Abstracts

Rationale: Resective epilepsy surgery is a safe and effective treatment for certain patients with intractible seizures. Stereotactic laser ablation (SLA) is a minimally invasive alternative to resective surgery that may provide comparable results with reduced hospital stay and morbidity. Localization and removal of the epileptogenic onset zone is critical for seizure freedom. Some children require intracranial monitoring for accurate localization. SEEG is a minimally invasive monitoring technique that complements the approach of SLA. We are evaluating the feasibility of combining minimally invasive techniques of SEEG and SLA through a case review of two children that underwent phase II intracranial monitoring using depth electrodes prior to SLA. Methods: Patient 1 is a 16 y.o. female with refractory symptomatic localization-related epilepsy associated with right mesial temporal sclerosis and a calcified neurocysticerosis lesion in the right superior temporal gyrus. The MRI scans, clinical semiology, and EEG/video monitoring were consistent with right temporal lobe onset of her seizures. The patient underwent SEEG evaluation with depth electrodes placed in the uncus, superior temporal gyrus, and the parahippocampal gyrus. Independent electrographic seizure onsets were identified from the uncus and the superior temporal gyrus near the cysticercosis lesion. Based on the findings, laser fibers were stereotactically placed in both the uncus and superior temporal gyrus for ablation. Patient 2 is a 4 y.o. female with refractory symptomatic localization-related epilepsy secondary to a right parietal focal cortical dysplasia. MRI revealed a type I focal cortical dysplasia involving the right parietal cortex deep to the intraparietal sulcus and the adjacent parietal opercular cortex. The patient underwent intracranial monitoring utilizing two depth electrodes placed into the dysplastic lesion and three subdural strip electrodes placed over cortical surface. Seizure onset was identified from both depth electrodes consistent with a deeper ictal source. Two adjacent laser ablations were performed that included the dysplasia and immediate surrounding cortex 4 cm from the surface and then another 2 cm from the surface creating a large lesion in the intraparietal sulcus. Results: Both patients tolerated the procedures well with no complications and were discharged by 48 hours after surgery. Follow up MRIs showed only routine post-ablation changes. One patient has remained seizure free post surgery, and the other patient has had a dramatic but incomplete improvement in seizure control. Conclusions: Tailored laser ablation based on SEEG is a feasible treatment for lesional epilepsy with multiple targets that can result in favorable seizure outcomes and minimization of surgical morbidity.