Origin and propagation of epileptic spasms delineated on electrocorticography.
OBJECTIVE
Ictal electrographic changes were analyzed on intracranial electrocorticography (ECoG) in children with medically refractory epileptic spasms to assess the dynamic changes of ictal discharges associated with spasms and their relation to interictal epileptiform activity and neuroimaging findings.


METHODS
We studied a consecutive series of 15 children (age 0.4 to 13 years; nine girls) with clusters of epileptic spasms recorded on prolonged intracranial subdural ECoG recordings, which were being performed for subsequent cortical resection, and in total, 62 spasms were analyzed by using quantitative methods.


RESULTS
Spasms were associated with either a "leading" spike followed by fast-wave bursts (type I: 42 events analyzed quantitatively) or fast-wave bursts without a "leading" spike (type II: 20 events analyzed quantitatively). Twenty-three of the 42 type I spasms but none of the 20 type II spasms were preceded by a focal seizure. A "leading" spike had a focal origin in all 42 type I spasms and involved the pre- or postcentral gyrus within 0.1 s in 37 of these spasms. A leading spike was associated with interictal spike activity >1/min in 40 of 42 type I spasms and originated within 2 cm from a positron emission tomography glucose hypometabolic region in all but two type I spasms. Failure to resect the cortex showing a leading spike was associated with poor surgical outcome (p = 0.01; Fisher's exact probability test). Fast-wave bursts associated with spasms involved neocortical regions extensively at least in two lobes within 1.28 s in all 62 spasms and involved the pre- or postcentral gyrus in 53 of 62 spasms.


CONCLUSIONS
Epileptic spasms may be triggered by a focal neocortical impulse in a subset of patients, and a leading spike, if present, might be used as a marker of the trigger zone for epileptic spasms. Rapidly emerging widespread fast-wave bursts might explain the clinical semiology of epileptic spasms.
Asano
Eishi
E
Department of Pediatrics, Children's Hospital of Michigan, Wayne State University, 3901 Beaubien Street, Detroit, MI 48201, U.S.A. eishi@pet.wayne.edu
Juhász
Csaba
C
Shah
Aashit
A
Muzik
Otto
O
Chugani
Diane C
DC
Shah
Jagdish
J
Sood
Sandeep
S
Chugani
Harry T
HT
D001931:Brain Mapping; D002540:Cerebral Cortex / Q000503:physiopathology* / Q000601:surgery; 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; D019788:Fluorodeoxyglucose F18; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D007223:Infant; D008297:Male; D009434:Neural Pathways / Q000503:physiopathology; D049268:Positron-Emission Tomography; D013036:Spasms, Infantile / Q000175:diagnosis* / Q000503:physiopathology / Q000601:surgery; D013355:Subdural Space; D016896:Treatment Outcome; D014402:Tuberous Sclerosis / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery; D014743:Videotape Recording
D019788:Fluorodeoxyglucose F18