Biomedical subjects

René Hugo

Publications and source records attributed to René Hugo.

7 recordsLinked to original sources

PubMed2006

Infant hearing screening at immunization clinics in South Africa.

OBJECTIVE: Benefits of early identification and subsequent intervention for hearing loss are not accessible to infants in developing countries like South Africa. There are no systematic screening programs and traditional platforms for newborn hearing screening, such as well-baby and intensive care nurseries, do not provide sufficient coverage due to the high incidence of births at home or in primary healthcare facilities. Primary healthcare structures, in the form of immunization clinics, have been proposed as an alternative screening platform. The current study, therefore, investigates a hearing screening program implemented at two immunization clinics in a representative South African community. METHODS: The two clinics in the current study were selected by a convenience sampling method in a community representative of large sections of the population. The hearing screening program was conducted over a 5-month period, and enrolled 510 infants (0-12 months of age). The screening protocol included Distortion Product Oto-Acoustic Emissions (DPOAE) and a high frequency probe tone (1000 Hz) tympanogram. Referral was based on one or both ears referring the DPOAE screen. Follow-up screening and diagnostic evaluations were scheduled for referred subjects. RESULTS: Coverage with DPOAE amounted to 95% of the sample ears (93% of sample subjects) compared to tympanogram coverage amounting to 94% (93% of sample subjects). OAE pass rates were 93% for the sample ears with neonatal ears indicating a higher pass rate of 95% compared to 92% for infant ears (5-52 weeks of age). Eighty-seven percent of the sample ears indicated peaked tympanograms indicative of normal middle-ear functioning and neonatal ears presented with an increased incidence of peaked tympanograms (92%). A highly significant association between the DPOAE and high frequency tympanometric result was found. Follow-up screening appointments were scheduled for 68 subjects (14% of screened sample). Only 40% returned for the second follow-up and 44% for the third follow-up. CONCLUSIONS: Immunization clinics indicate promise as infant hearing screening platforms, but identification of only bilateral hearing losses may be warranted initially to keep referral rates acceptably low. In addition to this efficient tracking systems are necessary to ensure acceptably high follow-up return rates are reached over time.

Acoustic Impedance Tests↗

PubMed2005

Predicting pure-tone thresholds with dichotic multiple frequency auditory steady state responses.

The accuracy of dichotic multiple frequency auditory steady state in predicting pure-tone thresholds at 0.5, 1, 2, and 4.0 kHz compared to an ABR protocol (click and tone burst at 0.5 kHz) were explored in a group of 25 hearing-impaired subjects across the degree and configuration spectrum. Mean steady state thresholds were within 14, 18, 15, and 14 dB of the pure tones at 0.5, 1, 2, and 4 kHz, compared to the tone-burst ABR at 0.5 kHz pure-tone difference of 24 dB, and a click-evoked pure-tone (2-4 kHz) difference of 9 dB. Recording time for the steady state protocol was 28 minutes (+/- 11) compared to 24 minutes (+/- 9) of the ABR protocol. Degree of loss had a significant effect on steady state; configuration of hearing loss had a limited effect. Mf ASSR predicted thresholds with relative accuracy although some configurations showed discrepancies for low-frequency estimates.

Acoustic Stimulation↗

PubMed2004

Auditory steady-state responses for children with severe to profound hearing loss.

OBJECTIVE: To investigate the clinical usefulness of the dichotic single-frequency auditory steady-state response (ASSR) for estimation of behavioral thresholds in children with severe to profound congenital sensorineural hearing loss. DESIGN: A comparative experimental research design was selected to compare behavioral and ASSR thresholds for the sample. Behavioral pure-tone audiometry served as the criterion standard. SETTING: Hearing Clinic, Department of Communication Pathology, University of Pretoria, Pretoria, South Africa. PATIENTS: A referred sample of 10 patients (20 ears), 5 girls and 5 boys aged 10 to 15 years (mean age, 13 years 4 months), with severe to profound sensorineural hearing impairment. MAIN OUTCOME MEASURES: The difference, and correlation, between 160 pure-tone behavioral and ASSR thresholds at 0.5, 1, 2, and 4 kHz. RESULTS: Mean differences between ASSR and behavioral thresholds were 6 dB for 0.5 kHz and 4 dB for 1, 2, and 4 kHz, with standard deviations varying between 8 and 12 dB. No significant differences (P<.05) were observed between ASSR and behavioral thresholds, except at 0.5 kHz, and Pearson correlation coefficients varied between 0.58 and 0.74 across the evaluated frequencies, with best correlation at 1 kHz and worst at 0.5 kHz. CONCLUSIONS: The ASSR thresholds provided reliable estimations of behavioral thresholds for children with severe to profound hearing loss and indicated an increased sensitivity for more profound hearing loss.

