Linking generalized spike-and-wave discharges and resting state brain activity by using EEG/fMRI in a patient with absence seizures.
OBJECTIVE
To illustrate a functional interpretation of blood oxygen level-dependent (BOLD) signal changes associated with generalized spike-and-wave discharges in patients with absence seizures and to demonstrate the reproducibility of these findings in one case.


METHODS
In a 47 year-old patient with frequent absence seizures, BOLD signal changes during generalized spike-and-wave discharges (GSWD) were mapped by using simultaneous and continuous electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) at 1.5 T and 6 months later at 3 T. GSWDs were modeled as individual events and as blocks.


RESULTS
The patient studied exhibited frequent generalized spike-wave activity with temporal properties ideal for study with EEG/fMRI. Highly reproducible GSWD-associated fMRI signal decreases (deactivations) were seen in bilateral frontal and temporoparietal cortices and the precuneus, in addition to activations in occipital cortex and, at 3 T, the posterior thalamus.


CONCLUSIONS
The GSWD-associated changes seen here involve cortical regions that have been shown to be more active at conscious rest compared with sleep and with various types of extroverted perception and action. These regions have been proposed to constitute the core of a functional "default mode" system. We propose that the findings of deactivation of this distributed brain system during GSWDs mirrors the clinical manifestation of GSWDs (i.e., absence seizures). Furthermore, we suggest that these deactivations may reflect the functional consequences of GSWDs on physiologic brain activity at rest rather than direct hemodynamic correlates of epileptic discharges.
Laufs
Helmut
H
Department of Neurology, Johann Wolfgang Goethe-University and Brain Imaging Center Frankfurt, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany. helmut@laufs.com
Lengler
Ulrike
U
Hamandi
Khalid
K
Kleinschmidt
Andreas
A
Krakow
Karsten
K
D001921:Brain / Q000503:physiopathology*; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000503:physiopathology; D003243:Consciousness / Q000502:physiology; D004569:Electroencephalography / Q000706:statistics & numerical data*; D004832:Epilepsy, Absence / Q000175:diagnosis* / Q000503:physiopathology; D005500:Follow-Up Studies; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods / Q000706:statistics & numerical data*; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D015203:Reproducibility of Results
D010100:Oxygen