Treatment of severe drooling with botulinum toxin in amyotrophic lateral sclerosis and Parkinson's disease: efficacy and possible mechanisms

Abstract

Objective: Drooling in neurodegenerative diseases is associated with social impediment. Previous treatments of drooling have little effect or are effective but with severe side effects. Therefore, there is a need to test new methods such as the use of botulinum toxin type A (BTX-A).

Material and methods: This open, prospective study deals with treatment of drooling in 12 patients with amyotrophic lateral sclerosis and three with Parkinson's disease. Injections of BTX-A (Botox) were given into the parotid (25-40 units) and submandibular (15-30 units) glands with ultrasonographic guidance. After BTX-A treatment, the patients were followed for 2 months with evaluations every second week by means of self-assessed rating scales for drooling intensity, discomfort and treatment effect, and determination of unstimulated whole saliva (UWS) flow rate, and inorganic and organic UWS composition. The treatment was repeated up to four times, but seven patients dropped out shortly after the first treatment due to marked worsening of their disease-related condition.

Results: Drooling and flow were reduced (P < 0.05) 2 weeks after treatment, without side-effects. The maximal reductions during the observation period were 40% for drooling and 30% for flow. There was a systematic variation in flow during the observation period, with an initial decrease and then an increase followed by a second decrease. Amylase activity and total protein concentration generally increased with decreasing flow (P ≤ 0.03).

Conclusion: Inhibition of acetylcholine release from postganglionic parasympathetic nerve endings by injection of BTX-A into salivary glands seemed useful for secondary sialorrhoea, although cyclic variations in flow may occur, possibly due to transitory sprouting and regeneration.