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Stimulation-Induced Seizures in Children Undergoing Stereo-EEG Evaluation
Ranjith Kumar Manokaran1, Ayako Ochi, Shelly Weiss
1Division of Neurology, Department of Paediatrics, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada.
Insights
Low-frequency (1-Hz) stimulation successfully provoked habitual stimulation-induced seizures (SIS) in nearly one-fourth of pediatric epilepsy patients undergoing stereo-EEG monitoring. This study offers initial pediatric insights into low-frequency cortical stimulation for seizure provocation.
Area of Science:
- Pediatric Neurology
- Epileptology
- Neurophysiology
Background:
- Drug-resistant epilepsy in children poses significant management challenges.
- Stereo-electroencephalography (stereo-EEG) is crucial for localizing seizure foci.
- Stimulation-induced seizures (SIS) can aid in understanding epilepsy networks.
Purpose of the Study:
- To evaluate the initial experience of using low-frequency stimulation to provoke SIS in pediatric patients with drug-resistant epilepsy.
- To assess the feasibility and effectiveness of 1-Hz stimulation during stereo-EEG evaluations.
- To identify factors associated with successful SIS provocation.
Main Methods:
- Retrospective analysis of 14 children (aged 2-18 years) with drug-resistant focal epilepsy undergoing stereo-EEG.
- Extraoperative direct electrical cortical stimulation using 1-Hz biphasic square waveforms (1ms pulse width, 1-3mA current, 20s trains).
- Collection and summary of epilepsy-related, imaging, neurophysiology, and surgery-related variables.
Main Results:
- Four patients (28.6%) experienced habitual SIS, all with extratemporal origins.
- Focal cortical dysplasia was the etiology in three patients with SIS.
- Interictal high-frequency oscillations were observed at contacts provoking SIS in 75% of cases.
- Two patients achieved excellent seizure control (Class 1 ILAE outcome) after resection of SIS-generating regions.
Conclusions:
- Low-frequency (1-Hz) stimulation can provoke habitual SIS in a subset of pediatric epilepsy patients undergoing stereo-EEG.
- This approach may help delineate seizure networks and guide surgical interventions.
- Further research is needed to expand the understanding of low-frequency stimulation in pediatric epilepsy.
Purpose:
This study reports our center's initial experience with the use of low-frequency stimulation in provoking stimulation-induced seizures (SIS) in children with drug-resistant epilepsy undergoing stereo-EEG evaluations.
Methods:
This retrospective study enrolled children aged 2 to 18 years with drug-resistant focal epilepsy who underwent stereo-EEG evaluation and extraoperative direct electrical cortical stimulation to elicit seizures. The low-frequency stimulation parameters consisted of biphasic square waveforms at frequency of 1 Hz, pulse width 1 millisecond, current 1 to 3 mA, and train duration of 20 seconds. Various epilepsy-related, imaging, neurophysiology, and surgery-related variables were collected and summarized.
Results:
Fourteen children (mean age 13 years; 57.1% girls) were included, 10 of whom had unilateral stereo-EEG coverage. Cortical stimulation for provoking seizures was performed after a median of 5 days after electrode implantation. The median number of electrode-contacts stimulated per patient was 42. Four patients (28.6%) experienced habitual SIS (all extratemporal). The etiology in three patients was focal cortical dysplasia. Interictal high-frequency oscillations at electrode-contacts provoking SIS were observed in three cases (75%). Two of these individuals (50%) had class 1 International League Against Epilepsy seizure outcome at last follow-up, after the resection of the brain regions generating SIS.
Conclusions:
Low-frequency (1-Hz) stimulation could provoke habitual SIS in nearly one-fourth of children with focal epilepsy undergoing stereo-EEG monitoring. This study provides a limited pediatric experience with the low-frequency cortical stimulation and SIS.
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