Management of cochlear implants in children--methods and results]

Selection criteria, basic principles of auditory training, development of an auditory test battery for children and results of 15 children between 4 and 14 years are presented and discussed. To summarize, results range from acoustic attention to tones and sounds and recognition of environmental sounds to the use of supra-segmental and segmental features of speech. Some children are able to recognize words and phrases from a closed list. One of the children has postlingual deafness and has had also a very short duration of deafness before implantation. This child shows better results than the pre and perilingually deaf children. Because of the fact that the patient group is small and there are also many intervening variables like age, duration of deafness and use of two different test instruments, it is difficult to find a relationship between the results and all other variables. The auditory test battery for children, which consists of seven subtests, measuring acoustic orientation and auditory speech perception on different linguistic levels, is much more suitable for the evaluation of auditory performance for this age group than the auditory test battery for adults (Eisenwort and Burian 1988).     

Mondini畸形多道人工耳蜗植入的效果分析

OBJECTIVE: To describe clinical experiences with multi-channel cochlear implantation in patients with Mondini malformation. METHODS: Among 300 patients who received multi-channel cochlear implants from 1996 to 2002 in Beijing Tongren Hospital, 15 patients were diagnosed with Mondini malformation. A retrospective analysis was performed dealing with the surgical techniques, mapping and rehabilitations characteristics after surgery. 15 patients with normal cochlear structure are consider as control group. RESULTS: Gusher is found more common than the normal cochlear implantation, most of them are serious. The electrodes are inserted in the "cochleostomy" in full length of 13 Patients, 2 pairs of electrodes remains outside of "cochleostomy" in 2 patients. No serious complications occurred after implantation. All patients have auditory sensations. The impedance of the electrodes, the T level, C level and the hearing threshold are similar with the normal cochlear implantation group. The results have no significant difference in compare with normal cochlear group(P > 0.05). CONCLUSION: Multi-channel cochlear implantation could be performed safely in patients with Mondini malformation. The primary outcome for patients with Mondini malformation are similar to those with normal cochlear structure following the multi-channel cochlear implantation.     

Multivariate study of auditory perception using multi-electrode cochlear implants]

The goal of this study was to determine the influence of auditory and cognitive factors in hearing or listening mechanisms with the Nucleus multielectrode cochlear implant. Accordingly, hearing sensitivity, psycho-acoustical masking functions and measures of temporal resolution were obtained from 14 adults with acquired deafness. In addition, six measures of open-set speech discrimination were introduced to represent a possible contribution of cognitive factors. Results indicated the contribution of both auditory and cognitive factors to speech understanding. Cognitive factors were most influential. Differences were also found in the relative importance of various cognitive factors, both before and after an intensive aural rehabilitation program. Initially, subjects relied more heavily on their ability to make efficient use of the linguistic redundancy of speech. At the end of the program, they paid more attention to speech acoustics, as a result of enhanced auditory spectral analysis and temporal resolution at about 2 kHz.     

Pediatric cochlear implants

Cochlear implants are a safe and effective treatment for children with severe to profound sensorineural hearing loss. As implant technology continues to improve and outcomes are analyzed, younger and younger children are being deemed candidates for implantation. The decision to operate is made after a thorough evaluation by a multidisciplinary team. This review will highlight the preoperative and postoperative issues related to pediatric cochlear implantation.     

双侧人工耳蜗植入者在噪声环境下的言语辨别能力

目的 探讨双侧人工耳蜗植入患者的言语辨别能力。方法 用2例双侧人工耳蜗植入者比较双侧与单侧人工耳蜗在不同信噪比下对广东话声调的辨别能力。结果 在 15, 10和 5的信噪比下,双侧人工耳蜗的平均能力为96%,92%和88%,而左耳及右耳单侧人工耳蜗的平均成绩为86%,83和74%。在0,-5,-10及-15的信噪比下,单侧人工耳蜗的平均能力近于0%,而双侧人工耳蜗的平均成绩为80%,72%,68%和54%。结论 在不同信噪比下,双侧人工耳蜗植入更有助于提高对广东话声调的辨别能力。进一步证明了双侧人工耳蜗植入患者运用双耳听力的优势。     

Radiology for cochlear implants

One fifth of patients selected for cochlear implants have such bony irregularities in the cochlear duct that full insertion of a multichannel electrode array is impossible. Three cases of cochlear deafness are presented where pre- and post-operative radiology played an important part in the management. Standard CT at 2 mm cuts is compared with ultra high resolution CT at 1 mm cuts. The pitfall of poor definition is that the inexperienced surgeon may find himself unexpectedly drilling out an obliterated cochlear duct. Sections 30 degrees caudal to Reid's infra orbito-meatal base line at 1 mm intervals give maximum information for minimum radiation. Plain films show the placement of individual platinum electrode contacts in relation to the spiral 'frequency map' of the cochlea. This is vital information for the audiologist who has to route specific frequencies to specific sites within the ear for a good hearing result.     

