AUTOMATIC DETECTION OF NYSTAGMUS IN BEDSIDE VOG RECORDINGS FROM PATIENTS WITH VERTIGO

Benign Paroxysmal Positional Vertigo (BPPV) is the most common cause of vertigo. It can be diagnosed and treated using simple maneuvers done by vestibular experts. However, patients with this condition presenting to the emergency department have high chance of being misdiagnosed. Such high rate of misdiagnosis results in significant morbidity to the patient and also incurs huge medical costs from unnecessary neuroimaging tests. Hence, automatic medical diagnosis is the next step to aid ED practitioners to reduce diagnostic errors. However, current software employed for this diagnosis has been found to have very low specificity. This can be attributed to factors such as low sampling frequency of recording device and the fact that bedside recordings from patients are susceptible to noise and artifacts. This study aims to improve methods for automatic quantification of nystagmus, a key sign of BPPV. Testing the current method using eye movement data recorded in patients during the diagnostic maneuver yielded better results than the commercial software

Comparative Literature Analysis of Peripheral Vestibular Function Assessment Tools

Objective Purpose: One main function of the peripheral vestibular system\u27s semicircular canals is to stabilize images on a target during head movements through the important vestibula-ocular reflex (VOR) in order to maintain clear vision. Abnormal VOR response results in fast, compensatory, catch­ up saccadic eye movements suggesting dysfunction in the semicircular canals. Several functional assessment tools have been developed since the twentieth century to measure the VOR response and saccadic eye movement, and some are still widely used currently, such as the caloric test, rotary chair test, bedside head impulse test (bHIT), scleral search coil technique, and video head impulse test (vHIT). However, with advancing technology and evidence-based medicine, what was traditionally used lack validity and reliability or clinical applicability. This paper aims to 1. evaluate each of the five assessment tools individually in describing its historical use, set-up parameters, benefits, and limitations, and 2. to compare current literature on the validity of the newest vHIT assessment tool against the other four, age-tested peripheral vestibular function assessment tools. Methods: A comparative literature analysis was performed, using a computerized literature search from Medline, CINAHL, PubMed, Google Scholar, and PEDro. Studies describing search words such as vestibular system, peripheral vestibular function, semicircular canal, VOR, saccades, assessment tools, caloric test, rotary chair test, bedside head impulse test (bHIT), scleral search coil technique, and video head impulse test (vHIT) were included. Human subjects and English language restrictions were imposed. 27 studies, textbooks and manuscripts were included. Results: In the current literature, the newest vHIT assessment tool was consistently found to provide accurate and objective data in identifying peripheral vestibular dysfunction of the semicircular canals, in both middle-aged and older healthy controls, as well as in patients in an acute and non-acute peripheral vestibular disease stage. In comparison to the other four assessment tools, the vHIT was also found to be portable, simple, affordable, quick, non­ invasive, and clinically easy-to-use. Conclusion: The findings of the comparative literature search suggest the newest assessment tool, the vHIT, can be considered the best available reference standard for an assessment tool in identifying peripheral vestibular dysfunction of the semicircular canals, based on its validity, reliability and widespread clinical applicability. Further clinical research is needed to determine if the theoretical comparisons are true

Evaluation of central and peripheral vestibular patients with the video-head impulse test

