Abstracts

This is a Late Breaking abstract

Rationale: Deep brain stimulation (DBS) is an emerging surgical option for patients with drug-resistant epilepsy (DRE) who are not candidates for resective/ablative surgery. Recent randomized controlled trials (RCT) have demonstrated efficacy of anterior thalamic nuclei (ANT) DBS for focal epilepsy, particularly those with frontal or temporal onsets, whereas centromedian (CM) DBS appears to be most effective in patients with well-defined generalized epilepsy syndromes. At our institution, DBS candidates who did not fit the populations represented in these RCTs were managed with DBS targeting multiple thalamic nuclei. Thalamic targets that were considered include the ANT and CM nuclei, as well as less studied nuclei, viz. the pulvinar and mediodorsal (MD) nuclei, based on anatomic connectivity to each patient’s seizure network.

Methods: Single-center retrospective study of adult patients with DRE who underwent DBS targeting multiple thalamic nuclei (until September 2022).

Results: Five patients underwent DBS targeting two or three thalamic nuclei (Table 1). One patient had symptomatic generalized epilepsy, who in addition to generalized seizures, had focal seizures arising from the frontal lobe in a region of subcortical grey-matter heterotopia. The remaining four patients had localization-related epilepsy, with multiple seizure foci that were distributed across at least three lobes (involving both hemispheres in one patient). Thalamic targets were determined on a case-by-case basis. The ANT was targeted in all patients given seizures of focal onset involving the temporal and/or frontal lobe. The CM nucleus was also targeted in three patients with generalized seizures or focal, non-limbic seizures. The pulvinar nucleus was included as an additional target in two patients with posterior quadrant epilepsy. Finally, the MD nucleus was also implanted in two patients with motor semiology, who also demonstrated evidence of increased connectivity between the MD nuclei and seizure foci on intracranial subcortical-cortical evoked potentials. Thalamic nuclei were targeted using a DBS construct comprised of two electrodes in each hemisphere, implanted through either a frontal or parietal trajectory (Table 2). There were no surgical complications. At the most recent follow-up (4.9-12.3 mo), two patients were responders (> 50% seizure frequency), and all patients reported decreased seizure severity and/or duration. Two patients had stimulation-related adverse effects, which resolved with adjustment of settings.

Conclusions: This study demonstrates that DBS targeting multiple thalamic nuclei is feasible and safe. Our results motivate future controlled studies to assess the efficacy of multi-thalamic nuclei DBS in patients with multi-focal and/or posterior-onset seizures, or patients with generalized seizures that do not fit a well-defined syndrome.

Funding: Not applicable