Intratympanic injection of various otoprotectants through the round window membrane (RWM) might become available in the near future as an alternative to the currently available medical and surgical methods used to treat several inner ear diseases. The most common outcome of such diseases is sensorineural hearing loss (SNHL). Two examples of  these otoprotectants are Edaravone and Brain-Derived Neurotrophic Factor (BDNF), both of which have already proved effective against  noise-induced hair cell loss, barotrauma  and ototoxicity caused by cisplatin. In four different studies we used two electrophysiological methods, auditory brainstem response (ABR) and distortion product otoacoustic emission (DPOAE), to study the effects of tobramycin and Pseudomonas aeruginosa exotoxin A (PaExoA) on the inner ears of 129 male Sprague-Dawley rats. In two investigations, not only the otoprotective effects of Edaravone on tobramycin-induced ABR threshold shifts and PaExoA-induced DPOAE  threshold changes, were studied but even different application times, in order to establish in which interval it was still possible to achieve effective otoprotection.We found that Edaravone gave otoprotection from tobramycin when injected simultaneously or within 7 days, but it had only a limited effect on the changes in DPOAE thresholds caused by PaExoA when injected 1, 2, or 4 hours after the exotoxin. The effect of BDNF on PaExoA-induced ABR threshold shifts was investigated in two studies, where different doses of intratympanically injected PaExoA were used and where BDNF was applied simultaneously, 12 or 72 hours efter exotoxin instillation. We found that BDNF had an otoprotective effect on SNHL induced by different doses PaExoA when injected simultaneously or with no more than 12 hours delay.

No description available.

INTRODUÇÃO: A identificação e preservação da audição residual em candidatos a implante coclear vêm assumindo maior importância clínica. A resposta auditiva de estado estável (RAEE) pode fornecer informação frequência-específica sobre o limiar auditivo em níveis de intensidade máximos de 120 dB NA, possibilitando a investigação da audição residual. Os objetivos deste estudo são avaliar a audição residual em candidatos a implante coclear, comparando os limiares eletrofisiológicos da RAEE com os limiares psicoacústicos da audiometria nas frequências de 500, 1 000, 2 000 e 4 000 Hz. MÉTODO: Foram avaliados 40 candidatos a implante coclear (80 orelhas) com perda auditiva neurossensorial severa a profunda bilateral. A audiometria foi realizada com o tom \"warble\" nas frequências de 500, 1 000, 2 000 e 4 000 Hz com intensidade máxima de estimulação de 120 dB NA. A RAEE foi obtida através da estimulação dicótica de uma frequência de tons contínuos sinusoidais modulados 100% em amplitude exponencial e 20% em frequência, nas frequências portadoras de 500, 1 000, 2 000 e 4 000 Hz, com estimulação máxima de 117, 120, 119 e 118 dB NA, respectivamente. RESULTADOS: Foram obtidos limiares mensuráveis em 62,5% de todas as frequências estudadas na audiometria tonal e em 63,1% na RAEE. A RAEE apresentou sensibilidade de 96% e especificidade de 91,6% na detecção da audição residual. As diferenças médias entre os limiares da audiometria tonal e da RAEE não apresentaram significância estatística em nenhuma das frequências. As correlações entre os limiares comportamentais e da RAEE foram significantes em todas as frequências avaliadas, sendo fortes em 500, 1 000 e 2 000 Hz e moderada em 4 000 Hz, com coeficiente de correlação de Pearson entre 0,65 e 0,81. Em 90% dos casos, os limiares da RAEE foram adquiridos nos limites de 10 dB dos limiares comportamentais. CONCLUSÕES: As correlações entre os limiares tonais e da RAEE foram significantes nas frequências de 500, 1 000, 2 000 e 4 000 Hz. A RAEE apresentou alta sensibilidade e especificidade na detecção da audição residual em candidatos a implante coclear, em comparação com a audiometria tonal / INTRODUCTION: Identification and preservation of residual hearing in cochlear implantation are becoming more important lately. Auditory steadystate response (ASSR) can provide frequency-specific information regarding the auditory thresholds at maximum intensity levels of 120 dB HL, allowing investigation of residual hearing. The study objectives are to assess residual hearing in cochlear implant candidates by comparing the electrophysiological thresholds obtained in ASSR with psychoacoustic thresholds of audiometry at 500, 1 000, 2 000 and 4 000 Hz. METHOD: Forty cochlear implant candidates (80 ears) with bilateral severe-to-profound sensorineural hearing loss were