Tinnitus and cochlear implants

Objective

Several published studies seem to confirm the clinical observation that cochlear implants (CI) have a suppressive effect on tinnitus in most CI users. The aim of this paper is to present our personal experiences on tinnitus improvement after cochlear implantation.

Methods

Before surgery, 51 post-lingually profoundly deaf adults, who underwent cochlear implantation between 2005 and 2007, filled out a questionnaire reporting tinnitus characteristics and the Italian version of the Tinnitus Handicap Inventory (THI-I). Moreover, they were asked to scale tinnitus loudness and annoyance. Six months after implant activation, patients repeated the same evaluations. Scores were statistically analysed by means of a Wilcoxon signed ranks test on the hypothesis that a CI could change the tinnitus magnitude and/or its annoyance.

Results

In our series of 36 patients, 36.10% reported total loudness suppression and another 41.6% reported a reduction. Annoyance scores reduced in 75% of patients. THI reduced in 72.2% of patients.

Conclusion

Tinnitus reduction after CI may manifest as several mechanisms, such as habituation, acoustic masking, direct electrical nerve stimulation and cortical reorganization. Nevertheless, it is our opinion that data on CI benefits on tinnitus should be interpreted with caution and it seems reasonable to admit that further data is still necessary before considering CI as a treatment of tinnitus especially in unilateral deafness.     

Binaural cochlear implants.

With the success of monaural cochlear implantation, patients frequently ask about having a second implant. We have performed binaural cochlear implants in 12 adult patients. Desire not to disrupt a functioning implant was the primary consideration in implanting the contralateral ear. Seven patients received a second 3M/House single-channel implant to upgrade to a magnetic external receiver. Four patients with a 3M/House device in one ear elected to place a Nucleus multichannel implant in the opposite ear. One patient with a poorly functioning Nucleus device elected to have a second Nucleus device. Four patients with a Nucleus and a 3M/House implant, one with binaural 3M/House implants, and one with binaural Nucleus implants were tested for auditory discrimination in order to quantify monaural versus binaural differences. The functional benefit of the second implant was mixed, but all patients showed some degree of objective improvement on one or more tests. Five of the six are regular users of both devices; the patient with binaural Nucleus implants wears only one. Despite the differing processing schemes, patients with a Nucleus device in one ear and a 3M/House device in the other ear are able to combine the two signals to advantage. We feel that cochlear implantation in the contralateral ear is an acceptable option in selected patients desiring an upgraded implant without placing a functioning implant at risk.     

Trends in cochlear implants

More than 60,000 people worldwide use cochlear implants as a means to restore functional hearing. Although individual performance variability is still high, an average implant user can talk on the phone in a quiet environment. Cochlear-implant research has also matured as a field, as evidenced by the exponential growth in both the patient population and scientific publication. The present report examines current issues related to audiologic, clinical, engineering, anatomic, and physiologic aspects of cochlear implants, focusing on their psychophysical, speech, music, and cognitive performance. This report also forecasts clinical and research trends related to presurgical evaluation, fitting protocols, signal processing, and postsurgical rehabilitation in cochlear implants. Finally, a future landscape in amplification is presented that requires a unique, yet complementary, contribution from hearing aids, middle ear implants, and cochlear implants to achieve a total solution to the entire spectrum of hearing loss treatment and management.     

Ethical and economical considerations on cochlear implants in developing countries]

An important factor that all cochlear implant teams have to deal with one way or another is the coast of the prostheses. This problem takes on very special characteristics in developing countries. This paper is based on the authors' experience in establishing the cochlear implant program of the "Hospital General Manuel Gea Gonzalez", a public hospital in Mexico City, and tries to determine which should be the optimal characteristics of an implant to be used in developing countries.     