Dizziness and vertigo are highly prevalent symptoms that accompany a wide variety of conditions including peripheral vestibular dysfunction, central (vestibular) lesions and somatoform disorders. A correct diagnosis is the prerequisite for successful treatment, which should be directed towards the underlying pathophysiology. Neurophysiological methods that test the integrity of the peripheral and central vestibular system circuitry are essential to make an accurate diagnosis in clinical practice. Currently, that assessment is achieved primarily through eye movement analysis in response to semicircular canal stimulation, namely through caloric stimulation and head impulses. The quantification of the vestibulo-ocular reflex (VOR) dynamic parameters and the characterization of quick eye movements (QEM) triggered with head impulses can now be non-invasively and easily assessed with the video headimpulse test (vHIT). This provided a unique opportunity to carry out neurophysiological studies on the oculomotor responses generated by head impulses in humans. Our aim was to determine if the involvement of central vestibular pathways caused differential disturbances in VOR dynamic changes when explored with the vHIT, which could contribute not only to the differential diagnosis of patients but also to the understanding of VOR control mechanisms. We explored normal subjects and patients diagnosed with acute vestibular syndrome with spontaneous nystagmus of peripheral and central origin and hereditary neurodegenerative disorders. Looking for a simple sign of peripheral disease with the vHIT we noticed anti-compensatory eye movements (AQEM) in patients with peripheral aetiologies of spontaneous nystagmus (SN). In the first study we looked for the accuracy of AQEM to differentiate central from peripheral origins of SN. We recorded the eye movements in response to horizontal head impulses in a group of 43 consecutive patients with acute vestibular syndrome (12 with central, 31 with peripheral disorders), 5 patients after acute vestibular neurectomy (positive controls) and 39 healthy subjects (negative controls). AQEM were defined as quick eye movements (peak velocity above 50°/s) in the direction of the head movement. All patients with peripheral disorders and positive controls had AQEM (latency 231±53ms, amplitude 3.4±1.4º, velocity 166±55º/s) when their head was moved to the opposite side of the lesion. Central patients did not have AQEM. AQEM occurrence rate was higher in peripheral patients with contralesional (74±4%, mean±SD) in comparison to ipsilesional (1±4%) impulses (p<0.001). Overall diagnostic accuracy for differentiating central from peripheral patients was 96% (95% CI for AUC ROC curve: 0.90 to 1.0) for VOR gain and 100% (95% CI: 1.0 to 1.0) for AQEM occurrence rate. These results suggest that AQEM are a sign of vestibular imbalance in a peripheral deficit and should be added to VOR gain analysis in acute vestibular syndrome patients. In the second study on acute vestibular syndrome we reported on a patient with benign paroxysmal positional vertigo (BPPV) and spontaneous nystagmus due to otoconia causing a plug in the horizontal semicircular canal. The video head-impulse test revealed an eye velocity saturation with ipsilesional head impulses that normalized after liberatory maneuvers, documenting for the first time a reversible deficiency of the cupularendolymph high-frequency system dynamics. Furthermore cervical and ocular vestibular myogenic potentials were absent during stimulation of the affected side before the liberatory maneuvers, but normalized within 30 to 80 days. These observations challenge the common belief that VEMPs are evoked by otolith stimulation only, as the assumption of a reversible canal dysfunction by a plug offers a more plausible explanation for all effects. Finally, we reported on a patient presenting with a one-year history of progressive unsteadiness, particularly when in darkness. The video-Head Impulse Test (vHIT)1 (Figure 1 B) revealed a significantly reduced vestibuloocular reflex (VOR) gain in both horizontal (0.38±0.07 and 0.29±0.05) and posterior canals (0.49±0.05 and 0.38±0.06) with covert and overt corrective saccades, but normal VOR responses in both anterior canals (0.89±0.08 and 1.04±0.15), for right and left impulses, respectively. No plausible combination of end-organ lesion should be responsible for these observations. A brain MRI disclosed a left inferior cerebellar peduncle lesion suggestive of a glioma. To the best of our knowledge, this is the first report where three-dimensional vHIT, by means of peripheral-unlikely combinations of VOR lesion, has shown to be of topodiagnostic value. In the second set of studies we explored patients diagnosed with hereditary neurodegenerative disorders with and without vestibular system involvement. In the first study we explored 18 genetically confirmed Huntington’s disease patients (44.7±8.1 years; male=9). VOR latency, VOR gain and QEM characteristics were not different from controls (p>0.11 for all comparisons), suggesting that VOR is preserved at physiological frequency domains in these patients, even in more advanced stages of the disease. In the final study we explored 23 patients with a clinical and genetically confirmed diagnosis of spinocerebellar ataxia (SCA) type 3 (n=15), type 2 (n=4) and type 1 (n=4]), and 9 patients with early onset Friedreich’s ataxia (FA). VOR latency was higher in FA (p<0.001) and SCA3 (p=0.02) as compared to controls, discriminating FA from other ataxic patients with an overall diagnostic accuracy of 88%. VORr, VOR40 and VOR60 were significantly lower in FA and SCA3 (p<0.01). VOR80 was only