Effects of Short Term Interferential Current Stimulation on Swallowing Reflex in Dysphagic Patients

Abstract

We have previously shown that surface interferential current (IFC) stimulation at the sensory threshold significantly increases the number of swallows. In the present study, we evaluated the effects of IFC stimulation at the sensory threshold on the swallowing reflex of dysphagic patients (7 male and 5 female, Age, 75.8 ± 5.3 years) by videofluoroscopic (VFS) measurements. Each subject underwent three series of VFS examination, before, during, and after the IFC stimulation. We tested three food types, juice, jelly, and biscuits, however, only juice consistency resulted in significant changes in temporal measurements of VFS parameters before, during and after IFC stimulation. For juice consistency, IFC stimulation shortened the pharyngeal response duration (the duration from the hyoid bone beginning maximum elevation to its return to the resting position, before IFC: 1.37 ± 0.31(SD) s vs. during IFC: 1.17 ± 0.29 s, p<0.001) without changing the amount of anterior and vertical displacements of the hyoid bone. The duration from the onset of elevation of the soft palate to return to the resting position was also significantly shortened by the IFC stimulation (before IFC: 0.72 ± 0.16 s vs. during IFC: 0.64 ± 0.19 s, p=0.035), suggesting that pharyngeal motor activation sequence as a whole was shortened by the IFC stimulation. No painful and/or uncomfortable sensations were reported. We conclude that surface interferential current stimulation has a potential to be an alternative mode of therapeutic electrical stimulation for dysphagic patients.