The Lee Silverman Voice Treatment Improves Vocal Loudness in Early Persian-speaking Patients With Parkinson’s Disease

Abstract

Objectives: In the early stages, most Parkinson’s patients display some degrees of voice and speech disorders. Speech disorders can negatively affect individuals’ social interactions and life; thus, treatment plans for the disorders in the early stages might be further beneficial than the late stages. Therefore, we aimed to investigate the effects of an intervention on Persian-speaking 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 patients with PD. The study participants were randomly assigned into one of two groups; 13 patients in the intervention group (PD-I), and 10 in No-Intervention (PD-NI) group. Normal Persons (NP) or the control group included 13 healthy participants who were neurologically normal and presented no speech and voice disorders. Besides, they were matched with the PD-I group concerning education, age, gender. 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); however, no significant change was observed between the PD-I and PD-NI groups’ scores in first assessment (P≥0.201). In contrast, the PD-NI group’s results in all measurements of final assessment were significantly lower than those in the PD-I (P≤0.001) and NP (P≤0.001) groups. The MPT also exhibited a considerable improvement in the PD-I group, compared with the controls. Discussion: The LSVT, as a therapeutic technique based on the motor learning theory was beneficial in improving the vocal loudness of Persian-speaking patients with PD in the early stages of their disease.