Sialorrhea in amyotrophic lateral sclerosis: a hypothesis of a new treatment--botulinum toxin A injections of the parotid glands.

The inhibitory action of botulinum toxin is not confined to the neuromuscular junction. The toxin has long been known to block all the autonomic cholinergic fibers, including the major secretomotor parasympathetic fibers to salivary glands. The parotids are the largest of the salivary glands and their selective chemodenervation with botulinum toxin A is likely to result in substantial reduction of saliva production. Injection of the parotid glands with botulinum toxin is proposed as an new treatment for sialorrhea in patients with amyotrophic lateral sclerosis and other neurological diseases.