes systematically with increasing age at implantation.

Age Factors↗

PubMedDate not supplied

Social hearing measured with the Performance Inventory for Profound and Severe Loss: a comparison between adult multichannel cochlear implant patients and users of acoustical hearing aids.

The objective of this study was to investigate social hearing in successful users of multichannel cochlear implants (CIs) and to compare the scores with those of a group of hearing-impaired adults using acoustical hearing aids (HAs). Out of 88 patients who had undergone surgery, 75 CI users with a mean age of 55 years and a mean pre-operative hearing level of 113dB in the better ear were compared with 59 users of acoustical HAs with a mean age of 56 years and a mean hearing level of 82dB in the better ear. Seven CI patients were non-users and were excluded from the study. The Performance Inventory for Profound and Severe Loss, a questionnaire that measures different aspects of hearing handicap, was used. The CI group scored significantly better than the HA group in three of six evaluated categories, measuring subjective intensity of sounds, speech with visual cues, and response to auditory failure. Awareness of environmental sounds, speech with no visual cues and personal reactions did not differ significantly. The group of successful CI users scored higher on a self-report measure than did a group of users of acoustical HAs with moderate- severe-profound deafness. The best CI users scored better than the best HA users, and the worst CI users scored worse than the worst HA users.

Adult↗

PubMedDate not supplied

[Cochlear implants in post-lingual persons: results during the first five years of the clinical course].

Abundant literature is available on the results of cochlear implants in postlingual persons. Nevertheless, there are few long-term studies with a follow-up of more than 1 year. We present the outcomes of 37 postlingual patients with a 5-year follow-up period. We examined the modifications that occurred with changes in coding strategy (MPEAK-SPEAK). After activation, the coding strategy was SPEAK in 10 patients. MPEAK in 20: 7 other SPEAK had changed from MPEAK. Significant improvement (p < 0.01) was observed in all the tests in the first 6 months. Subsequent assessments revealed a constant improvement in all tests. The results were statistically significant (p < 0.05) for vowels, consonants and bisyllables. Performance with the SPEAK strategy was better than with MPEAK. These results were statistically significant for consonants (p < 0.05), monosyllables (p < 0.05) and bisyllables (p < 0.01). We concluded that the results of postlingual patients after cochlear implantation showed clear benefits of these devices in profound bilateral deafness, better results with the SPEAK coding strategy than with MPEAK and constant improvement in results, even after the first year of surgery.

Adolescent↗

PubMed1998

Case study of a deaf/blind person with a cochlear implant.

This paper accompanies a poster presentation demonstrating outcomes after cochlear implantation of a deaf/blind person. In particular, changes in the patients voice quality and improvements in her pragmatic skills will be discussed.

Adult↗