Effectiveness of the Botulinum Toxin for Treating Sialorrhea in Patients with Parkinson's Disease: A Systematic Review

The main objective was to assess the efficacy of botulinum toxin-based treatment for sialorrhea in adult patients with Parkinson's disease. The search was performed by using the Medline-PubMed, EMBASE and Cochrane Library databases from January 2000-December 2017, in English/Spanish in patients with Parkinson's disease and sialorrhea. The methodological quality of trials was carried out by following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) criteria and the Newcastle-Ottawa Scale (NOS). Finally, a total of 21 articles were identified as fulfilling the inclusion criteria. There is no consensus regarding the site of injection of the toxin (single or multiple points), toxin dose or follow-up period. In all cases there was a reduction of sialorrhea. Treatment safety increases with the use of ultrasonography. Effects approximately occur at one week post-injection and for 3-5 months. Botulinum toxin is an effective therapeutic strategy or option in treating sialorrhea in adult patients with Parkinson's disease. More studies with a better design, larger samples and a longer follow-up period are required to confirm these data.