Abstracts

Rationale: Stereoelectroencephalography (sEEG) is commonly utilized as a diagnostic tool in the presurgical evaluation for drug resistant epilepsy (DRE) patients. Clinical observation raised concerns regarding delayed time to recommended intervention in patients who undergo sEEG. In reports of sEEG outcomes, there is a consistent high rate of non-intervention after sEEG, ranging from 18-33%. These patients take on the full burden of potential morbidity and mortality of intracranial EEG monitoring, while foregoing the potential benefits of epilepsy surgery. Additionally, delay to intervention increases potential for sudden unexpected death in epilepsy (SUDEP), and early surgical therapy has been shown to improve odds for seizure freedom, decreased cognitive burden and quality of life. Data on the delay from the sEEG implant to therapeutic intervention are typically not reported. We undertook a review of delayed intervention and non-intervention cases in our center. Methods: We retrospectively identified patients who underwent sEEG as part of their presurgical evaluation at the CUIMC Epilepsy Center between 2014 and 2018. A comparison was conducted using data from subdural implants performed between 2005 and 2014, prior to initiation of sEEG at our institution. Demographics, epilepsy history, and results of pre-surgical testing, including the pre-operative hypothesis, were used to compare the two populations. Review included data from the presurgical evaluation, case conference presentation, and post-surgical follow-ups. Results: During the study period, 103 patients underwent sEEG recording. Eighty-one patients proceeded to a therapeutic intervention, with 67 procedures with curative intent (65%) vs. 14 palliative procedures (14%).  Of these, 18 (22%) patients received their recommended intervention more than 6 months after implant and 8 (10%) patients waited more than 1 year.  Twenty-two patients (21%) did not receive further intervention after explantation, five of whom were pediatric.  Fourteen were recommended for further surgical intervention (resection, ablation, or subsequent subdural implant), and six were recommended for a palliative intervention. In two patients, no definite surgical recommendation was made.  Nineteen patients received post-explant recommendations and were followed clinically for at least 6 months after implant (mean 23.9 months, range 6-44 months).  Three patients declined to proceed due to reporting post-implant seizure freedom (2) or significant improvement (1).  Reasons for declining were mixed in the remaining cases. In comparison, six of 92 (7%) patients receiving subdural implants did not undergo therapeutic intervention (chi-square p=0.003), and four patients (4%) received palliative therapy (chi-square p=0.008). Conclusions: Retrospective analysis of post-sEEG outcomes in our center reveals that our non-intervention rate is comparable to those reported in the literature. This finding, as well as delays to therapeutic intervention, warrant clinical concern in patients who continue to have seizures after sEEG implant. These results support the need to explore factors that may contribute to non-intervention or delay to surgical treatment, such as co-morbid psychiatric disorders and socioeconomic status. Funding: No funding