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

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).

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.

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.

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.