Effects of Intensive Speech Treatment for an Individual with Spastic Dysarthria Secondary to Stroke

Abstract

Objective: This study investigated the impact of an intensive speech treatment on listener-rated communication success and functional outcome measures of communication for an individual with spastic dysarthria secondary to stroke. Method: A single-subject A-B-A-A experimental design was used to measure the effects of an intensive speech treatment that incorporated principles of motor learning to drive activity-dependent changes in neural plasticity. The primary dependent variables were listener-rated communication success (comprehensibility transcription in two conditions and listener perceptual ratings of speech and voice), and functional outcome measures as rated by the participant and his spouse. Secondary dependent variables included acoustic factors: vowel space area, phonatory stability, and vocal dB SPL during speech tasks. Results: Multiple comparisons with t-tests were used to determine statistically significant changes in primary and secondary dependent variables. Statistically significant changes (p<0.05) were present immediately post-treatment in listener perceptual ratings for speech naturalness in sentences (p=0.00), but demonstrated a preference for pre-treatment sustained vowel phonation (p=0.04). All functional outcome measure reflected the participant’s perception of increased communicative effectiveness, decreased psychosocial impacts of dysarthria, and increased social participation. There were statistically significant changes in secondary variables at post-treatment including phonatory stability in amplitude perturbation quotient (p=0.02), and vocal dB SPL during sustained vowel phonation (p=0.01), and sentence reading (p=0.03). Vowel space area increased by 13% at post-treatment. Three months following treatment, there were statistically significant changes in listener comprehensibility at the single word length (p=0.02) and sentence length (p=0.03), and listener perceptual ratings of speech naturalness (p=0.02). All functional outcome measures displayed maintained post-treatment effect. Vowel space area increased by 25% compared to pre-treatment. There were no statistically significant changes in phonatory stability or vocal dB SPL three months following treatment. Conclusions: Treatment outcomes were specific to the research participant's individual characteristics. The improvements measured immediately post- and three months following treatment cannot be generalized beyond this individual with dysarthria secondary to stroke. However, the positive treatment effects for STR03 indicated that individuals in the chronic stages of recovery with dysarthria can improve and maintain speech comprehensibility as well as increase communication effectiveness and reduce some of the negative emotional and social components of chronic dysarthria, even four years post-onset, warranting further investigation.