Effect of transcranial direct current stimulation on improving speech production in post-stroke Cantonese dysarthric patients

Abstract

The present study investigated the potential effect of transcranial direct current stimulation (tDCS) on speech production in post-stroke Cantonese dysarthric patients. Nine participants were recruited and they were randomly assigned into stimulation or sham group. Both groups received ten consecutive days of conventional speech therapy, while only the stimulation group was supplemented with simultaneous anodal tDCS. Anodal tDCS was delivered to participants’ left inferior primary motor cortex (C5) at 2 mA for 15 minutes. Perceptual, acoustic and kinematic analysis (using electromagnetic articulography) were conducted. The results revealed a significant improvement in perceptual speech intelligibility at the word level, verified with reduced perturbation of voice amplitude and improved articulatory accuracy in context of rapid syllable repetition and sentence production as shown in kinematic parameters. The findings suggest that tDCS is a desirable adjuvant strategy in enhancing the treatment efficiency of conventional speech therapy.