Stereo-electroencephalography (SEEG) in pediatric epilepsy: Utility in children with and without prior epilepsy surgery failure.

Background: When noninvasive modalities fail to adequately localize the seizure onset zone (SOZ) in children with medically refractory epilepsy, invasive interrogation with stereo-electroencephalography (SEEG) or subdural electrodes may be required. Our center utilizes SEEG for invasive monitoring in a carefully selected population of children, many of whom have seizures despite a prior surgical resection. We describe the cohort of patients who underwent SEEG in the first 5 years of its employment in our institution, almost half of which had a history of a failed epilepsy surgery.
Methods: We retrospectively reviewed the records of the first 44 consecutive children who underwent SEEG at Nicklaus Children's Hospital (Miami, Florida), a large, level 4 epilepsy referral center. Patient demographic, clinical, radiographic, and electrophysiological information was collected prospectively. Student's t-test was used for sampling of means and analysis of variance (ANOVA) for evaluation of variance beyond 2 means; chi-square test of independence was used to assess the relationship between categorical variables.
Results: There were 44 patients in this cohort, of whom 17 (38.6 %) were male. The mean age of seizure onset was 6.2 years. Twenty-one patients (47.7 %) had previously failed an epilepsy surgery. Patients with a history of prior epilepsy surgery failure were older at SEEG implantation (17.6 vs. 13.7 years; p = 0.043), were more likely to have SEEG for identification of resection margins (9 vs. 4; p = 0.034), and had fewer electrodes placed (5.9 vs. 7.5; p = 0.016). No difference was seen in complication rates between groups with only 3/297 electrodes placed associated with complications, all of which were minor. Post-SEEG, 29 (65.9 %) patients underwent focal resection, 7 patients had VNS insertion, 3 underwent RNS placement, and 5 had no further intervention. The majority of patients that underwent resection in both groups experienced an improvement in seizures (Engel class I-III), reported by 13/15 (86.7 %) in those naive to surgery and 10/14 (71.4 %) in those with prior surgical failure. Seizure-freedom was much lower in those with prior epilepsy surgery, seen in only 4/14 (28.6 %) versus 8/15 (53.3 %).
Conclusion: Our data supports current literature on SEEG as a safe and effective method of electrophysiological evaluation in children naive to surgery and adds that it is a safe technique in children with a history of failed epilepsy surgery. There was no difference in complication rates, which were <1 % in both groups. A favorable outcome was seen in the majority of patients in both groups; the seizure freedom rate, however, was much lower in those with prior epilepsy surgery.
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