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Swallowing dysfunction (dysphagia) is a common disorder in patients with neurological impairments, head/neck injuries or brain-stem stroke. The main objectives of this thesis were to use acoustical analysis of swallowing and breath sounds for 1) understanding the swallowing mechanism and the main cause of dysphagia, and 2) developing a noninvasive diagnostic technology to detect swallowing aspiration (the entry of bolus into airway); thus, identifying individuals at high risk of severe dysphagia. As the first objective of the study, swallowing mechanism modeling in two groups of healthy individuals and dysphagic patients (due to cerebral palsy or stroke) was approached by using two different assumptions to relate the swallowing sounds either to the pharyngeal response or to the neural activities that initiate the swallow. The results showed that the model with the assumption of neural activities as the cause of dysphagia was a better fit to the available data. As the second main objective of the study, we analyzed breathing and swallowing sounds of 50 dysphagic individuals during the fiberoptic endoscopic evaluation of swallowing (FEES) or the videofluoroscopic swallowing study (VFS). The results showed 91% sensitivity and 85% specificity in identifying patients with severe aspirations. Also, the algorithm was able to detect the silent aspiration among the swallows of each patient. The proposed methods led to development of a non-invasive and reliable diagnostic/screening tool as an aid to the clinical examination of swallowing. The proposed acoustic method can be performed at the patients’ bedside to determine the appropriate further assessment or a dietetic treatment; thus, reducing the health care cost by prioritizing the patients’ referrals to the VFS/FEES tests.

No description available.

Swallowing dysfunction, or dysphagia, can result from any structural or neurological impairment that affects the swallowing mechanism. Accelerometry is a non-invasive technique that may be used to measure the epidermal vibration signals on a patient’s throat during swallowing. The purpose of this study was to map out the trajectories of the hyoid bone and arytenoids during swallowing to determine if a relationship exists between their trajectories and the signals obtained from an accelerometer placed on a participant’s neck during a scheduled videofluoroscopic swallowing study. Participants included 43 adult patients with neurogenic dysphagia. A software program was created to track the desired anatomy on the videofluoroscopic videos frame-by-frame. The data from the software was then compared to the integrated acceleration data multiple linear regression. The results show that the hyoid and larynx are not always correlated during swallowing and further suggest hyolaryngeal excursion as the primary physiological source of accelerometry.

Swallowing dysfunction, or dysphagia, can result from any structural or neurological impairment that affects the swallowing mechanism. Accelerometry is a non-invasive technique that may be used to measure the epidermal vibration signals on a patient’s throat during swallowing. The purpose of this study was to map out the trajectories of the hyoid bone and arytenoids during swallowing to determine if a relationship exists between their trajectories and the signals obtained from an accelerometer placed on a participant’s neck during a scheduled videofluoroscopic swallowing study. Participants included 43 adult patients with neurogenic dysphagia. A software program was created to track the desired anatomy on the videofluoroscopic videos frame-by-frame. The data from the software was then compared to the integrated acceleration data multiple linear regression. The results show that the hyoid and larynx are not always correlated during swallowing and further suggest hyolaryngeal excursion as the primary physiological source of accelerometry.

Rationale: Lower respiratory tract infections (LRTI) are a common cause of morbidity and mortality in children. Swallowing problems are also common in children. Aspiration is one outcome of swallowing dysfunction that may be a contributing factor to LRTI. Methods: Retrospective review of children undergoing videofluoroscopic swallow study was done to identify the prevalence and correlates of aspiration and LRTI. Results: Aspiration prevalence was 36.6%. Significant factors on univariate analysis included: developmental delay, LRTI, pneumonia, digestive tract anomalies, indigenous heritage, cough and congestion. With logistic regression, congestion and LRTI correlated with aspiration. Prevalence of LRTI was 42%. Using univariate analysis pneumonia, aspiration and indigenous heritage were significant. With logistic regression, respiratory issues and indigenous heritage correlated with LRTI. Conclusion: The etiology of LRTI is complex and multifactoral. Understanding the relationship between all factors is imperative given that current interventions are invasive and the untreated outcome can be progressive lung injury.

Rationale: Lower respiratory tract infections (LRTI) are a common cause of morbidity and mortality in children. Swallowing problems are also common in children. Aspiration is one outcome of swallowing dysfunction that may be a contributing factor to LRTI. Methods: Retrospective review of children undergoing videofluoroscopic swallow study was done to identify the prevalence and correlates of aspiration and LRTI. Results: Aspiration prevalence was 36.6%. Significant factors on univariate analysis included: developmental delay, LRTI, pneumonia, digestive tract anomalies, indigenous heritage, cough and congestion. With logistic regression, congestion and LRTI correlated with aspiration. Prevalence of LRTI was 42%. Using univariate analysis pneumonia, aspiration and indigenous heritage were significant. With logistic regression, respiratory issues and indigenous heritage correlated with LRTI. Conclusion: The etiology of LRTI is complex and multifactoral. Understanding the relationship between all factors is imperative given that current interventions are invasive and the untreated outcome can be progressive lung injury.

