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PubMed1995

Consonant perception by users of Nucleus and Clarion multichannel cochlear implants.

A study was carried out to compare the consonant perceptions of five Nucleus multichannel cochlear implant users, five Clarion-CIS users, and four Clarion-CA users. All subjects were administered the Iowa Medical Consonant Recognition Test in the auditory-only condition. The groups averaged approximately 1 year of implant use at the time of testing, and the average age at implantation was 47 years for the Nucleus users, 60 years for the Clarion-CIS users, and 56 years for the Clarion-CA users. The percent-corrected scores for all three devices were variable and ranged from 34% to 84%, with each group averaging about 50% correct consonant recognition. Consonant feature information transmission was calculated for five features: manner of articulation, nasality, place of articulation, duration, and voicing. The highest information transmission in the Nucleus group was for the features of duration (71%), nasality (60%), and voicing (57%), which agrees with previous studies. The Clarion-CIS group had the highest information transmission for duration, place of articulation, manner of articulation, and nasality (50%, 29%, 28%, and 27%). The Clarion-CA group had the highest information transmission for the features voicing, place of articulation, and duration (41%, 40%, and 37%). This study indicates that the Clarion device may carry some acoustic information related to place of articulation, a feature that has not been found to be encoded well by other multichannel cochlear implants.

Adult↗

PubMed2001

Effect of residual hearing prior to cochlear implantation on speech perception in children.

We examined the impact of residual hearing prior to cochlear implantation on pre- and postimplantation speech perception outcomes in children. Stimulation of the auditory system prior to implantation because of the presence of residual hearing is important for development of the central auditory pathways, whereas, in the absence of such stimulation, the pathways show less development. We hypothesized that children who had some degree of residual hearing preimplantation achieve better speech perception skills than their peers with poorer hearing. From the 133 children followed in our program, we identified 37 children who had an audiometric pure-tone average of better than 95 dB HL in the better ear at any time preimplantation. Psychophysical speech perception measures, the Word Identification Picture Inventory and the Phonetically Balanced Kindergarten list, in these children were compared with those of 96 implanted children who had poorer hearing prior to implantation. Children with more residual hearing showed higher speech perception scores both before implantation and over their first year of implant use than children with poorer hearing, suggesting that there is an advantage in having a greater degree of residual hearing preimplantation. We suggest that this advantage is promoted, in part, by the greater potential for auditory stimulation provided by high-gain hearing aids in children with greater degrees of residual hearing. This advantage appears to be maintained at least over 1 year postimplantation, yet the rates of development of postimplantation speech perception are not different between the groups. We suggest that this may be due to the unique aspects of electrical stimulation from a cochlear implant. Our findings suggest that it is important to minimize the delay of speech perception skills in the preimplantation phase, particularly in children with poor residual hearing. This can be accomplished by implanting children with congenital severe to profound hearing loss at young ages and children with acquired hearing loss soon after the onset. Also, auditory stimulation prior to implantation should be maximized through the consistent use of hearing aids and therapy that emphasizes development of auditory skills.

Child↗

PubMed2002

A multidimensional scaling analysis of tone discrimination ability in Cantonese-speaking children using a cochlear implant.

Tone discrimination testing with two groups of profoundly hearing-impaired children using a cochlear implant and one group of normally hearing children suggests that pitch level is perceptually more salient than pitch contour. In this paper, the discrimination results from these children are submitted to a multidimensional scaling analysis to determine what differences if any exist between the children in the information they use to discriminate between tone types. Through the multidimensional scaling analysis it is shown that, 'average pitch height' and 'pitch direction' are the most salient acoustic features in tone with pitch height being perceptually more important than pitch level. Furthermore, these acoustic features are similarly salient for all three groups of children despite differences in the source of auditory information and linguistic experience. Finally, the two groups of cochlear implant users who employ different speech processing strategies with their implant are shown to be distinguishable by differences in the relative salience of pitch direction.

