Preconditioning of the motor network with repetitive navigated transcranial magnetic stimulation (rnTMS) to improve oncological and functional outcome in brain tumor surgery: a study protocol for a randomized, sham-controlled, triple-blind clinical trial

Abstract

Background The extent of resection of glioma is one of the most important predictors of the survival duration of patients after surgery. The presence of eloquent areas within or near a tumor often limits resection, as resection of these areas would result in functional loss and reduced quality of life. The aim of this randomized, triple-blind, sham-controlled study is to investigate the capability of repetitive navigated transcranial magnetic stimulation (rnTMS) over the primary motor cortex to facilitate the functional reorganization of the motor network.MethodsOne hundred forty-eight patients with tumors in movement-relevant areas will be included in this randomized, sham-controlled, bicentric, triple-blind clinical trial. Patients considered at high risk for postoperative motor deficits according to an initial nTMS assessment will receive inhibitory rnTMS at 1 Hz for 30 min followed by a short motor training of 10 min. Stimulation will be applied to the fiber endings of the corticospinal tract closest to the tumor based on individualized tractography. Stimulation will be performed twice daily for each 30 min for 5-28 days depending on the individually available time between study inclusion and surgery. The intervention is controlled by a sham stimulation group (1:1 randomization), where a plastic adapter will be placed on the coil. We expect a comparable or better motor status 3 months postoperatively as measured by the British Medical Research Council (BMRC) score for the affected upper extremity (non-inferiority) and a higher rate of gross total resections (superiority) in the rnTMS compared to the sham group.DiscussionThe generated reorganization of the brain's areas for motor function should allow a more extensive and safer removal of the tumor while preserving neurological and motor function. This would improve both survival and quality of life of our patients.