OWE-029 Magneto-electric stimulation of the human cerebellum prevents swallowing dysfunction induced by a cortical virtual lesion

Abstract

Introduction Repetitive transcranial magnetic stimulation (rTMS) is a neurostimulatory technique which can be used to alter neuronal activity within targeted regions of the brain. Furthermore, in post stroke dysphagia, recovery of swallowing function is thought to be related to increased activity in the undamaged cortical swallowing hemisphere.1 Here, we wanted to determine if stimulation of the cerebellum, known to be activated during swallowing 2 can enhance swallowing when disrupted by a virtual lesion as a prelude to using cerebellar stimulation therapeutically. Aim To compare the effects of ipsilateral and contralateral 10 Hz cerebellar rTMS versus sham stimulation on swallowing behaviour following a virtual lesion to the pharyngeal motor cortex. Method Healthy human participants (n≥10) were intubated with a pharyngeal catheter. Baseline swallowing performance was then measured using a water swallowing reaction time task. Participants received 10 min of 1 Hz rTMS (virtual lesion) to the pharyngeal motor cortex which elicited the largest pharyngeal motor evoked potentials. This causes a disruption of swallowing behaviour. Over 3 separate visits to the laboratory, participants were then randomised to receive 250 pulses of 10 Hz cerebellar rTMS to the ipsilateral side, contralateral side or sham (2). Swallowing performance was measured at 15 min intervals up to an hour after cerebellar rTMS. Results rTMS was well tolerated by all subjects. Sham stimulation was associated with the expected increase in fast swallow time latency (χ2≥11.429 p≥0.044) with changes from baseline at 15 min post intervention (Z≥- Abstract OWE-029 Figure 1 1.988, p≥0.047) and 60 min post intervention (Z≥−1.988, p≥0.047) and poorer performance in challenged swallows at 30 min post intervention (Z≥−2.352, p≥0.019). By contrast, participants who received ipsilateral or contralateral cerebellar rTMS showed no evidence for the expected disruption of fast and challenge swallows compared to baseline (p>0.05), implying a reversal effect (Fig 1). Conclusion Ipsilateral and contralateral 10 Hz cerebellar rTMS was able to block the disruptive effects of a virtual lesion in the swallowing motor cortex. There were no differences ipsilateral and contralateral cerebellar stimulation on swallowing behaviour, suggesting that activation of either cerebellar hemisphere might be therapeutically useful in dysphagic stroke. References Hamdy S, et al. Recovery of swallowing after dysphagic stroke relates to functional reorganization in the intact motor cortex. Gastro 1998 Vasant, et al. High-frequency focal repetitive cerebellar stimulation induces prolonged increases in human pharyngeal motor cortex excitability. J Physiol2015