Quantitative interictal subdural EEG analyses in children with neocortical epilepsy.
OBJECTIVE
We studied the relation between quantitative interictal subdural EEG data and visually defined ictal subdural EEG findings in children with intractable neocortical epilepsy, and determined whether interictal EEG data are predictive of ictal EEG onset zones.


METHODS
Thirteen children (aged 1.2-15.4 years) underwent prolonged intracranial EEG recording, using 48- to 120-channel subdural electrodes. Three distinct 10-min segments of the continuous interictal EEG recording were selected for each patient, and the spike frequency for each channel was determined by using an automatic spike-detection program. Subsequently the average spike frequency of each electrode was compared with ictal assessment (onset, spread, and no early ictal involvement). In addition, 50 distinct interictal spikes were averaged for each patient, and the amplitude and latency after the leading spike (averaged spike showing the earliest peak) were measured for each electrode and analyzed with respect to ictal EEG findings.


RESULTS
Reproducibility of the spike-frequency pattern derived from three 10-min segments was high (Kendall's W, 0.85 +/- 0.08). Electrodes showing the highest spike frequency, the highest spike amplitude, and the leading spike were found to be a part of the seizure onset in 13 of 13, 12 of 13, and 10 of 13 cases, respectively. There was significant correlation between ictal assessment and spike frequency as well as spike amplitude. A receiver operating characteristics analysis showed that a cutoff threshold at 14% of the maximal spike frequency resulted in a specificity of 0.90 and a sensitivity of 0.77 for the detection of seizure-onset electrodes.


CONCLUSIONS
Quantitative interictal subdural EEG may predict ictal-onset zones in children with intractable neocortical epilepsy.
Asano
Eishi
E
Department of Pediatrics, Children's Hospital of Michigan, Detroit, Michigan 48201, USA.
Muzik
Otto
O
Shah
Aashit
A
Juhász
Csaba
C
Chugani
Diane C
DC
Sood
Sandeep
S
Janisse
James
J
Ergun
Eser Lay
EL
Ahn-Ewing
Judy
J
Shen
Chenggang
C
Gotman
Jean
J
Chugani
Harry T
HT
D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D004567:Electrodes, Implanted; D004569:Electroencephalography / Q000379:methods / Q000706:statistics & numerical data*; D004827:Epilepsy / Q000175:diagnosis* / Q000503:physiopathology / Q000601:surgery; D005260:Female; D006801:Humans; D007223:Infant; D008279:Magnetic Resonance Imaging; D008297:Male; D019579:Neocortex / Q000503:physiopathology* / Q000601:surgery; D012372:ROC Curve; D012680:Sensitivity and Specificity; D013355:Subdural Space; D016896:Treatment Outcome