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PubMed1998

Cochlear implantation after subtotal petrosectomies.

Among cochlear implant candidates there are patients who have abnormal middle and/or inner-ear conditions that make them unsuitable for implantation. Insertion of a foreign body may also be contraindicated in the setting of an existing or potential intracranial communication, or when the ear is prone to infection. Five patients presented with such unfavorable conditions. These included a Mondini dysplasia with persistent cerebrospinal fluid leak, an atretic mastoid with meningocele, chronic otitis media, a transverse petrous bone fracture, and a temporal bone adenoma. All patients underwent subtotal petrosectomies and cochlear implantations. In four cases implantation was performed concomitantly with subtotal petrosectomy, while the remaining case required a two-stage procedure. No complications occurred. The technique is described in detail, and the cases and the indications for surgery are discussed. By obliterating and isolating the tympanomastoid cleft from the outer environment and utilizing the technique of subtotal petrosectomy, a broader spectrum of patients can now be implanted safely.

Adult↗

PubMed2002

The application of bionic wavelet transform to speech signal processing in cochlear implants using neural network simulations.

Cochlear implants (CIs) restore partial hearing to people with severe to profound sensorineural deafness; but there is still a marked performance gap in speech recognition between those who have received cochlear implant and people with a normal hearing capability. One of the factors that may lead to this performance gap is the inadequate signal processing method used in CIs. This paper investigates the application of an improved signal-processing method called bionic wavelet transform (BWT). This method is based upon the auditory model and allows for signal processing. Comparing the neural network simulations on the same experimental materials processed by wavelet transform (WT) and BWT, the application of BWT to speech signal processing in CI has a number of advantages, including: improvement in recognition rates for both consonants and vowels, reduction of the number of required channels, reduction of the average stimulation duration for words, and high noise tolerance. Consonant recognition results in 15 normal hearing subjects show that the BWT produces significantly better performance than the WT (t = -4.36276, p = 0.00065). The BWT has great potential to reduce the performance gap between CI listeners and people with a normal hearing capability in the future.

Cochlear Implants↗

PubMed1986

Audiological assessment in the selection of cochlear implant candidates.

In the UCH/RNID Cochlear Implant Programme, patients referred for further audiological assessment are all post-lingually deafened adults with bilateral hearing losses in excess of 90 dB HL in the frequency range 500 Hz to 4 kHz. The purpose of this assessment as part of the selection procedure for implant candidates is to ascertain whether or not the patient has any residual auditory function which can be aided by conventional means. The procedure includes measurement of thresholds of sensation (whether auditory or vibrotactile) for pure tones, and testing for Uncomfortable Loudness Levels up to 130 dB HL. It also includes measurements of frequency discrimination and abnormal adaptation, and assessment of the effect of acoustic stimulation on tinnitus if present. Those with measurable hearing are further tested for discrimination of simple sound patterns related to the perception of speech. Results of assessment, and criteria of suitability for a trial with a high-powered hearing aid are discussed in this paper. Of the 29 patients tested to date, 14 were judged to have sufficient residual auditory function to justify a hearing aid trial. In 10 cases the trial was successful and these people were then no longer considered to be potential candidates for cochlear implantation.

Acoustic Stimulation↗

PubMed2005

Bilateral cochlear implantation: current concepts.

PURPOSE OF REVIEW: Recent experience has shown an advantage of bilateral cochlear implantation over unilateral implantation. These documented benefits include improved speech perception in noisy environments and improved sound localization. Recently, investigators have studied the long-term benefit, evaluation of neural integration, programming, vestibular effects, and complications of bilateral cochlear implantation. This article summarizes the current research endeavors to improve our understanding and utilization of bilateral cochlear implantation. RECENT FINDINGS: Numerous positive benefits of bilateral cochlear implantation have been confirmed. Patients receive significant head shadow benefit from bilateral implantation, and obtain nominal benefits from summation and squelch effects. Sound localization benefits have been confirmed. Speech perception in noise with bilateral implantation is significantly better than unilateral implantation and continues to improve 24 months after implantation. Areas for further improvement have also been identified. Despite technological improvements in speech processing strategies, measured intraaural time differences in bilateral cochlear implant recipients remain considerably greater than those with normal hearing. Programming challenges persist to optimize sound processing with bilateral implants. Vestibular effects of bilateral cochlear implantation appear safe but need further study. Important considerations including the duration of implant function, long-term complication rate, and improvements in implant technology will continue to strongly influence the role of bilateral cochlear implantation. SUMMARY: Bilateral cochlear implantation provides advantages over unilateral implantation including improved speech perception in noise and improved sound localization. Further research is needed to define the optimal indications and to maximize the benefit of bilateral implantation.

