Biomedical subjects

Wolf-Dieter Baumgartner

Publications and source records attributed to Wolf-Dieter Baumgartner.

15 recordsLinked to original sources

PubMed2006

Telephone use: what benefit do cochlear implant users receive?

This study evaluated the use of landline and mobile phones in an international sample of cochlear implant users. A custom-designed survey was mailed to cochlear implant users from four different countries. A link to the survey was posted on the MED-EL website, with responses from a further six countries. Results from 196 surveys show that there is a significant shift from pre-operative non-use of a telephone to use of a telephone post-operatively. Seventy-one percent of MED-EL cochlear implant users are able to use a landline telephone to some extent and 54% are able to use a mobile phone to some extent. Talking to familiar speakers about familiar topics is the easiest listening condition on the telephone, and it is easier to recognize a voice using the landline. Many respondents found it difficult to make a call without some assistance. Most respondents could manage to call someone in an emergency, even on a mobile phone. Data obtained should provide useful information in the counselling and rehabilitation of cochlear implant recipients and candidates.

Adolescent↗

PubMed2006

Effects of interaural time differences in fine structure and envelope on lateral discrimination in electric hearing.

Bilateral cochlear implant (CI) listeners currently use stimulation strategies which encode interaural time differences (ITD) in the temporal envelope but which do not transmit ITD in the fine structure, due to the constant phase in the electric pulse train. To determine the utility of encoding ITD in the fine structure, ITD-based lateralization was investigated with four CI listeners and four normal hearing (NH) subjects listening to a simulation of electric stimulation. Lateralization discrimination was tested at different pulse rates for various combinations of independently controlled fine structure ITD and envelope ITD. Results for electric hearing show that the fine structure ITD had the strongest impact on lateralization at lower pulse rates, with significant effects for pulse rates up to 800 pulses per second. At higher pulse rates, lateralization discrimination depended solely on the envelope ITD. The data suggest that bilateral CI listeners benefit from transmitting fine structure ITD at lower pulse rates. However, there were strong interindividual differences: the better performing CI listeners performed comparably to the NH listeners.

Acoustic Stimulation↗

PubMed2005

GJB2 mutations in hearing impairment: identification of a broad clinical spectrum for improved genetic counseling.

OBJECTIVES/HYPOTHESIS: Hearing impairment has a high prevalence affecting approximately 1 in 1000 newborn children. Alterations in the gap junction protein beta 2 (GJB2) and gap junction protein beta 6 (GJB6) are associated with nonsyndromic hearing impairment and should have a significant impact on genetic counseling. STUDY DESIGN: Various cases of nonsyndromic hearing impairment were screened for alterations in GJB2 and GJB6 in this clinical study. METHODS: The prevalence of mutations in GJB2 encoding for connexin 26 in a patient group with nonsyndromic hearing impairment comprising 45 families and 57 sporadic cases was initially determined by sequencing. The role of GJB2 was then assessed in individuals with hearing impairment (3 families and 20 sporadic cases) who are usually excluded from analysis because of the presence of additional symptoms or in cases in which a role for nongenetic factors cannot be eliminated. In hearing-impaired individuals with heterozygous GJB2 mutations the recently identified 342-kb deletion truncating GJB6 called del(GJB6-D13S1830) as a digenetic component in hearing impairment was excluded by polymerase chain reaction. RESULTS: Autosomal recessively inherited GJB2 mutations induced hearing impairment in 25.5% of individuals in the nonsyndromic hearing impairment group. GJB2 alterations were also seen in 17.4% of individuals in whom additional symptoms or a role for nongenetic involvement could not be excluded. In all, 15 different alterations in GJB2 were detected, including the previously unknown 154G>C, 557C>T, and 682C>T mutations, and these were correlated to clinical parameters. CONCLUSION: Improved genetic counseling can be performed by screening for GJB2 alterations in patients with nonsyndromic hearing impairment including patients within groups for which a role for exogenetic factors cannot be excluded. Specific genetic counseling for GJB2-linked hearing impairment in heterozygotes will depend on future research.