Child↗

PubMed2006

Combining perimodiolar electrode placement and atraumatic insertion properties in cochlear implantation -- fact or fantasy?

CONCLUSIONS: Except for basal cochlear traumatization, all specimens implanted into scala tympani showed atraumatic insertion properties and good perimodiolar electrode positioning. Cochleostomy preparation and placement can have a significant impact on levels of basal cochlear trauma. OBJECTIVE: In the past, perimodiolar cochlear implant electrodes increased the risk for intracochlear traumatization when compared to free-fitting arrays. Recently, however, clinical evidence for atraumatic perimodiolar implantations with preservation of residual hearing has been described. The aim of this paper was to histologically evaluate a perimodiolar cochlear implant array for its insertion properties in cadaver human temporal bones. Surgical and electrode factors, as well as preparation artifacts influencing intracochlear trauma, were considered in the evaluation. MATERIALS AND METHODS: Sixteen human temporal bones were harvested up to 24 hours post mortem and implanted immediately with the Nucleus 24 Contour Advance cochlear implant electrode array. Implantations were either performed using a regular caudal approach cochleostomy or through the round window membrane. After implantation, all bones underwent special histological processing, which allowed sectioning of undecalcified bone. Insertion properties were evaluated according to a grading system. RESULTS: Fourteen specimens were implanted into scala tympani and only two exhibited basal trauma attributable to electrode insertion characteristics. Two bones were implanted into scala vestibuli after causing trauma in the region of the cochleostomy. Insertion depths ranged from 180 degrees to 400 degrees. All bones showed good perimodiolar electrode positioning. Basal trauma due to surgical issues and histological artifacts was present in 10 of 16 bones.

Auditory Threshold↗

PubMed2000

[Postoperative imaging and evaluation of the electrode position and depth of insertion of multichannel cochlear implants by means of high-resolution computed tomography and conventional X-rays].

Following cochlear implantation, postoperative imaging of the electrode is very important in order to measure the depth of insertion and the position of the electrode, so that kinking and incorrect electrode placement can be clearly identified. The aim of this study was to outline the diagnostic value of CT and conventional X-ray for these parameters. For this purpose we obtained radiographs of patients who had received a cochlear implant. Computed tomography was performed by obtaining axial sections. For conventional X-ray we used digital imaging, utilising a modified Chausse III projection. The images were then rated according to electrode position, insertion depth and possible complications. We also measured the radiation dose using a dummy and evaluated the cost of each examination. Both examinations permit excellent identification of electrode position and insertion depth. However, the depth of insertion can be measured much more accurately by means of digital X-ray. The radiation dose of CT was 230 times higher than that of conventional X-ray and the cost of CT 5 times that of digital X-ray.

Austria↗

PubMed2005

Substance distribution in a cochlea model using different pump rates for cochlear implant drug delivery electrode prototypes.

Several studies using animals have shown the protective effects of neurotrophic factors (NF) on spiral ganglion cells (SGC). This is of particular importance since the number of SGCs is considered to be among the factors defining the efficacy of cochlear implants. A device for local inner ear treatment is therefore of great interest. As described previously, we modified a Contour(TM) cochlear implant electrode, to examine the inbuilt canal to be used for fluid release [Paasche, G., Gibson, P., Averbeck, T., Becker, H., Lenarz, T., Stöver, T., 2003. Technical report: modification of a cochlear implant electrode for drug delivery to the inner ear. Otol. Neurotol. 24, 222-227]. In the present study, three different electrode prototypes with openings of the delivery channel at various locations along the electrode array were examined to determine distribution of dye in a cochlea model over time. We compared dye delivery with: (a) release of the dye at the tip, (b) release of the dye at the tip and the side of the electrode, and (c) release of the dye only at the side of the electrode (6 mm from the tip). A mechanical pump was used to drive the system at pump rates of 100, 10, and 1 microl/h. Dye concentration changes along the length of the whole cochlea were investigated. Mean values for all experimental conditions show that the distribution along the array is fastest with two outlets whereas the distribution via a single outlet at the side of the electrode array is not considered to be sufficient. The established experimental setup provides the possibility of investigating prototypes of a fluid based drug delivery system for the treatment of inner ear pathologies in combination with electrical stimulation.

