Multidimensional voice assessment after Lee Silverman Voice Therapy (LSVT^®) in Parkinson's disease

To investigate the effectiveness of Lee Silvermann Voice Treatment (LSVT^®) in improving prosody in patients with Parkinson's disease over medium-term follow-up.

15 patients with Parkinson's disease were assessed before LSVT^®, within one week, and 3 and 6 months after treatment. Subjective and objective evaluation included: Voice Handicap Index - 10 (VHI-10), perceptual assessment by GRBAS scale and item 18 of the Unified Parkinson's Disease Rating Scale III (UPDRS III), maximum phonation time (MPT /s/) and acoustic analysis by means the Voice Range Profile (VRP) and the "Intonation Stimulability Protocol" of the Motor Speech Profile (MSP).

A significant increase of the mean values of Imax and rF0 was observed until 6 months post-therapy (p < 0.001), whereas Running Speech Standard Deviation (rSTD) (p = 0.004), Amplitude Variability (rVAm) (p = 0.02) and Frequency Variability (rvF₀) (p = 0-01) improved significantly after 3 months, but returned to pre-therapy levels after 6 months. The score of item 18 of the UPDRS III increased significantly early post-therapy (p = 0.03), but did not maintain the improvement at 3 and 6 months. Median values of Grade (G), Asthenia (A) and mean values VHI-10 score significantly decreased at each post-therapy control (p < 0.05).

In addition to the subjective and perceptual beneficial effect of LSVT^®, we found a long-lasting increase of loudness and fundamental frequency. There was also improvement of acoustic parameters related to prosody, although it was temporary.