Improving the effectiveness of ANT DBS therapy for epilepsy with optimal current targeting.

Objective: Deep brain stimulation of the ANT is a novel treatment option in refractory epilepsy with an established efficacy at the group level. However, data on the effect of individualized programming are currently lacking. We report the effect of programming changes on outcome in deep brain stimulation of anterior nucleus of thalamus (ANT DBS). Secondly, we investigated whether the effect differs between seizure types. Thirdly, we compared the response status between patients with stimulation contacts verified inside the ANT with patients with contacts located outside of ANT.
Methods: The participants were 27 consecutive patients with ANT DBS implantation with at least two-year follow-up. Seizures were subdivided into focal aware (FAS), focal impaired awareness (FIAS), and focal to bilateral tonic-clonic seizures (FBTCS). The patients' seizure diaries were analyzed retrospectively to assess changes in different seizure types. Active contact locations for each patient were verified from preoperative MRI and postoperative CT fusion images using SureTune III (Medtronic Inc, Minneapolis, MN) software.
Results: A significant reduction in monthly mean seizure frequency occurred in FIAS: 56% at two-year and 65% at five-year follow-up. The effects on FAS and FBTCS were less pronounced. Patients with contacts inside the ANT or on the anterolateral border of ANT experienced a greater reduction in seizure frequency than patients with outside-ANT contacts. Ultimately, seven patients became responders due to changes in DBS programming or repositioning of contacts, increasing our responder rate from 44% to 70% as measured by a seizure reduction of at least 50%.
Significance: ANT DBS appears to be especially effective in reducing FIAS, when the appropriately chosen contacts are activated.
Competing Interests: SJ has received study grants from Maire Taponen Foundation, Finnish Epilepsy Research Foundation, Finnish Medical Foundation and Instrumentarium Science Foundation. JP has received speaker and consultation fees from Medtronic. KL has received speaker honoraria and travel grant from Medtronic, and Abbot. KL has received lecture fees from Medtronic, Otsuka Pharmaceutical, and Lundbeck and has been sponsored to travel and attend to a medical congress by Medtronic. SR declares no conflict of interest. TM has received study grants from Finnish Epilepsy Research Foundation, Maire Taponen Foundation, and Finnish Medical Foundation and has been sponsored to travel and attend medical congresses by Medtronic and Boston Scientific. We confirm that we have read the Journal's position on issues involved in ethical publication and affirm that this report is consistent with those guidelines.
(© 2020 The Authors. Epilepsia Open published by Wiley Periodicals LLC on behalf of International League Against Epilepsy.)