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

Abstract

One in every 25 Americans suffers 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. The pharyngeal phase of swallowing is also involuntary and involves coordination among various parts of the brain to execute which results in variation of efficacy of treatments administered to patients The proposed medical device uses a closed-loop neural stimulation approach for treating swallowing problems. This approach monitors the start of involuntary phase of swallowing by detecting tongue-tip pressure. The lesser palatine nerve is located on the soft palate where most of the food makes contact before swallowing. The nerve is also known to be involved in sensorimotor loop of swallowing function. After detecting the start of involuntary phase of swallowing, we timely stimulate the soft palatal area inside the 2nd molar, potentially lesser palatine nerve, as a closed-loop. We hypothesize that the closed-loop stimulation on lesser palatine nerve augments the sensory feedback and strongly triggers the pharyngeal swallowing phase, which would result in stronger swallowing. Two experiments were performed to test the hypothesis. A prototype system built using Arduino DUE was used to perform these experiments. 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 is 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. The idea of the proposed medical device was validated in the market as part of NSF I-Corps Site program organized by Texas A&M University. Additional research has been done to build a wireless prototype of the proposed device using a CC2640R2F microcontroller which uses Blue-tooth Low Energy(BLE) for communication.