Animals↗

PubMed2003

Changes over time in the psycho-electric parameters in children with cochlear implants.

Information regarding typical changes in electrical stimulation levels during different stages post-implantation in children is scarce. Clinically, this information can serve as a general guideline to the nature and frequency of these changes, and consequently help to determine programming schedules that would optimize performance with the implant. Furthermore, it may have implications for the design of cochlear implants, and for monitoring the condition of the implanted cochlea. The main goal of the present study was, therefore, to evaluate changes over time in psycho-electric parameters, i.e. threshold levels, comfortable levels, and dynamic range, in children with the Nucleus 22 cochlear implant system. The maps of 37 prelingual children were examined at five time intervals: 1, 6, 12, 18 and 24 months post-connection. Maps were analyzed according to three cochlear segments: basal, medial, and apical. The results indicated significant changes in the psycho-electric parameters during the first 2 years post-implantation. Specifically, threshold (T) levels increased significantly during the first year and stabilized during the second year, whereas comfort (C) levels and dynamic range (DR) increased significantly during the entire 2-year follow-up. In addition, psycho-electric parameters varied among the different cochlear segments, resulting in a narrower DR in the basal one. Regardless of the underlying cause for these changes, the results of the present study suggest that, in children, the stabilization of psycho-electric parameters is a prolonged, gradual process. Since psycho-electric parameters play an important role in speech perception, these findings emphasize the need for frequent programming in the first 2 years of implant use in children.

Analysis of Variance↗

PubMed1994

Identifying electrode failures with cochlear implant generated surface potentials.

A procedure for measuring surface potentials called electrode-by-electrode (E-E) mapping is described that can detect the nonintermittent malfunctioning of the implanted receiver and electrode array of multichannel cochlear implants, such as the Cochlear (Nucleus) device. E-E mapping is based on the sequential stimulation of all paired combinations of electrodes. The recorded waveforms were averaged and all peak-to-peak amplitudes were combined into one graph for a comprehensive check on open circuit or short-circuited electrodes. Normative data from 21 patients are given. E-E mapping detected electrode failure in three patients whose behavioral thresholds were in agreement with hardware problems, including one case of overstimulation at high stimulus levels. In one patient who was suffering from overstimulation without any deviant thresholds, no failure could be detected. The procedure takes about a quarter of an hour and the stimulus amplitude needed is below threshold for most patients, which makes it especially useful in children. An informative partial E-E map can be made during implantation and requires virtually no extra theater time.

Adult↗

PubMed1998

Educational placement of deaf children following cochlear implantation.

This study examined the educational placements, before cochlear implantation, of 121 deaf children, and the educational placements, two years after implantation, of the 48 children who had reached that stage, looking at the influence of age at implantation and duration of deafness on the placement of these children. In addition, it compared the educational placements of those given implants prior to schooling, and those given implants when already in an educational setting. Categories used were pre-school, school for the deaf, unit or resource base within a mainstream school and full-time mainstream provision. Age at implantation and duration of deafness were found to be significant predictors of placement two years after implantation. The duration of deafness of children in schools for the deaf or units was twice that of children in mainstream education. Fifty-three per cent of children who were in pre-school at the time of implantation were in mainstream schools two years after implantation, whereas only 6% of those who were already in educational placements at the time of implantation were in mainstream education. This difference was statistically significant. The results indicate that children who are given implants early, before an educational decision has been made, are more likely to go to mainstream schools than those given implants when already in an educational setting.

