Effects of Active Interferential Current Stimulation on Swallowing Function in Patients with Dysphagia: A Cross-Sectional Study

Dysphagia is prevalent among elderly and neurologically impaired individuals, causing serious complications such as aspiration pneumonia. Interferential Current Stimulation (IFC), a non-invasive sensory method, may improve swallowing by reducing reflex latency. This study aimed to investigate the effects observed during active IFC stimulation of IFC on swallowing function using Laryngeal Elevation Delay Time (LEDT), Stage Transition Duration (STD), and Penetration-Aspiration Scale (PAS). Forty-six participants (ages 29–98) undergoing videofluoroscopic swallowing studies received IFC stimulation with electrodes bilaterally placed on the thyroid cartilage. Swallowing parameters were analyzed frame-by-frame using ImageJ software. LEDT measured the time from contrast arrival at the bottom of the piriform sinus to maximum laryngeal elevation. STD was the interval from oral bolus transit to pharyngeal swallow initiation. PAS assessed penetration and aspiration severity. LEDT significantly improved from baseline (median [IQR]: 0.15 [0.00–0.35] s) to 10 min during IFC stimulation (0.00 [0.00–0.19] s; p = 0.02, r = 0.46, 95% CI [0.11–0.76]). No significant changes were found in STD (STD1: p = 0.37; STD2: p = 0.37) or PAS scores (PAS1: p = 0.20; PAS2: p = 0.71). Responder analysis indicated substantial individual variability: approximately 70% improved in LEDT, while only 37–45% improved in STD. Higher responder rates were noted among participants with respiratory and cerebral disorders. IFC stimulation significantly shortened swallowing reflex latency (LEDT), suggesting its potential benefit for dysphagia rehabilitation. However, it did not significantly alter stage transition duration (STD) or penetration-aspiration safety (PAS). Further studies should explore long-term effects and optimal stimulation parameters.