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K Stephan

Publications and source records attributed to K Stephan.

78 records · Page 5Linked to original sources
PubMedDate not supplied

Evaluation of performance with the COMBI40 cochlear implant in adults: a multicentric clinical study.

The present multicentric clinical study involves 19 centres, 16 of them in German-speaking countries, 1 British, 1 Polish and 1 Hungarian. 60 postlingually deafened adults with a mean age of 47.5 years (20-70) and mean duration of deafness of 5.3 years (0.5-20) have been evaluated with the MED-EL COMBI 40 cochlear implant which implements a high-rate continuous-interleaved-sampling strategy with 8 channels. Safety and effectiveness data have been collected. Speech perception tests include a 16-consonant, an 8-vowel, a sentence and a monosyllabic-word test in all languages and a 2-digit figure test in all languages but English. Test intervals are 1, 3, 6 months and 1 year after first fitting. 41 of the 60 postlingually deafened adult study patients have completed their 6-month evaluation. While their pre-operative monosyllabic-word score was 0%, their mean monosyllabic-word score 6 months after first fitting was 48% (8-90) with a median of 50%. The mean sentence understanding was 84% (24-100) with a median of 90%. The respective values for the 1-year evaluations with 25 patients are a mean of 50% (5-85), with a median of 60% for the monosyllables and a mean of 89% (30-100), with a median of 97%, for the sentences.

Adult↗
PubMedDate not supplied

Post-operative stapedius reflex tests with simultaneous loudness scaling in patients supplied with cochlear implants.

The estimation of the maximum comfort loudness levels (MCL) by measurements of the electrically elicited stapedius reflex was examined in six experienced cochlear implant users supplied with the COMBI 40 implant system. The stapedius reflex was tested and loudness scaling was performed simultaneously using an up/down stimulation protocol close to the reflex threshold with automated recording of both test procedures. The electrical stapedius reflex threshold (ESRT) and loudness scaling were evaluated separately. Scaling at the reflex threshold ranged between normal and loud. The range of stimulus intensities corresponding to ESRT is much smaller than that at a particular loudness category. The overall correlation between ESRT and MCL was high (r=0.92), with a similar dependence of ESRT and MCL on the channel stimulated. Thus, when the stapedius reflex can be detected post-operatively, the ESRT can be applied successfully for the fitting procedure of the speech processor. Simultaneous loudness scaling during the entire reflex test showed that overstimulation via the implant can be avoided effectively.

Adult↗
PubMedDate not supplied

Effect of stimulus duration on stapedius reflex threshold in electrical stimulation via cochlear implant.

The effect of stimulus duration on the threshold of the contralateral stapedius reflex was investigated in patients supplied with a Vienna cochlear implant (analog stimulation via CI) and compared to results of a normal-hearing reference group in case of acoustic stimulation. Changes in reflex threshold were determined at four frequencies (125, 500, 1,000 and 2,000 Hz in case of electrostimulation and at 500, 1,000, 2,000 and 4,000 Hz for acoustic stimulation) and for five durations (30, 50, 100, 300 and 500 ms). The comparison of the two stimulation modes was accomplished by using the same instrumentation and procedure. Reflex threshold was evaluated according to an objective criterion based on the individual noise distribution of recordings without reflex and by subjective judgement. For both stimulation modes a strong effect of stimulus duration on reflex threshold was observed (p < 0.001). The amount of temporal integration reflected by the threshold difference between 500 and 50 ms was approximately 2-4 dB for electrical stimulation via CI and 6 dB for acoustic stimulation in normal-hearing individuals. In case of electrostimulation, the reflex threshold for stimuli of 30 ms was most often above the limit of uncomfortable loudness sensation; the increase in reflex threshold for acoustic stimulation between 500 and 30 ms was approximately 14 dB. There was no evidence of frequency effect on reflex threshold nor an interaction between frequency and stimulus duration for either stimulation mode.

Adult↗
PubMedDate not supplied

Confirmation of transiently evoked otoacoustic emissions based on user-independent criteria.

Transiently evoked otoacoustic emissions (TEOAEs) were recorded from 525 ears (children, 3-11 years). Based on visual evaluation, the recordings were classified as TEOAEs present, absent or uncertain. Within each group the distribution of response level and reproducibility as well as of four derived parameters were calculated. The latter comprised: (1) corrected response level (difference between response level and approximated noise), (2) weighted response level (product of response level and correlation), (3) weighted sound pressure of the response (product of sound pressure and correlation) and (4) level of the weighted sound pressure of the response (weighted sound pressure of the response transformed to decibels). Based on these distributions, criteria to separate recordings with TEOAEs from recordings without TEOAEs were established. In this study the cutoff point is the parameter value where the amount of incorrectly identified recordings with TEOAEs is equal to the amount of correctly identified recordings without TEOAEs. The corresponding limiting values are: (a) response level 7.3 dB with 7.6% incorrect identifications for each group, (b) reproducibility 56% with 4.2% incorrect identifications, (c) corrected response level 2.4 dB with 5% incorrect identifications, (d) weighted response level 3.7 dB with 3.2% of incorrect identifications, (e) sound pressure of the response 0.027 mPa with 2% incorrect identifications and (f) level of the weighted sound pressure of the response 1.22 dB with 2% incorrect identifications.

Child↗
PubMedDate not supplied

Age-specific doses of lormetazepam as a night sedative in cases of chronic sleep disturbance.

Lormetazepam, a new benzodiazepine derivative, was tested under double blind conditions in order to find the optimal dosage for different age groups of out-patients. 120 patients suffering from chronic sleep disturbance were included in the study: a younger group (age 20 to 55) and an older group (age 56 to 85 years). Four different doses were given to each age group: 0.5, 1.0, 2.0, and 3.0 mg to the younger group and 0.5, 1.0, 1.5, and 2.0 mg to the older group. A pre-placebo week (i.e. when all patients received placebo) in which baseline data were recorded preceded the two verum weeks, and these were followed by a post-placebo or withdrawal week (again all patients receiving placebo). The level of significance accepted for statistical decisions was alpha = 0.05. No differences in effects between the different doses were observed with regard to sleep pattern variables (sleep latency, sleep duration, frequency of awakenings, sleep quality, occurrence of 'bad' dreams) with the exception of sleep quality which was better in the older group than in the younger group after 0.5 mg in week 2. Considerable differences with regard to hangover feelings the next morning and during the next day (morning feelings, tranquility, alertness, and concentration), comparison of the effects of discontinuing therapy upon the above-mentioned sleep pattern variables and small differences in side effects--which were few--led to the following conclusion: --0.5 mg stood out as the best dose for the older group. --None of the dosages given to the younger group emerged clearly as superior. However, it would seem that the 1 mg dose should be the dose recommended, since fewer unfavourable scores and side effects appeared after this dose.

Adult↗