Pathophysiology underlying drooling in Parkinson's disease: oropharyngeal bradykinesia

We aimed to investigate the association between drooling and possible etiological factors in Parkinson's disease (PD) and to determine its effect on the quality of life. Demographic data of the 63 patients with idiopathic PD were recorded. Radboud Oral Motor Inventory for Parkinson's disease (ROMP) test was administered to all patients to evaluate speech, swallowing functions, and saliva control. The freezing of gait questionnaire (FOGQ) was used to evaluate gait and freezing of gait. Dynamic Parkinson gait scale (DYPAGS) was administered for the objective quantification of PD gait features. Disease severity was assessed by UPDRS and modified Hoehn & Yahr Scale. PD specific health-related quality was evaluated by PDQ-39 questionnaire. Drooling was only significantly correlated to UPDRS score; a stronger association was found between drooling and UPDRS 3 motor score; and a more significant association was determined between drooling and the bradykinesia questions of the motor part of UPDRS 3. Interestingly, no significant association was found between sialorrhea score and PDQ-39 score. Based on the results of this study, we concluded that oropharyngeal bradykinesia may be responsible for drooling in PD. In contrast to a general expectation, we did not find any adverse impact of drooling on the quality of life.