Abstracts

This is a Late Breaking abstract

Rationale: We aim to characterize seizure outcomes in patients with drug-resistant epilepsy implanted with the deep brain stimulator device (DBS) at a single level 4 epilepsy center. 

Methods: This is a retrospective analysis on our cohort of 12 patients implanted with DBS devices targeting the anterior thalamic nuclei (ANT) between 2019 and 2022. We compared seizure burden (defined by seizure frequency and severity) pre-implant and at the last follow up in the context of pertinent risk factors and clinical characteristics.  

Results: Average age at time of DBS placement was 42 years (range, 18-66 years). Of the 12 patients implanted, 4 had previous resective epilepsy surgery, 9 had vagus nerve stimulator (VNS), 1 had responsive neurostimulator (RNS). Nine out of 12 patients had stereo-EEG (SEEG) evaluation before DBS, SEEG ictal onset was broad or multifocal in all (7 bilateral and 2 unilateral). Epilepsy etiology was bilateral malformation of cortical development (MCD) – 1, traumatic brain injury (TBI) – 1, confirmed genetic – 2 (SCN1A with Dravet phenotype and HCN1), presumed serum and CSF negative autoimmune encephalitis – 1, unknown – 7. Average follow up duration was 15.6 (4-29) months, 7 patients had more than 1 year follow up, in two patients DBS was not turned on (excluded from outcome analysis). Eight out of 10 patients were responders with >50% of seizure frequency reduction, 7 – at 1-year and subsequent follow-ups, 1 – at 5-month follow-up. Of these 8 responders, 3 had previous resective surgery, 6-VNS, 1-VNS and RNS, 6-SEEG before DBS. Epilepsy etiology was bilateral MCD – 1, TBI – 1, confirmed genetic – 1 (SCN1A), presumed serum and CSF negative autoimmune encephalitis – 1, unknown – 4. Both non-responders had previous SEEG (broad bilateral onsets) and short follow-up, 9 (HCN1-positive) and 4 months (unknown etiology). Particular focus was given to the changes in frequency of focal to bilateral tonic clonic (FBTC) seizures and seizure-clusters control in response to DBS-ANT therapy, and of the 5 patients (3 responders, 2 non-responders) who had more than one FBTC per year prior implantation, 3 had resolved at last follow-up (responders) and 2 had not (non-responders). Three patients had seizure-clusters pre-DBS, controlled at the last follow-up in 2 (responders) and uncontrolled in 1 (non-responder).

Conclusions: Our study demonstrated that DBS-ANT therapy could be effective in patients with drug-resistant epilepsy of different etiology even if the patients failed the previous surgical intervention(s), and seizure frequency reduction was observed at 1-year and subsequent follow ups in majority of DBS responders. Also, we noted a trend of FBTC and seizure-clusters control with DBS-ANT therapy in the responders’ cohort.

Funding: None