studied. Warble-tone audiometry was performed at the frequencies 500, 1 000, 2 000 e 4 000 Hz, with stimuli up to 120 dB HL. ASSR was obtained with dichotic single-frequency stimulation of sinusoidal continuous tones modulated in exponential amplitude of 100% and in frequency of 20%, at the carrier frequencies of 500, 1 000, 2 000 and 4 000 Hz at maximum stimulation levels of 117, 120, 119 and 118 dB HL, respectively. RESULTS: Thresholds were obtained in 62,5% of all frequencies evaluated in warbletone audiometry and in 63,1% in the ASSR. ASSR showed sensitivity of 96% and specificity of 91,6% in the detection of residual hearing. The mean difference between the thresholds of behavioral audiometry and ASSR were not statistically significant in any of the frequencies. Strong correlations between behavioral and ASSR thresholds were observed in 500, 1 000 and 2 000 Hz and moderate in 4 000 Hz, with Pearson correlation coefficient between 0,65 and 0,81. In 90% of the occasions, ASSR thresholds were within 10 dB of behavioral thresholds. CONCLUSIONS: The correlations between behavioral and ASSR thresholds were significant at 500, 1 000, 2 000 and 4 000 Hz. ASSR showed high sensitivity and specificity in the detection of residual hearing in cochlear implant candidates, compared to warble-tone audiometry

The pediatric audiology landscape changed dramatically with the advances in screening and diagnostic procedures, amplification possibilities and early identification outcomes. Pediatricians play a key role in this rapidly developing field. The aim of this study was to investigate Pediatricians’ knowledge and attitudes regarding the diagnosis and intervention of infants and children with a sensorineural hearing loss. A questionnaire was compiled to obtain the relevant empirical data. This was distributed to 257 pediatricians in the Gauteng Province. Of the 257 questionnaires only 47 could be utilised. According to the results obtained from the pediatricians it appears that the respondents possess adequate knowledge regarding the diagnosis and intervention of infants and children with sensorineural hearing loss. This is despite having received limited or no information and training on this subject. As is discussed in Chapter 4 it became evident that knowledge gaps were found to exist. The pediatrician is an important team member of the hearing intervention team. Their involvement is crucial and their referral can be the important stepping-stone for early identification and intervention. A lack of skills and proficient knowledge is a major constraint during the implementation of efficient primary health care services in developing countries. Throughout the results of this study, it is found that pediatricians have a need for additional information and training in the intervention process of infants and children with sensorineural hearing loss, therefore showing a positive attitude towards continuous education. This is based on the results found throughout the study, in terms of a void in certain areas surrounding effective intervention of hearing loss. The aim of the study was to highlight areas of uncertainty that the respondents might experience and to provide educational programmes in order to equip them with the relevant knowledge with regards to sensorineural hearing loss. The findings of this study would hopefully encourage future research and a more in-depth study regarding this topic. / Dissertation (M (Communication Pathology))--University of Pretoria, 2006. / Speech-Language Pathology and Audiology / Unrestricted

Introdução: O acesso pela via da fossa craniana média para colocação do implante coclear provou ser uma alternativa valiosa em pacientes com otite média crônica e cavidades de mastoidectomia instáveis, cócleas parcialmente ossificadas e em alguns casos de displasia do ouvido interno. Até hoje não existem pesquisas que descrevam se a inserção do feixe de eletrodos pela via da fossa média pode ser feita com um mínimo de traumatismo intracoclear, comparável ao observado nas inserções pela janela redonda. Objetivo: Avaliar o trauma intracoclear com dois modelos distintos de implante quando o feixe de eletrodos é inserido por cocleostomia na fossa craniana média em ossos temporais. Método: 20 ossos temporais retirados antes de 24 horas pós-óbito, foram implantados através do local da cocleostomia no giro basal da cóclea identificado no assoalho da fossa cerebral média. Dez peças receberam um implante reto e dez um pré-curvado, e foram fixadas em resina epóxi. Foi realizada tomografia computadorizada para determinar a colocação adequada do feixe eletrodos, profundidade de inserção e a