Pathophysiology of diurnal drooling in Parkinson's disease

Abstract

Drooling is an incapacitating feature of Parkinson's disease. Better pathophysiological insights are needed to improve treatment. In this study, we tested the hypothesis that the cause of drooling is multifactorial. We examined 15 patients with Parkinson's disease with distinct diurnal saliva loss ("droolers") and 15 patients with Parkinson's disease without drooling complaints ("nondroolers"). We evaluated all factors that could potentially contribute to drooling: swallowing capacity (maximum volume), functional swallowing (assessed with the dysphagia subscale of the Therapy Outcome Measures for rehabilitation specialists), unintentional mouth opening due to hypomimia (Unified Parkinson's Disease Rating Scale item), posture (quantified from sagittal photographs), and nose-breathing ability. We also quantified the frequency of spontaneous swallowing during 45 minutes of quiet sitting, using polygraphy. Droolers had more advanced Parkinson's disease than nondroolers (Unified Parkinson's Disease Rating Scale motor score 31 vs 22; P=.014). Droolers also scored significantly worse on all recorded variables except for nose breathing. Swallowing frequency tended to be higher, possibly to compensate for less efficient swallowing. Logistic regression with adjustment for age and disease severity showed that hypomimia correlated best with drooling. Linear regression with hypomimia as the dependent variable identified disease severity, dysphagia, and male sex as significant explanatory factors. Drooling in Parkinson's disease results from multiple risk factors, with hypomimia being the most prominent. When monitored, patients appear to compensate by increasing their swallowing frequency, much like the increased cadence that is used to compensate for stepping akinesia. These findings can provide a rationale for behavioral approaches to treat drooling.

Diurnal drooling in Chinese patients with Parkinson's disease

“…In addition, motor severity of PD was observed to be associated with diurnal drooling in the current study, which is consistent with the finding of a case-control study on a Dutch population [6], and another study on a Canadian population [7], which found that all-day drooling was more prevalent with disease progression, especially in H&Y stage 4. However, no association was found between diurnal drooling and disease duration in the current study.…”

“…However, no association was found between diurnal drooling and disease duration in the current study. This finding is consistent with a previous American study on all-day drooling [8], but inconsistent with two studies on all-day drooling, including a study on a French population [9] and another study on a Dutch population [6]. Although our previous study [3] found that all-day drooling has no correlation with disease duration and severity of PD, our current findings revealed that diurnal drooling is related to the severity of PD, further indicating that the pathogenic mechanism of diurnal drooling may be different from that of nocturnal drooling.…”

“…However, only few studies have focused on it. A case-control study on 15 Dutch patients with diurnal drooling and another 15 patients without diurnal drooling found that diurnal drooling was related to disease severity, dysphagia and male sex [6]. Another observational study on 104 Dutch patients found that involuntary mouth opening and dysphagia were the correlated factors with diurnal drooling [4].…”

Dysphagia in Parkinson’s disease: Prevalence, Impact and Management Challenges

“…Additionally of the difficulty to swallowing, these patients have a faster excretion of saliva, leading to easier saliva retention in the mouth or sialorrhea (drooling) [24,25]. Ou et al [7] reported that 52.7% of the PD patients complained about sialorrhea, and this symptom was more frequent in patients with a late-onset of the disease.…”

“…Ou et al [7] reported that 52.7% of the PD patients complained about sialorrhea, and this symptom was more frequent in patients with a late-onset of the disease. Also, Kalf et al [25] observed that the patients, in most advanced stages of PD, with sialorrhea attempted to compensate the excess of saliva increasing the swallowing frequency.…”