Coordination of swallowing and breathing in Parkinson's disease

Abstract

Introduction: Parkinson disease (PD) is often accompanied by swallowing difficulties. Coregistration of swallowing and breathing in healthy subjects has shown a common pattern of expiration, deglutition with apnoea followed by expiration. Recent publications showed alterations of this pattern in PD patients with several swallows followed by expiration. PD patients are known to exhibit and increased number of swallows induced already by very low swallowing volumes. The purpose of the present investigation was to analyze natural, self induced deglutitions with both solid and liquid media by recording airflow and submental EMG activity. Methods: We investigated 28 patients with PD with 50 healthy subjects. Data was registered following a protocol with 8 runs, each concerning four swallows (5-, 10- and 15ml of water, applesauce). Evaluation was performed by recording the duration of swallowing apnoea, submental muscle activity and the swallowing latency. Airflow direction before and after swallow was noted. We developed a system allowing to mark EMG-activity and swallows and to describe the complex deglutition pattern for statistical evaluation. Using this tool, we registered the main EMG-activity duration and the mean amplitude, the number of EMG-side events and swallows. Results: The majority of healthy individuals expirated after swallowing. The deglutition apnoe in the PD group was significantly more often followed by expiration (odd's ratio 0.007 vs. 0.004). There was a tendency towards prolonged apnoea-durations and negative latencies in the PD group. Logistic regression revealed a negative correlation. Large differences of the swallowing pattern between both groups were observed. The overall activation duration of the EMG in healthy is prolonged in PD patients. Patients have more swallowing events (Mean side-swallows [number]: Healthy: 15ml of water: 0,73; PD: 2,19). Submental EMG activity apart from deglutition appeared in a significant number of patients. Applesauce has induced the most obvious differences between the groups. Discussion: Our results show that using coregistration of breathing and the submental muscle activity, differences between healthy subjects and non-dysphagic PD patients can be observed. A thicker bolus consistency was shown to be most appropriate to detect differences. Beside the main event of swallowing, a variety of specific swallowing patterns is the most striking difference between PD patients and healthy subjects.