distância entre a janela redonda e a cocleostomia. Por último, as peças foram polidas em série, tingidas e visualizadas por estereomicroscópio para avaliar a posição do feixe e trauma intracoclear. Resultados: A tomografia mostrou um posicionamento intracoclear do feixe de eletrodos nas 20 peças. No grupo dos implantes retos a média de eletrodos inserido foi 12,3 (10 a 14) e dos pré-curvados 15,1 (14 a 16) com uma diferença significativa (U=78, p=0,0001). A mediana de profundidade de inserção foi maior para o eletrodo pré-curvado (14,5mm) que para o reto (12,5mm) com diferenças estatisticamente significativas (U = 66, p = 0,021). Só uma das 20 inserções foi atraumática e 70% tiveram graus de trauma altos (grau 3 ou 4). Não foram observadas diferenças significativas do grau de trauma entre os dois tipos de feixes nem quando as inserções foram no sentido da janela redonda, comparado com o sentido do giro médio. Conclusões: A técnica cirúrgica utilizada permitiu a inserção do feixe de eletrodos na cóclea em todas as peças, porém sem garantir uma inserção na escala timpânica e com alto risco de trauma nas microestruturas da cóclea / Introduction: In recent years, a middle fossa approach has been described for the insertion of cochlear implants, and it proved to be a reliable alternative for implantation in patients with chronic supurative otitis media, unstable mastoid cavities with recurrent otorrhea, partially ossified cochlea and in some cases of inner ear dysplasia. Until now, no research has been done to describe if this approach allows for anatomic preservation and non-traumatic insertions comparable to those through the round window. Objective: To evaluate cochlear trauma when the cochlear implant electrode is inserted through a middle fossa approach by means of histologic and imaging studies in temporal bones. Methods: 20 temporal bones retrieved before 24 hours after death were implanted through a middle cranial fossa cochleostomy in the basal turn of the cochlea. Ten received a straight electrode and 10 a perimodiolar electrode. After reducing the bone size with preservation of the inner ear structures, the temporal bones were fixed, dehydrated and embedded in an epoxy resin. CT scans were performed to determine if an adequate direction of insertion was attained, the depth of insertion and the distance between the cochleostomy and the round window. At last, the samples were polished by micro-grinding technique and microscopically visualized to evaluate intracochlear trauma. Results: The CT-scan showed an adequate intracoclear position of the electrode in all the samples. In the straight electrode group the average number of inserted electrodes was 12.3 (10 to 14) against 15.1 (14- 16) for the perimodiolar (U=78, p=0.0001). The median depth of insertion was significantly larger for the perimodiolar electrode group (14.4mm vs. 12.5mm U=66, p = 0.021). Only one atraumatic insertion was achieved and 70% of the samples had important trauma (grades 3 and 4). No differences were identified for the trauma grades between the two groups of electrodes. Also, there were no differences in trauma if the cochlear implants were inserted in the direction of the basal turn of the cochlea or in the direction of the middle and apical turns. Conclusions: The surgical technique that was used allowed for a proper intracochlear insertion of the electrodes in all 20 temporal bones but it does not guarantee a correct scala tympani position and carries high trauma risk for the intracochlear microstructures

Introdução: O acesso pela via da fossa craniana média para colocação do implante coclear provou ser uma alternativa valiosa em pacientes com otite média crônica e cavidades de mastoidectomia instáveis, cócleas parcialmente ossificadas e em alguns casos de displasia do ouvido interno. Até hoje não existem pesquisas que descrevam se a inserção do feixe de eletrodos pela via da fossa média pode ser feita com um mínimo de traumatismo intracoclear, comparável ao observado nas inserções pela janela redonda. Objetivo: Avaliar o trauma intracoclear com dois modelos distintos de implante quando o feixe de eletrodos é inserido por cocleostomia na fossa craniana média em ossos temporais. Método: 20 ossos temporais retirados antes de 24 horas pós-óbito, foram implantados através do local da cocleostomia no giro basal da cóclea identificado no assoalho da fossa cerebral média. Dez peças receberam um implante reto e dez um pré-curvado, e foram fixadas em resina epóxi. Foi realizada tomografia computadorizada para determinar a colocação adequada do feixe eletrodos, profundidade de inserção e a distância entre a janela