Pathophysiology underlying drooling in Parkinson’s disease: oropharyngeal bradykinesia

Abstract

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.

Saliva changes in Parkinson’s disease patients after injection of Botulinum neurotoxin type A

“…PD patients report more often oral health-related problems compared to age-and gender-matched control subjects, and the problems increase significantly with increasing UPDRS score for motor impairment [26]. Caries, periodontal disease, and tooth loss may occur due to the inability to perform proper oral hygiene; also, the chewing process is less efficient because of tremor, rigidity, and hypokinesia [9]. Reduced jaw mobility and slowness of jaw movements as well as dysphagia-related food retention are common problems [26].…”

“…Drooling is not among the most frequent non-motor symptoms with its prevalence ranging from 10 to 84% across different studies and it may affect the quality of life remarkably [7][8][9][10]. It is defined as the inability to control oral secretions, resulting in excessive saliva accumulation in the oropharynx.…”

“…It is defined as the inability to control oral secretions, resulting in excessive saliva accumulation in the oropharynx. Usually, the main problem in PD with saliva excess is related to the dysfunctional oral motor control when the glutation process is abnormal due to the weak muscle function [7][8][9]11]. Based on yet unpublished data of the PD prevalence study in Estonia, excessive drooling was commonly described affecting 47% patients but mostly not as a severe symptom.…”

“…Several case-control studies have demonstrated that patients with PD have lower salivary flow [12,13], but increased excretion velocity to stimulus [7] compared to healthy controls. Drooling may also be associated with oropharyngeal bradykinesia [9], hypomimia, and dysphagia [8,9]. There is some evidence that levodopa might stimulate salivary flow rate and lead to excessive amount of saliva [12].…”

Advances in clinical neurology through the journal “Neurological Sciences” (2015–2016)

“…Indoor and outdoor falls among people with PD often result in activity limitations, participation restrictions, social isolation or premature mortality [122]. Oropharyngeal bradykinesia may be responsible for drooling in PD [123]. Botulinum toxin is a safe and effective therapy for the treatment of sialorrhea, applied without the requirement of ultrasound guidance [124].…”