Sialorrhea refers to an excessive secretion of saliva, which generally results in drooling. It can result from several neurological disorders, including Down's syndrome, cerebral palsy, and Parkinson's disease. It can also be a result of some medications.
While the condition rarely if ever puts the patient in danger, it does tend to be extraordinarily embarrassing, particularly when it's so severe that the patient drools in public. Treatments are varied, and can include dental care, speech pathology, biofeedback, tonsillectomy, and rerouting or removal of some of the salivary glands. The latter treatment is done only in the most serious cases, as it can result in xerostomia, or pathologically low levels of saliva; this presents a problem because saliva is vital for digestion, oral health, and swallowing.