redonda e a cocleostomia. Por último, as peças foram polidas em série, tingidas e visualizadas por estereomicroscópio para avaliar a posição do feixe e trauma intracoclear. Resultados: A tomografia mostrou um posicionamento intracoclear do feixe de eletrodos nas 20 peças. No grupo dos implantes retos a média de eletrodos inserido foi 12,3 (10 a 14) e dos pré-curvados 15,1 (14 a 16) com uma diferença significativa (U=78, p=0,0001). A mediana de profundidade de inserção foi maior para o eletrodo pré-curvado (14,5mm) que para o reto (12,5mm) com diferenças estatisticamente significativas (U = 66, p = 0,021). Só uma das 20 inserções foi atraumática e 70% tiveram graus de trauma altos (grau 3 ou 4). Não foram observadas diferenças significativas do grau de trauma entre os dois tipos de feixes nem quando as inserções foram no sentido da janela redonda, comparado com o sentido do giro médio. Conclusões: A técnica cirúrgica utilizada permitiu a inserção do feixe de eletrodos na cóclea em todas as peças, porém sem garantir uma inserção na escala timpânica e com alto risco de trauma nas microestruturas da cóclea / Introduction: In recent years, a middle fossa approach has been described for the insertion of cochlear implants, and it proved to be a reliable alternative for implantation in patients with chronic supurative otitis media, unstable mastoid cavities with recurrent otorrhea, partially ossified cochlea and in some cases of inner ear dysplasia. Until now, no research has been done to describe if this approach allows for anatomic preservation and non-traumatic insertions comparable to those through the round window. Objective: To evaluate cochlear trauma when the cochlear implant electrode is inserted through a middle fossa approach by means of histologic and imaging studies in temporal bones. Methods: 20 temporal bones retrieved before 24 hours after death were implanted through a middle cranial fossa cochleostomy in the basal turn of the cochlea. Ten received a straight electrode and 10 a perimodiolar electrode. After reducing the bone size with preservation of the inner ear structures, the temporal bones were fixed, dehydrated and embedded in an epoxy resin. CT scans were performed to determine if an adequate direction of insertion was attained, the depth of insertion and the distance between the cochleostomy and the round window. At last, the samples were polished by micro-grinding technique and microscopically visualized to evaluate intracochlear trauma. Results: The CT-scan showed an adequate intracoclear position of the electrode in all the samples. In the straight electrode group the average number of inserted electrodes was 12.3 (10 to 14) against 15.1 (14- 16) for the perimodiolar (U=78, p=0.0001). The median depth of insertion was significantly larger for the perimodiolar electrode group (14.4mm vs. 12.5mm U=66, p = 0.021). Only one atraumatic insertion was achieved and 70% of the samples had important trauma (grades 3 and 4). No differences were identified for the trauma grades between the two groups of electrodes. Also, there were no differences in trauma if the cochlear implants were inserted in the direction of the basal turn of the cochlea or in the direction of the middle and apical turns. Conclusions: The surgical technique that was used allowed for a proper intracochlear insertion of the electrodes in all 20 temporal bones but it does not guarantee a correct scala tympani position and carries high trauma risk for the intracochlear microstructures

Vestibular evoked myogenic potentials (VEMPs) are short-latency electromyograms evoked by high-level acoustic stimuli recorded from surface electrodes over the tonically contracted sternocleidomastoid (SCM) muscle. These responses are presumed to originate in the saccule. The purpose of this preliminary report is to provide an overview of our initial experience with the VEMP by describing the responses obtained in five subjects. Click-evoked VEMPs were present at short latencies in two normal-hearing subjects, one patient with profound congenital sensorineural hearing loss, and one patient with a severe sensorineural hearing loss due to Meniere's disease. Additionally, VEMPs were absent in a patient with profound sensorineural hearing loss following removal of a cerebellopontine angle tumor. The amplitude of the VEMP was influenced by the amount of background activity of the SCM muscle, stimulus level, and stimulus frequency. Tone-burst evoked responses showed an inverse relationship between stimulus frequency and response latency. VEMPs may prove to be a reliable technique in the clinical assessment of vestibular function.

