What is Hypersalivation (Sialorrhea)?
Hypersalivation, also known as sialorrhea or drooling, is a condition of relatively excessive salivary flow that results from insufficient oro-motor function, dysphagia, or decreased central control and coordination—not from actual overproduction of saliva. 1
Definition and Pathophysiology
Sialorrhea describes excessive salivary flow that wets the patient and their surroundings 2, 1. The key distinction is that this condition typically results from impaired swallowing and poor oral neuromuscular control rather than true hypersecretion of saliva 3. The underlying mechanisms include:
- Insufficient oro-motor function - weakness or incoordination of the muscles controlling the mouth and tongue
- Dysphagia - difficulty swallowing that prevents normal clearance of saliva
- Decreased central control and coordination - neurological impairment affecting the swallowing reflex
- Poor oral or pharyngeal neuromuscular control 4
Clinical Significance
Sialorrhea is particularly common and distressing in neuromuscular diseases (especially ALS), reducing quality of life and increasing the risk of aspiration and pneumonia due to problems with swallowing, airway protection, and cough effectiveness 4. The condition can be socially incapacitating, with patients experiencing significant social stigmas from occult drooling or needing to regularly evacuate saliva into tissues or "spit cups" 5.
Common Causes
The condition occurs most frequently in:
- Neuromuscular diseases, particularly amyotrophic lateral sclerosis (ALS) 4
- Cerebral palsy in children 6
- Neurodegenerative disorders in adults 6
- Parkinson's disease 7
- Stroke 7
- Head and neck cancer 7
Additional causes include certain medications (clozapine, risperidone, lithium) 8, 5, 9, gastroesophageal reflux disease (water brash), esophageal obstruction, and various infections 5.
Clinical Assessment
Assessment should focus on identifying dysphagia, saliva aspiration, and oro-motor deficiencies 2, 1. Fiberoptic endoscopic evaluation of swallowing generates important data on therapy selection and control 2, 1. The severity can be measured using validated scales like the Drooling Severity and Frequency Scale or Toronto Nocturnal Hypersalivation scale 8.