Adolescent↗

PubMed2004

Electrophysiologic and objective monitoring of the cochlear implant during surgery: implementation, audit and outcomes.

Electrophysiologic and objective measures are reviewed with respect to their implementation as monitoring tools for cochlear implants in the operating room and their value in the management of children. The current intraoperative test protocol in Nottingham consists of back-telemetry (BT) diagnostic testing of implant function, including impedance telemetry (ImpT), integrity testing (IT), electrical stapedius reflex response (ESR), electrical auditory brainstem response (EABR) and Neural Response Telemetry (NRT). Of 427 cases of implantation in the period 1990-2003, 303 (71%) were completely normal for all components of the protocol. In the remaining cases, some results were either simply anomalous, with no direct impact on management during surgery, and some were more significant, resulting in actions such as the use of the back-up device or repositioning of the electrode array. Normal intraoperative findings provided immediate reassurance to the implant team and parents of young children that the implant was fully functioning and that electrical stimulation was activating the auditory pathways These objective measures also identified potentially challenging cases, such as those with low levels of sensitivity to electrical stimulation and susceptibility to facial nerve stimulation. An audit showed that intraoperative measures provided valuable assistance in the initial fitting of the device.

Action Potentials↗

PubMed1997

[Rehabilitation of patients with hearing loss by cochlear implants].

In the last decade, the rehabilitation of postlingually deaf adults and prelingually deaf children with cochlear implants has been established as a treatment of deafness. The technological development of the implant devices and improvement of the surgical technique have led to a considerable increase of hearing performance during the last years. The postlingually deaf adults are able to use the telephone and may be integrated in their original job. Prelingually deaf children can even visit normal schools after cochlear implantation and hearing rehabilitation training. In order to preoperatively establish the state of the cochlea, radiological diagnosis of the temporal bone is necessary. High resolution computerized tomography imaging of the temporal bone with coronar and axial 1 mm slices and MRI with thin slice technique (three dimensional, T2 weighted turbo-spinecho sequence with 0.7 mm slices) have proved to be valuable according to our experience. Furthermore a postoperative synoptical X-ray, in a modified Chausse III projection, offers good information about the position of the implant and insertion of the stimulating electrode into the cochlea.

Adult↗

PubMed2002

Parent interaction course in order to enhance communication skills between parents and children following pediatric cochlear implantation.

OBJECTIVE: To assess the effect of a parent interaction training course on the communication skills of parents of young implanted children. The training course was designed to help parents to be less controlling in their interactions with their deaf children and to facilitate the development of spoken language. STUDY DESIGN: Prospective study comparing the communication skills of parents of deaf children fitted with cochlear implants before and after a parent interaction training course. SETTING: Pediatric tertiary referral center for cochlear implantation. METHODS: Video samples were taken of parents interacting with their children 1 month before the course (ranging from 15 days to 2 months) and after the course (ranging from 15 days to 1 month). Video samples were then transcribed orthographically and parents' turns in the interaction were assigned to one of two categories: (a) initiations--the parent initiates conversation or introduces a new topic and (b) responses--the parent responds to the child's previous turn. 12 months after completion of the course, the process was repeated in order to establish the relative permanence of changes in behavior. HYPOTHESIS: The parents' turns would shift from a predominance of initiations to a predominance of responses as a result of attendance on the course. This would demonstrate that the parents were less controlling of their children in communication and were exhibiting more contingent behavior--responding to their child's initiations rather than expecting the child to respond to theirs. PATIENTS: The study involved 17 parents of 11 implanted children. The mean age at implantation was 4 years (range: 2.2-6.3 years). The implant experience of the children ranged from 2 to 23 months at the time of the study. All children used total communication. RESULTS: The post-course initiations were half those of the pre-course ones (median from 14 decreased to 7) and the responses were almost double following the course (median from 8 increased to 14). Both differences were statistically significant (P < 0.05). 12 months after the course, the responses score remained high with a median score of 16.5. However, a slight but significant increase in the initiation scores was also noted (median from 7 to 8.5). Parental satisfaction of the course was found to be high as no families failed to attend on any of the occasions despite the great distances some of them had to travel. CONCLUSION: The format of the parent interaction training course was found to be highly acceptable to the parents and the components covered proved to be effective in promoting positive changes in parental communication behavior. Clinicians need to provide a responsive environment for implanted deaf children and help others to do the same. The training course provided a very useful forum to share insights and skills and to evaluate ways of enhancing the communication between parents and children following cochlear implantation.