Cochlear Implantation↗

PubMed1992

Digital speech processing for cochlear implants.

A rather general basic working hypothesis for cochlear implant research might be formulated as follows. Signal processing for cochlear implants should carefully select a subset of the total information contained in the sound signal and transform these elements into those physical stimulation parameters which can generate distinctive perceptions for the listener. Several new digital processing strategies have thus been implemented on a laboratory cochlear implant speech processor for the Nucleus 22-electrode system. One of the approaches (PES, pitch excited sampler) is based on the maximum peak channel vocoder concept whereby the spectral energy of a number of frequency bands is transformed into appropriate electrical stimulation parameters for up to 22 electrodes using a voice pitch synchronous pulse rate at any electrode. Another approach (CIS, continuous interleaved sampler) uses a maximally high pitch-independent stimulation pulse rate on a selected number of electrodes. As only one electrode can be stimulated at any instance of time, the rate of stimulation is limited by the required stimulus pulse widths (as determined individually for each subject) and some additional constraints and parameters which have to be optimized and fine tuned by psychophysical measurements. Evaluation experiments with 5 cochlear implant users resulted in significantly improved performance in consonant identification tests with the new processing strategies as compared with the subjects own wearable speech processors whereas improvements in vowel identification tasks were rarely observed. The pitch-synchronous coding (PES) resulted in worse performance compared to the coding without explicit pitch extraction (CIS).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1988

Cochlear implants in children: physiological considerations.

Cochlear implants now play a standard role in the management of adults with acquired profound sensorineural deafness. Their role in children is more controversial. However, as demonstrated by a 1979 report on childhood deafness in the European Communities, there is no reason for complacency in the present management of profoundly deaf children. Transtympanic electrocochleography has been used as a method of estimating neural survival in deafened adults being assessed for the U.C.H./R.N.I.D. single channel extracochlear implant and also in a parallel group of profoundly deaf children referred by a paediatric hearing assessment clinic. In adults the effectiveness of electrocochleography in judging neural survival was monitored by electrical stimulation of the cochlea and found to be significantly effective. This result was extrapolated to the paediatric group to estimate the proportion of congenitally deaf children who might benefit from a cochlear implant. It is suggested that in a programme designed to implant such children at 2 years of age, techniques should be chosen that neither damage the cochlea nor the middle ear sound conducting mechanism.

Adult↗

PubMed2003

Scuba diving with cochlear implants.

We report on a patient with bilateral cochlear implants (a Med-El Combi40 and a Med-El Combi40+), as well as considerable experience in scuba diving with both of his implants. After having been exposed to 68 and 89 dives, respectively, in depths of up to 43 m, both cochlear implants are in working order and the patient continues to receive excellent speech recognition scores with both cochlear implant systems. The presented data show that scuba diving after cochlear implantation is possible over a considerable number of dives without any major negative impact on the implants.

Cochlear Implants↗

PubMed2004

Changes in programming over time in postmeningitis cochlear implant users.

OBJECTIVE: Although successful cochlear implantation of patients with deafness following meningitis is expected, long-term stability of electrical current requirements has not been systematically evaluated. This study evaluated changes in programming for patients deafened by bacterial meningitis and stability of auditory performance over time. STUDY DESIGN AND SETTING: In this retrospective descriptive study, cochlear implant (CI) stimulation mode and performance of 14 patients deafened by meningitis were compared with those of an age-matched control group of patients deafened by other causes. RESULTS: There were no significant differences in mean performance between the meningitis group and control group (P > 0.05). However, the postmeningitis group required progressively higher stimulation levels and higher programming modes over time as compared to the control group. CONCLUSIONS: Even with deafness accompanied by labyrinthine ossification attributed to meningitis, neural elements were present and could be stimulated. Because increasing levels of stimulation were required over time, postmeningitic children with CIs, and those with cochlear ossification in particular, may need frequent programming adjustments to maintain performance. SIGNIFICANCE: These patients need close follow-up of stimulation levels and programming modes postoperatively in order to perform optimally with CIs. EBM RATING: B-3.

