Audiology and Speech Pathology - Theses
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ItemThe unmet need for ear and hearing care in low- and middle- income countries: a case study on Cambodia( 2023-05)The body of work presented explores the unmet need for ear and hearing care in Cambodia, with a particular focus on the barriers to accessing ear care. The main objectives of this thesis are to highlight the current state of ear and hearing care service provision in Cambodia, to describe and analyse the main experiences of patients in their pathway for seeking EHC, and providers in their delivery of EHC services, and to consider the implications that these findings have for the development of appropriate public health interventions, and the practice of health policy making in Cambodia. The main analytic stance adopted is one of a public health approach to examine the supply and demand constraints on the patient-centred pathway to hearing health. To do so, mixed methods studies were employed to address the topic. Study I aimed to investigate the severity of ear disease and hearing loss of a cohort of patients attending an NGO Hospital in Phnom Penh, to make an analysis of their health care-seeking for diagnosis and treatment, including delays in accessing care, the severity of the disease, distance to care and the nature of EHC service delivery. Method. Mixed methods design using a retrospective analysis of the hospital patient record system, a quantitative facility-based survey and semi-structured qualitative interviews examining proxy measures of access to care, causal attributes and demand-side barriers to ear care. Results. Patients presented with advanced middle ear disease, with associated hearing loss amongst the highest per capita levels globally. Patients reported several structural, financial and sociocultural barriers. This study reveals a significant burden of ear disease in Cambodia, which reflects a delay in receiving timely and effective treatment. Conclusion. The article highlights the opportunity to integrate effective ear and hearing care into primary care service provision, strengthening the package of activities delivered at government facilities. Study II aimed to investigate the supply-side barriers to the delivery of ear and hearing services in Cambodia Method. Mixed methods design using a cross-sectional quantitative survey followed by semi-structured qualitative interviews to examine perspectives of stake-holders and front-line staff from a range of providers. Results. The overarching issues voiced by providers were supply-side shortages of health providers trained in ear and hearing care across all sectors, especially in primary health care and in rural areas, limited training opportunities in specialist surgical care, a lack of infrastructure and resources to support aural rehabilitation, and poor coordination of care amongst providers. Conclusion. The article highlights the opportunity to integrate effective ear and hearing care into primary care service provision, through strengthening the workforce, improving coordination through effective care pathways, building trust through health promotion and patient-centeredness, and expanding the package of activities delivered at government facilities.
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ItemBuilding the evidence-base for a top-down approach to the implementation of person-centred care in Australian hearing rehabilitation organisations( 2020)Thesis abstract Background: Previous studies suggest person-centred care (PCC) might improve adult hearing rehabilitation uptake and use. Despite this, PCC has not been widely implemented within hearing rehabilitation organisations (HROs) in Australia. To date, research has not focused on the criteria used by senior managers, who are ultimately responsible for decisions on implementation of clinical practice within their HRO, to evaluate outcomes of providing PCC or its impact on organisational success. Better understanding of these criteria may be relevant to understanding the current low uptake of PCC in clinical practice and how this might be increased. Aims: To investigate how senior managers of HROs in Australia define and evaluate: i) success; and ii) PCC; and iii) to identify their perceived facilitators of and barriers to PCC evaluation. Following these, iv) to evaluate the organisational-valued outcomes of a person-centred intervention delivered to graduate intern audiologists. Design: We used a pragmatic, exploratory sequential mixed-methods design. In the qualitative first phase, we conducted semi-structured interviews with sixteen senior managers from twelve HROs across Australia. For the quantitative second phase, a non-randomised cohort comparison trial was conducted within a large HRO between two groups of interns and their clients. Intervention group interns received training and support to use psychosocial communication with their clients in addition to the standard training received by control group interns. Organisational-valued client, clinician and financial outcomes were identified from the first phase. Sixteen intervention and eleven control group interns completed surveys three months after commencing their internships. Clients (intervention n = 235, control n = 181) seen in the following three months had their appointment details analysed and received postal surveys two months after their initial appointment. Results: In phase one, senior managers defined success as the crucial interplay of client success and financial success. This interaction was influenced by staff factors, the organisation’s ethos and the senior manager’s role. Financial success was evaluated more rigorously than client success, with client success assessed primarily in clients who adopted hearing aids. PCC was defined well but not evaluated by senior managers due to beliefs that their clinicians and clinical processes were effective in providing PCC based on existing client and financial successes. In phase two, intervention group interns reported significantly greater intention to stay with the organisation. Intervention group clients adhered significantly more to clinician recommendations of hearing aids and reported greater benefit with hearing aids in social situations. Control group clients were significantly more likely to recommend hearing aids and the clinic to friends and family. PCC evaluation measures did not reveal significant overall differences between groups. Non-significant results may be clinically relevant as device technology levels and uptake were higher for the intervention group for fewer total appointments. Implications Senior managers of HROs valued PCC in success but did directly evaluate it. Clinically validated PCC evaluation tools are still needed. The psychosocial communication intervention was associated with benefits to the HRO that were valued by senior managers, but further investigation is warranted to assist the uptake of PCC in HROs.
