Effects of Repeated Botulinum Toxin Treatment for Sialorrhea in Patients with Parkinson's Disease

To evaluate the efficacy and adverse effects of repeated onabotulinumtoxinA (BoNT-A) treatment in patients suffering from Parkinson's disease (PD) with sialorrhea.

A retrospective analysis of 16 patients with sialorrhea treated with BoNT-A at our movement disorders outpatient clinic was conducted from February 2009 to September 2013. A patient with adult cerebral palsy and a patient with PD who received only a single application were excluded. BoNT-A was injected into the parotid glands without ultrasound guidance. Pre-treatment sialorrhea severity was quantified according to the Drooling Frequency and Severity Scale (DFSS). The efficacy was evaluated four weeks after BoNT-A injections using DFSS and according to the subjective assessment of the patients and/or caregivers.

The mean age of the patients was 70.00±9.82 years and the mean follow-up duration was 18.78±10.37 months. Totally, 37 applications were performed. The mean BoNT-A total dose was 34.35±6.41 units. The mean scores of DFSS before and after injections were 7.00±1.03 and 3.21±0.89, respectively (p<0.001). Efficacy was 100%, and the mean experienced sialorrhea improvement was 71.78±12.95%. We found a significant difference between the first and last application in the mean duration of efficacy (17.28±9.21 weeks and 18.03±9.02 weeks, respectively, p=0.001). We did not observe side effects in this study group.

Repeated injections of BoNT-A are safe and effective in treating sialorrhea in patients with PD. Based on our results, it seems that there is a maintenance of efficacy after a three-year period and an increase in the mean duration of efficacy with the number of injections. Further prospective clinical studies with larger number of patients and more longer duration of follow-up are needed to confirm our results.