P343 Effects of unilateral and bilateral cerebellar magneto-electric stimulation on pharyngeal cortical activity and swallowing behaviour

Background The cerebellum is recognised to bilaterally modulate sensorimotor function and has recently been shown to play a role in swallowing. Indeed, we have previously shown that unilateral cerebellar repetitive trans-cranial magnetic stimulation (rTMS) can excite corticobulbar motor pathways to the pharynx. However, the comparative effects of bilateral versus unilateral cerebellar rTMS on these pathways remain unknown. Method In this cross-over study, healthy participants (n=13) were randomly allocated to receive unilateral or bilateral 10 Hertz cerebellar rTMS. Participants were intubated with pharyngeal electromyography and/or manometry catheters to acquire motor evoked potentials (MEPs) and pressure recordings. The first part of the study involved using single pulse TMS to measure baseline motor cortex pharyngeal MEP amplitudes, before either unilateral or bilateral cerebellar rTMS was administered. Repeat measures of PMEP amplitude were performed at 15-minute intervals for an hour following in interventions. Thereafter, in further studies, a cortical ‘virtual lesion’ (V/L) was applied prior to cerebellar rTMS with pre and post PMEPs and measurements of swallowing accuracy using a behavioural task. Results Across the study arms, bilateral cerebellar rTMS was significantly more effective than unilateral (Unilateral vs bilateral MEP P=0.0005 figure 1; V/L MEP and behaviour P=0.0005 and 0.0005 respectively). Conclusion Bilateral cerebellar rTMS shows greater facilitatory brain and behavioural swallowing effects than unilateral stimulation with the potential to be a more powerful clinical therapy for neurogenic dysphagia.