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At least 343 records · Page 19Linked to original sources

PubMed2005

Cochlear implant failures and revision.

OBJECTIVE: To review cases involving implant failure and revision surgery in a large cochlear implant program. STUDY DESIGN: Retrospective case series. SETTING: Cochlear implant program in an academic medical center. PATIENTS: Adults and children who underwent revision cochlear implantation (n = 58). INTERVENTION: Diagnosis and explantation of failed cochlear implants, with subsequent reimplantation. Assessment of implant function and speech perception. MAIN OUTCOME MEASURES: Device type, time from implantation to revision, cause of failure, performance with original implant versus revision, number of electrodes placed, and surgical challenges related to reimplantation. RESULTS: Forty-five patients initially implanted at this program and 13 patients implanted elsewhere underwent revision surgery. The institutional device failure rate was 3.7% and the overall revision rate was 5.1%. Reasons for implant revision included documented internal device failure (46%), scalp flap complications (17%), optimization of electrode placement (13%), unexplained deterioration of performance (12%), technology upgrade (10%), and intratemporal pathology (3%). Revision surgery typically involved only minor anatomic challenges, but five patients required circumodiolar drillout procedures to improve electrode position. Electrode insertion was equal or deeper in 53 of 58 cases. Speech perception ability decreased in only three patients. CONCLUSIONS: Management of implant failures and performance of revision surgery are becoming increasingly important in cochlear implant programs. Outcomes are generally excellent. Revision implantation is a safe and appropriate procedure that should be pursued in a timely fashion when patients experience cochlear implant failure.

Adult↗

PubMed2003

Speech coding strategies and revised cochlear implant candidacy: an analysis of post-implant performance.

OBJECTIVE: Technological advances in cochlear implant systems on which a sequence of speech coding strategies have been implemented seem to have resulted in improved speech perception. However, changing selection criteria for implantation have coincided with evolving technology and may confound post-implantation speech perception performance. This study compares speech coding strategy with speech perception performance in severe and profound postlingually deafened adults using one of three successive generations of Nucleus Cochlear Implant speech processors (i.e., Mini Speech Processor, Spectra 22, and SPrint) implementing three speech coding strategies (i.e., MPEAK, SPEAK, and Advanced Combination Encoders; Cochlear Corporation, Englewood, CO, U.S.A.). STUDY DESIGN: Four cohorts of patients were retrospectively reviewed. SETTING: Multicenter, tertiary referral cochlear implant programs in Ontario, Canada. METHODS: Four cohorts of patients (n = 139) were identified based on preimplant audiological measures, duration of deafness, device type, and speech coding strategy. Word and sentence recognition scores at 12 months after implantation were compared using MPEAK with SPEAK22 implemented on the Nucleus 22 speech processors (Mini Speech Processor and Spectra22, respectively) and SPEAK24 as well as Advanced Combination Encoders implemented on the Nucleus 24 SPrint processor. RESULTS: Open-set speech recognition batteries revealed significant improvements in word and sentence scores as advancing technology implemented new speech coding strategies. Subgroup analysis of profoundly deafened patients supported this. Analysis of covariance confirmed that the measured differences could not be accounted for by changing selection criteria for implantation. CONCLUSION: Improvements in performance can be attributed to evolving speech coding strategies and speech processors rather than to differences in preimplant candidacy.

Audiometry, Pure-Tone↗

PubMed2002

The relative importance of amplitude, temporal, and spectral cues for cochlear implant processor design.

Speech understanding with cochlear implants has improved steadily over the last 25 years, and the success of implants has provided a powerful tool for understanding speech recognition in general. Comparing speech recognition in normal-hearing listeners and in cochlear-implant listeners has revealed many important lessons about the types of information necessary for good speech recognition--and some of the lessons are surprising. This paper presents a summary of speech perception research over the last 25 years with cochlear-implant and normal-hearing listeners. As long as the speech is audible, even the relatively severe amplitude distortion has only a mild effect on intelligibility. Temporal cues appear to be useful for speech intelligibility only up to about 20 Hz. Whereas temporal information above 20 Hz may contribute to improved quality, it contributes little to speech understanding. In contrast, the quantity and quality of spectral information appear to be critical for speech understanding. Only four spectral "channels" of information can produce good speech understanding, but more channels are required for difficult listening situations. Speech understanding is sensitive to the placement of spectral information along the cochlea. In prosthetic devices, in which the spectral information can be delivered to any cochlear location, it is critical to present spectral information to the normal acoustic tonotopic location for that information. If there is a shift or distortion of 2 to 3 mm between frequency and cochlear place, speech recognition is decreased dramatically.