significantly lower than controls in SCA3 (p<0.01), discriminating these from other ataxic patients with an overall diagnostic accuracy of 78%. Covert saccades were only triggered in SCA3 but with low occurrence rate and peak velocity (11.1±28.5% and 77.50±15.30°/s) whereas overt saccades were present in all groups. VORr gain showed a negative correlation with disease severity evaluated with SARA (Spearman r=-0.46, p=0.01). vHIT provides phenotypic information that differentiates the most common autosomal ataxias and can serve as a strategy to orient genetic diagnosis. A correlation between VOR and SARA raises the possibility of using VOR gain as a neurophysiologic biomarker for disease severity. Altogether these results supply relevant data in distinguishing peripheral and central nervous system (CNS) vestibular deficits, particularly acute deficits in emergency situation, as acute CNS vertigo can be life-threatening (stroke) and require immediate medical action. We first demonstrated that not only VOR instantaneous gain analysis has topodiagnostic value but also the analysis of gain dynamic changes, as these can point to individual aetiologies, e.g. a SCC plug. Secondly we demonstrated that quick eye movements also supply topodiagnostic cues, and should have their latency, peak velocity, direction and occurrence rate analysed. At a neurophysiological level, the oculomotor responses generated by head impulses also provide an understanding of both the biomechanical cupular-endolymph dynamics, the VOR dynamic control processes taking place and the modulation of vestibular spontaneous nystagmus with head impulsesA vertigem e a tontura são sintomas muito prevalentes que acompanham uma grande variedade de patologias, nomeadamente as vestibulopatias periféricas, centrais e as perturbações somatoformes. Um diagnóstico correcto é o pré-requisito para um tratamento eficaz, o qual deverá ser dirigido à patofisiologia de base. Os métodos neurofisiológicos que testam a integridade dos circuitos do sistema vestibular central e periférico são essenciais para alcançar um diagnóstico preciso na prática clínica. Actualmente, essa avaliação é realizada principalmente pela análise dos movimentos oculares originados pela estimulação dos canais semicirculares, nomeadamente a estimulação calórica e os impulsos cefálicos. A quantificação do parâmetros dinâmicos do reflexo vestíbulo-oculomotor (VOR) bem como a caracterização dos movimentos oculares rápidos (QEM, Quick Eye Movements) desencadeados com os impulsos cefálicos podem agora ser avaliados de forma fácil e nãoinvasiva com o vídeo Head Impulse Test (vHIT). Tal proporciona a oportunidade única de promover estudos neurofisiológicos das respostas oculomotoras desencadeadas pelos impulsos cefálicos em humanos. Acelerações horizontais da cabeça geram, na obscuridade, movimentos oculares conjugados lentos e compensatórios na direção oposta, sendo este reflexo denominado VOR. O principal objetivo deste reflexo é a manutenção de visão nítida e clara por estabilização da imagem na retina, principalmente durante os movimentos rápidos da cabeça. O Head Impulse Test (HIT)1 ou teste de impulsão cefálica é um teste clínico ativo em que este VOR angular é testado a alta frequência. O clínico, ao colocar-se de frente para o doente, aplica movimentos de frequência e direção imprevisíveis segundo o plano horizontal, de baixa amplitude (10-25º), alta aceleração (3.000-6.000º/s2) e velocidade (150-300º/s), enquanto o doente é instruído a manter a fixação num ponto. Se o VOR estiver intacto, o doente será capaz de manter a fixação, não se observando qualquer movimento rápido do olho, denominando-se o HIT de normal ou negativo. Pelo contrário, se o VOR não for compensatório, o olho acompanhará a cabeça durante a rotação impulsiva pelo que no final do impulso será necessário realizar uma sacada de refixação para recolocar o alvo 1 Halmagyi GM, Curthoys IS, Cremer PD, et al. The human horizontal vestibulo-ocular reflex in response to high-acceleration stimulation before and after unilateral vestibular neurectomy. Exp Brain Res. 1990;81(3):479–90. na fóvea, denominando-se o HIT de positivo ou patológico. Dado que não é possível ao olho humano detectar o movimento de fase lenta do VOR durante este impulso, a presença de uma sacada compensatória no final de um HIT clínico é entendida como um sinal indireto de uma fase lenta não compensatória. Enquanto o HIT unicamente permite a identificação da presença de sacadas após o impulso cefálico, o vídeo HIT (vHIT)2 possibilita não só a identificação e a quantificação da fase lenta do VOR, como também das fases rápidas geradas durante e após o impulso cefálico. Indivíduos saudáveis geram fases lentas compensatórias de baixa latência (7-10 ms), gerando fases rápidas ocasionais após os impulsos. Pelo contrário, doentes com lesão vestibular unilateral (UVL) desencadeiam fases lentas com latência aumentada, nãocompensatórias durante impulsos ipsilesionais , assim como movimentos oculares rápidos durante ou após os mesmos. Estes movimentos rápidos são conhecidos como sacadas covert se desencadeadas durante o impulso cefálico, dado a sua observação não ser possível a olho nu, ou como sacadas overt se desencadeadas após o impulso cefálico. Dado que estas fases rápidas apresentam o mesmo sentido da fase lenta deficitária, diminuindo o erro ocular, são consideradas sacadas compensatórias. Os doentes UVL agudos também podem gerar fases lentas não compensatórias durante os impulsos contralesionais, resultado da lesão da via inibitória ipsilesional, bem como gerar fases rápidas. A quantificação do HIT por vídeo-oculografia permite aumentar substancialmente a sensibilidade e