Interictal EEG spikes identify the region of electrographic seizure onset in some, but not all, pediatric epilepsy patients.
OBJECTIVE
The role of sharps and spikes, interictal epileptiform discharges (IEDs), in guiding epilepsy surgery in children remains controversial, particularly with intracranial electroencephalography (IEEG). Although ictal recording is the mainstay of localizing epileptic networks for surgical resection, current practice dictates removing regions generating frequent IEDs if they are near the ictal onset zone. Indeed, past studies suggest an inconsistent relationship between IED and seizure-onset location, although these studies were based upon relatively short EEG epochs.


METHODS
We employ a previously validated, computerized spike detector to measure and localize IED activity over prolonged, representative segments of IEEG recorded from 19 children with intractable, mostly extratemporal lobe epilepsy. Approximately 8 h of IEEG, randomly selected 30-min segments of continuous interictal IEEG per patient, were analyzed over all intracranial electrode contacts.


RESULTS
When spike frequency was averaged over the 16-time segments, electrodes with the highest mean spike frequency were found to be within the seizure-onset region in 11 of 19 patients. There was significant variability between individual 30-min segments in these patients, indicating that large statistical samples of interictal activity were required for improved localization. Low-voltage fast EEG at seizure onset was the only clinical factor predicting IED localization to the seizure-onset region.


CONCLUSIONS
Our data suggest that automated IED detection over multiple representative samples of IEEG may be of utility in planning epilepsy surgery for children with intractable epilepsy. Further research is required to better determine which patients may benefit from this technique a priori.
Division of Child Neurology, Department of Neurology and Pediatrics, Children's Hospital of Philadelphia, The University of Pennsylvania, Philadelphia, PA 19104, USA. marshe@email.chop.edu
Eric D
ED
Marsh
Bradley
B
Peltzer
Merritt W
MW
Brown
Courtney
C
Wusthoff
Phillip B
PB
Storm
Brian
B
Litt
Brenda E
BE
Porter
D000293:Adolescent; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000503:physiopathology / Q000601:surgery; D002648:Child; D002675:Child, Preschool; D004292:Dominance, Cerebral / Q000502:physiology; D004567:Electrodes, Implanted; D004569:Electroencephalography; D004828:Epilepsies, Partial / Q000175:diagnosis* / Q000503:physiopathology* / Q000601:surgery; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D012815:Signal Processing, Computer-Assisted; D055815:Young Adult