Effectiveness of Lee Silverman Voice Treatment (LSVT)® on hypernasality in non-progressive dysarthria: the need for further research

Abstract

Background: Hypernasality is a common feature of non-progressive dysarthria. However, limited research has investigated the effectiveness of treatments for this impairment. Preliminary research has revealed positive effects on nasalance when using increased loudness in certain non-progressive dysarthric speakers. However, the long-term effects of loud speech on nasalance as part of a structured intervention such as Lee Silverman Voice Treatment (LSVT)re yet to be investigated in this population. Aims: The study aimed to investigate the short- and long-term effects of LSVTn hypernasality (perceptual ratings and degree of nasalance) in non-progressive dysarthria; and secondly, to evaluate the effects of traditional dysarthria therapy on these same measures, in comparison with the effects of LSVT Methods & Procedures: Ten non-progressive dysarthric speakers with varying levels of hypernasality (taken from a larger research study) were randomly allocated to receive LSVTn = 5) or individually tailored traditional dysarthria therapy (n = 5). Both treatments were administered four times weekly for 4 weeks (that is, 16 נ 1-hour sessions). Participants were assessed twice before treatment, twice immediately post-treatment, and twice at follow-up 6 months post-treatment using a perceptual rating task performed by two independent speech pathologists, and the Nasometer. Changes to individual mean nasalance scores were compared against clinically significant criterion and perceptual ratings were analysed descriptively. Outcomes & Results: Three out of five participants demonstrated reductions in perceived hypernasality immediately following LSVTbut these changes were maintained at follow-up for only one participant. Two of these three participants demonstrated a corresponding reduction in mean nasalance. Limited changes in perceived hypernasality and nasalance scores were found following traditional dysarthria therapy, with only one participant exhibiting reduced nasalance at follow-up. Conclusions & Implications: Due to the small sample size in the present research and variability between participants, further exploration into the effects of LSVTn nasality with a larger population with different dysarthria types is essential.