Bioimpedance Measurement to Evaluate Swallowing in a Patient with Amyotrophic Lateral Sclerosis

Objective: Swallowing dysfunction is an increasingly common symptom in the patients with amyotrophic lateral sclerosis (ALS). The traditional videoflouroscopy method allows observation of the entire oropharyngeal swallowing process during the examination; however, it is expensive and requires the use of ionizing radiation. Impedance pharyngography (IPG) is a new cost-effective and non-invasive method for real-time swallowing monitoring. The goal of the present pilot study is to investigate whether IPG could be used for evaluating the swallowing process in ALS patients and to learn how IPG waveforms relate with videoflouroscopy data. Method: A new IPG measurement system based on a lock-in amplifier was developed, which can be used for acquiring both the impedance magnitude and phase of the IPG signal, rather than impedance magnitude-only information as is typically done today. Results: Physiological significance of the obtained IPG waveform was confirmed by comparing the chronological series of anatomical events recorded simultaneously with the videoflouroscopy swallowing exam. Significance: IPG may be used as a simple clinical tool for estimating swallowing function of ALS patients with minimal stress and inconvenience.