Abstracts

Rationale: A strong body of evidence in epilepsy research has shifted the standard of care for refractory epilepsy to surgical intervention. Stereoencephalography (sEEG) plays a significant role in the evaluation of refractory patients to test the preimplantation hypotheses, determine the epileptic zone, optimize resection strategy, and reduce functional deficit. SEEG also provides the benefits of invasive monitoring with less morbidity than with grid implantation. In the US literature only the major surgical epilepsy centers have demonstrated the safety and efficacy of using sEEG as a standard for invasive monitoring. To improve the generalizability of existing sEEG safety and efficacy data, the same results should be demonstrable at a newly established center. Presented here is the University of Kansas Health System experience as the surgical epilepsy program expanded from 20 implantation cases from 2011-2015 to 122 implantation cases from 2016-2019. Methods: A retrospective case review of all sEEG cases from 2016-2019 was performed. 122 procedures were reviewed for number of electrodes, duration of implantation, addition of electrodes, delayed reimplantation, method of stereotaxis, resulting therapeutic procedure, seizure outcome, and clinically significant complications. Clinically significant complications were defined by neurological status change, electrode retention, or alteration of treatment course. Results: 103 patients underwent a total of 122 implantation procedures for a total of 1221 depth electrodes implanted. Mean age was 39 +- 13 years. Average number of electrodes placed was 10 +- 4.0 for an average length of 10 +- 3.8 days. Twelve patients had additional electrodes implanted in the same setting and 7 underwent delayed reimplantation. The procedures were done with stereotactic arm (3), Robot (27), and stereotactic frame (92). There were 6 clinically significant complications related to depth placement: retained electrode(2), unintentional electrode removal (2), parenchymal hematoma(1), and development of status while implanted (1) for a complication rate of 5.8% per patient and 0.5% per depth electrode. Only one complication, the parenchymal hematoma, resulted in an irreversible neurological deficit.Implantations resulted in 74 (60.5%) procedures: temporal lobectomy(19), focus resection (17), stereotactic laser amygdalohippocampotomy (10), radio frequency ablation (RFA) (8), laser ablation of non-mesial temporal focus (6), responsive neurostimulation (RNS) (9), and other (5). For the patients with at least one year follow up post procedure available, the seizure freedom rate is 52.2% (12/23), 60% if RNS and RFA procedures are excluded; mean duration of seizure freedom is 15.3 +- 2.3 months and median duration of seizure freedom is 14 months. Conclusions: SEEG at a rapidly growing epilepsy surgery program has a similar complication rate and seizure outcomes to previously reported data. This suggests the potential for any properly supported level 4 epilepsy center to utilize sEEG in the surgical treatment of drug resistant epilepsy. Funding: No funding