Tolerability and Efficacy of Continuous Theta-burst Stimulation for Essential Tremor: A Randomized Study.

Essential tremor (ET) is one of the most common movement disorders in adults. The prevalence rate among the elderly over 65 years old is about 4.6%. Tremor usually worsens with age, leading to disability and loss of independence, which has an adverse impact on the quality of life of patients. However, the traditional first-line treatment drugs are neither effective enough nor completely safe for ET patients. Although surgical procedures such as deep brain stimulation (DBS) and thalamotomy can be used to better control unilateral limb tremor, many patients are reluctant to choose surgical treatment because it's invasive. Therefore, there is an urgent need to develop new drugs or non-invasive therapies as a better treatment option for ET. The pathology of the disease is not yet clear, it is generally believed that genetic, aging and environmental factors are related to ET. Hyperactivity of cerebellar function and changes of cerebello-thalamo- cortical (CTC) pathways are currently considered to be the most important pathophysiological mechanisms of ET. Therefore, the cerebellum and cortex may be the best targets for the treatment of tremor. Continuous theta burst stimulation (cTBS) is one of the non-invasive electrophysiological techniques characterized by plexus stimulation, which is similar to low-frequency repetitive transcranial magnetic stimulation (rTMS) but closer to the physiological state of neural activity, and may inhibit the excitability of the stimulated cortex. The stimulation duration is greatly shortened, which is simpler and easier than the low-frequency rTMS of 20-30 minutes. In addition, functional near infrared spectroscopy (fNIRS) is a new non-invasive functional neuroimaging technique. It mainly uses the difference characteristics of oxyhemoglobin and deoxyhemoglobin in brain tissue for near-infrared light absorption at different wavelengths of 600-900nm. The efficacy, safety, and mechanisms involved in non-invasive stimulation therapy for ET pa