Thalamic LFPs and VIM DBS in Essential Tremor: Correlation, Evolution, and Therapeutic Perspectives

Essential tremor (ET) is one of the most common adult movement disorders with a prevalence of 4% in the general population. Although several medications (primidone, beta-adrenergic blockers, benzodiazepines...) are commonly used, few of them are truly effective for controlling the severe forms of ET. Since 1987, an alternative has emerged with the development of high frequency deep brain stimulation (DBS) of the thalamic nucleus ventralis intermedius (VIM). This surgical technique now represents the gold standard treatment for tremor-disabled ET patients. Although VIM-DBS is clearly effective for treatment of essential tremor (ET) a partial loss of DBS effectiveness may occur over time in some patients. This loss of DBS effectiveness could be related to an adaptation of the local neuronal network to chronic stimulation (changes in synaptic plasticity). In order to avoid this problem, investigators plan to develop a intermittent mode of VIM stimulation using a new Medtronic device combining a DBS system with local field potential (LFPs) sensing capability. First, investigators propose to analyse VIM LFPs in order to define a tremor biomarker in 10 patients operated for severe ET. Thereafter, investigators will automatically detect this biomarker using a specific algorithm and use it to trigger stimulation at the onset of tremor only. Thus, this project will allow us to optimize DBS therapy in ET, by improving the longevity of implantable devices and avoiding the loss of efficacy previously reported