Heart rate and blood pressure responses to corticomotor stimulation in young, healthy adults

Single-pulse transcranial magnetic stimulation (sp-TMS) is used to measure cortical excitability (Chen et al., 2016). Serious adverse events of syncope have occurred with sp-TMS (Gillick et al., 2015, Keller-Ross et al., 2018) . One such event is neurocardiogenic syncope (Gillick et al., 2015), which occurs from transient blood pressure (BP) changes in response to precipitating factors such as anxiety in combination with a mild noxious, novel stimulus (Grubb, 2005). Previous work investigating the effect of sp-TMS on cardiovascular function has demonstrated equivocal findings. For example, it has been demonstrated that sp-TMS does not alter heart rate (HR) and BP (Keller-Ross et al., 2018, Macefield et al., 1998), yet sympathetic inhibition has been reported, which could reduce BP. However, most prior reports were not designed primarily to measure direct influences of sp-TMS on BP. Thus, it is currently unclear whether sp-TMS reduces BP to subsequently result in neurocardiogenic syncope. The purpose of this study was to directly assess the influence of sp-TMS on BP in healthy adults. Based on previous findings, we hypothesized that sp-TMS would not directly reduce BP to precede neurocardiogenic syncope.