A pilot study on the efficacy of transcranial direct current stimulation applied to the pharyngeal motor cortex for dysphagia associated with brainstem involvement in multiple sclerosis

Objective: we investigated the effect of anodal transcranial direct current stimulation (tDCS) applied over the pharyngeal motor area in dysphagia associated with multiple sclerosis (MS). Methods: Eighteen MS patients with dysphagia associated with brainstem involvement were randomized to receive either real or sham tDCS. Primary outcome: The Penetration/Aspiration Scale (PAS). Secondary outcomes: changes in electromyographic (EMG) parameters and pharyngeal cortical motor evoked potentials (MEPs). Patients were evaluated at baseline (T-0), at the end of 5-session cycle of tDCS stimulations (T-1), after two (T-2), and four (T-3) weeks. Results: the PAS values were significantly lower in the active group than in sham group at T-1, and at T-3. Over the post-stimulation periods, PAS significantly improved only in the real group. As regards the secondary outcomes, we observed a statistically significant difference between the 2 groups only in the MEPs amplitude at T-1. The comparison between baseline and each of the post-stimulation times showed significant differences only of the real group across all the secondary parameters. Conclusions: Our findings support a beneficial effect of anodal tDCS applied to the pharyngeal motor cortex in MS-associated dysphagia. Significance: Considering its safety and efficacy, tDCS may represent an important resource in MS-associated dysphagia. (C) 2019 Published by Elsevier B.V. on behalf of International Federation of Clinical Neurophysiology.