High-frequency cerebellar tACS for managing essential tremor

Abstract Objectives: Essential tremor (ET) is a disabling condition resulting from a cerebello-thalamo-cortical circuitry dysfunction. Deep brain stimulation of the thalamic ventral intermediate nucleus (VIM-DBS) is effective in managing severe postural and action tremor. Non-invasive electrical stimulation of the cerebellum has recently emerged as a potential therapeutic option for these patients. In this study, we aim to investigate the effects of high-frequency non-invasive cerebellar transcranial alternating current stimulation (tACS) in ET patients implanted with VIM-DBS. Methods: Eleven ET patients with VIM-DBS and a control group of 10 ET patients, without VIM-DBS, and clinically similarly impaired, were included in this double-blind proof-of-concept controlled study. Both patient groups received high-frequency cerebellar tACS (∼130Hz) for 10 minutes. The amplitude and severity of the tremor were assessed at baseline, during sham-tACS, and during active tACS and 0, 20, 40 minutes after current offset, using kinetics recordings during posture and action (‘nose-to-target’ task), and clinical scores (Fahn-Tolosa-Marin scale) on videos subsequently assessed by two independent blinded investigators. Results: In the VIM-DBS ET group, active-tACS significantly improved both postural tremor amplitude and action, as well as clinical severity when compared to baseline during, and 0, 20 and 40 minutes after the end of the stimulation. There was no effect of sham-tACS. In the control ET group, similar observations were made for action tremor and clinical severity but not for postural tremor amplitude. There was a significant effect of sham-tACS on clinical severity. Conclusions: These data support the efficacy and safety of short-term high-frequency cerebellar tACS to reduce essential tremor amplitude and severity. Research Category and Technology and Methods Clinical Research: 8. Transcranial Alternating Current Stimulation (tACS) Keywords: tACS, Essential tremor, Deep Brain Stimulation