An Intraoral Closed-Loop Monitoring and Stimulation System for Treatment of Swallowing Problems

Abstract

One in every 25 Americans suffer from swallowing disorders, referred to as Dysphagia. Problems in the pharyngeal phase of swallowing are hard to treat because of the neuromuscular complexity in the region and the quick passage of food (< 1 s) through the pharyngeal region. This paper proposes a new closed-loop neural stimulation approach for treating swallowing problems. This approach monitors the start of involuntary phase of swallowing by detecting the tongue-tip pressure and stimulating the soft palatal area inside the 2nd molar, potentially lesser palatine nerve, as a closed-loop. We hypothesize that the closed-loop stimulation on the soft palatal area inside the 2nd molar, timed with the onset of the pharyngeal swallowing, augments the sensory feedback and promotes triggering of the pharyngeal swallowing phase. Two experiments were performed to test the hypothesis. In the first experiment, the swallowing time and acceleration of laryngeal excursion was recorded without any stimulation. In the second experiment, stimulation was provided to the lesser palatine nerve for 500 ms when tongue tip was detached from the incisors, and the swallowing time and acceleration of laryngeal excursion was recorded. Two human subjects participated in the study. Without stimulation, both subjects showed consistent swallowing in both duration and amplitude. Stimulation reduced the peak-to-peak duration of laryngeal excursion, but the peak-to-peak amplitude of laryngeal excursion was not changed by stimulation. This study found that closed-loop stimulation onto the palatal area inside the 2nd molar, timed with the onset of the pharyngeal swallowing, can reduce the duration of the pharyngeal swallowing.