Chromosome Deletion↗

PubMed2004

Lack of association between Connexin 31 (GJB3) alterations and sensorineural deafness in Austria.

Mutations in the gap junction protein beta 3 (GJB3) gene encoding Connexin 31 (Cx31) are known to cause autosomal inherited sensorineural deafness, erythrokeratodermia and neuropathy. The role of Cx31 mutations has not been described in familial cases of non-syndromic hearing impairment (NSHI) in central European populations. To identify mutations in the Austrian population, highly selected familial (n=24) and sporadic (n=21) cases of isolated NSHI were screened by analysis of the complete coding sequence of Cx31, after exclusion of a common Cx26 causing deafness. Three different variations occurring in a total of 37% of all cases were identified. A C94T (R32W) missense mutation was seen in 4.4% of cases and two silent alterations C357T and C798T were detected in 8.9% and 24.4% of cases exclusively in a heterozygous pattern. No correlation between Cx31 alterations and deafness was found. To investigate the role of heterozygous Cx31 variations for a possibly combination allelic disease inheritance with Cx26 mutations as shown for Connexin 30 and Connexin 26, patients with Cx26 variations were tested. Our data suggest that Cx31 alterations are common but have no or a low genetic relevance in the Austrian hearing impaired population with or without Cx26 alterations.

Austria↗

PubMed2004

Screening for monogenetic del(GJB6-D13S1830) and digenic del(GJB6-D13S1830)/GJB2 patterns of inheritance in deaf individuals from Eastern Austria.

Genetically caused congenital deafness is a common trait affecting 1 in 2000 newborn children and is predominantly inherited in an autosomal recessive fashion. Genes such as the gap junction protein beta 2 (GJB2) encoding for Connexin (Cx26) and GJB6 (Cx30) are known to cause sensorineural deafness. Autosomal recessive deafness has been linked both to the monogenetic occurrence of mutated GJB2 or the GJB6 deletion del(GJB6-D13S1830) and digenic GJB2/del(GJB6-D13S1830) inheritance. Monogenetic GJB2 alterations are responsible for 25.5% of deafness in the eastern Austrian population. An additional 9.8% are heterozygous carriers of a single GJB2 mutation which is not responsible for deafness alone. Del(GJB6-D13S1830) and GJB2/del(GJB6-D13S1830) mutations have been shown to be the second most frequent cause of deafness in different populations. To address the question of the relevance of mutations in GJB6 either as a monogenetic or a digenic GJB2/del(GJB6-D13S1830) cause of deafness in this population, 76 unrelated individuals (33 families and 43 sporadic cases) were screened using PCR strategies. Similar to studies in other hard of hearing populations with similar or lower carrier frequencies of single GJB2 mutations, the presence of del(GJB6-D13S1830) was not detected in any individual within the patient group. Data therefore exclude a digenetic association of del(GJB6-D13S1830) with heterozygous GJB2 mutations as a cause of deafness in a representative sample of the population from Eastern Austria.

Austria↗

PubMed2004

Hearing preservation in cochlear implantation for electric acoustic stimulation.

OBJECTIVE: To evaluate the possibility of preservation of low-frequency hearing in atraumatic cochlear implant electrode insertion procedures for combined, ipsilateral electric and acoustic stimulation. MATERIAL AND METHODS: A total of 21 patients were implanted with a MED EL C40+ cochlear implant using an atraumatic electrode insertion technique to preserve residual low-frequency hearing. Pure-tone audiometric thresholds were measured pre- and postoperatively to evaluate the degree of preserved hearing. Speech discrimination tests in quiet and with background noise were performed in a patient with successful hearing preservation. RESULTS: Using the atraumatic electrode insertion procedure with an insertion depth of 360 degrees (18-24 mm), hearing preservation could be achieved in 18/21 patients (85.7%). Three patients (14.3%) lost their residual low-frequency hearing after the implantation. Residual hearing was preserved completely in 13 patients (61.9%) and partial hearing preservation was possible in 5 (23.8%). Preliminary speech discrimination tests showed a dramatic benefit for the combined electric and acoustic stimulation mode compared to cochlear implantation alone. CONCLUSION: Preservation of low-frequency hearing in cochlear implantation is possible in patients implanted because of profound high-frequency deafness. With the development of new, more atraumatic electrode designs, preservation of residual hearing should be further improved.