Cochlear Implants↗

PubMedDate not supplied

[Complications of cochlear implant surgery].

During the last several decades, cochlear implant has been fully recognized in treatment of severe hearing loss. Development of modern technology enabled inconceivable possibilities of technical qualities of the device as well as development of usable coding strategies, which led to extraordinary results in patient rehabilitation. Although cochlear implantation has become one of the routine operative procedures throughout the world nowadays, it gives rise to certain complications. These complications, though rare, can sometimes be very serious, even with fatal outcome. If cochlear implantation is performed by experienced and well-educated team of experts, the possibility of complications is minimal and is certainly not the argument against cochlear implantation as a method of treatment of severe hearing impairments.

Adult↗

PubMed1986

A survey of speech and other auditory perception assessment materials used by cochlear implant centers.

A questionnaire assessing the various auditory perception materials used by cochlear implant centers in evaluating cochlear implant candidates and patients was developed, pilot tested, and mailed in August, 1985, to 135 cochlear implant centers. After a follow-up, there was a 45% return rate. The questionnaire sampled responses pertaining to the respondents' demographics, the types of assessment materials they used, and their opinions about speech and other auditory perception tests for evaluating cochlear implant patients. The data revealed that most centers use the same tests repeatedly for both pre- and post-implant assessments. Several factors relating to the tests and their administration were identified. Only 36% of the centers expressed satisfaction with the currently-used materials. The tests most frequently used were not necessarily considered to be the best or most appropriate for evaluating cochlear implants. Most respondents stated a need for the development of new test materials, and some suggestions were provided.

Auditory Perception↗

PubMedDate not supplied

Speech perception and language criteria for paediatric cochlear implant candidature.

Existing criteria for cochlear implantation of children with impaired hearing aim to select children who will eventually achieve better speech perception scores with an implant than with a hearing aid. It is difficult to predict the eventual outcomes with hearing aid and implant because speech perception scores typically increase with age, and because the distribution of scores for implant and hearing aid users overlap considerably at all ages. This paper shows how speech perception scores can be combined with spoken language measures to arrive at an objective criterion for implant selection. The method also allows estimation of the likely increase in speech perception score within a few months of implantation and estimation of the probability that the child will perform better with the implant than the hearing aid. The criteria were based on data from 135 evaluations of 50 children using cochlear implants with monosyllabic words, open-set sentences, the Clinical Evaluation of Language Fundamentals, and the Peabody Picture Vocabulary Test. Data from 114 evaluations of 43 children using hearing aids were used to illustrate the sensitivity of the criteria.

Audiometry, Pure-Tone↗

PubMed2006

Silicone allergy: A new cause for cochlear implant extrusion and its management.

OBJECTIVE: We introduce silicone allergy as a rare cause for cochlear implant extrusion and discuss its management. STUDY DESIGN: Retrospective case series and literature review. SETTING: Tertiary referral centers. PATIENTS: Primary eligibility criteria included patients who experienced a delayed extrusion of their cochlear implants with negative wound cultures and had a suspected or a test-proven allergy to silicone components of an implant. INTERVENTIONS: Silicone allergy testing, explantation of a cochlear implant containing allergenic silicone materials, reimplantation with a custom-made cochlear implant excluding an allergenic silicone component. OUTCOME MEASURES: Uneventful wound healing and extrusion-free long-term follow-up after the reimplantation with a custom-made cochlear implant excluding an allergenic silicone component. RESULTS: Three known cases of cochlear implant extrusion as a result of silicone allergy have been noted from 1991 through 2004 in three cochlear implant programs in the United States. All three devices extruded, resulting in explantation of the old device and reimplantation with a new custom-made device eliminating the allergenic silicone component. Wound cultures were negative in all cases. All three patients experienced a delayed extrusion of their devices. Two of these patients had a test-proven allergy to the implant's silicone components, whereas the third patient was presumed to have a hypersensitivity solely on the basis of a clinical presentation. CONCLUSION: We propose that silicone allergy is a rare cause of cochlear implant extrusion. Patients experiencing cochlear implant extrusion, particularly with a delayed onset and negative wound culture results, should be tested for silicone allergy.

Child, Preschool↗

PubMed2005

Effects of stimulation mode, level and location on forward-masked excitation patterns in cochlear implant patients.

