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How responsive neurostimulation (RNS) decreases seizure frequency is unclear. Stimulation may alter epileptic networks during inter-ictal epochs. Definitions of the epileptic network vary but fast ripples (FRs) may be an important substrate. We, therefore, examined whether stimulation of FR-generating networks differed in RNS super responders and intermediate responders. In 10 patients, with subsequent RNS placement, we detected FRs from stereo-electroencephalography (SEEG) contacts during pre-surgical evaluation. The normalized coordinates of the SEEG contacts were compared with those of the eight RNS contacts, and RNS-stimulated SEEG contacts were defined as those within 1.5 cm 3 of the RNS contacts. We compared the post-RNS placement seizure outcome to (1) the ratio of stimulated SEEG contacts in the seizure-onset zone (SOZ stimulation ratio [SR]); (2) the ratio of FR events on stimulated contacts (FR SR); and (3) the global efficiency of the FR temporal correlational network on stimulated contacts (FR SGe). We found that the SOZ SR (p = .18) and FR SR (p = .06) did not differ in the RNS super responders and intermediate responders, but the FR SGe did (p = .02). In super responders, highly active desynchronous sites of the FR network were stimulated. RNS that better targets FR networks, as compared to the SOZ, may reduce epileptogenicity more., (© 2023 International League Against Epilepsy.)

Responsive neurostimulation (RNS) is an effective treatment modality for refractory temporal lobe epilepsy (TLE). However, the optimal placement of RNS leads is not known. We use an orthogonal approach to lead placement instead of the more common longitudinal approach to target the entorhinal cortex (EC), given its potential for modulating activity entering and leaving the hippocampus. An orthogonal approach allows for coverage of the EC as well as the anterior lateral temporal cortex, which may be particularly beneficial for patients with mesial-lateral TLE and may also enable greater modulation of the limbic network. The objective of this study was to determine treatment outcomes for orthogonally placed RNS depth leads targeting the EC. We performed a retrospective analysis of prospectively collected data on a cohort of 13 patients. Mean follow-up duration was 57.3 months, and the 50% responder rate was 76.9%. These results show that orthogonally placed RNS leads are safe and effective for the treatment of refractory TLE. Larger cohorts are needed to further delineate the clinical utility of this novel targeting strategy., (© 2022 International League Against Epilepsy.)

Deep brain stimulation of the anterior nuclei of thalamus (ANT-DBS) is effective for reduction of seizures, but little evidence is available to guide practitioners in the practical use of this therapy. In an attempt to fill this gap, a questionnaire with 37 questions was circulated to 578 clinicians who were either engaged in clinical trials of or known users of DBS for epilepsy, with responses from 141, of whom 58.2% were epileptologists and 28.4% neurosurgeons. Multiple regions of the world were represented. The survey found that the best candidates for DBS were considered those with temporal or frontal seizures, refractory to at least two medicines. Motivations for renewing therapy upon battery depletion were reduced convulsive, impaired awareness, and severe seizures and improved quality of life. Targeting of leads mainly was by magnetic resonance imaging, sometimes with intraoperative imaging or microelectrode recording. The majority used transventricular approaches. Stimulation parameters mostly imitated the SANTE study parameters, except for initial stimulation amplitudes in the 2-3-V or -mA range, versus 5 V in the SANTE study. Stimulation intensity was most often increased or reduced, respectively, for lack of efficacy or side effects, but changes in active contacts, cycle time, and pulse duration were also employed. Mood or memory problems or paresthesias were the side effects most responsible for adjustments. Off-label sites stimulated included centromedian thalamus, hippocampus, neocortex, and a few others. Several physicians used DBS in conjunction with vagus nerve stimulation or responsive neurostimulation, although our study did not track efficacy for combined use. Experienced users varied more from published parameters than did inexperienced users. In conclusion, surveys of experts can provide Class IV evidence for the most prevalent practical use of ANT-DBS. We present a flowchart for one protocol combining common practices. Controlled comparisons will be needed to choose the best approach., (© 2021 International League Against Epilepsy.)