Adolescent↗

PubMed2006

Indication and surgical consideration of cochlear implantation at Ramathibodi Hospital.

OBJECTIVES: To demonstrate selection criteria for cochlear implant candidates as well as the outcome of quality of life (QoL) after cochlear implant surgery. MATERIAL AND METHOD: Retrospective review was performed of all cochlear implants at Ramathibodi Hospital. A total number of 33 cochlear implantations were performed during the period of 10 years from December 1995 to December 2005. Inclusion criteria were established and the audiological criteria were then evaluated using the electrical promontory stimulation test. The etiology of severe sensory neural hearing loss was detected. The CT scan and MRI of the inner ear were studied in the different causes of deafness. RESULTS: The main cause of deafness in the present study (16 adults and 17 children) was suffering from pregnancy rubella. The second one was familial congenital deafness. The CT scan studied in the rubella cases showed anatomical normal cochlea and the hereditary cause of deafness showed abnormal cochlea that caused a strong perilymphatic gusher in a 14 year- old boy. There were 16 cases of adolescent and adult patients who all had good response in the promontory stimulation test. The QoL post implantation was evaluated in regards to improvement in education and communication. CONCLUSION: Multi-channel cochlear implantation in severe profound hearing loss patients could improve the hearing in both normal and abnormal cochlea, congenital rubella deafness and the familial cause of deafness. The outcomes of the QoL after surgery were better in hearing detection, speech perception, school performance, communication and return to work.

Adolescent↗

PubMed2002

Cochlear implantation in children with CHARGE association.

OBJECTIVE: To explore the anomalies of the temporal bone found on radiologic examination, technical challenges in cochlear implantation, and audiologic benefit derived from cochlear implantation in a series of children with CHARGE association. DESIGN: Case series report. SETTING: Tertiary referral children's hospital pediatric cochlear implant program. PATIENTS: Six children with CHARGE association and sensorineural hearing loss. INTERVENTION: All patients were evaluated and followed up by the cochlear implant team. Cochlear implantation was attempted in all 6 children. MAIN OUTCOME MEASURES: Computed tomographic scans and cochlear implantation operative records were reviewed, and their findings were correlated. Audiometric and speech perception data before and after cochlear implantation were compared. RESULTS: Five children with CHARGE association received implants. A sixth child did not because of an aberrant course to the facial nerve. The 5 children receiving implants obtained varying degrees of measurable benefit from their implants. All 6 children had temporal bone abnormalities seen on their computed tomographic scans and documented at the time of surgery. CONCLUSIONS: Variations in the temporal bone anatomy of patients with CHARGE association can lead to increased technical challenges and risk to the facial nerve during cochlear implantation. Individual outcomes after implantation may vary; our patients receiving implants obtained benefit. Parents should be counseled thoroughly and have appropriate expectations before proceeding with implantation.

Abnormalities, Multiple↗

PubMed1997

Electrical middle ear muscle reflex: use in cochlear implant programming.

Programming of multichannel cochlear implants (CIs) requires subjective responses to a series of sophisticated psychophysical percepts. It is often difficult for young prelinguistically deaf children to provide adequate responses for device fitting. This is especially true in setting levels of maximum comfortable loudness, whereby failure to indicate growth of loudness may result in elevation of stimulus levels to the threshold of pain. The acoustic or stapedial muscle reflex has been used previously to provide objective confirmation of acoustic stimulation, and there have been attempts to use the reflex in hearing aid fitting. It has also been suggested that electrically elicited middle ear muscle reflexes (eMEMR) may have applicability in confirming and quantifying electrical stimulation through a CI. To assess the relationship between eMEMR characteristics and levels of loudness perception with CIs, determine reliability of the response, and investigate potential use of eMEMR in CI programming, 25 postlinguistically deafened adult CI users were evaluated. Reflexes have also been attempted on 40 children, with responses present in 31 (71%). Comfort levels predicted by eMEMR were highly correlated with those obtained through subjective judgments in the adult subjects. The eMEMR provides an objective, accurate, and rapid method of estimating maximum comfortable loudness levels, which may be useful in the initial programming of young implant recipients.

