What causes sialorrhea (drooling) in amyotrophic lateral sclerosis (ALS)?

Updated: Jan 02, 2020
  • Author: Divakara Kedlaya, MBBS; Chief Editor: Ryan O Stephenson, DO  more...
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Sialorrhea (drooling), the unintentional loss of saliva from the mouth, occurs in up to 25% of patients with motor neuron disease and affects almost all patients with bulbar involvement. It can significantly affect quality of life. It is caused by dysphagia with inability to swallow secretions because of tongue spasticity; weakness of face, mouth, and pharyngeal muscles; and loss of oropharyngeal coordination and function and is not due to increased production of saliva. There are 2 main types of saliva produced by the 3 major salivary glands: serous saliva, which is thin and watery and is mediated by cholinergic receptors, and mucoidal saliva, which is thicker and more viscous and is mediated by beta-adrenergic receptors. [31]

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