Priming the Epileptic Brain: tVNS to Improve Efficacy of add-on AED in Patients With Focal Epilepsy

The most prevalent neurological disorder with also immense burden of disease, epilepsy, is in over 30 percent of patients difficult to treat. The ideal treatment regime would give complete control of disease in an early stage, not only for patient well-being, but also to prevent the onset of persistent pathologic epileptic networks in the brain. The first step in treatment is the trial, and error, of multiple anti-epileptic drugs (AEDs), while invasive brain stimulation (BS) techniques with network modulating properties are saved as a last resort. The investigators hypothesize that pharmacotherapeutic treatment of epilepsy can be more successful after \"priming\" (preparing) the brain using BS as a short-term neuromodulation treatment. The limitation of testing this hypothesis is the invasive aspect of the most used classic vagal nerve stimulation (VNS) treatment for epilepsy, but the recent development of transcutaneous vagal nerve stimulation (tVNS) offered a possibility to combine chemical and electrical modulation in an earlier stage of disease, which is not tested before. The investigators want to determine the priming effect on the epileptic brain of tVNS, to make it more susceptible to add-on treatment with Brivaracetam (BRV), an AED. In addition, the investigators aim to visualize these changes in the brain because of priming, possibly altered network-organisation.