Audiology and Speech Pathology - Research Publications

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    The Effect of Cochlear Implants on Cognitive Function in Older Adults: Initial Baseline and 18-Month Follow Up Results for a Prospective International Longitudinal Study
    Sarant, J ; Harris, D ; Busby, P ; Maruff, P ; Schembri, A ; Dowell, R ; Briggs, R (Frontiers Media, 2019-08-02)
    In older adults, hearing loss is independently associated with an increased rate of cognitive decline, and has been identified to be a modifiable risk factor for dementia. The mechanism underlying the cognitive decline associated with hearing loss is not understood, but it is known that the greater the hearing loss, the faster the rate of decline. It is unknown whether remediation of hearing loss with hearing devices can delay cognitive decline. This 5-year international longitudinal study is investigating the impact of cochlear implants on cognitive function in older people with severe-profound hearing loss, and whether remediation of hearing loss could delay the onset of cognitive impairment. This is the first study to examine the major primary risk factors associated with dementia in the same cohort. Participants were assessed before cochlear implantation and 18 months later using an identical battery including a visually presented cognitive assessment tool (Cogstate battery) that is highly sensitive to small changes in cognition and suitable for use with people with hearing loss. Hearing and speech perception ability were assessed in sound-treated conditions by an audiologist, and a range of questionnaire tools was administered to assess self-perceived ease of listening, quality of life, physical activity, diet, social and emotional loneliness, isolation, anxiety, and depression. A detailed medical health history was taken. Pre-operatively, despite the small initial sample size (n = 59), increased hearing loss and age predicted significantly poorer executive function and visual attention, while tertiary education predicted better executive function. Better self-reported quality of life was correlated with better visual learning performance, and engaging in frequent vigorous physical activity was correlated with poorer visual learning performance. At 18 months, for the first 20 participants, significant benefits of cochlear implants were seen in terms of speech perception, communication ability, and quality of life. Multiple linear regression modeling showed executive function improved significantly for non-tertiary educated males, while cognitive function remained stable for other participants. Further follow-up at 18 month intervals with a larger sample will reveal the effects of cochlear implant intervention on all outcomes, and whether this can delay cognitive decline.
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    The narrow window: early cochlear implant use
    Dettman, SJD ; Leigh, JRL ; Dowell, RCD ; Pinder, DP ; Briggs, RJB ( 2007)
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    Cochlear Implants in Forty-Eight Children with Cochlear and/or Vestibular Abnormality
    Dettman, S ; Sadeghi-Barzalighi, A ; Ambett, R ; Dowell, R ; Trotter, M ; Briggs, R (KARGER, 2011)
    CT and MRI scans for 48 children with cochlear and/or vestibular abnormality were classified in decreasing severity; common cavity, Mondini plus enlarged vestibular aqueduct, Mondini dysplasia alone and enlarged vestibular aqueduct alone. No significant relationship between degree of cochlea abnormality and surgical issues (cerebrospinal fluid gusher, depth of insertion, number of electrodes) or speech perception/language outcomes was found. A significant relationship was observed between cerebrospinal fluid gusher and partial electrode insertion, fewer active electrodes and poorer sentence understanding. Optimum language outcomes were associated with younger age at implant.
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    Long term communication outcomes for children receiving cochlear implants younger than 12 months: A multi-centre study
    Dettman, S ; Dowell, R ; Choo, D ; Arnott,, W ; Abrahams, Y ; Davis, A ; Dornan, D ; Leigh, J ; Constantinescue, G ; Cowan, R ; Briggs, R (Wolters Kluwer, 2017)
    Objective: Examine the influence of age at implant on speech perception, language and speech production outcomes in a large unselected paediatric cohort. Study Design: This study pools available assessment data (collected prospectively and entered into respective databases from 1990 to 2014) from three Australian centres. Patients: Children (N=403) with congenital bilateral severe to profound hearing loss who received cochlear implants under 6 years of age (excluding those with acquired onset of profound hearing loss after 12 months, those with progressive hearing loss and those with mild/moderate/severe additional cognitive delay/disability). Main Outcome Measure(s): Speech Perception; open-set words (scored for words and phonemes correct) and sentence understanding at school entry and late primary school time points. Language; PLS and PPVT standard score equivalents at school entry, CELF standard scores. Speech Production; DEAP percentage accuracy of vowels, consonants, phonemes-total and clusters and percentage word-intelligibility at school entry. Results: Regression analysis indicated a significant effect for age-at-implant for all outcome measures. Cognitive skills also accounted for significant variance in all outcome measures except open-set phoneme scores. ANOVA with Tukey pairwise comparisons examined group differences for children implanted younger than 12 months (Group 1), between 13 and 18 months (Group 2), between 19 and 24 months (Group 3), between 25 and 42 months (Group 4), and between 43 to 72 months (Group 5). Open-set speech perception scores for Groups 1, 2 and 3 were significantly higher than Groups 4 and 5. Language standard scores for Group 1 were significantly higher than Groups 2, 3, 4 and 5. Speech production outcomes for Group 1 were significantly higher than scores obtained for Groups 2, 3, and 4 combined. Cross tabulation and Chi-square tests supported the hypothesis that a greater percentage of Group 1 children (than Groups 2, 3, 4, or 5) demonstrated language performance within the normative range by school entry. Conclusions: Results support provision of cochlear implants younger than 12 months of age for children with severe to profound hearing loss to optimise speech perception and subsequent language acquisition and speech production accuracy.
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    Speech detection and localization results and clinical outcomes for children receiving sequential bilateral cochlear implants before four years of age
    Galvin, KL ; Mok, M ; Dowell, RC ; Briggs, RJ (INFORMA HEALTHCARE, 2008)
    The aim of this study was to describe the adaptation to bilateral cochlear implant use and the perceptual benefits demonstrated by 10 children who were successful users of a first implant when a second was received before four years of age. Although one subject rejected the second implant at switch-on, the nine subjects who accepted the device adapted easily to bilateral implant use and developed useful listening skills with the second implant. Tests of localization (left versus right) and speech detection in noise were administered in the unilateral and bilateral conditions, usually after six months experience. All subjects demonstrated some bilateral benefit on speech detection testing (mostly due to a headshadow effect), and the majority localized left versus right. Results suggested that outcomes may be negatively impacted by increased age at the time of second implant switch-on. The majority of the subjects adapted well to bilateral implant use within six months and demonstrated some perceptual benefit and, according to subjective parent reports, improved daily functioning; however, device rejection must be discussed pre-operatively as a possibility.