Η παρούσα προοπτική ελεγχόμενη κλινική μελέτη διεξήχθη για να ερευνήσει τη συσχέτιση του συνδρόμου αποφολίδωσης με τη νευροαισθητήρια απώλεια ακοής. Τα άτομα της ομάδας μελέτης εμφάνιζαν το σύνδρομο στον ένα ή αμφοτέρους τους οφθαλμούς, ενώ τα άτομα της ομάδας ελέγχου δεν εμφάνιζαν το σύνδρομο σε κανένα οφθαλμό. Κριτήρια αποκλεισμού από τη μελέτη ήταν: προηγηθείσα ωτολογική επέμβαση, οξείες ή χρόνιες ωτολογικές παθήσεις, τραύμα κεφαλής ή ωτός, έκθεση σε θόρυβο, λήψη ωτοτοξικών φαρμάκων, λοίμωξη ανωτέρου αναπνευστικού συστήματος, γλαύκωμα, οφθαλμική υπερτονία και διάφορες συστηματικές παθήσεις. Οι συμμετέχοντες υπεβλήθησαν σε μέτρηση οπτικής οξύτητας, βιομικροσκόπηση, τονομέτρηση, γωνιοσκοπία, βυθοσκόπηση μετά από μυδρίαση, εξέταση οπτικών πεδίων, επισκόπηση και ψηλάφηση ώτων, ωτοσκόπηση, εξέταση ρινοφάρυγγα, εξέταση με τονοδότες και ακοομετρία καθαρών τόνων. Κατά την ακοομετρία υπολογίστηκε για κάθε ους ο ουδός ακοής, για την αέρινη και την οστέινη αγωγή, στις συχνότητες των 0.25, 0.5, 1, 2, 4 και 8kHz. Συνολικά έλαβαν μέρος στη μελέτη 69 άτομα (47 στην ομάδα μελέτης και 22 στην ομάδα ελέγχου). Η μέση ηλικία των συμμετεχόντων ήταν 74,7 ετών και στις δύο ομάδες. Δεν υπήρξαν στατιστικά σημαντικές διαφορές στην κατανομή ηλικιών και φύλων ανάμεσα στις δύο ομάδες. Σε όλους τους εξετασθέντες οι ουδοί ακοής αέρινης και οστέινης αγωγής ήταν ταυτόσημοι για κάθε συχνότητα, γεγονός που υποδήλωνε αμιγή νευροαισθητήρια απώλεια ακοής ή φυσιολογική ακοή. Δεν προέκυψαν κλινικά σημαντικές διαφορές, μεταξύ ουδών ακοής δεξιού και αριστερού ωτός, σε κανένα άτομο. Τα άτομα της ομάδας μελέτης, σε σύγκριση με εκείνα της ομάδας ελέγχου, παρουσίασαν: Α) Σημαντικά υψηλότερα ποσοστά επιπολασμού απώλειας ακοής στις συχνότητες των 1, 2, 4 και 8kHz. Β) Σημαντικά υψηλότερους μέσους ουδούς ακοής και σοβαρότερη απώλεια ακοής στις συχνότητες των 4 και 8kHz. Η μεγαλύτερη διαφορά στη σύγκριση των μέσων ουδών ακοής παρατηρήθηκε στα 8kHz. Τα ανωτέρω αποτελέσματα συνηγορούν υπέρ πολλαπλής συσχέτισης του συνδρόμου αποφολίδωσης με τη νευροαισθητήρια απώλεια ακοής και αφενός επιβεβαιώνουν μαρτυρίες από προηγούμενες έρευνες, αφετέρου παρέχουν ένα εντελώς νέο εύρημα που είναι η στατιστικά σημαντική επίδραση του συνδρόμου στη σοβαρότητα απώλειας ακοής στις υψηλές συχνότητες. Σε σύγκριση με προηγούμενες μελέτες, η παρούσα μελέτη πλεονεκτεί διότι η διερεύνηση της επίδρασης του συνδρόμου στον επιπολασμό και στη σοβαρότητα απώλειας ακοής έγινε με πιο αναλυτική διαδικασία, ετέθησαν λεπτομερέστερα κριτήρια αποκλεισμού υποψηφίων, o ακοομετρικός έλεγχος αφορούσε σε μεγαλύτερο αριθμό συχνοτήτων και αποκλείστηκαν γλαυκωματικοί ασθενείς, ώστε η σχέση μεταξύ συνδρόμου αποφολίδωσης και απώλειας ακοής να εξεταστεί με πιο αντικειμενικό τρόπο. Τα ευρήματα της παρούσας μελέτης επαληθεύουν τη θεωρία ότι το σύνδρομο αποφολίδωσης δεν αποτελεί μόνο οφθαλμολογική πάθηση, αλλά συστηματική διαταραχή με πολυάριθμες επιπλοκές, μία εκ των οποίων αφορά το έσω ους. Συνεπώς, στους ασθενείς με σύνδρομο αποφολίδωσης, εκτός από την οφθαλμολογική εξέταση, συνιστάται η