Oropharyngeal freezing and its relation to dysphagia - An analogy to freezing of gait

Introduction: The pathophysiology of dysphagia in Parkinson's disease (PD) is heterogeneous and poorly understood at present. This study investigated the phenotypes, prevalence and pathophysiology of oropharyngeal freezing (OPF) in PD and its relation to dysphagia. Methods: In a prospective study, 50 PD patients were systematically screened for OPF using flexible endoscopic evaluation of swallowing (FEES). In addition, FEES-videos of 50 patients with post-stroke dysphagia and 50 healthy subjects were retrospectively evaluated as control groups. In PD patients freezing was assessed with the freezing of gait (FoG) questionnaire and the relationship between OPF and FoG was analyzed. Results: In analogy to FoG, signs for OPF presented as either temporarily missing or delayed swallowing reflex in combination with freezing associated movement abnormalities e.g. festination, trembling, or akinesia. Seventeen PD patients (34%) showed considerable signs for OPF (15 cases of festination, 3 cases of trembling, 3 cases of akinesia). In the patients with post-stroke dysphagia, OPF was detected in 2 patients (4%). The healthy subjects showed no signs for OPF. The distribution of OPF differed significantly between the investigated groups (p < 0.01). PD patients with signs for OPF scored significantly higher in the FoG-questionnaire (12.69 +/- 6.37) compared to patients without OPF (7.29 +/- 5.17; p < 0.01). Conclusion: Swallowing in PD patients can be impaired by OPF. We suggest that OPF and FoG share common pathophysiologic mechanisms based on their association and similar semiologies.