Adolescent↗

PubMed2004

Establishing normal hearing with the dichotic multiple-frequency auditory steady-state response compared to an auditory brainstem response protocol.

OBJECTIVE: To determine the clinical usefulness of the dichotic multiple-frequency (MF) auditory steady-state response (ASSR) technique for estimating normal hearing compared to a 0.5-kHz tone burst and broadband click auditory brainstem response (ABR) protocol in a sample of adults. MATERIAL AND METHODS: A comparative experimental research design was selected in order to compare estimations of normal hearing obtained with the dichotic ASSR technique at 0.5, 1, 2 and 4 kHz with a 0.5-kHz tone burst and broadband click ABR protocol. The recording times required for each procedure were also compared. Normal-hearing subjects (n = 28) were selected according to immittance values within normal limits and pure-tone behavioural thresholds of < 25 dB HL across frequencies. RESULTS: The dichotic MF ASSR estimated normal hearing to be, on average, 30-34 dB HL across the range 0.5-4 kHz. The mean estimate of normal hearing for 0.5 kHz using tone burst ABRs was 30 dB nHL and the mean click ABR threshold was 16 dB nHL, i.e. 14-18 dB better than the ASSR thresholds. The dichotic MFASSR technique recorded 8 thresholds (4 in each ear) in a mean time of 23 min. The ABR protocol recorded 4 thresholds (2 in each ear) in a mean time of 25 min. CONCLUSION: Both the dichotic MF ASSR and ABR protocols provided a time-efficient estimation of normal hearing. There was no significant difference between the tone burst ABR and MF ASSR techniques in terms of estimation of normal hearing at 0.5 kHz. The dichotic MF ASSR technique proved more time-efficient by determining more thresholds in a shorter time compared to the ABR protocol.

Adolescent↗

PubMed2004

The needs of teachers of children with hearing loss within the inclusive education system.

In South Africa, the current movement towards the inclusion of children with disabilities, including children with hearing loss, is likely to have far-reaching consequences for both teachers and learners. Undoubtedly, needs will arise from teachers during the transition, especially in the areas pertaining to the audiological and educational management of children with hearing loss. Therefore, a descriptive research design was developed comprising of a questionnaire survey followed by focus group interviews to determine teachers' needs. The questionnaire survey explored the needs of 664 teachers while focus group interviews were conducted with 19 teachers of children with hearing loss. Teachers were mostly from special schools as only a very small number of children are educated outside these establishments. Findings revealed that, although participants realised the importance of various aspects of development of the child with hearing loss, they generally did not realise the importance of receiving support from an educational audiologist.

Attitude↗

PubMed2002

Predicting hearing loss from otoacoustic emissions using an artificial neural network.

Normal and impaired pure tone thresholds (PTTs) were predicted from distortion product otoacoustic emissions (DPOAEs) using a feed-forward artificial neural network (ANN) with a back-propagation training algorithm. The ANN used a map of present and absent DPOAEs from eight DPgrams, (2f1-f2 = 406-4031 Hz) to predict PTTs at 0.5, 1, 2 and 4 kHz. With normal hearing as < 25 dB HL, prediction accuracy of normal hearing was 94% at 500, 88% at 1000, 88% at 2000 and 93% at 4000 Hz. Prediction of hearing-impaired categories was less accurate, due to insufficient data for the ANN to train on. This research indicates the possibility of accurately predicting hearing ability within 10 dB in normal hearing individuals and in hearing-impaired listeners with DPOAEs and ANNs from 500-4000 Hz.

Adolescent↗

PubMedDate not supplied

Estimations of auditory sensitivity for young cochlear implant candidates using the ASSR: preliminary results.

This paper presents preliminary results obtained with the use of the auditory steady-state response (ASSR) technique as part of a cochlear implant candidacy assessment protocol for infants Fifteen infants (30 ears), between 10 and 60 months of age, with severe-to-profound hearing loss participated in the study. ASSR measurements were performed for 0.5, 1, 2 and 4kHz at intensities up to 120-128dB HL. The ASSR thresholds were obtained in 74%, of the measurements, and exceeded the maximum auditory brainstem response (ABR) intensity output in 91% of cases and the maximum free-field behavioral intensity output in 84% of cases. Eighty-seven per cent of ASSR threshold measurements were measured at intensities of 100dB HL or higher, and almost half (47%) were measured at intensities of 115 dB HL and higher. Preliminary results indicate that absent ABR and behavioral thresholds do not preclude the possibility of residual hearing, making the ASSR a primary source of information regarding profound levels of hearing loss.

Auditory Perception↗