Electric stimulation on human cortex suppresses fast cortical activity and epileptic spikes.
OBJECTIVE
To investigate underlying mechanisms and adequate parameters for electric cortical stimulation to inhibit epileptic focus in humans.


METHODS
A patient with intractable partial epilepsy had subdural electrodes implanted for preoperative evaluation. Cortical functional mapping was performed by using 50-Hz alternating square pulse of 0.3-ms duration, 1 to 7 mA, within 5 s. Spike frequency and electrocorticogram (ECoG) power spectra were compared before and after the stimulation when epileptic focus and distant area were stimulated. A similar comparison also was performed in low-frequency stimulation of 0.9 Hz applied for 15 min.


RESULTS
Interictal spikes were reduced after electric cortical stimulation of the epileptic area at a frequency of 50 Hz as well as 0.9 Hz, with concomitant decrease in the electrographic fast activities at 50-Hz stimulation.


CONCLUSIONS
These data suggest that electric cortical stimulation at both high and low frequency has a suppressive effect on epileptic activities in human cortex, possibly through distinct mechanisms.
Kinoshita
Masako
M
Departments of Neurology, Graduate School of Medicine, Kyoto Universtiy, Kyoto, Japan.
Ikeda
Akio
A
Matsumoto
Riki
R
Begum
Tahamina
T
Usui
Keiko
K
Yamamoto
Junichi
J
Matsuhashi
Masao
M
Takayama
Motohiro
M
Mikuni
Nobuhiro
N
Takahashi
Jun
J
Miyamoto
Susumu
S
Shibasaki
Hiroshi
H
D000328:Adult; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000502:physiology* / Q000503:physiopathology; D004599:Electric Stimulation Therapy / Q000379:methods / Q000706:statistics & numerical data; D004567:Electrodes, Implanted; D004569:Electroencephalography / Q000706:statistics & numerical data*; D004827:Epilepsy / Q000503:physiopathology / Q000517:prevention & control* / Q000628:therapy; D005260:Female; D006801:Humans; D036881:Long-Term Synaptic Depression / Q000502:physiology; D008279:Magnetic Resonance Imaging; D019579:Neocortex / Q000502:physiology / Q000503:physiopathology; D016896:Treatment Outcome; D014741:Video Recording