In multi-channel cochlear implants, electrical current is delivered to appropriate electrodes in the cochlea to approximate the spatial representation of speech. Theoretically, electrode configurations that restrict the current spread within the cochlea (e.g., bi- or tri-polar stimulation) may provide better spatial selectivity, and in turn, better speech recognition than configurations that produce a broader current spread (e.g., monopolar stimulation). However, the effects of electrode configuration on supra-threshold excitation patterns have not been systematically studied in cochlear implant patients. In the present study, forward-masked excitation patterns were measured in cochlear implant patients as functions of stimulation mode, level and location within the cochlea. All stimuli were 500 pulses-per-second biphasic pulse trains (200 micros/phase, 20 micros inter-phase gap). Masker stimuli were 200 ms in duration; the bi-polar configuration was varied from narrow (BP+1) to wide (BP+17), depending on the test condition. Probe stimuli were 20 ms in duration and the masker-probe delay was 5 ms; the probe configuration was fixed at BP+1. The results indicated that as the distance between the active and return electrodes in a bi-polar pair was increased, the excitation pattern broadened within the cochlea. When the distance between active and return electrodes was sufficiently wide, two peaks were often observed in the excitation pattern, comparable to non-overlapping electric fields produced by widely separated dipoles. Analyses of the normalized data showed little effect of stimulation level on the shape of the excitation pattern.

Adult↗

PubMed2003

Language development in deaf infants following cochlear implantation.

OBJECTIVE: To evaluate the benefits of cochlear implantation in infancy and compare them to those obtained in children implanted at a slightly older age. MATERIAL AND METHODS: Using standard language measurement tools, including the Grammatical Analysis of Elicited Language--Presentence Level (GAEL-P) and the Reynell Developmental Language Scales, progress was documented in a child who received a cochlear implant in infancy and compared to that achieved in children implanted at older ages. A new measurement tool, the Visual Habituation Procedure, was used to document early skills and the results were compared to those obtained in normal-hearing infants. RESULTS: By the age of 2 years the subject implanted in infancy achieved scores on the GAEL-P which were nearly equivalent to those achieved at the age of 5 1/2 years by children implanted at later ages. Age-equivalent scores on the Reynell Developmental Language Scales were achieved by the subject implanted in infancy and the ability to discriminate speech patterns was demonstrated using the Visual Habituation Procedure. CONCLUSION: This report demonstrates enhanced language development in an infant who received a cochlear implant at the age of 6 months.

Age Factors↗

PubMed2006

Cochlear implants: informing commissioning decisions, based on need.

Cochlear implantation is a high cost, low volume intervention which is provided to adults and children with profound hearing impairment. Demand is increasing in the UK as a result of improved technology, changes in intervention criteria and the national newborn hearing screening programme. In order to inform commissioning policy for cochlear implantation in five English primary care trusts, we reviewed the evidence and assessed the complexities of developing needs and of service provision assessment and planning. Our results indicated that the current level of provision was well below what would be expected if the majority of people meeting current criteria were given a cochlear implant. Gaps between the clinical intervention thresholds and the level of service commissioned have widened. Long-term cost effectiveness and incidence studies are needed to assess cochlear implantation in the light of these lower clinical intervention thresholds.

Child↗

PubMed2004

Assessing candidate children for cochlear implantation with the Nottingham Children's Implant Profile (NChIP): the first 200 children.

BACKGROUND/OBJECTIVE: Nottingham Children's Implant Profile (NChIP) is a profile designed to assess candidate children for cochlear implantation. It includes the demographic details of the children (chronological age and duration of deafness), medical and radiological conditions, the outcomes of audiological assessments, language and speech abilities, multiple handicaps or disabilities, family structure and support, educational environment, the availability of support services, expectations of the family and deaf child, cognitive abilities, and learning style. The aim of the present study is to present the NChIP data obtained on the first 200 children implanted in the same cochlear implant programme and evaluate NChIP's use in the selection phase of cochlear implantation. PATIENTS: The study assessed 200 profoundly deaf children. Fifty-six children (28%) were deafened by meningitis, 132 (66%) were born deaf, and 12 (6%) were deafened from other causes (head injury, viral infection, progressive deafness). RESULTS: Chronological age at the time of assessment (before implantation) was the most common factor of major concern (9% of the children studied) and the pre-implant language and speech abilities of the children was the most common factor of mild to moderate concern, affecting 63% of the children. The second most common factor of mild to moderate concern was duration of deafness (37%) and the third was the learning style of the children (33%). Availability of support services was the least factor of concern as 179 children (90%) did not have any problems in this area. CONCLUSIONS: Earlier identification of deafness (by universal neonatal hearing screening programs) may reduce age at implantation and duration of deafness as areas of concern in the future. However, the pre-implant language and speech abilities of the candidate children, the gap between chronological and language age, and the learning style of children are now emerging as key areas of research in the field. NChIP was found to be a very useful casework tool in the initial evaluation of the deaf children promoting and enhancing interdisciplinary teamwork across the different professionals. NChIP was also used as part of the decision-making process by the cochlear implant programme professionals and as a counselling tool for the parents. Finally, NChIP has helped to identify those children and families who need additional support. In the case of recently established paediatric cochlear implant programmes it would be a 'neutral' yet sensitive way of promoting good interdisciplinary collaboration and also peer support within team discussions when selecting children for cochlear implantation.

