Introduction: Stereotactic electroencephalography (sEEG) and magnetic resonance guided laser interstitial thermal therapy (MRgLITT) have both emerged as minimally invasive alternatives to open surgery for the localization and treatment of medically refractory lesional epilepsy. Data remains limited on the use of these procedures individually and is almost non-existent on their use in conjunction. Our aim is to report early outcomes regarding efficacy and safety of sEEG followed by MRgLITT for localization and ablation of seizure foci in the pediatric population of medically refractory lesional epilepsy.

Methods: A single-center retrospective review of pediatric patients who underwent sEEG followed by MRgLITT procedures was performed. Demographic, intraoperative, and outcome data were compiled and analyzed.

Results: Four pediatric patients with nine total lesions underwent sEEG followed by MRgLITT procedures between January and September 2017. Mean age at surgery was 10.75 (2-21) years. Surgical substrates included two patients with tuberous sclerosis and two patients with focal cortical dysplasia. Methods of stereotaxis consisted of BrainLab Varioguide and ROSA robotic guidance, with successful localization of seizure foci in all cases. sEEG procedure length averaged 153 (67-235) minutes, with a mean of 6 (4-8) electrodes and 56 (18-84) contacts per patient. MRgLITT procedure length averaged 223 (179-252) minutes. Mean duration of monitoring was 5.75 (4-8) days, and mean total hospital stay was 8 (5-11) days. Over a mean follow-up duration of 5.75 (3-10) months, three patients were seizure free (Engel I, 75%), while one patient saw significant improvement in seizure frequency (Engel II, 25%). There were no complications.

Conclusions: This early data demonstrates that sEEG followed by MRgLITT can safely and effectively localize and ablate epileptogenic foci in a minimally invasive paradigm for treatment of medically refractory lesional epilepsy in pediatric populations. Continued collection of data with extended follow-up is needed.

Patient Care: This study presents early outcome data demonstrating the safety and efficacy of stereoelectroencephalography followed by MR-guided laser interstitial thermal therapy. As more data is collected, these techniques will help shape a paradigm for minimally invasive epilepsy surgery by both improving outcomes and decreasing morbidity associated with such procedures.

Learning Objectives: By the conclusion of this session, participants should be able to: 1) Understand the incidence of and treatment options for pediatric refractory lesional epilepsy 2) Describe the operative techniques for stereoelectroencephalography and MR-guided laser interstitial thermal therapy 3) Discuss the advantages of minimally invasive epilepsy surgery 4) Identify patients who would benefit from minimally invasive epilepsy surgery

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