Cortical and thalamic fMRI responses in partial epilepsy with focal and bilateral synchronous spikes.
OBJECTIVE
To determine the blood oxygen level-dependent (BOLD) responses to epileptic discharges in the thalamus and cerebral cortex in patients with partial epilepsy.


METHODS
Among 64 tested patients, 40 had EEG spikes during scanning and were divided in two groups: unilateral or bilateral independent spikes (29 patients) and bilaterally synchronous spikes (11 patients). Each spike topography was analyzed separately, yielding 40 studies in the first group and 17 in the second.


RESULTS
Forty-five percent of focal spike studies showed significant BOLD responses. Cortical activation (positive BOLD) represented the dominant response and had a better correlation with spike location than cortical deactivation (negative BOLD). In the second group, all patients had significant BOLD responses; they were more widespread compared to the first group, and deactivated areas were as important as activated regions. A thalamic response was seen in 12.5% of studies in the first group and 55% in the second.


CONCLUSIONS
The thalamus is involved in partial epilepsy during interictal discharges. This involvement and also cortical deactivation are more commonly seen with bilateral spikes than focal discharges.


CONCLUSIONS
These findings show evidence for a role for the thalamus and a more important role for inhibition in secondary bilateral synchrony.
Aghakhani
Y
Y
Montreal Neurological Institute and Hospital, McGill University, Montréal, Que., Canada.
Kobayashi
E
E
Bagshaw
A P
AP
Hawco
C
C
Bénar
C G
CG
Dubeau
F
F
Gotman
J
J
D000293:Adolescent; D000328:Adult; D000368:Aged; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000098:blood supply* / Q000503:physiopathology; D004569:Electroencephalography / Q000379:methods; D004828:Epilepsies, Partial / Q000473:pathology / Q000503:physiopathology*; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood*; D013788:Thalamus / Q000098:blood supply* / Q000503:physiopathology; D013997:Time Factors
D010100:Oxygen