Transcranial Direct Current Stimulation (tDCS) for Patients With Oro-pharyngeal Dysphagia Associated to Brainstem Stroke

Sixty consecutive patients with dysphagia associated to isolated acute (within the previous 24 hours) brainstem ischemic stroke satisfying the inclusion/exclusion criteria will be enrolled.

Swallowing evaluation Clinical evaluation comprises fiberoptic endoscopy that will be used for scoring the Penetration/Aspiration Scale. The Penetration/Aspiration Scale will be scored by two otolaryngologists and one neurologist blinded to the patient's study group allocation. Moreover, feeding status will be evaluated by the clinical "Dysphagia Severity Rating Scale", ranging from 0 (normal fluids, normal diet, and eating independently) to 12 (no oral fluids, no oral feeding). Moreover the "Functional Oral Intake Scale", ranging from 1 (nothing by mouth) to 7 (total oral diet with no restriction), and the "Dysphagia Limit Test", evaluating the amount of water that can be swallowed without piece-meal deglutition or clinical signs of aspiration, will be used in patient evaluation. Piecemeal deglutition will be evaluated both clinically and by means of electromyographic recordings from the mouth floor muscles. Moreover, simultaneous electromyographic/mechanographic recordings from the above mentioned muscles, as well as from cricopharyngeal muscle and from the thyroid cartilage will be also performed. The changes in cortico-pharyngeal excitability will be evaluated by recording motor evoked potentials from the pharyngeal muscles after transcranial magnetic stimulation.

Randomization: patients will be randomly assigned to either the active treatment (real) or sham groups according to a computer-generated list. Randomization will be stratified in order to match age, and severity of dysphagia.

Transcranial direct current stimulation: anodal transcranial direct current stimulation will be delivered through two 25-cm2 rectangular surface electrodes, with the active one placed over the "pharyngeal" area of the motor cortex contralateral to the side of brainstem lesion and the reference one on the contralateral supraorbital ridge. Furthermore, the electrodes will be fixed in their position using a set of adjustable rubber straps placed around the head. For the active intervention (the "real" stimulation group), current intensity will be slowly increased up to 2mA. This intensity will be maintained for 20 min before the stimulation will be slowly turned off over a 10-sec period. For the "sham" intervention, the current will be left on only for 30 sec, while the electrodes will be left in place for a further 20-min period. All patients will be evaluated at baseline, and after 4 consecutive days of stimulation.