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ItemUsing novel diffusion magnetic resonance imaging techniques to aid in the diagnosis of auditory neuropathy( 2020)‘Auditory neuropathy’ is a nosological term coined by Starr et al. (1996) used to describe a group of hearing disorders, which are characterised by abnormal auditory nerve activity in the presence of normal cochlear outer hair cell function. While our understanding of this condition has advanced significantly since it was first identified almost 30 years ago, limitations in current diagnostic assessments make it difficult for clinicians to determine both the site(s) of lesion and the extent of dysfunction in an affected individual. As such, determining the most appropriate management strategy can be difficult. This is particularly salient for cochlear implantation, which is currently the intervention strategy of choice for individuals with auditory neuropathy. Cochlear implant outcomes, however, vary considerably and the inconsistency in post-operative speech perception ability is thought to be directly dependent on both the site(s) of lesion and extent of dysfunction. In this thesis, advanced diffusion MRI techniques were used to investigate changes in the white matter fibres of the VIII nerve and auditory brainstem in individuals with different forms of auditory neuropathy. Three major research questions formed the basis of this thesis and subsequently the three studies contained herein: (1) Can dMRI-based tractography techniques be used to reconstruct the pathways of the auditory brainstem in-vivo using clinically accessible MRI field strengths?; (2) Can newly developed dMRI-based quantitative analysis techniques be used to elucidate neurodegenerative changes within the brainstem of a genetically defined group of individuals with X-linked auditory neuropathy?; (3) Can these techniques be used to further our understanding of the underlying lesion site(s) and extent of neural dysfunction in a group of individuals with auditory neuropathy due to different aetiologies? The first study investigated the use of different diffusion models and tractography algorithms. Using these techniques, the pathways between the left VIII nerve and bilateral inferior colliculi were mapped in three normal hearing control subjects. Furthermore, the accuracy of tract reconstructions was compared between two different diffusion models: (i) the classic diffusion tensor model, and (ii) a high-order diffusion model called Single-Shell 3-Tissue constrained spherical deconvolution. Finally, the benefits of using the Anatomically-Constrained Tractography algorithm were also examined. To address question two, the second study used a novel dMRI-based quantitative analysis measure called Apparent Fibre Density as obtained from Single-Shell 3-Tissue Constrained Spherical Deconvolution and analysed with the fixel-based analysis framework to investigate white matter fibre-specific degeneration in a genetically characterised group of individuals with X-linked auditory neuropathy. This case-control study showed that individuals with X-linked auditory neuropathy had axonal degeneration throughout the auditory pathways, with the most significant degeneration being localised to the VIII nerve region. The results were supported by several objective auditory measures, which showed normal cochlear sensory function but significantly disrupted auditory nerve activity. Moreover, the results showed that the degree of temporal processing deficit was related to the severity of axonal degeneration in individuals with X-linked auditory neuropathy. Behavioural auditory assessments of sound detection, speech perception, and the processing of binaural cues were also significantly poorer in affected individuals compared to the normal hearing controls. Finally, the third study of this thesis used similar techniques to the second study, this experiment examined axonal degeneration in the VIII nerve region of individuals with auditory neuropathy from various aetiologies. Results were compared against participants with normal hearing. The Apparent Fibre Density findings showed that the auditory neuropathy group had significantly fewer auditory nerve fibres compared to controls. Overall, the Apparent Fibre Density metric was significantly correlated with auditory measures including, sound detection thresholds, speech perception and temporal processing ability, auditory brainstem response amplitudes, and binaural processing ability. Furthermore, the degree of axonal degeneration observed in each affected individual was consistent with the other available data, including clinical information, such as disease progression/duration of disease, and the known/assumed pathophysiological mechanism(s) underlying the auditory neuropathy phenotype. The results of this thesis offer insights into the site of lesion(s) and pathophysiological process underlying the auditory neuropathy phenotype. Furthermore, the findings provide evidence for the ability of advanced diffusion MRI techniques to be used as a diagnostic tool to examine the auditory subcortical white matter pathways in-vivo. Hence this technique may prove to be a useful adjunct to existing auditory assessments, which may in the future guide rehabilitation options for individuals with auditory neuropathy. Importantly, these techniques may be applied to related conditions where VIII nerve axonal density may affect patient outcomes, including managing cochlear or brainstem implant candidacy.