a especificidade do HIT na avaliação do VOR sem as dificuldades técnicas dos coils, de difícil utilização na prática clínica. As novas câmaras digitais apresentam características de peso, forma, resolução espacial e de taxa de amostragem que permitem a sua utilização na prática clínica na quantificação do HIT com boas taxas de correlação com o coil . O registo dos perfis de velocidades ocular e cefálica durante o impulso cefálico permite o cálculo do ganho do VOR, definido como o ratio entre estas velocidades. Esse ratio pode ser calculado em momentos específicos, como p.ex. a 40, 60 e 80 ms após inicio do impulso (ganho instantâneo) ou como resultante de regressão linear (ganho por regressão). Enquanto que o último 2 Bartl K, Lehnen N, Kohlbecher S, Schneider E. Head Impulse Testing Using Videooculography. Ann N Y Acad Sci. 2009;1164(1):331–3.parece ser o valor mais robusto, o primeiro permite a avaliação variação dinâmica do ganho do VOR durante o impulso. Para o cálculo do VOR contribui a sua latência, de tal forma que se esta fosse zero deveríamos ter valores de ganho de 1.0 . Dada a existência de uma latência e, portanto, de uma discrepância entre as curvas de velocidades cefálica e ocular, os valores de normalização que obtivemos no nosso laboratório são ligeiramente inferiores (0.95±0.09). Calculando os limites de normalidade do ganho de VOR, obtivemos valores de 0.77 a 1.13. A avaliação do ganho de VOR permite por último o cálculo da assimetria interaural, que apresenta nas nossas séries, valores de normalidade muito baixos (<6.97%), quando comparados com os valores de normalidade para as provas calóricas (<25%). Os QEM são identificados como picos de aceleração bidirecionais e são classificados de acordo com o sentido relativo à fase lenta, a latência (ms), o pico de velocidade (º/s) e a taxa de ocorrência (%, taxa de impulsos que geram esses QEM). Os QEM podem apresentar o sentido da fase lenta do VOR deficitário e contribuir para a diminuição do erro ocular, sendo consideradas sacadas de correção ou sacadas catch-up, em analogia com os QEM da perseguição sacádica. Nas situações em que o ganho do VOR apresenta valores superiores à normalidade (situação observada em doentes com algumas patologias centrais) podem assumir o sentido contrário ao da fase lenta do VOR e ser igualmente classificadas como sacadas de correção uma vez que trazem a retina de regresso ao alvo. Nos indivíduos normais por nós estudados as sacadas overt apresentam valores de velocidade e de taxa de ocorrência relativamente baixos, enquanto as sacadas covert são inexistentes. Assim, a existência de uma lesão vestibular aguda (UVL) é verificável através do vHIT pela presença de uma fase lenta não compensatória durante os impulsos ipsilesionais. O cálculo do ganho do VOR e do índice de assimetria, permitem quantificar o grau da lesão. Nas fase aguda da lesão, o erro ocular resultante de um menor ganho de VOR é mais elevado, pelo que são identificadas sacadas compensatórias mais frequentes, com maior velocidade de pico e maior amplitude, tanto durante como após o impulso ipsilesional. Pelo contrário, durante a recuperação da fase lenta verifica-se o aumento progressivo da latência e diminuição da taxa de ocorrência destas sacadas. A maior parte dos doentes com síndrome vestibular agudo3 , definido como vertigem espontânea com nistagmo espontâneo, náuseas, vómitos e 3 Hotson JR, Baloh RW. Acute vestibular syndrome. N Engl J Med. 1998;339(10):680–5. desequilíbrio, resultam de lesão vestibular unilateral aguda. No entanto, a identificação no serviço de urgência daqueles que resultam de lesões do sistema nervoso central (CNS) e potencialmente em maior risco constitui um desafio. Como a análise isolada do tipo de nistagmo espontâneo não é suficiente para diferenciar os doentes com patologia periférica daqueles com patologia do sistema nervosa central, desenvolveram-se para este efeito algumas provas clínicas. Uma das mais importantes é o HIT. A ausência de sacada de refixação durante os impulsos ipsilesionais em doentes com nistagmo espontâneo e sem evidência de outros sinais e sintomas neurológicos, parece ser o que melhor prevê isoladamente a existência disfunção do CNS como causa do síndrome vestibular agudo4. A presença de nistagmo espontâneo constitui no entanto uma dificuldade adicional dado que as fases rápidas do nistagmo e a sacadas overt apresentam a mesma direção, ambas fazem o reset da fixação ocular e partilham propriedades cinemáticas. A realização de provas adicionais tais como o alinhamento ocular vertical (vertical skew) e sentido do nistagmo na levo e dextroversão aumentam o valor diagnóstico do HIT, mas requerem aptidões e competências habitualmente não disponíveis no serviço de urgência. Dado que o vHIT permite a quantificação das respostas oculomotoras aos estímulos impulsivos e apresenta uma curva de aprendizagem rápida na execução da prova, procurámos realizar um conjunto de experiências com o objetivo de determinar se o envolvimento de vias vestibulares centrais causam alterações do VOR dinâmico objectiváveis com o vHIT. Colocámos como hipótese que tais alterações poderiam ser não só traduzidas num algoritmo para topodiagnóstico clínico mas também contribuir para a compreensão dos mecanismos neurofisiológicos de controlo do VOR impulsivo. Para tal estudámos indivíduos saudáveis, doentes com UVL e nistagmo espontâneo de origem periférica e central e doentes com diagnósticos específicos de doença neurodegenerativa hereditária, com e sem envolvimento das vias vestibulares centrais. Nos próximos parágrafos são sumariamente descritos os fundamentos, objectivos, métodos, resultados e conclusões das experiências realizadas.