Child↗

PubMed2004

Speech intelligibility of pediatric cochlear implant recipients with 7 years of device experience.

Speech intelligibility of 24 prelingually deaf pediatric cochlear implant (CI) recipients with 84 months of device experience was investigated. Each CI participant's speech samples were judged by a panel of 3 listeners. Intelligibility scores were calculated as the average of the 3 listeners' responses. The average write-down intelligibility score was 71.54% (SD = 29.89), and the average rating-scale intelligibility score was 3.03 points (SD = 1.01). Write-down and rating-scale intelligibility scores were highly correlated (r = .91, p < .001). Linear regression analyses revealed that both age at implantation and different speech-coding strategies contribute to the variability of CI participants' speech intelligibility. Implantation at a younger age and the use of the spectral-peak speech-coding strategy yielded higher intelligibility scores than implantation at an older age and the use of the multipeak speech-coding strategy. These results serve as indices for clinical applications when long-term advancements in spoken-language development are considered for pediatric CI recipients.

Adolescent↗

PubMed1993

Vestibular function in cochlear implant patients.

Thirty-five patients receiving a cochlear implant were evaluated using vestibular function tests. Twenty-five patients received an intracochlear implant (Nucleus). Three out of 6 patients with normo- or hyporeflexia before implantation showed postoperative vestibular damage. In one case this was iatrogenic. Together with available data from the literature the risk of losing preoperative vestibular function is estimated to be around 60%. Improvement of implantation techniques can probably reduce this risk considerably.

Adult↗

PubMed2001

Minimum spectral contrast needed for vowel identification by normal hearing and cochlear implant listeners.

The minimum spectral contrast needed for vowel identification by normal-hearing and cochlear implant listeners was determined in this study. In experiment 1, a spectral modification algorithm was used that manipulated the channel amplitudes extracted from a 6-channel continuous interleaved sampling (CIS) processor to have a 1-10 dB spectral contrast. The spectrally modified amplitudes of eight natural vowels were presented to six Med-EI/CIS-link users for identification. Results showed that subjects required a 4-6 dB contrast to identify vowels with relatively high accuracy. A 4-6 dB contrast was needed independent of the individual subject's dynamic range (range 9-28 dB). Some cochlear implant (CI) users obtained significantly higher scores with vowels enhanced to 6 dB contrast compared to the original, unenhanced vowels, suggesting that spectral contrast enhancement can improve the vowel identification scores for some CI users. To determine whether the minimum spectral contrast needed for vowel identification was dependent on spectral resolution (number of channels available), vowels were processed in experiment 2 through n (n =4, 6, 8, 12) channels, and synthesized as a linear combination of n sine waves with amplitudes manipulated to have a 1-20 dB spectral contrast. For vowels processed through 4 channels, normal-hearing listeners needed a 6 dB contrast, for 6 and 8 channels a 4 dB contrast was needed, consistent with our findings with CI listeners, and for 12 channels a 1 dB contrast was sufficient to achieve high accuracy (>80%). The above-mentioned findings with normal-hearing listeners suggest that when the spectral resolution is poor, a larger spectral contrast is needed for vowel identification. Conversely, when the spectral resolution is fine, a small spectral contrast (1 dB) is sufficient. The high identification score (82%) achieved with 1 dB contrast was significantly higher than any of the scores reported in the literature using synthetic vowels, and this can be attributed to the fact that we used natural vowels which contained duration and spectral cues (e.g., formant movements) present in fluent speech. The outcomes of experiments 1 and 2, taken together, suggest that CI listeners need a larger spectral contrast (4-6 dB) than normal-hearing listeners to achieve high recognition accuracy, not because of the limited dynamic range, but because of the limited spectral resolution.

