The Effects of Midline Cerebellar rTMS on Human Pharyngeal Cortical Activity in the Intact Swallowing Motor System

We sought to compare the effects of 10 Hz cerebellar vermis (vs. unilateral hemispheric and sham) repetitive transcranial magnetic stimulation (rTMS) on cortical neuroelectrical activity and thereafter 10 Hz cerebellar vermis (vs. sham) rTMS on swallowing behaviour. Healthy participants (n = 25) were randomly allocated to receive vermis, unilateral hemisphere or sham 10 Hz cerebellar rTMS. Recordings were made using pharyngeal electromyography and manometry catheters, obtaining motor-evoked potentials (MEPs) and pressure recordings. The amplitudes of MEPs elicited using single-pulse TMS delivered to the pharyngeal areas of the motor cortex bilaterally were measured pre- and post-cerebellar stimulation. As in previous studies, abductor policis brevis (APB) MEPs were measured to assess post-rTMS modulation specificity. Swallowing was assessed using a swallowing accuracy task. Measurements were made at baseline and 15-min intervals for an hour post-intervention. Measurements involved TMS being used to elicit 10 MEPs bilaterally over the pharyngeal areas of the motor cortex, over the APB cortical representation adjacent to the pharyngeal area with the lowest resting motor threshold and 5 MEPs bilaterally over pharyngeal areas of the cerebellar hemispheres. Swallowing accuracy was assessed by giving participants 10 attempts to swallow and hit a digital target. Cerebellar vermis rTMS caused significant suppression of cortical pharyngeal MEP amplitudes compared with unilateral rTMS and sham (P = 0.0005, 0.002). APB and cerebellar MEP amplitudes were unaffected as were pharyngeal and APB MEP latencies. Following cerebellar vermis rTMS there was a significant reduction in swallowing accuracy compared with sham (P = 0.001). Our findings demonstrate cerebellar vermis rTMS exerts a suppressive effect on pharyngeal motor cortical activity and swallowing behaviour

An Exploration of the Application of Noninvasive Cerebellar Stimulation in the Neuro-rehabilitation of Dysphagia after Stroke (EXCITES) Protocol

BACKGROUND: Poststroke dysphagia is common, associated with a poor outcome and has no definitive treatments. Repetitive transcranial magnetic stimulation (rTMS) targeting the cerebellum is a noninvasive technique requiring minimal physical or cognitive input from the patient, and has been shown to induce positive swallow-related brain changes in physiological studies as measured by increased cortical excitability. AIM: To explore in patients with acute/sub-acute poststroke dysphagia: (1) the feasibility and immediate effect; and (2) the optimal dose for long-term benefit, of cerebellar rTMS in patients with dysphagia in acute/sub-acute stroke. METHODS: Two double-blind sham-controlled randomized phase II trials. Participants will be recruited from stroke units in Nottingham and Greater Manchester. Dysphagia will be confirmed via baseline videofluoroscopy (VFS). Participants will be blinded to treatment and receive cerebellar rTMS or sham stimulation: (1) single treatment of (10Hz, 250 pulse) in 24 participants; (2) daily for 3 days, twice-daily for 5 days, or twice-daily sham treatment for 5 days, in 48 participants. RESULTS: The severity of dysphagia will be assessed with VFS, using the penetration aspiration scale (PAS) at: (1) 1-hour, (2) 2-weeks, post-treatment. Additional comparative measures will be taken from: (1) pharyngeal motor evoked potential (MEP) amplitudes, (2) the functional oral intake score and dysphagia severity rating scale. CONCLUSIONS: If these studies demonstrate feasibility and identify optimal dosing, further trials to assess the safety and efficacy of cerebellar rTMS as a treatment for poststroke dysphagia will be warranted