Acoustic Stimulation↗

PubMed2000

A cost-utility analysis of pediatric cochlear implantation.

OBJECTIVE/HYPOTHESIS: The aim of this study was to explore the cost-utility of pediatric cochlear implantation, incorporating savings associated with education into the analysis. METHODS: The costs of pediatric cochlear implantation were based on the full costs levied to purchasers, inclusive of complications and maintenance, by a large pediatric cochlear implant program in the United Kingdom. After implantation, profoundly hearing-impaired children have been found to develop hearing threshold levels equivalent to severely hearing-impaired children who wear hearing aids. An independent study calculated the educational costs for severely hearing-impaired and profoundly hearing-impaired children. From this study, savings in educational costs that would result from enabling the profoundly hearing-impaired to function as severely hearing-impaired were determined. Cost-utility was established conservatively by applying to children the known gains in utility reported by adults with cochlear implants. RESULTS: The discounted costs of creating a pediatric cochlear implant user and of maintaining the child over the first 12 years were 48,757 pound silver($78,011). The discounted difference in education costs associated with a profoundly hearing-impaired child (HL >95 dB) as compared with a severely hearing-impaired child (HL 70-95 dB) over the same period was 26,781 pound silver($42,850). These represent the potential savings in educational costs associated with pediatric cochlear implantation. Assuming implantation at age 4 years, the discounted net average cost of pediatric cochlear implantation over compulsory school years (ages 4-16) was 21,976 pound silver ($35,162). Cochlear implants have been shown to improve the quality of life in adults by 0.23 points per annum (where quality of life is rated on a scale from 0 to 1). Applying this weight to children receiving implantation at age 4 years, and assuming a life expectancy of 74 years, the quality-adjusted life-year (QALY) gain is calculated to be 16.33. The cost per undiscounted QALY gain was estimated to be 1,345.70 pound silver ($2153.12) and per discounted QALY gain to be 10,341 pound silver ($16,545.60). CONCLUSION: This study provides evidence, based on conservative assumptions, to support the view that pediatric cochlear implantation is a cost-effective health care intervention in profoundly hearing-impaired young children.

Child↗

PubMed2005

Cochlear implants: the view from the brain.

The cochlear implant arguably is the most successful neural prosthesis. Studies of the responses of the central auditory system to prosthetic electrical stimulation of the cochlea are revealing the success with which electrical stimulation of a deaf ear can mimic acoustic stimulation of a normal-hearing ear. Understanding of the physiology of central auditory structures can lead to improved restoration of hearing with cochlear implants. In turn, the cochlear implant can be exploited as an experimental tool for examining central hearing mechanisms isolated from the effects of cochlear mechanics and transduction.

Acoustic Stimulation↗

PubMed1997

Nucleus 22 cochlear implantation results in postmeningitic deafness.

Cochlear implant surgery was performed on 13 patients with postmeningitic deafness (seven adults, six children). Two adults and two children (30.8%) had severe labyrinthitis ossificans requiring radical "drill-out." Five of 13 (38.5%) had some bone growth requiring partial drill-out, and four of 13 (30.8%) had normal insertion with no drill-out. Hearing results for patients with no bone growth were similar to nonmeningitic patients; three of four (75%) had open-set speech recognition. Performance of patients with total drill-out was poor; "auditory only" performance was limited to detection and pattern perception of speech, and no patients had open-set speech recognition. Results for patients with partial drill-out were similar to results in patients with no bone growth. Labyrinthitis ossificans not only presents surgical challenges to cochlear implantation but may also adversely affect hearing outcome.

Adolescent↗

PubMed2002

Benefits of syllabic input compression for users of cochlear implants.