Adolescent↗

PubMed2001

Ethical dimension of paediatric cochlear implantation.

In congenitally or prelingually deaf children cochlear implantation is open to serious ethical challenge. The ethical dimension of this technology is closely related to both a social standard of quality of life and to the uncertainty of the overall results of cochlear implantation. Uncertainty with regards the acquisition of oral communicative skills. However, in the western world, available data suggest that deafness is associated with the lowest educational level and the lowest family income. Notwithstanding the existence of a Deaf-World, deafness should be considered as a handicap. Therefore, society should provide the means for the fulfilment of a deaf child's specific needs. For the time being there is no definitive answer with regard the best way to rehabilitate a particular deaf child. Therefore, communitarian values may be acceptable. If the deaf child parents' decide not to implant, their decision should be respected. Guardians are entitled to determine which standard of best interest to use in a specific circumstance. They are the proper judges of what (re)habilitation process is best for their deaf child. However, most deaf children are born to two hearing parents. Probably, they will not be acculturated in the Deaf-World. It follows that cochlear implantation is a welcomed (re)habilitation technology. If auditory (re)habilitation will in the future provide the necessary communicative skills, in particular oral language acquisition, customs, values and attitudes of the hearing world should be regarded as necessary to accomplish a deaf child's right to an open future. If cochlear implantation technology will provide all deaf children with the capacity to develop acceptable oral communicative skills--whatever the hearing status of the family and the cultural environment--then auditory (re)habilitation will be an ethical imperative.

Attitude to Health↗

PubMed2000

Localization of cochlear implant electrodes in radiographs.

Multielectrode cochlear implantation is the most effective treatment for profound sensorineural hearing loss. In vivo three-dimensional 3-D localization of cochlear implant electrodes is important for modeling of the electrical field in the cochlea, design of electrode arrays, and may improve speech processor programming for better speech recognition. The prerequisite for 3-D localization of the electrodes is their 2-D localization in x-ray radiographs. In this paper, we develop a practical method to localize the electrodes with high efficiency, accuracy, and reproducibility. In this method, a priori knowledge of the electrodes and their approximate positions are utilized, an intelligent thresholding and segmentation mechanism is embedded, and the electrode center is computed as the weighted geometric center of segmented electrode pixels. Experiments with physical phantoms and human data demonstrate the feasibility and utility of this method. The PC-based program developed for this project is disseminated on the Web.

Cochlear Implants↗

PubMed2004

Cochlear implantation for the treatment of deafness.

Cochlear implants have dramatically changed the treatment and prognosis for patients with profound sensorineural hearing loss. Deaf adults and children can be successfully (re)integrated into the hearing world through a multidisciplinary approach involving otolaryngologists, audiologists, and speech/language pathologists. As the technology of the cochlear prosthesis advances, the candidacy for these devices continues to broaden. This review addresses the basic technology, candidacy criteria, and important issues in the fields of adult and pediatric cochlear implantation. Cost utility and future directions in the treatment of the profoundly hearing impaired are discussed.

Adult↗

PubMed1997

Integrity testing of cochlear implants in the awake child.

Cochlear implantation is becoming a routine rehabilitation process for profoundly deaf adults and children. Often children are implanted at just two or three years of age and therefore the subsequent tuning of the device is challenging. Although some children demonstrate quick and reliable responses to electrical stimulation, there are others who do not respond consistently thus causing concern about the functioning of the device. It is therefore desirable to have an objective test of the integrity of the implanted electrodes. The principle of the integrity test is the measurement of voltages generated by the biphasic current pulses at the electrode array; this is accomplished using surface electrodes placed around the implanted ear, in conjunction with recording and averaging equipment typically used for evoked response testing. Traditional integrity testing usually requires a general anaesthetic in young children, however this study demonstrated a simple, quick and reliable method of obtaining results in the normally active child using ear-clip electrodes. Results are presented from 12 children tested in this way, and compared with results from 20 children who were tested in theatre using a different electrode configuration. The tests were performed in common ground stimulation mode, but some measurements were also made in bipolar + 1 and pseudo-monopolar modes. The three stimulation modes were compared, with the conclusion that common ground mode provides an efficient check of implant function in the awake child, while pseudo-monopolar mode may be preferable for anaesthetized patients. In addition, measurements were made in vitro using a functioning cochlear implant in a saline tank in order to investigate the current flow during stimulation. The standard procedure in this department is to perform a full intra-operative integrity test on all implanted children. The simplified technique is used to repeat the measurement post-operatively if required.

