Transcutaneous electrical stimulation in chronic post-stroke oropharyngeal dysphagia: pooled biomechanical and kinematic analysis from a one-year randomized controlled clinical trial

Abstract

Oropharyngeal dysphagia in chronic post-stroke (PS-OD) patients is associated with impaired oropharyngeal sensory/motor function. We aimed to evaluate the effect of transcutaneous electrical stimulation (TES) on the biomechanics and kinetics of swallowing in PS-OD patients in a randomized controlled clinical trial with 1-year follow-up. 71 PS-OD patients with impaired safety of swallow (ISS) were randomized into 2 groups, (1) 26 with compensatory treatment (CT): thickeners and texture-modified diets, and (2) 45 with active treatment (TES + CT) with 2 cycles of TES (VitalStim; Enovis, USA), at baseline and 6 months. Each TES cycle consisted of 15 1-hour sessions over 2 weeks. Its effect was assessed by videofluoroscopy (baseline, post-treatment 1, 6 months, post-treatment 2, 12 months). Both groups were homogeneous, patients had 74.41 ± 11.28 years (31.00% women), functional decline (Barthel 72 ± 31), comorbidities (Charlson 3.00 ± 1.57), nutritional risk (MNA-sf 10.29 ± 2.59) and moderate stroke (NIHSS 3.35 ± 4.01). All had ISS (penetration-aspiration scale [PAS] 4.61 ± 1.67, only 9.86% could swallow thin liquid safely) and biomechanical delay (time to laryngeal vestibular closure [LVC] 402.82 ± 111.98ms). Swallowing parameters improved significantly between baseline and 12 months in the TES group (ISS, p < 0.001; PAS, safe thin liquid hydration, LVC, p < 0.0001; bolus kinematics, p < 0.05). No changes were observed in hyoid bone movement or timing. The CT group did not show any significant biomechanical changes. No relevant adverse events were associated with TES. TES is a safe and effective therapy for PS-OD. After 1 year of follow up, it improved ISS, time to LVC, bolus kinetics, and reduced the need for thickening agents.

Fig. 1

Time to laryngeal vestibule closure, mean maximal PAS and liquid hydration during the study over the several evaluation points in the transcutaneous electrical stimulation and control groups. (A) Time to laryngeal vestibule closure (ms) over the different study follow-up points; (B) Mean maximum PAS score across all videofluoroscopies at different study follow-up points; (C) Percentage of patients that can swallow thin liquid viscosity safely at different study follow-up points. To make the graph, for the control group we have considered the same values for PTT2 as those at the 12 m follow-up, as the control group did not have a PTT2 visit. Abbreviations: LVC indicates laryngeal vestibule closure; PAS, penetration-aspiration scale; TES, transcutaneous electrical stimulation; PTT1, post-treatment 1 visit; 6 m, six months visit; PTT2, post-treatment 2 visit; 12 m, 12 months visit. *p < 0.05, ^** p < 0.01, ^*** p < 0.001, ^**** p < 0.0001, versus baseline visit.