Authors :
Presenting Author: Mikaela Speakes, MD – Children's Hospital of Pittsburgh, UPMC
Leen Alkalbani, MD – Children's Hospital of Pittsburgh, UPMC
Emily Harford, MA – Children's Hospital of Pittsburgh, UPMC
Sarah Laughlin, PhD – Children's Hospital of Pittsburgh, UPMC
Melissa Sutcliffe, PhD – Children's Hospital of Pittsburgh, UPMC
Geetha Vasudevan, MD – Children's Hospital of Pittsburgh, UPMC
Nicholas Benjamin, MD – Children's Hospital of Pittsburgh, UPMC
Himadri Patel, MD – Children's Hospital of Pittsburgh, UPMC
Taylor Abel, MD – Children's Hospital of Pittsburgh, UPMC
William Welch, MD – Children's Hospital of Pittsburgh, UPMC
Ruba Al-Ramadhani, MD – Children's Hospital of Pittsburgh, UPMC
Rationale:
Electrical stimulation is performed during sEEG evaluation to map the epileptic zone and eloquent cortex. Stimulation-induced seizures (SIS) may be a helpful diagnostic tool for defining the seizure onset zone and may be associated with improved surgical outcomes. There is ongoing investigation into the diagnostic yield for SIS with low frequency versus high frequency stimulation.1, 2, 3 The objective of this study is to report our center’s experience with SIS during sEEG evaluation in pediatric patients and to compare seizure outcomes following surgical intervention in patients with habitual seizures provoked with low frequency versus high frequency stimulation. The primary outcome was Engel class at time of most recent follow-up appointment.
Methods: A retrospective chart review was performed for all patients (n=33) who underwent electrical stimulation for functional mapping during sEEG evaluation. Low frequency stimulation was defined as stimulation between 1-5 Hz, and high frequency stimulation was defined as stimulation between 20-50 Hz. Patients were divided into three groups: habitual seizures induced by low frequency stimulation (n=8, 24.2%), habitual seizures induced by high frequency stimulation (n=16, 48.5%), or no stimulation-induced seizures (n=9, 27.3%).
Results:
A total of 33 patients were identified (57% female, age range 4-21 years, mean age 14 years). Of this cohort, eight patients (24%) had temporal lobe epilepsy and 25 patients (76%) had extratemporal lobe epilepsy. 18 patients (54%) had a lesion at the area of seizure focus on MRI, of which there was a higher percentage in the high frequency SIS and no SIS groups. Four patients (12%) had a prior tumor resection. Surgical treatment included resection (n=23, 70%), ablation (n=5, 15%), and RNS placement (n=5, 15%). Patients were followed for a median 17 months (IQR: 13-56 months) following surgical intervention. There was no statistically significant difference in history of prior surgery, type of surgical intervention, need for repeat surgical intervention, or follow up time between groups.
75% of the low frequency SIS group, 56% of the high frequency SIS group, and 66% of the no SIS group achieved an Engel class I outcome. There was no statistically significant difference between Engel class outcomes among the three groups (p=0.548, Kruskal-Wallis). Presence of a lesion on MRI was not significantly associated with Engel outcome (p=0.932; Fisher’s Exact), and type of surgery was also not significantly associated with Engel outcome (p=0.096; Kruskal-Wallis).
Conclusions:
This study highlights our center’s experience with both low and high frequency SIS during sEEG evaluation in pediatric patients. A higher percentage of patients in the low frequency SIS group achieved an Engel class I outcome, but there was not a statistically significant difference in Engel class outcomes between groups. Larger systematic studies are needed to determine the benefit of SIS during epilepsy surgery evaluation.
1. Cuello-Oderiz C et al. JAMA Neurol. 2019;76(9)
2. Fox J et al. Epilepsy Behav. 2025;110518
3. Manokaran RK. J Clin Neurophysiol. 2025;42(2)
Funding: None