Cerebellar Oscillatory Patterns in Essential Tremor: Modulatory Effects of VIM-DBS.

Essential tremor (ET) is a common movement disorder, and while ventral intermediate nucleus deep brain stimulation (VIM-DBS) is a well-established treatment, its precise mechanisms or modulatory effects, particularly in relation to cerebellar oscillations, remain unclear. In this study, we hypothesized that VIM-DBS would modulate cerebellar oscillatory activity across both resting and motor task conditions, reflecting its impact on cerebello-thalamic pathways. Ten patients diagnosed with ET participated in this study. We examined the effects of VIM-DBS on mid-cerebellar oscillations during resting-state and lower-limb pedaling motor tasks. Frequency analysis was conducted on the resting-state signal and time-frequency analysis was performed on motor task-related signals. We explored the modulatory effects of VIM-DBS on oscillatory activity across delta, theta, alpha, beta, and gamma frequency bands. We found that ON VIM-DBS increased mid-cerebellar relative theta power during resting-state conditions, with no significant changes in other frequency bands. During a pedaling motor task, VIM-DBS led to significant reductions in theta, alpha, and gamma power, highlighting the frequency-specific effects of stimulation. VIM-DBS also increased peak acceleration of leg movements during the pedaling task. Furthermore, VIM-DBS selectively increased mid-frontal relative theta and beta power as well as mid-occipital relative theta power during resting condition, suggesting localized mid-cerebellar modulation. Moreover, similarity analyses between mid-cerebellar and nearby mid-occipital signals revealed differences in coherence, phase coherence, and cross-spectrum phase coherence. Overall, these results support the role of VIM-DBS in modulating mid-cerebellar oscillations in ET and provide new insights into the neural mechanisms underlying DBS efficacy.