The role of non-invasive camera technology for gait analysis in patients with vestibular disorders

Purpose of the study Current balance assessments performed in clinical settings do not provide objective measurements of gait. Further, objective gait analysis typically requires expensive, large and dedicated laboratory facilities. The aim of this pilot study was to develop and assess a low-cost, non-invasive camera technology for gait analysis, to assist the clinical assessment of patients with vestibular disorders. Materials and methods used This is a prospective, case-controlled study that was developed jointly by the local Neurotology Department and the Centre for Sports Engineering Research. Eligible participants were approached and recruited at the local Neurotology Clinic. The gait assessment included two repetitions of a straight 7-metre walk. The gait analysis system, comprised of a camera (P3215-V, Axis Communications, Sweden) and analysis software was installed in an appropriately sized clinic room. Parameters extruded were walking velocity, step velocity, step length, cadence and step count per meter. The effect sizes (ESB) were calculated using the MatLab and were considered large, medium or small if >0.8, 0.5 and 0.2 respectively. This study was granted ethical approval by the Coventry and Warwickshire Research Ethics Committee (15/WM/0448). Results Six patients with vestibular dysfunction (P group) and six age-matched healthy volunteers (V group) were recruited in this study. The average velocity of gait for P group was 1189.1 ± 69.0 mm·s-1 whereas for V group it was 1351.4 ± 179.2 mm·s-1, (ESB: -0.91). The mean step velocities were 1353.1 ± 591.8 mm·s-1 and 1434.0 ± 396.5 mm·s-1 for P and V groups respectively (ESB: -0.20). The average cadence was 2.3 ± 0.9 Hz and 2.0 ± 0.5 Hz for P and V groups respectively (ESB: 0.60). The mean step length was 620.5 ± 150.7 mm for the P group and 728.5 ± 86.0 mm for the V group (ESB = -1.26). The average step count per meter was 1.7 ± 0.3 and 1.4 ± 0.1 for P and V groups respectively (ESB = 3.38). Conclusion This pilot study used a low-cost, non-invasive camera technology to identify changes in gait characteristics. Further, gait measurements were obtained without the application of markers or sensors to patients (i.e. non-invasive), thus allowing current, clinical practice to be supplemented by objective measurement, with minimal procedural impact. Further work needs to be undertaken to refine the device and produce normative data. In the future, similar technologies could be used in the community setting, providing an excellent diagnostic and monitoring tool for balance patients