Acoustic Stimulation↗

PubMed2004

Sensitivity to interaural level and envelope time differences of two bilateral cochlear implant listeners using clinical sound processors.

OBJECTIVES: To assess the sensitivity of two bilateral cochlear implant users to interaural level and time differences (ILDs and ITDs) for various signals presented through the auxiliary inputs of clinical sound processors that discard fine timing information and only preserve envelope cues. DESIGN: In a lateralization discrimination experiment, the just noticeable difference (JND) for ILDs and envelope ITDs was measured by means of an adaptive 2-AFC method. Different stimuli were used, including click trains at varying repetition rates, a speech fragment, and noise bursts. For one cochlear implant listener and one stimulus, the sensitivity to envelope ITDs was also determined with the method of constant stimuli. The dependency of ILD-JNDs on the interaural place difference was studied with stimulation at single electrode pairs by using sinusoidal input signals in combination with appropriate single-channel processor fittings. In a lateralization position experiment, subjects were required to use a visual pointer on a computer screen to indicate in-the-head positions for blocks of stimuli containing either ILD or ITD cues. All stimuli were loudness balanced (before applying ILD) and fed directly into the auxiliary inputs of the BTE processors (TEMPO+, Med-El Corp.). The automatic gain control and the processors' microphones were deactivated. RESULTS: Both cochlear implant listeners were highly sensitive to ILDs in all broadband stimuli used; JNDs approached those of normal-hearing listeners. Pitch-matched single electrode pairs showed significantly lower ILD-JNDs than pitch-mismatched electrode pairs. Envelope ITD-JNDs of cochlear implant listeners obtained with the adaptive method were substantially higher and showed a higher test-retest variability than waveform ITD-JNDs of normal-hearing control listeners and envelope ITD-JNDs of normal-hearing listeners reported in the literature for comparable signals. The envelope ITD-JNDs for the click trains were significantly lower than for the speech token or the noise bursts. The best envelope ITD-JND measured was ca. 250 mus for the click train at 100 cycles per sec. Direct measurement of the psychometric function for envelope ITD by the method of constant stimuli showed discrimination above chance level down to 150 micros. The lateralization position experiment showed that both ILDs and envelope ITDs can lead to monotonic changes in lateral percept. CONCLUSIONS: The two cochlear implant users tested showed strong effects of ILDs in various broadband stimuli with respect to JNDs as well as lateralization position. The high dependency of ILD-JNDs on the interaural pitch difference suggests the potential importance of pitch-matched assignment of electrodes in the two ears by the speech processors. Envelope ITDs appear to be more ambiguous cues than ILDs, as reflected by the higher and more variable JNDs compared with normal-hearing listeners. The envelope ITD-JNDs of cochlear implant listeners depended on the stimulus.

Acoustic Stimulation↗

PubMed2004

Coding of vowellike signals in cochlear implant listeners.

Neural-population interactions resulting from excitation overlap in multi-channel cochlear implants (CI) may cause blurring of the "internal" auditory representation of complex sounds such as vowels. In experiment I, confusion matrices for eight German steady-state vowellike signals were obtained from seven CI listeners. Identification performance ranged between 42% and 74% correct. On the basis of an information transmission analysis across all vowels, pairs of most and least frequently confused vowels were selected for each subject. In experiment II, vowel masking patterns (VMPs) were obtained using the previously selected vowels as maskers. The VMPs were found to resemble the "electrical" vowel spectra to a large extent, indicating a relatively weak effect of neural-population interactions. Correlation between vowel identification data and VMP spectral similarity, measured by means of several spectral distance metrics, showed that the CI listeners identified the vowels based on differences in the between-peak spectral information as well as the location of spectral peaks. The effect of nonlinear amplitude mapping of acoustic into "electrical" vowels, as performed in the implant processors, was evaluated separately and compared to the effect of neural-population interactions. Amplitude mapping was found to cause more blurring than neural-population interactions. Subjects exhibiting strong blurring effects yielded lower overall vowel identification scores.

