CHRONIC COUGH AND EXTRATHORACIC AIRWAY HYPERRESPONSIVENESS SYNDROME: CHARACTERISTICS AND TREATMENT EFFICACY

Vertigan, Anne Elizabeth (2007). CHRONIC COUGH AND EXTRATHORACIC AIRWAY HYPERRESPONSIVENESS SYNDROME: CHARACTERISTICS AND TREATMENT EFFICACY PhD Thesis, School of Health and Rehabilitation Sciences , University of Queensland.

       
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Author Vertigan, Anne Elizabeth
Thesis Title CHRONIC COUGH AND EXTRATHORACIC AIRWAY HYPERRESPONSIVENESS SYNDROME: CHARACTERISTICS AND TREATMENT EFFICACY
School, Centre or Institute School of Health and Rehabilitation Sciences
Institution University of Queensland
Publication date 2007
Thesis type PhD Thesis
Supervisor Associate Professor Deborah Theodoros
Abstract/Summary Chronic Cough (CC) and Extrathoracic Airway Hyperresponsiveness Syndrome (EAHRS) are common debilitating conditions that are poorly understood in terms of their pathogenesis and have a limited evidence base to support their management. The purpose of this thesis was to investigate symptoms, voice characteristics and respiratory function in people with CC and EAHRS, to explore the relationship between the two conditions and to determine the effectiveness of speech pathology management of CC. Participants included 55 adults with a combination of CC and EAHRS (Cough + EAHRS), 8 with EAHRS Alone, 56 with Cough Alone, 25 with Muscle Tension Dysphonia (MTD) and 27 healthy controls. A cross sectional design was used to compare the clinical case history, symptom frequency and severity rating, the Hospital Anxiety and Depression Scale, and baseline spirometry and hypertonic saline challenge amongst these participant groups. Vocal function was analysed using perceptual voice analysis of samples of connected speech by blinded perceptual judges and acoustic assessment of sustained vowels using the PRAAT acoustics program. Electroglottographic analysis was conducted during connected speech using the Laryngograph ® Speech Studio software. Two additional studies examined the efficacy of speech pathology management for persons with CC through a single blind, randomised, placebo controlled trial. Eighty seven participants with CC were randomly allocated to receive either direct speech pathology intervention for the CC (treatment) or an equivalent course of healthy lifestyle education (placebo). Each group received four intervention sessions over a two-month period. Outcome measures included symptom ratings, perceptual, acoustic, and electroglottographic analyses of voice and vocal function. The results demonstrated considerable overlap in medical history, symptoms, and baseline respiratory function between the Cough + EAHRS and Cough Alone groups indicating that these disorders may be linked. Participants with EAHRS Alone and MTD overlapped with the Cough + EAHRS and Cough Alone groups on some features however significant differences remained between them and these appeared to be distinct conditions. The majority of participants in all groups had normal ratings on the Hospital Anxiety and Depression scale, however there were significant group differences in anxiety and depression. Clinically significant perceptual ratings of vocal quality were identified in approximately 40% of individuals with CC and EAHRS in comparison to only 4% of healthy controls. Acoustic voice assessment revealed abnormal phonation times, standard deviation of fundamental frequency, jitter and harmonic to noise ratios in the participants with CC and EAHRS compared to healthy controls while electroglottographic analysis demonstrated reduced fundamental frequency and decreased closed phase of vocal fold vibration in the former group. The hypertonic saline challenge revealed reduced inspiratory flow indicative of glottal constriction in 52% of participants with CC. Results of the randomised treatment trial demonstrated a significantly greater improvement in all symptom scores in the treatment group compared to the placebo group. There was a significant pre to post-intervention improvement in breathing, cough and limitation scores in both treatment and placebo groups but significant improvement in pre- to post-intervention voice and upper airway scores in the treatment group only. Perceptual voice ratings demonstrated greater improvement in the treatment group compared to the placebo group. The treatment group also demonstrated a significant pre to post-intervention improvement in some acoustic voice measures, although the degree of change was not significantly different to that of the placebo group. The results of this research support a relationship between CC and EAHRS and suggest that these conditions cannot be differentiated on the basis of their symptom profile, vocal features or baseline respiratory function. The results suggest that EAHRS might be a possible explanation for a substantial proportion of individuals with CC and that psychiatric causes cannot automatically be assumed in CC and EAHRS. Voice problems can occur in a substantial proportion of individuals with CC and EAHRS. In addition to improved control of cough and respiratory symptoms, speech pathology intervention also results in improvements in vocal quality. This improvement suggests that voice problems in CC and EAHRS may be integral to the conditions rather than evidence of a separate co-existing disorder. The findings of this study have indicated that medical treatment protocols for CC could be expanded to include speech pathology intervention. Speech pathology intervention may be a viable alternative for individuals with CC that persists despite optimal medical treatment.

 
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