εκτίμηση της ακουστικής ικανότητας με ακοομετρική δοκιμασία. / The present prospective case control clinical study was conducted to investigate the relationship between exfoliation syndrome and sensorineural hearing loss. Study group subjects manifested the syndrome in one or both eyes, whereas control group subjects didn’t manifest the syndrome in either eye. Exclusion criteria from the study were: previous ear surgery, acute or chronic ear diseases, ear or head trauma, noise exposure, oto-toxic drug intake, upper respiratory system infection, glaucoma, ocular hypertension and various systemic diseases. All participants underwent visual acuity measurement, biomicroscopy, tonometry, gonioscopy, dilated fundoscopy, visual field testing, ear inspection and palpation, otoscopy, nasopharyngeal examination, tuning fork testing and pure-tone audiometry. During audiometry the hearing threshold was calculated for every ear, using air and bone conduction, at frequencies of 0.25, 0.5, 1, 2, 4 and 8kHz. A total of 69 subjects participated in the study (47 in study group and 22 in control group). Mean age of participants was 74.7 years in both groups. Differences in age and gender distribution between the two groups were not statistically significant. Hearing thresholds were identical for both air and bone conduction, in all examined subjects at each frequency, signifying pure sensorineural hearing loss or normal hearing. No clinically significant differences were found, between hearing thresholds of left and right ear, in any subject. Compared to control group, study group subjects displayed: A) Significantly higher prevalence rates of hearing loss at frequencies of 1, 2, 4 and 8kHz. B) Significantly higher mean hearing thresholds and more severe hearing loss at frequencies of 4 and 8kHz. The greatest difference in the comparison of mean hearing thresholds was observed at 8kHz. The above results advocate for a multiple association between exfoliation syndrome and sensorineural hearing loss and on the one hand support evidence from previous research, on the other hand provide a totally new finding, that is the statistically significant effect of the syndrome on severity of hearing loss at high frequencies. Compared to previous studies, the present study has advantages because the syndrome effect on prevalence and severity of hearing loss was investigated in a more thorough manner, the candidate exclusion criteria were more detailed, audiometric testing involved a greater number of frequencies and glaucomatous patients were excluded, in order the relationship between exfoliation syndrome and hearing loss to be examined in a more objective way. The findings of the present study verify the theory that exfoliation syndrome is not only an ocular disease, but also a systemic disorder with numerous complications, one of which concerns the inner ear. Consequently, in patients with exfoliation syndrome, besides the ophthalmologic examination, an assessment of hearing ability with audiometric testing is recommended.