Frequency mapping in cochlear implants

OBJECTIVE: To understand the short-term ("acute") effects of parametric variations to the frequency-to-electrode mapping on phoneme identification by Nucleus-22 cochlear implant listeners. METHODS: Phoneme recognition was measured in five Nucleus-22 cochlear implant listeners using custom four-channel continuous interleaved sampler (CIS) processors. For the four-channel processors, speech signals were band-pass filtered into four broad frequency bands. The temporal envelope in each band was extracted by half-wave rectification and low-pass filtering at 160 Hz. The extracted envelope was then transformed to electric currents by a power function with an exponent of 0.2. The resulting electric currents were delivered to four electrode pairs (18,22), (13,17), (8,12), (3,7). The effect of frequency-to-electrode mapping was investigated by systematically varying the parameters of band-pass filters while fixing the electrode locations. Experiment 1 measured phoneme recognition as a function of the slope of band-pass filters. The slope of band-pass filters varied from 48 dB/octave to 6 dB/octave; the corner frequencies of band-pass filters were not varied. Experiment 2 measured phoneme recognition as a function of the distribution of band-pass filters across a fixed overall frequency range. The frequency divisions of a fixed overall frequency range were systematically varied from a logarithmic to a linear distribution. Experiment 3 measured phoneme recognition as a function of the bandwidth of the band-pass filters. The bandwidth of each filter varied from 0.2 to 2 octaves; the center frequencies for each band were not varied. No practice or feedback was provided for subjects in all experiments. RESULTS: The slope of the band-pass filters had little effect on both vowel and consonant recognition. A slight performance drop was observed for only the shallowest slope condition (6 dB/octave). In contrast, the distribution of the band-pass filters had a strong effect on vowel recognition but a weak effect on consonant recognition. Best performance was achieved when a logarithmic or near-logarithmic frequency distribution was used to divide the overall frequency range. The bandwidth of the band-pass filters had a moderate effect on both vowel and consonant recognition. Vowel scores dropped significantly when the bandwidth of filters was too broad, whereas consonant scores dropped significantly when a narrower bandwidth was used. CONCLUSION: Under "acute" testing conditions, phoneme recognition with a four-channel CIS strategy seems to be only mildly affected by the slope of the band-pass filters, but can be significantly affected by the distribution of filters as well as the bandwidth of the filters. Optimal or near-optimal performance can be achieved with a logarithmic frequency distribution. Vowels are more susceptible to broad bandwidths, whereas consonants are more susceptible to narrow bandwidths.     

Audiologists' attitudes to cochlear implants

215 audiologists completed a cross-sectional survey concerning attitudes towards cochlear implants and associated referral behaviours. Audiologists were found to hold positive attitudes towards cochlear implants, with the majority (65%) having referred at least one client for an assessment. Audiologists reported that the implant was a safe and effective technology and that they were satisfied with the progress made by clients with the device. Nonetheless, 84% of audiologists expressed concern about the psychosocial needs of clients within the implant programme. Referral behaviours were primarily associated with knowledge on how and when to refer a person for an assessment. Secondary factors included funding awareness, professional experience and training, and knowledge of, confidence in, and relationship to, a local implant programme. Referrals to implant clinics may be enhanced by fostering relationships within the broader audiological community.     

Tinnitus suppression by cochlear implants

The beneficial effects of cochlear implants on tinnitus have been noted in several studies, but few detailed appraisals of the phenomenon have been made. Six patients fitted with the UCSF/Storz cochlear implant device were studied. The effects of use of the implant device on tinnitus were monitored, and suppression of tinnitus was tracked throughout periods of stimulation and poststimulation. Tinnitus was effectively suppressed in five of six patients with the device on and with noise input, and reduction of perceived tinnitus loudness occurred in four of six with the device on but without acoustic input to the speech processor. Unilateral stimulation frequently resulted in bilateral tinnitus suppression. These studies reveal that profound tinnitus suppression is obtained by patients using their cochlear implants. Further work is required to quantify the optimal mode of stimulation, but these findings suggest that tinnitus sufferers may ultimately benefit from development of electrical stimulation tinnitus suppression devices.     

Surgical techniques in cochlear implants

Cochlear implants have a remarkable history and a promising future. As the cochlear implant has evolved, so has the surgical technique. This review encompasses a history of the cochlear implant, a summary of the evolution of the implant incision and the methods used to secure the device and the electrode, the cochleostomy versus round window debate, and a discussion of the validity of intraoperative tests. Advanced technology, new surgical techniques, and refining established techniques are hallmarks of cochlear implant surgery. Advancements, including image-guided surgery, hearing preservation with full insertion, and telemetry-based advanced programming, are expected to be standard in the future.     

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.     

Research advances for cochlear implants

Considerable progress has been made with speech processing for multiple-channel cochlear implants, with a mean open-set CNC word score of 40% for electrical stimulation alone for the Nucleus SPEAK strategy. Further advances should be achieved through the following: beam-forming dual microphone systems for hearing in noise; better reproduction of the coding of sound frequencies; and taking advantage of plasticity in the central auditory pathways in young children. The reproduction of frequency coding will be facilitated with speech processors such as the Nucleus 24 system which can provide higher stimulus rates, and a new generation of electrode arrays where a greater number of electrodes lie close to the spiral ganglion cells.