The Lee Silverman Voice Treatment Improves Vocal loudness in Early Persian Parkinson’s Patients: A Pilot Study

Objectives: In the early stages, most Parkinson’s patients display some degrees of voice and speech disorders. Speech disorders can negatively affect social interactions and human life, thus treatment plans for the disorders in the early stages might be further beneficial than the late stages. Therefore, we aimed to investigate on the effect of an intervention on Persian patients with early mild Parkinson’s disease (PD). The intervention was the Lee Silverman voice treatment (LSVT). Methods: This was an interventional study and included 23 PD patients. They were randomly assigned into one of two groups; 13 patients in intervention group (PD-I), and 10 in no-intervention group (PD-NI). Normal persons (NP) or control group including 13 healthy participants who were neurologically normal and had not speech and voice disorders and their matching with the PD-I group was according to education, age, sex. Results: There was a significant impairment in maximum phonation time (MPT), vocal loudness in vowel /a/, in reading and during a monologue speech in the PD group compared with the NP group (p≤0.001). The LSVT resulted in a significant improvement in all measures in the PD-I group (p≤0.001), whereas no significant change was observed between the PD-I and PD-NI groups’ scores in first assessment (p≥ 0.201), but the PD-NI group’s results in all measurements of final assessment were significantly lower than the measurements in PD-I (p≤0.001) and NP (p≤0.001) groups. The MPT was also exhibited a considerable improvement in the PD-I group compared with the controls. Conclusions: The LSVT, as a therapeutic technique based on the motor learning theory, is beneficial in improving vocal loudness of Persian patients with PD in early stages of their disease.