Double-blind, placebo-controlled study to evaluate the efficacy and safety of botulinum toxin type A in the treatment of drooling Parkinsonism

Drooling is a frequent symptom in Parkinson's disease (PD), occurring in almost 75% of all patients. Although it is now well known that drooling in PD is the result of swallowing difficulties rather than excessive saliva production, few treatments have been developed to reduce it. Clinical studies suggest that botulinum toxin A (BTX) injections into salivary glands are effective in decreasing drooling in PD patients. In this double-blind, placebo-controlted study, 20 patients with parkinsonism (idiopathic PD or multiple system atrophy), were randomly assigned to receive 450 U of BTX (Dysport; Ipsen, Berkshire, UK) or 2 ml of placebo, injected into the parotids and submandibular glands under ultrasonographic guidance. Treatment efficacy and safety were assessed at baseline, 1 week and 3 months after BTX injections using clinical scales (Drooling Severity and Drooling Frequency scales) and side effects surveillance. After treatment, the average secretion of saliva in the BTX group was significantly lower than in the placebo group, as appraised by clinical measurements. No side effects were observed in either group. BTX injection into parotids and submandibular glands, under ultrasonographic guidance, is an effective and safe treatment for drooling in parkinsonism.