In Reply: Feasibility of Endovascular Deep Brain Stimulation of Anterior Nucleus of the Thalamus for Refractory Epilepsy

To the Editor: We were encouraged by Dr Ioannis Mavridis's letter1 regarding our recent publication, Feasibility of Endovascular Deep Brain Stimulation of Anterior Nucleus of the Thalamus for Refractory Epilepsy,2 and appreciate his expert perspective on our findings. Having seen the results in our in vivo model firsthand, we certainly share Dr Mavridis's enthusiasm for the potential long-range implication of our findings. The concept of using an endovascular approach to deliver deep brain stimulation (DBS) has been the subject of discussion and preliminary exploration in recent years,3-8 but supportive in vivo evidence of feasibility has to date been elusive. We are encouraged by the in vivo results from our study where we confirmed accurate lead placement, stimulation delivery, and evoked response detection (ie, sensing capability) comparable between leads placed in the thalamostriate vein and in the anterior nucleus of the thalamus parenchyma. As proofs of concept, these are exciting in vivo results and a promising start. Of course, translation to the clinic will require extensive, multidisciplinary research efforts. We believe that our modeling of endovascular stimulation in humans through in vitro testing of signal attenuation and a multimodal imaging–based detailed anatomical model to map stimulation field coverage and potential off-target effects are exciting first steps in this respect. Future studies to evaluate endovascular DBS technology in a chronic model with form factors to study effects of long-term endovascular implantation in this vasculature will be critical. Furthermore, studying other approved parenchymal DBS targets and their access through the vasculature would be of great clinical interest. With coordinated efforts at the bench and in the clinic, endovascular stimulation will hopefully 1 day open new frontiers for clinicians and patients alike.