Ten users of multielectrode cochlear implants participated in an evaluation of the perceptual effects of input-signal compression. A syllabic compressor was introduced into the microphone circuit of Spectra-22 or SPrint sound processors. The post-compression gain was adjusted to provide similar loudness for speech at an average level of 65 dBA with compression either enabled or disabled. Sentence recognition was measured at three levels. Averaged across all listeners, statistically significant score increases were obtained at each level with compression enabled (45 dBA: 19.6 percentage points, p < .0001; 55 dBA: 16.6 percentage points, p < .0001; 70 dBA: 3.1 percentage points, p = .031). A test of speech intelligibility in noise showed no significant effect of compression. Generally, participants in the trial reported improved perception of low-level sounds with compression, although a few disliked the increased loudness of some background noises. Some participants suggested that the ability to enable or disable compression with a manual switch would be helpful. Overall, the results show that input compression can improve the performance of these sound processors for users of cochlear implants, especially when listening to speech at low levels.

Adult↗

PubMedDate not supplied

Vestibulo-ocular and vestibulospinal function before and after cochlear implant surgery.

Vestibular function in cochlear implant candidates varies from normal to total absence of function. In patients with intact vestibular function preoperatively, invasion of the otic capsule places residual vestibular function at risk. Speech-processing strategies that result in large amplitude electrical transients or strategies that employ high amplitude broad frequency carrier signals have the potential for disrupting vestibular function. Five patients were tested with and without electrical stimulation via cochlear electrodes. Two patients experienced subjective vestibular effects that were quickly resolved. No long-term vestibular effects were noted for the two types of second generation cochlear implants evaluated. Histopathological findings from another patient, who had electrically generated vestibular reflex responses to intramodiolar electrodes, indicated that responses elicited were a function of several variables including electrode location, stimulus intensity, stimulus amplitude, and stimulus frequency. Differential auditory, vestibulocolic, and vestibulospinal reflexes were demonstrated from the same electrode as a function of stimulus amplitude, frequency, and duration.

Aged↗

PubMed2007

[Discrimination of musical pitch with cochlear implants].

BACKGROUND: Numerous people with cochlear implants (CI) report difficulties in listening to music even though they understand speech quite well. One reason for this is a limited perception of pitch and timbre. In this study ability of adult CI subjects to discriminate musical pitch is investigated. PATIENTS AND METHODS: In two psychoacoustic experiments, each conducted in 10 adult CI subjects provided with MED-EL Combi 40+ cochlear implant devices and a control group of subjects with normal hearing, individual discrimination abilities for musical pitch perception were determined. To investigate the influence of the group of instruments on discrimination ability, stimuli representing four different groups of instruments were used: woodwind (clarinet), brass (trumpet), strings (violin) and keyboard instruments (piano). RESULTS: The discrimination thresholds determined varied between individual CI subjects, and on average they were significantly higher for the piano than for the other three instruments. CONCLUSIONS: The results show that in subjects with CI pitch perception differs from instrument to instrument and is in general worse than in persons with normal hearing.

Adult↗

PubMed2001

Perimodiolar electrodes in cochlear implant surgery.

Perimodiolar-positioned cochlear implant electrodes have been developed in order to bring the electrode contacts as close as possible to the spiral ganglion cells, which are the target of electrostimulation. This results in lower electrical thresholds, higher dynamic ranges and less channel interaction when compared with normal implant electrodes which are usually located peripherally within the scala tympani. In this study we evaluated 4 different types of perimodiolar electrode: the Clarion Preformed electrode, the Clarion Preformed electrode with positioner, the Nucleus Contour electrode and the Med-El Perimodiolar Combi 40 electrode. These devices require different approaches to achieve a perimodiolar electrode position. The electrodes were inserted in fresh human temporal bones. After processing these bones with the electrodes in situ by employing a sawing, grinding and polishing technique, the inner ear structures as well as the electrode positions could be evaluated in detail. All electrode types studied had a more or less perimodiolar position; however, each type produced a certain amount of trauma to cochlear structures which is discussed in relation to mechanical properties. Further human temporal bone studies with improved perimodiolar cochlear implant electrodes are necessary in order to find an optimized type of electrode.

Cochlea↗