Is intraoperative electrocorticography reliable in children with intractable neocortical epilepsy?
OBJECTIVE
To study the relation between the spike frequency during intraoperative electrocorticography (ECoG) under general anesthesia with isoflurane and that during extraoperative ECoG monitoring in children with intractable neocortical epilepsy.


METHODS
Twenty-one children (age, 1-16 years; 15 boys and six girls) who underwent intraoperative and extraoperative ECoG monitoring with subdural electrode arrays were studied. The spike frequency and the spatial pattern of spike frequency were compared between intraoperative and extraoperative ECoGs for each patient (by using Wilcoxon signed-ranks and Spearman's rank correlation, respectively).


RESULTS
In 15 of 21 patients, the spike frequency was significantly lower during intraoperative than during extraoperative ECoG (mean z = -6.3; p < 0.001). In four of 21 patients, no significant difference was found in the spike frequency between intraoperative and extraoperative recordings. In two of 21 patients, spike frequency reached one spike/min neither during intraoperative nor extraoperative recording; therefore appropriate comparison of spike frequency was not possible. A significant positive correlation in the spike-frequency pattern was seen between intraoperative and extraoperative recordings in nine of nine cases who had > or = 10 spikes/min during intraoperative ECoG (mean rho = 0.62; p < 0.01), in five of six cases with one to nine spikes/min (mean rho = 0.50; p < 0.01), and in none of five cases with less than one spike/min (mean rho = 0.13).


CONCLUSIONS
General anesthesia often decreases the spike frequency in children with neocortical epilepsy, yet intraoperative ECoG can reliably reflect the awake interictal spiking pattern when spike frequency exceeds one spike/min during intraoperative ECoG recording.
Asano
Eishi
E
Department of Pediatrics, Children's Hospital of Michigan, Wayne State University, Detroit, Michigan 48201, USA. eishi@pet.wayne.edu
Benedek
Krisztina
K
Shah
Aashit
A
Juhász
Csaba
C
Shah
Jagdish
J
Chugani
Diane C
DC
Muzik
Otto
O
Sood
Sandeep
S
Chugani
Harry T
HT
D000293:Adolescent; D000768:Anesthesia, General / Q000379:methods; D001931:Brain Mapping; D002648:Child; D002675:Child, Preschool; D004567:Electrodes, Implanted; D004569:Electroencephalography / Q000187:drug effects / Q000379:methods / Q000706:statistics & numerical data*; D004828:Epilepsies, Partial / Q000175:diagnosis / Q000503:physiopathology* / Q000601:surgery*; D005071:Evoked Potentials; D005260:Female; D006801:Humans; D007223:Infant; D007530:Isoflurane / Q000008:administration & dosage / Q000494:pharmacology; D008297:Male; D016343:Monitoring, Intraoperative / Q000379:methods* / Q000706:statistics & numerical data; D008991:Monitoring, Physiologic / Q000379:methods / Q000706:statistics & numerical data*; D019579:Neocortex / Q000503:physiopathology* / Q000601:surgery*; D012372:ROC Curve; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric; D014402:Tuberous Sclerosis / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery
D007530:Isoflurane