Aged↗

PubMed2004

Speech perception with a cochlear implant used in conjunction with a hearing aid in the opposite ear.

The aim of this study was to determine the improvement in speech recognition provided by a cochlear implant (CI) in conjunction with a hearing aid (HA) in the opposite ear. The study was a retrospective cohort study in the context of a university teaching hospital CI programme. Seven CI patients who still use their HA in the opposite ear were tested. The scores with the CI alone and the CI in conjunction with an HA were evaluated by using three speech perception tests in quiet (Freiburger Numbers. Freiburger Monosyllables, and Innsbrucker Sentence Test). In the majority of tests and subjects. the CI alone performed better than the HA alone, and the bimodal (CI + HA) condition was superior to the CI alone. On the sentence test, the patients as a group improved from 47 96% (mean: 79%; CI alone) to 50-100% (mean: 88.1%; CI + HA, pv < 0.05). With the more difficult monosyllable test, the scores improved from 15-52% (mean: 37.2%; CI alone) to 15 82% (mean: 48.7%; CI + HA, p < 0.05). On the numbers test. scores increased from 65-98% (mean: 83%; CI alone) to 75-98% (mean: 88.7%; CI + HA, p < 0.05). All patients in this study were implanted in the poorer ear. The results of the present study suggest the advantage of CI usage in conjunction with an HA in the opposite ear.

Acoustic Stimulation↗

PubMed2003

Localized pericochlear hypoattenuating foci at temporal-bone thin-section CT in pediatric patients: nonpathologic differential diagnostic entity?

PURPOSE: To evaluate the prevalence of localized hypoattenuating areas in the cochlear otic capsule at temporal-bone thin-section computed tomography (CT) in pediatric patients and correlate the findings with clinical information. MATERIALS AND METHODS: Temporal-bone thin-section CT images obtained in 73 patients aged 0-9 years (20 Austrian, 53 Finnish; 36 female and 37 male patients) were evaluated for the presence of localized hypoattenuating foci in the region of the fissula ante fenestram of the otic capsule. Clinical information collected for all patients was also evaluated. The data were analyzed with a logistic regression model. RESULTS: Hypoattenuating areas in the region of the fissula ante fenestram were observed in 23 of 73 patients (32%). Hypoattenuating foci were substantially more prevalent in patients younger than 3 years than in those 3 years or older (odds ratio, 0.14; 95% CI: 0.04, 0.52; P =.001). The prevalence did not differ between sexes or according to clinical diagnosis. Only three of the 23 patients with hypoattenuating foci had clinical findings suggestive of otosclerosis, and none had osteogenesis imperfecta. After adjustment for age and sex, the finding was more prevalent among the Finnish patients (odds ratio, 5.4; 95% CI: 1.19, 24.52; P =.02) than among the Austrian patients. CONCLUSION: Hypoattenuating areas in the region of the fissula ante fenestram in the otic capsule at thin-section CT are prevalent among children younger than 3 years in the absence of clinical evidence of otosclerosis or osteogenesis imperfecta and appear in children up to 9 years old.

Child↗

PubMed2003

Variables affecting speech perception in postlingually deaf adults following cochlear implantation.

OBJECTIVE: To evaluate the time span over which there is greatest improvement in postlingually deaf adults undergoing cochlear implantation. Additionally, to quantify potential patient and device factors that may predict the postoperative results. MATERIAL AND METHODS: A longitudinal study was conducted. Numbers, monosyllables and sentence test results were collected for 66 cochlear implant subjects [Combi 40/40 +, n = 60; Clarion HF2, n = 2; Nucleus 24m/k, n = 4] at regular intervals for up to 6 years following cochlear implantation. RESULTS: All patients showed a steady improvement over time on all tests. Progress during the first 12 months was statistically significant, with further improvements being recorded after the 12-month testing period. The duration of deafness and the number of electrodes (8 for the Combi 40, 12 for the Combi 40 + ) appeared to be weakly correlated with postoperative performance. Re-implantation after device failure had no negative effect on speech reception. Subjects who were "upgraded" from an analogue to a digital cochlear implant improved their test results almost twofold. CONCLUSION: All the patients in our study gained substantial benefit from their cochlear implants. It is encouraging to note that the factors examined were not deemed to be relevant predictors of performance. Even long-term deaf subjects and re-implantees are able to achieve an excellent level of speech perception.