Child↗

PubMed2000

A concept for a research tool for experiments with cochlear implant users.

APEX, an acronym for computer Application for Psycho-Electrical eXperiments, is a user friendly tool used to conduct psychophysical experiments and to investigate new speech coding algorithms with cochlear implant users. Most common psychophysical experiments can be easily programmed and all stimuli can be easily created without any knowledge of computer programing. The pulsatile stimuli are composed off-line using custom-made MATLAB (Registered trademark of The Mathworks, Inc., http://www.mathworks.com) functions and are stored on hard disk or CD ROM. These functions convert either a speech signal into a pulse sequence or generate any sequence of pulses based on the parameters specified by the experimenter. The APEX personal computer (PC) software reads a text file which specifies the experiment and the stimuli, controls the experiment, delivers the stimuli to the subject through a digital signal processor (DSP) board, collects the responses via a computer mouse or a graphics tablet, and writes the results to the same file. At present, the APEX system is implemented for the LAURA (Registered trademark of Philips Hearing Implants) cochlear implant. However, the concept-and many parts of the system-is portable to any other device. Also, psycho-acoustical experiments can be conducted by presenting the stimuli acoustically through a sound card.

Cochlear Implants↗

PubMed2006

Incidence and characteristics of facial nerve stimulation in children with cochlear implants.

OBJECTIVES: Electrical stimulation from a cochlear implant can spread beyond the auditory nerve. The aims of this study were to accurately measure facial nerve stimulation in pediatric implant users and to determine the characteristics and incidence of this unwanted activity. Part A consisted of a prospective study of a randomized sample of 44 pediatric implant users. Part B consisted of a retrospective analysis of 121 children with previously recorded electrically evoked auditory brainstem responses (EABR). STUDY DESIGN AND METHODS: Responses were evoked by 3 electrodes along the implant array in three groups of children: 1) postmeningitic, 2) abnormal cochlea, and 3) neither. Intraoperative measures were obtained under anesthesia; all other recordings were completed in awake children. RESULTS: Intraoperative recordings revealed large nonauditory responses in a number of channels, including the midline EABR. Under paralysis, these responses disappeared, and clear EABRs were recorded. Similarly, prospective postoperative electromyographic (EMG) responses from the facial nerve were found in more than 59% (26 of 44) of experienced implant users (Nucleus 24): 31% of postmeningitic children (4 of 13), 80% of those with abnormal cochlea (8 of 10), and 66% of those with neither (14 of 21). Retrospective analysis of previously recorded postoperative EABRs demonstrated facial nerve stimulation in 35% (42 of 121). In most cases, facial nerve stimulation occurred when levels were perceptually loud but comfortable. CONCLUSIONS: 1) Facial nerve potentials can be recorded using EMG in a large proportion of cochlear implant users at high levels of stimulation. 2) The EABR can be obscured in the presence of facial nerve stimulation and care should be taken to distinguish it from the EMG response, particularly when auditory brainstem activity is in question. 3) Use of surface EMG provides an additional objective measure to ensure the safe and comfortable use of cochlear implants.

Auditory Perception↗

PubMed1996

The scala vestibuli for cochlear implantation. An anatomic study.

BACKGROUND: Traditionally, cochlear implantation has used the scala tympani (ST) for electrode insertion. When faced with ST ossification, the surgeon may elect to drill out the cochlea to accomplish partial electrode insertion. Theoretically, another option in this situation is to insert the electrode into the scala vestibuli (SV). OBJECTIVE: To determine whether or not the dimensions of the SV are sufficient to accommodate an electrode array so as to assess the feasibility of SV cochlear implantation. METHODS: The study of 20 normal human temporal bones, comparing the maximum diameter and surface area of the ST with those of the combined SV and scala media. RESULTS: The dimensions of the SV and scala media were comparable to those of the ST and appeared sufficient to accommodate a cochlear implant electrode array. CONCLUSION: It appears that the combination of SV and scala media is a viable alternative route for electrode insertion, at least on the basis of anatomic dimensions, in those cases in which the ST is obliterated.

Cochlea↗