Transcranial static magnetic field stimulation of the primary motor cortex in essential tremor: a randomized pilot study

Alterations in the motor cortex may contribute to essential tremor (ET) pathophysiology. Transcranial static magnetic field stimulation (tSMS), a non-invasive and portable technique, reduces corticospinal excitability, but its therapeutic potential for ET remains untested. This randomized, double-blind pilot study (clinicaltrials.gov#: NCT03780426, registered on December 19, 2018) investigated the acute effects of tSMS applied to the primary motor cortex in 27 ET patients (mean age: 66.9 ± 12.1 years). Patients received a 30-min tSMS session on either the left (n = 13) or right (n = 14) hemisphere. Postural tremor was assessed by accelerometry, and kinetic tremor by part B of the Clinical Rating Scale for Tremor. Twenty-three patients were included in the final analysis for primary and secondary outcomes. Bayesian analysis showed moderate evidence for a bilateral reduction in postural and rest tremor following unilateral tSMS, with anecdotal reduction of kinetic tremor and moderate evidence of absence of change in tremor frequency. These preliminary findings warrant further studies to assess tSMS as a therapeutic option for ET.