The STEREO-DBS ET Study: 7-Tesla MRI Brain Network Analysis for Deep Brain Stimulation in Essential Tremor

Rationale: Deep brain stimulation (DBS) of the thalamus is an effective surgical treatment for the patients with advanced essential tremor, despite optimal pharmacological treatment. However, individual improvement after DBS remains variable and 20% of patients experience side effects. To date, DBS-electrode placement and settings in the highly connected thalamus are based on 1,5-Tesla or 3-Tesla MR-images. These low resolution and solely structural modalities are unable to visualize the multiple brain networks to this small nucleus and prevent electrode activation directed at its cortical projections. By using structural 7-Tesla MRI (7T MRI) connectivity to visualize (malfunctioning) brain networks, DBS-electrode placement and activation can be individualized. Objective: Primary objective of the study is to determine whether visualisation of cortical projections originating in the thalamus and the position of the DBS electrode relative to these projections using 7T MRI improves tremor as measured by the clinically validated Essential Tremor Rating Assessment Scale after six months of DBS. Secondary outcomes are: disease related daily functioning, adverse effects, operation time, quality of life, patient satisfaction with treatment outcome and patient evaluation of treatment burden. Study design: The study will be a single center prospective observational study. Study population: Enrollment will be ongoing from June 2023. Intervention (if applicable): No intervention will be applied. Application of 7T MRI for DBS is standard care and outcome scores used will be readily accessible from the already existing advanced electronic DBS database. Main study parameters/endpoints: The primary outcome measure is the change in motor symptoms as measured by the disease-specific Essential Tremor Rating Assessment Scale (TETRAS). This is measured after 6 months of DBS as part of standard care. The secondary outcome measures are the Amsterdam Linear Disability Score for functional health status, Quality of Life in Essential Tremor Questionnaire, patient satisfaction with the treatment, patient evaluation of treatment burden, operating time, hospitalization time, change of tremor medication, side effects and complications. Nature and extent of the burden and risks associated with participation, benefit and group relatedness: The proposed observational research project involves treatment options that are standard care in daily practice. The therapies will not be combined with other research products. Participation in this study constitutes negligible risk according to NFU criteria for human research.