Abstracts

Rationale: The Responsive Neurostimulation System (RNS) was approved as an adjunctive therapy for medically refractory focal epilepsy in 2013. The device detects epileptiform patterns and delivers electrical stimulation to abort seizures. The use of robotic guidance for stereotactic procedures has gained interest because of the increase in accuracy and precision and is well described for stereoelectroencephalography (sEEG). The authors describe a novel technique to implant RNS electrodes to target ictal onset zones based upon sEEG localization and also demonstrate the presence of identical ictal patterns in specific sEEG electrodes compared with RNS electrodes. Methods: A total of sixteen patients with medically refractory focal epilepsy underwent sEEG implantation for ictal onset localization followed by robotic RNS implantation at the University of California, Irvine from 2015 to 2017.  All cases were discussed in epilepsy management conference. Four patients undergoing RNS implantation with strip leads were excluded from the study.  The electrode most correlative with ictal onset on sEEG was chosen as the target for the RNS electrode.  Seizure control was measured at six months and one year follow up.  Ictal onset ECoG data from RNS was compared with ictal onset from sEEG leads based on calculations of lead target to actual lead location from the ROSA robot and also compared with literature. Results: All patients had at least six-month follow-up and four were seen at one-year.  At six months follow-up, the average percent seizure reduction decreased to 82%.  At one year follow up, the five patients had an average of 93% seizure reduction and the remaining patients had an average of 70% seizure reduction at 6 months. The location of seizure onset from ECoG data show similar onset from sEEG leads within 0.165 mm discrepancy.  Conclusions: Our study demonstrates a novel means of targeting the previously identified ictal onset zone for RNS lead implantation and the specific benefits associated with robotic implantation. This may improve early outcomes in patients undergoing RNS.  The robot provides an ideal method to target and implant RNS leads, especially when targeting previously identified ictal onset zones based upon sEEG patterns. Funding: No funding