Swallowing is an important physiological function leading to nourishment of the organism, controlled by complicated interactions between the muscles, the cranial nerves and multiple brain structures. Swallowing impairments, also called dysphagia, are a major health burden for patients with neurological diseases such as stroke, Parkinson’s disease as well as community dwelling elderly individuals. It has been shown that activation of undamaged swallowing motor cortex compensates for the initial lost swallowing function in stroke patients. Non-invasive brain stimulation provides a tool to explore excitability within the areas of the motor cortex responsible for swallowing muscles. Repetitive transcranial magnetic stimulation (rTMS) is one such technique, with defined frequency parameters, however the underlying reasons for the heterogeneity is responses to low (1Hz) and high (5Hz) frequencies is unclear. These physiological interactions affecting the neurological control of swallowing may be influenced by multiple genes and proteins. Insights into the molecular basis of swallowing through genetic interactions could provide a source of information which can be further used in understanding and treating swallowing impairments. Existing evidence is limited in terms of candidate proteins, genes and pathways which might drive the neural control of swallowing. The aim of my doctoral research was to explore genes which might be involved in swallowing neurophysiology and pathophysiology. My hypothesis is that swallowing due to its complicated physiology is most likely affected by multiple genes and interactions between genes and proteins. To study this hypothesis I used two experimentally distinct study designs. Firstly I explored a number of single nucleotide polymorphisms (SNPs) and potential candidate genes presented in the existing literature. Then, I performed a SNP- and gene-based Genome-Wide Association Study (GWAS) of self-reported swallowing impairments compared with over 500,000 single nucleotide changes. For GWAS I used a group of 555 community dwelling individuals from the Dyne Steel Cohort from the areas of Manchester and Newcastle. Further research involved replication of selected genes and SNPs from literature screening and GWAS using two rTMS paradigms on the largest to date cohort of healthy young volunteers. Forty one volunteers (were assessed for corticobulbar excitability after single-pulse TMS. Repeated measurements of motor evoked potentials from the pharynx and the hand were recorded after the interventions of 1Hz and 5Hz rTMS. The subjects’ individual responses were grouped according to multiple criteria and then associated with factors such as gender, ethnicity, time of day of the stimulation and individual genetic information. GWAS analysis for association with swallowing impairment identified one SNP rs17601696 which achieved genome-wide significance (P-value=5×10(-8)) within a non-coding region of chromosome 10. Gene-based analysis did not result in any genome-wide significant association. In replication of these findings and following a priori selected genes from the literature (BDNF, COMT, TRKB, APOE, DRD2, GRIN2B and GRIN1) from neurophysiological studies applying TMS, two main conclusions were formed. Firstly, rTMS paradigms showed high variability in responses which made the phenotype more complicated. Secondly the result from GWAS could not be confirmed. By contrast, SNP rs6269 from the COMT gene was associated with responsiveness of the pharyngeal MEPs after delivering 1Hz paradigm and rs1800497 from the DRD2 gene with responsiveness after 5Hz rTMS.Lack of replication of the findings between two experiments might be caused by high variability in responsiveness with complex molecular networks of swallowing control where multiple genes with small genetic effects are involved. Although our findings support the hypothesis that molecular markers can be associated with swallowing, more studies are needed to understand the individual factors that determine responsiveness and effectiveness of treatment therapies of swallowing impairments.

Many research questions in dysphagia research require frame-by-frame annotation of anatomical landmarks visible in videofluorographs as part of the research workflow, which can be a tedious and error prone process. Such annotation is done manually using image analysis tools, is error prone, and characterized by poor rater reliability. In this thesis, a computer-assisted workflow that uses a point tracking technique based on the Kanade-Lucas-Tomasi tracker to semi-automate the annotation process, is developed and evaluated. Techniques to semi-automate the annotation process have been explored but none have had their research value demonstrated. To demonstrate the research value of a workflow based on point tracking in enhancing the annotation process, the developed workflow was used to perform an enhanced version of the recently published Coordinate Mapping swallowing study annotation technique to determine several swallowing parameters. Evaluation was done on eight swallow studies obtained from a variety of clinical sources and showed that the workflow produced annotation results with clinically insignificant spatial errors. The workflow has the potential to significantly enhance research processes that require frame-by-frame annotation of anatomical landmarks in videofluorographs as part of their data preparation steps, by reducing the total time required to annotate clinical cases