Cochlear Implantation↗

PubMed2002

Connexin 26 mutations in cases of sensorineural deafness in eastern Austria.

Mutations in the connexin 26 (Cx26) gene (GJB2) are associated with autosomal nonsyndromic sensorineural hearing loss. This study describes mutations in the Cx26 gene in cases of familial and sporadic hearing loss (HL) by gene sequencing and identifies the allelic frequency of the most common mutation leading to HL (35delG) in the population of eastern Austria. For this purpose we have developed and applied a molecular beacon based real-time mutation detection assay. Mutation frequencies in the Cx26 gene of individuals from affected families (14 out of 46) and sporadic cases (11 out of 40) were 30.4% and 27.5%, respectively. In addition to known disease related alterations, a novel mutation 262 G-->T (A88S) was also identified. 35delG accounted for almost 77% of all Cx26 mutations detected and displayed an allelic frequency in the normal hearing population of 1.7% (2 out of 120). The high prevalence of the 35delG mutation in eastern Austria would therefore allow screening of individuals and family members with Cx26 dependent deafness by a highly specific and semi-automated method.

Adolescent↗

PubMedDate not supplied

Characteristics of fricatives and sentence duration after cochlear implantation.

Ten postlingually deafened patients (5 male, 5 female) were examined after cochlear implantation to measure improvements in their quality of speech. Parameters such as the spectral maximum of fricatives and the duration of utterances were analysed in speech recordings taken at regular intervals after implantation. The speech samples were recorded in an audiological chamber. Parameters were analysed using ST(x) (S-Tools Software). Frequency analyses based on the fast Fourier transform and spectral estimation methods, as well as fundamental frequency and formant extraction (cepstrum, LPC = linear prediction coding) and digital filter implementations were prepared. The results indicate a tendency towards improvement in the spectral maximum of the fricatives and affricates and a shortening of the duration of the fricative parts in affricates and of sentences in nearly all our subjects. These results showed the restored auditory feedback produced by cochlear implantation to have a favourable effect on speech production.

Adolescent↗

PubMedDate not supplied

Changes in vowel quality after cochlear implantation.

Since auditory feedback is partially restored after cochlear implantation, the aim of the present study was to investigate features of vowels, which reflect improvements in speech production. Ten postlingually deafened subjects (5 male/5 female) were recorded reading a German text before and 3 and 12 months after implantation, respectively. Selected vowels were analysed regarding the fundamental frequency (F(0)), the formant frequencies (F(1), F(2), F(3)) and the vowel space (difference between F(1) and F(2) in hertz). The F(0) decreased only descriptively after 3 and 12 months, respectively. F(1) of the vowel /e/ was significantly lower after 12 months (411 +/- 20 compared to 349 +/- 25 Hz, p < or = 0.05) and for /o/ after 3 months (446 +/- 29 compared to 408 +/- 31 Hz, p < or = 0.05) for the male patients: their vowel space also expanded significantly for the vowel /o/ (372 +/- 37 compared to 467 +/- 32 Hz, p < or = 0.05) after 12 months. Regained auditory feedback after cochlear implantation had an effect on the improvement of the production of vowels.

Adolescent↗

PubMedDate not supplied

A novel connexin 26 mutation associated with autosomal recessive sensorineural deafness.

Mutations in the connexin 26 (Cx26) gene (GJB2) are a common cause of hereditary hearing impairment which affects approximately 1 in 2000 newborn children. We report the identification of a novel Cx26 point mutation (439 G-->A) linked to familial, autosomal recessive, sensorineural hearing loss. This missense mutation (E147K) is located in the highly conserved, putative K(+) channel lining sequence of the third transmembrane domain (TM3) of Cx26. Hearing impairment associated with this mutation was congenital, moderate to profound and showed no signs of progressive deterioration.

Adolescent↗