摘要:

Electrically evoked auditory brainstem responses (EABR) were recorded in completely deaf patients implanted with IneraidTM multichannel cochlear implants. Clear and reproducible EABR were obtained from all patients. Parametric differences with auditory brainstem responses (ABR) were demonstrated and can be explained by the different natures of both types of stimulations (electric versus acoustic). Evidence is given that other well-known properties of auditory evoked responses, like ‘binaural interaction’ or suppression of responses in a forward masking paradigm, can be observed in EABR of implanted patie

ISSN:0301-1569    

DOI:10.1159/000276317

出版商:S. Karger AG    

年代:1992

数据来源: Karger

摘要:

The exploratory cochleotomy is a new diagnostic procedure for the selection of cochlear implant candidates. We use this procedure to assess the excitability of the auditory nerve, the patency of the cochlea and to detect undesirable side effects of electrical stimulation, such as facial nerve activation. The exploratory cochleotomy is a limited surgical procedure performed under local anesthesia in adults and light sedation in children. It is combined with the recording of electrically evoked brainstem responses elicited by an intracochlear probe electrode.

ISSN:0301-1569    

DOI:10.1159/000276318

出版商:S. Karger AG    

年代:1992

数据来源: Karger

摘要:

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). A great portion of the improvement is probably due to better transmission of sibilant and fricative (and to a lesser extent place of articulation) information.

ISSN:0301-1569    

DOI:10.1159/000276319

出版商:S. Karger AG    

年代:1992

数据来源: Karger

摘要:

Following the experience with nearly 150 patients with the Nucleus cochlear implant, a more sophisticated and lighter speech processor was tested successfully in terms of better speech understanding. In order to prepare further miniaturization, the standard bipolar stimulation mode was compared with an unipolar mode. It was found that unipolar stimulation needs less energy, without decreasing speech understanding. Preconditions for supplying very young children with a cochlear implant were the use of electrically elicited stapedius reflex thresholds, obtained intraoperatively, for the fitting of the speech processor and the setup of a special rehabilitation center, where children together with their mothers could be trained in hearing and understanding by special teachers and engineers for 12 weeks, distributed over the 1st postoperative year.

ISSN:0301-1569    

DOI:10.1159/000276320

出版商:S. Karger AG    

年代:1992

数据来源: Karger

摘要:

Ineraid is a multichannel intracochlear implant of recent design that can provide high levels of speech recognition to totally deaf patients. We chose this device when it became available in 1985 because of our clinical and research interests. We had no commercial ties and could therefore critically assess the value of this implant in an array of patients, including congenital deafness, ossified cochleas and perilingual children.

ISSN:0301-1569    

DOI:10.1159/000276321

出版商:S. Karger AG    

年代:1992

数据来源: Karger

摘要:

A pilot study was performed with 8 deaf patients who received the ‘Ineraid’ multichannel cochlear implant in Geneva, Switzerland. The mechanisms of psychological adaptation in these patients are summari

ISSN:0301-1569    

DOI:10.1159/000276322

出版商:S. Karger AG    

年代:1992

数据来源: Karger

摘要:

On the occasion of the Cochlear Implant Symposium in Geneva in October 1991, top hearing results attained by a young postlingually deaf woman with cochlear implant systems were presented in video recordings. These data are centered on demanding hearing performances in test situations and in a telephone conversation. For various reasons, two reimplantations were necessary in this deaf patient. Initially, she was provided with a single-channel extracochlear electrode of the Vienna type, which she found to improve her lipreading substantially, and she attained an unexpectedly good understanding of speech on a purely auditory basis. Today, this postlingually deaf women uses a multichannel intracochlear electrode of the Nucleus type. The excellent results with the first extracochlear system are clearly surpassed with the intracochlear system. Not least because of her above-average speech competence, the cochlear implant user attains a high degree of open speech understanding. Her verbal hearing efficiency is comparable to that of a person with mild to moderately severe hearing loss.

ISSN:0301-1569    

DOI:10.1159/000276323

出版商:S. Karger AG    

年代:1992

数据来源: Karger

摘要:

Although using autogenous ossicles in reconstruction offers stable hearing results with good tendency for healing and minimal extrusion, their use in cholesteatomatous ears has been criticized for the possibility of progressive osteitis, bone resorption and cholesteatoma recurrence. In the present study we have been investigating a way which affords safe re-implantation of such ossicles. Treatment by burring followed by autoclaving seems to offer an implant that is safe both bacteriologically and pathologically. We have found no evidence that cholesteatoma could develop from such treated ossicles.

ISSN:0301-1569    

DOI:10.1159/000276324

出版商:S. Karger AG    

年代:1992

数据来源: Karger

摘要:

Histopathological characteristics of 20 ear herodion polyps with a certain localisation and a well-known underlying pathological process were studied in order to elucidate the pathogenesis of ear mucosal polyp formation. Only 12 of the polyps were covered with epithelium; either a squamous keratinized epithelium or a cylindrical epithelium. Three polyps were covered with cylindrical and squamous keratinized epithelium. Incipient gland formation was seen and glands were only found in 35% of the polyps. It seems possible that the polyp is a local newly formed process and may have the aim of catching, eliminating and digesting bacteria and dead cells.

ISSN:0301-1569    

DOI:10.1159/000276325

出版商:S. Karger AG    

年代:1992

数据来源: Karger

摘要:

An unusual case of Castleman’s disease (CD) restricted to the left cervical area is reported. CD is rarely confined to the cervical area; when it occurs, it is usually of the hyaline-vascular subtype and small in size. This case was atypical due to its histology (plasma-cell variant), big size (15 × 11 × 6 cm) and the absence of general symptoms. In spite of surgical excision, the disease recurred 11 months later. However, subsequent surgery followed by chemotherapy resulted in a long-lasting control of the dise

ISSN:0301-1569    

DOI:10.1159/000276326

出版商:S. Karger AG    

年代:1992

数据来源: Karger