Considerations for quantifying vestibular function

Vestibular dysfunction typically leads to disabling symptoms like dizziness, imbalance, and blurred vision during head movements. It affects up to 95 million adults in Europe and the USA. However, the diagnosis might be inconsistent due-to the lack of standardization of the vestibular tests. To improve the situation, this research quantified discrepancies in the outcomes of the main objective test caused by changing the methodology of testing and by different technical realizations. The effect of age in the tested population on the outcomes in the main functional test has also been studied. In addition, the existing test battery has been extended and the ways of analysis of data for patients fitted with the vestibular implant, a device that should restore the vestibular function as the cochlear implant restores hearing. The results of this PhD can facilitate standardization of the main vestibular tests, as well as to help improve evaluation of the impact of the vestibular implant

Vestibular Influences on Neuropsychological Outcomes in UK Military Veterans with Mild Traumatic Brain Injury

Abstract The epidemiology and treatment of mild traumatic brain injury (mTBI), along with its co-morbid symptoms, has previously received little attention in UK military samples. In US military veterans, mTBI is among the most frequently seen and challenging of conditions to arise as a consequence of the conflicts in Iraq and Afghanistan. mTBI has been shown to represent a complicated and particularly harmful polymorbid condition when accompanied by PTSD and depression, resulting in poor life outcomes. Symptoms of dizziness are one of the most common comorbid symptoms of mTBI and PTSD. In fact, the symptomology of mTBI and PTSD share many distinct features that can also be seen in patients with vestibular disorders. This is perhaps unsurprising given the diffuse nature of the ascending vestibular pathways. Despite this anatomical feature, vestibular influences in mTBI have yet to be explored in UK military veterans. To this end, this thesis first aimed to determine if vestibular disturbance influenced the neurobehavioural and affective symptoms of mTBI. A further line of investigation examined if the vestibular pathways can be artificially modulated using galvanic vestibular stimulation (GVS) to ameliorate some of these symptoms. Chapter 1 of this thesis describes the main features of mTBI in both the UK and US military, outlining the classification/current diagnostic criteria, mechanisms of injury and co-occurring cognitive, psychiatric symptoms of mTBI. It will be argued that mTBI commonly occurs in military samples as a result of blast exposure, and is particularly difficult to diagnose and treat. Chapter 2 will illustrate that both blunt and blast mTBI frequently result's in damage to the vestibular system and thereon assesses the potential contributions of vestibular dysfunction to the chronic symptoms of mTBI. Drawing on previous intervention studies from civilian samples, it will illustrate how the vestibular system may provide a novel pathway to treat mTBI. Chapter 3 reports results from an epidemiological study of 162 UK military veterans which show that 72% of the sample reported one or more mTBI in their lifetime. Vestibular disturbance affected 69% of these individuals and was most frequently seen in those who had sustained both blunt and blast injuries. Mediation analysis indicated that when PTSD, depression and anxiety were accounted for, vestibular disturbance was directly associated with increased neurobehavioural symptoms and functional disability. These findings indicate that vestibular disturbance is common particularly after combined blunt and blast head injuries and is singularly predictive of poor long-term mental health and functional disability. In light of the newfound association between vestibular disturbance and mTBI, the remaining chapters sought to establish if and how artificial vestibular stimulation can remediate aspects of mTBI. To help determine whether to target positive or negative symptoms, in Chapter 4 I sought to determine if GVS could induce either long-term potentiation (LTP) or depression (LTD) type effects, in neurologically healthy individuals up to 24hours post stimulation. The results showed that in participants who demonstrated cortical hyperexcitability at baseline, GVS induced a significant LTD type effect at 24hours post-stimulation. This indicated that conditions such as anxiety and PTSD, which are associated with cortical hyperexcitability, should be targeted. In Chapter 5 a small proof of concept study evaluated the efficacy of GVS in treating current symptoms of anxiety in 5 UK military veterans. The results showed that state symptoms of anxiety were exacerbated at 24hours post active GVS, which although further introduces a link between the vestibular system and anxiety in mTBI, did not support therapeutic application of GVS. In Chapter 6, the general discussion concludes that, vestibular disturbance is predictive of poor long-term mental health and therefore needs to be routinely screened and treated. Further studies are also needed to establish how to yoke the novel effects of GVS on cortical excitability observed here for treatment of mTBI symptoms

