The Effect of Sensory Level Versus Motor Level Electrical Stimulation of Pharyngeal Muscles in Acute Stroke Patients with Dysphagia: A Randomized Trial

Dysphagia is a serious cause of morbidity and mortality in stroke survivors. Electrical stimulation is often included as part of the treatment plan for dysphagia and can be applied at a sensory or motor level intensity. However, evidence to support these different modes of stimulation is lacking. This study compared the effectiveness of sensory and motor level stimulation on post-stroke dysphagia. This is a randomized trial conducted in an inpatient rehabilitation facility. Thirty-one participants who had dysphagia caused by stroke within 6 months prior to enrolment were included. Participants were excluded if they had a contraindication for electrical stimulation, previous stroke, psychiatric disorder, contraindications for modified barium swallow study (MBSS), or pre-morbid dysphagia. Each patient received ten sessions that included 45 min of anterior neck sensory or motor level electrical stimulation in addition to traditional dysphagia therapy. Motor stimulation was administered at an intensity sufficient to produce muscle contractions. Sensory stimulation was defined as the threshold at which the patient feels a tingling sensation on their skin. Swallow functional assessment measure (FAM), dysphagia outcome severity scale (DOSS), national outcome measurement system (NOMS), penetration aspiration scale (PAS), diet change, and the swallowing quality of life questionnaire (SWAL-QOL). Clinical outcomes were analyzed using a Wilcoxon signed-rank test, Mann-Whitney U test, RM ANOVA, or chi-square analysis. There was no significant difference in age, length of stay, or initial swallow FAM between groups. Patients in the sensory group showed significant improvement on swallow FAM, DOSS, and NOMS, while those in the motor group did not (Sensory: Swallow FAM (S = 48, p = 0.01), DOSS (S = 49.5, p = 0.001), NOMS (S = 52.5, p = 0.006); Motor: Swallow FAM (S = 20.5, p = 0.2), DOSS (S = 21, p = 0.05), NOMS (S = 29.5, p = 0.2)). When the groups were combined, there was statistically significant improvement on all measures except the PAS (Swallow FAM (S = 138.5, p = 0.003), DOSS (S = 134.5, p < 0.001), NOMS (S = 164, p = 0.0004)). When comparing motor to sensory NMES, there was no significant difference between groups for Swallow FAM (p = .12), DOSS (p = 0.52), or NOMS (p = 0.41). There was no significant difference in diet change for solid food or liquids among the groups, although 50% more participants in the sensory group saw improvement in diet. This study supports the use of electrical stimulation as part of the treatment plan for post-stroke dysphagia. Sensory-level stimulation was associated with greater improvement on outcome measures compared to motor level stimulation.