Conventional hearing aid circuitry is often unable to provide children with hearing loss with sufficient high frequency information in order to develop adequate oral language skills due to the risk of acoustic feedback and the narrower frequency spectrum of conventional amplification. The purpose of this study was to investigate word recognition abilities of children with moderate-to-severe hearing loss using hearing aids with linear frequency transposition. Seven children with moderate-to-severe sensorineural hearing loss between the ages of 5 years 0 months and 7 years 11 months were selected for the participant group. Word recognition assessments were first performed with the participants using their own previous generation digital signal processing hearing aids. Twenty-five-word lists from the Word Intelligibility by Picture Identification (WIPI) test were presented to the participants in three test conditions, namely: at 55 dB HL in quiet, 55 dB HL with a +5 dB signal-to-noise ratio (SNR) and at 35 dB HL. The participants were then fitted with an ISP-based hearing aid without linear frequency transposition, and the word recognition assessments were repeated with different WIPI word lists under the same conditions as the first assessment. Linear frequency transposition was then activated in the ISP-based hearing aid and different WIPI word lists were presented once more under identical conditions as the previous assessments. A 12-day acclimatization period was allowed between assessments, and all fittings were verified according to the DSL v5 fitting algorithm. Results indicated a significant increase of more than 12% in word recognition score for some of the participants when they used the ISP-based hearing aid with linear frequency transposition. A significant decrease was also seen for some of the participants when they used the ISP-based hearing aid with linear frequency transposition, but all participants presented with better word recognition scores when they used the ISP-based hearing aids without linear frequency transposition compared to their previous generation digital signal processing hearing aids. This study has shown that linear frequency transposition may improve the word recognition skills of some children with moderate-to-severe sensorineural hearing loss, and more research is needed to explore the criteria that can be used to determine candidacy for linear frequency transposition. / Dissertation (MCommunication Pathology)--University of Pretoria, 2010. / Speech-Language Pathology and Audiology / Unrestricted

Made available in DSpace on 2016-01-26T12:51:55Z (GMT). No. of bitstreams: 1 vaniapiatto_tese.pdf: 1479841 bytes, checksum: 96e04c84851d635167398b1a4196d2fe (MD5) Previous issue date: 2003-11-28 / Mutações no gene que codifica a proteína conexina 26 têm contribuído para a maioria das deficiências auditivas pré-lingual, sensorioneural não-sindrômicas recessivas. Uma mutação específica, a 35delG, é a mais freqüente das mutações detectadas no gene GJB2 nos vários grupos étnicos estudados. O objetivo foi determinar a prevalência de mutações no gene GJB2 em pacientes com deficiência auditiva sensorioneural não sindrômica, do Serviço de Otorrinolaringologia da FAMERP, em São José do Rio Preto, SP. Trinta e três casos-índice foram avaliados por exames fisico e complementares para excluir formas sindrômicas e causas ambientais da deficiência auditiva e, pela reação em cadeia da polimerase alelo-específico (AS-PCR) para a detecção da mutação 35delG. Os pacientes heterozigotos para a mutação 35delG e aqueles que não tiveram a mutação detectada foram submetidos, posteriormente, ao PCR para detecção da mutação A(GJB6-D 1381830) e ao sequenciamento automático direto para análise da região codificante do gene GJB2. A mutação 35delG foi detectada em 27,3% dos casos-índice (9/3 3) ou em 2 1,2% dos alelos (14/66). A mutação A(GJB6-DI3SI 830) foi encontrada em um (3,0%) caso-índice heterozigoto 35delG. O seqüenciamento direto nos casos-índice heterozigotos identificou um paciente (3,0%) com as mutações 35delG/V3 71. As mutações no gene GJB2 são responsáveis por mais de um quarto das deficiências auditivas sensorioneural não-sindrômica na população do estudo e, o teste PCR alelo-específico (AS-PCR) é um método fácil para rastreamento da mutação 35delG e os resultados positivos podem estabelecer o diagnóstico etiológico e aconselhamento genético nos pacientes afetados.