Topographic movie of ictal high-frequency oscillations on the brain surface using subdural EEG in neocortical epilepsy.
OBJECTIVE
To understand the rapid dynamic changes of ictal intracranial high-frequency oscillations (HFOs) in neocortical epilepsy.


METHODS
We integrated multiple band frequency analysis and brain-surface topographic maps of HFOs from ictal subdural EEG (SDEEG) recordings. We used SDEEG to record partial seizures consisting of right-arm jerks with secondary generalization in a 17-year-old right-handed girl. We selected 20-s EEG sections that included preclinical seizure recordings. We averaged the HFO power between 60 and 120 Hz for 25 selected electrodes, made topographic maps from these averaged powers, and superimposed the maps on the brain-surface image. We filmed consecutive HFO maps at a 10-ms frame rate.


RESULTS
Before clinical seizure onset, high-power HFOs emerged at the superior portion of the left precentral gyrus, then appeared in the middle of the left postcentral gyrus, and subsequently reverberated between both regions as well as the posterior portion of the left postcentral gyrus. Right-arm extension and facial grimacing started as the HFO power decreased. As generalized tonic-clonic seizures evolved, HFO power increased but remained within the central region.


CONCLUSIONS
Topographic movies of intracranial HFOs on the brain surface allow visualization of the dynamic ictal changes in neocortical epilepsy.
Akiyama
Tomoyuki
T
Division of Neurology, The Hospital for Sick Children, Toronto, Ontario, Canada.
Otsubo
Hiroshi
H
Ochi
Ayako
A
Galicia
Elaine Z
EZ
Weiss
Shelly K
SK
Donner
Elizabeth J
EJ
Rutka
James T
JT
Snead
O Carter
OC
D000293:Adolescent; D001931:Brain Mapping / Q000379:methods*; D002540:Cerebral Cortex / Q000503:physiopathology*; D004566:Electrodes; D004569:Electroencephalography / Q000379:methods / Q000706:statistics & numerical data*; D004827:Epilepsy / Q000175:diagnosis / Q000503:physiopathology*; D005260:Female; D006612:High-Frequency Ventilation / Q000706:statistics & numerical data; D006801:Humans; D009040:Motion Pictures; D019579:Neocortex / Q000503:physiopathology*; D012815:Signal Processing, Computer-Assisted; D013355:Subdural Space