The Assessment and Treatment of Disordered Speech and Voice in Parkinson’s Disease Using a PC-based Telerehabilitation System

Individuals with Parkinson’s disease (PD) face numerous access barriers to speech-language pathology services including their own physical incapacity, difficulties with transport, travel, cost of travel and the large distances to healthcare facilities. Telerehabilitation is a possible solution for these problems, whereby rehabilitation services may be delivered remotely to patients via telecommunication and information technologies. A number of studies have demonstrated the feasibility of telerehabilitation via personal computer (PC) based systems for assessment and treatment of dysarthria, apraxia of speech, aphasia and voice disorders in adults with neurological impairments. To date, however, no large-scale studies have specifically focused on the online assessment and treatment of the speech and voice disorder associated with PD. The aim of this thesis was to investigate the validity of telerehabilitation for the assessment and treatment of PD and to provide a framework for telerehabilitation use in this area. For the studies in this thesis, a custom made PC-based telerehabilitation system was developed. The system incorporated a number of features to meet face-to-face requirements for the management of PD including: (1) real-time videoconferencing which operated on a 128 kbit/s Internet connection; (2) control of the participant web cameras remotely; (3) store-and-forward function; (4) the ability to display printed materials for the participant remotely; (5) ease of operation; and (6) the ability to objectively measure real-time calibrated average recordings of vocal sound pressure level (SPL), fundamental frequency (F0) and duration. The initial component of the research established the validity of the telerehabilitation system as an acoustic measurement tool via a series of calibration and verification phases, where comparisons were made to standard face-to-face reference measurement tools (Chapter 2). The studies confirmed the accuracy of the telerehabilitation system with non-significant differences in acoustic measures obtained between the telerehabilitation system and reference tools. All measures also fell within predetermined clinical criteria. Following this, a series of four studies were conducted to achieve the aim of this thesis. The first cohort study aimed to investigate the validity and reliability of online assessment of the speech and voice disorder associated with PD (Chapter 3). A total of 61 participants with PD and mild to severe hypokinetic dysarthria took part in the laboratory-based equivalence study. The participants were assessed simultaneously in the online and face-to-face environments. The assessment protocol included perceptual measures of voice and oromotor function, articulatory precision, speech intelligibility, and acoustic measures of mean SPL, maximum F0 range and maximum duration of sustained vowel phonation. The level of agreement between the online and face-to-face ratings was determined using several different analyses, depending on the parameter. These included percent close agreement, quadratic weighted Kappa and the Bland and Altman limits of agreement. The results revealed that for all perceptual parameters, percent close agreement between the two environments was within the predetermined clinical criterion of 80%. However, a number of these parameters fell below the clinical criterion of good agreement based on the quadratic weighted Kappa. The discrepancy in findings was considered to relate to rater variability commonly seen in perceptual ratings and/or the nature of the statistic per se, rather than the online environment. For the remaining speech intelligibility and acoustic parameters, the Bland and Altman limits of agreement analysis revealed comparability between the two environments, with only the word intelligibility values falling below the clinical criterion. It was suggested that speaker severity may have influenced the results on this parameter. The intra- and inter-rater reliability scores were also comparable between the online and face-to-face environments, achieving moderate to very good agreement for all tasks. Subsequent to the validation of the online assessment of hypokinetic dysarthria, three treatment studies were conducted. The first was a laboratory-based randomised controlled non-inferiority trial investigating the validity of online treatment delivery for the speech and voice disorder associated with PD. In this study, 34 participants with idiopathic PD (IPD) and mild to moderate hypokinetic dysarthria received the Lee Silverman Voice Treatment (LSVT®) for PD, in either the online or face-to-face environment (n = 17 in each). The study findings were very promising, with non-inferiority of the online LSVT® modality confirmed for the primary outcome measure of mean change in SPL on a monologue task. Non-significant main effects of treatment environment, dysarthria severity and interaction effects were also noted across all of the acoustic and perceptual parameters (p > .05). Further, it was encouraging to note that significant gains following the LSVT® were made on the majority of acoustic and perceptual parameters for participants in both treatment environments (p < .05 for SPL tasks; maximum F0 range; all voice parameters and speech intelligibility). In order to determine the feasibility of online LSVT® for complex cases of PD, the second laboratory-based treatment study was conducted. Four participants with marked communication, cognitive and physical difficulties took part in the study. The participants had been diagnosed with either IPD and had undergone neurosurgical intervention or with progressive supranuclear palsy. Online treatment delivery for these complex cases showed promise, with functional improvements in communication reported for all cases. Although the treatment gains on the perceptual and acoustic measures were generally variable, it was evident that the outcomes were influenced by the complex participant factors that were all external to the treatment environment. In the final study, a single participant with IPD and mild hypokinetic dysarthria received the LSVT® remotely from his home, in order to determine the feasibly of home telecare for PD. Substantial improvements were achieved on the majority of acoustic parameters (SPL tasks and maximum duration of sustained vowel phonation), and on the perceptual measure of vocal breathiness. The results of the study demonstrated the feasibility of home-based treatment for PD in the real-world setting, within an individual’s most natural and preferred environment. Overall, the findings presented in this thesis provide evidence for the validity of assessing and treating the disordered speech and voice of PD via telerehabilitation. Although some challenges unique to the online environment were encountered in the studies and were mainly due to the audio and video quality during videoconferencing, the participants and speech-language pathologists (SLPs) were able to appropriately manage these without substantial impact on the online delivery overall. The high participant satisfaction with the online modality across all studies further supported this, where the majority of participants (80% and above) were more than satisfied or very satisfied with the online modality overall. The thesis provides a framework for the delivery of telerehabilitation services for people with PD, with the potential to alleviate the current access issues that exist for this population. Further research is needed to build on the findings in this thesis and should include the validity of home-based assessment and treatment, in-depth investigations of participant and SLP satisfaction and cost-benefit analyses of telerehabilitation for PD. Such investigations are necessary in order to determine the complete benefits of telerehabilitation as an additional or alternate mode of service delivery for this population, and the circumstances in which this approach is most suitable.