Adult↗

PubMed1995

Multichannel cochlear implantation with inner ear malformation: case report of performance and management.

A small percentage of children who have received the Nucleus multichannel cochlear implant have cochlear malformations of the inner ear and consequent partial electrode insertions. This case describes one child with a cochlear "common cavity" who received an implant at a young age. The case has been further complicated by a gradual malfunction of the electrode array, although the device has not failed completely. Despite the increase in the number of nonfunctional electrodes over time, the subject has continued to improve in auditory, speech production, and language development over a 30-month period. Methods are discussed for clinical monitoring of both performance and the stability of electrodes over time. The circumstances of this case reinforce the importance of postimplant collaboration with families and school staff and highlight the need for objective measures to evaluate both longitudinal changes in performance and device integrity.

Audiometry, Speech↗

PubMed1994

[History of the development and functional description of the Nucleus cochlear implant].

For deaf children and adults who derive no significant benefit from conventional hearing aids the cochlear implant (CI) has become a clinically accepted alternative. More than 7,000 people worldwide, including over 2,000 children, have received the 22 channel Nucleus Mini System during the last decade. The functional principle of the CI is the translation of acoustic sound signals into electrical impulses for direct stimulation of the hearing nerve. The middle ear and the damaged sensory organ of the inner ear are completely bypassed. The function of the healthy ear is replaced by a microphone, an electronic speech processor, and stimulation electrodes. Approximately two thirds of the postlingually deafened CI users achieve open set speech understanding without lipreading through the Nucleus implant. The Nucleus system is a programmable digital device and is continuously being improved in terms of both performance and ease of use. It is the only CI system with FDA approval for use in both adults and children from 2 years of age. Over 100 European clinics in more than 20 countries are carrying out successful CI programs with the Nucleus device in compliance with strict pre- and postsurgical diagnostic and rehabilitative guidelines. In Austria it was introduced to the Landeskrankenanstalten Salzburg in 1992. A successful program, including specialized rehabilitation, is carried on in close cooperation with the world's largest Cochlear Implant Center in Hannover, Germany.

Adult↗

PubMed2000

[Hybrid 3D visualization and virtual endoscopy in cochlear implants].

PURPOSE: The aim of this study was to demonstrate on a complex anatomical structure the possibilities and the advantages of a superimposition of a color-coded surface and volume rendering (hybrid rendering) method with the possibility of the performance of a virtual endoscopy. MATERIAL AND METHOD: In 6 patients with cochlear implants a high-resolution spiral computed tomography of the petrous bone was performed. The cochlear implants, the middle and inner ear structures were visualized using a color-coded surface rendering method, either shaded or as a grid. The petrous bone was visualized using a transparent volume rendering method. RESULTS: The hybrid 3D visualization uses the advantages of both the color-coded 3D surface and volume rendering method. In comparison to the axial source images, the hybrid 3D visualization thus facilitates a clearer representation and better assessment of the complex topographical relationship without loss of diagnostic information. The virtual endoscopy facilitates an intraluminal visualization and inspection of all color-coded 3D surface- and volume rendered structures. CONCLUSIONS: The hybrid rendering and virtual endoscopy make the morphological assessment of cochlear implants easier by the simultaneous visualization of the surrounding structures and thereby support the diagnostic imaging methods. This image processing method can be used pre-operatively for the individual planning, simulation, training and further development of surgical procedures and interventions and post-operatively for the control of the position and further developments of implants.

Adolescent↗