The Motor Speech Disorder Associated with Friedreich’s Ataxia

Joanne Folker (2010). The Motor Speech Disorder Associated with Friedreich’s Ataxia PhD Thesis, School of Health & Rehabilitation Sciences, The University of Queensland.

       
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Author Joanne Folker
Thesis Title The Motor Speech Disorder Associated with Friedreich’s Ataxia
School, Centre or Institute School of Health & Rehabilitation Sciences
Institution The University of Queensland
Publication date 2010-09
Thesis type PhD Thesis
Supervisor Prof Bruce Murdoch
Dr Louise Cahill
Total pages 211
Total colour pages 6
Total black and white pages 205
Subjects 11 Medical and Health Sciences
Abstract/Summary Friedreich’s Ataxia (FRDA) is an autosomal recessive neurodegenerative disorder and the most common of the hereditary ataxias. Pathological degeneration primarily involves the spinal cord with the degeneration of neurones in the spinocerebellar tracts. Dysarthria is a diagnostic clinical feature of FRDA. While the dysarthria associated with FRDA is classically described as ataxic, neurological involvement can extend beyond the spinocerebellar tracts, particularly as the disease progresses, resulting in a mixed dysarthria. The current keystone of knowledge regarding the dysarthria associated with FRDA has arisen largely from perceptual descriptions. Hence, the primary aim of this thesis is to provide a comprehensive assessment of speech function in individuals with a confirmed genetic diagnosis of FRDA, applying perceptual and instrumental techniques. Thirty-eight individuals with FRDA participated in the perceptual speech assessment with a subgroup of seven participants completing an instrumental battery of assessments. Perceptual speech assessment was conducted on the cohort of 38 individuals with FRDA and a group of 20 non-neurologically impaired individuals, who served as controls. Assessment included the perceptual analysis of a speech sample investigating 30 different dimensions of speech, an overall dysarthria severity rating, and the Assessment of Intelligibility of Dysarthria Speech (ASSIDS). The FRDA participants presented with dysarthria of severities ranging from mild to moderate. Correlation analysis revealed a significant relationship between dysarthria severity and parameters of disease duration and overall disease severity, but not with age of onset or the size of the genetic mutation. The perceptual profiles obtained from the perceptual analysis were subjected to a cluster analysis, suggesting the existence of three subgroups, defined according to their perceptual speech characteristics. The first subgroup presented with mild dysarthric symptoms, the second was characterised by the presence of hypernasality and the third distinguished by an increased phonatory dysfunction. A subgroup of seven individuals with FRDA participated in a series of instrumental assessments, including acoustic and physiological measures (Nasometer and Respitrace), selected to provide an overview of motor speech function encapsulating all aspects of speech production including: articulation, phonation, resonance and speech breathing. Instrumental assessment supported the perceptual findings and the clustering of subgroups, representing distinct impairments of the speech mechanism and perhaps reflective of differing evolutions beyond the cerebellum. A further aim of this thesis was to specifically investigate the articulatory impairment that is prominent in the dysarthria associated with FRDA, using physiological instrumentation. Electropalatography (EPG) was used to describe the pattern of linguopalatal contact and the consonant phase durations exhibited by seven individuals with FRDA. The FRDA group exhibited significantly increased consonant durations compared to the controls while maintaining normal linguopalatal contact patterns, suggesting that the articulatory impairment in FRDA manifests as a temporal rather than spatial disturbance. Lingual kinematics were investigated in two subsequent studies using electromagnetic articulography (EMA). Due to the demands of the assessment, a smaller group of four individuals with FRDA participated in the study. The first study investigated lingual movements across sentence productions of the tongue–tip sentence Tess told Dan to stay fit and the tongue-back sentence Karl got a croaking frog. Kinematic parameters included velocity, acceleration/deceleration, distance travelled and duration of movement for the approach phase and release phase of consonant productions across the sentence. The FRDA group demonstrated greater movement durations, increased articulatory distances and reduced speed measures during the approach phase of consonant productions. The final EMA study sought to further investigate the articulatory kinematics in the dysarthria associated with FRDA, by looking specifically at the production of the alveolar consonant /t/ and the velar consonant /k/ as produced within a sentence utterance, as well as in a syllable repetition task. Results revealed significantly greater movement durations and increased articulatory distances, most predominantly during the approach phase of consonant production. A task difference was observed with lingual kinematics more disturbed during the syllable repetition task than during the sentence utterance. Despite expectations of slowed articulatory movements in FRDA dysarthria, the EMA data indicated that the observed prolongation of consonant phase durations was generally associated with greater articulatory distances, rather than slowed movement execution. Slowed movement execution was evident only in the participant who presented with a more severe dysarthria, associated with a more severe disease progression. This thesis provides the largest study of the dysarthria associated with FRDA to date. It is anticipated that this research will provide a baseline for a longitudinal study of speech function in FRDA. The quantification of speech function in this population may have an important role in providing a significant functional measure of neurological decline. This may lead to the development of more sensitive assessment tools to measure change in performance in clinical trials, for determining the benefits of speech pathology interventions and for therapies targeting the central nervous system (CNS) involvement in FRDA.
Keyword Friedreich’s ataxia
dysarthria
electromagnetic articulography
electropalatography
Additional Notes Colour pages: 157,203,205,207,210,211 Landscape pages: 65,82-86,107,114,115,133,153

 
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Created: Tue, 21 Dec 2010, 11:40:26 EST by Joanne Folker on behalf of Library - Information Access Service