Clinicians’ perspectives and clinical efficacy of a health information technology tool in hospital falls risk assessment and prevention among older persons

Background The expanding ageing population has resulted in a focus on older persons within many healthcare systems. Falls present a growing problem with a significant impact on the community and healthcare system. Identifying falls risk factors and preventing falls have become priorities for many hospital and government policies, yet the evidence for the acceptability and efficacy of such interventions remains limited. Health technology has the potential to influence the field of falls prevention. Within research and clinical use, single and multi-component health technology strategies have been trialled to identify falls risk and prevent falls incidents. These have included sensor systems, video surveillance, and electronic health records. This thesis sought to evaluate the role of health technology in falls risk assessment and prevention, its perceptions by clinicians as end-users, and its effectiveness in reducing falls in hospital. More specifically, the thesis examined clinicians’ perspectives and use of a health information technology tool. This tool incorporated an iPad™ device and automatically generated visual cues to highlight individual patients’ falls risk. Its accuracy and efficacy in identifying and addressing falls risk scenarios, was evaluated compared to a standard screening tool. The aim of this study was to ultimately develop an acceptable and usable tool, in collaboration with clinicians, to deliver effective falls prevention in hospital. Methods Two methodologies and separate analyses were undertaken to complete this thesis: 1) An integrative review collated evidence for the effectiveness and clinicians’ perspectives of health technology use in falls prevention; and 2) an action research study evaluated clinicians’ perspectives on the health information technology tool, and informs its clinical use and efficacy in reducing hospital fall rates. Data was derived from focus group and survey research, with implementation of the health information technology tool occurring over consecutive 12-week periods on two medical wards at a single hospital setting. Both qualitative and quantitative analyses were applied to the data. Results Integrative review evidence, presented for the first time in this thesis, highlighted the lack of robust, consistent evidence for the acceptability and efficacy of health technology measures in falls prevention. The research conducted in this thesis addressed this gap in knowledge by evaluating staff’s attitudes towards the health information technology tool. It evaluated its positive and negative aspects, barriers to use, and recommendations for improvement; alongside its accuracy and effectiveness in reducing fall rates. Overall, clinicians were supportive for incorporating the tool into clinical practice. They perceived it as a useful, timely means of alerting staff and patients to falls risk scenarios, and resulting in better quality of care and understanding of falls risk for patients. Clinicians identified issues with usability and lack of time for tool use, and highlighted potential improvements to tool design. As befitting action research methodology, the health information technology tool has undergone refinement based on clinicians’ feedback. This has resulted in improved technology, clearer functioning of selection keys, colour coding of patients’ falls risk, having an automated trigger for patient education on falls risk, and provision of more iPad™ devices for more efficient use. The falls risk scores for the health information technology tool and standard falls risk in older person screening tool were similar, and did not differentiate between falls-risk and non-risk situations. Both tools had high sensitivity and low specificity for identifying falls-risk scenarios. They had similar rates of completion by clinicians on the wards. Implementation of the intervention tool had mixed outcomes on hospital fall rates. Conclusion This thesis contributed new information to address the knowledge gap on health technology uptake and efficacy in addressing hospital falls risk. Clinicians were willing to use the health information technology tool, and identified benefits to using the tool for themselves and their patients. The intervention tool demonstrated similar acceptability and accuracy to the standard falls risk screening tool. Staff’s concerns about usability are addressed in tool refinement, with active participation of end-users were considered key to improving intervention acceptance and usage, along with maximising useful feedback to further inform tool development. The effect of implementing the intervention tool on fall rates was mixed, highlighting the challenges of identifying and managing falls risk scenarios in hospital settings. The work arising from this thesis informed the development of a hand held android device used in the Ambience Intelligence Geriatric Management (AmbiGEM) system, incorporating printed visual cues with movement sensor alarms that alert clinicians to high-risk patient manoeuvres. Future research directions will involve evaluation of the acceptability and efficacy of the AmbiGEM system, which is currently undergoing clinical trial in two hospitals in South and Western Australia.Thesis (MPhil) -- University of Adelaide, Adelaide Medical School, 201