Role of immediate postictal diffusion-weighted MRI in localizing epileptogenic foci of mesial temporal lobe epilepsy and non-lesional neocortical epilepsy.
OBJECTIVE
To determine whether meaningful changes in signal intensity or in the apparent diffusion coefficient of water (ADC) in the ictal onset zone can be detected through immediate postictal and interictal diffusion-weighted magnetic resonance imaging (DWMRI) in patients with localization-related epilepsy.


METHODS
In randomly selected 10 medial and lateral temporal lobe epilepsy (TLE) and four extratemporal epilepsy patients, DWMRI was performed immediately after a seizure and during the interictal period. All 14 patients were non-lesional except for hippocampal sclerosis detected on MRI. The mean time interval from seizure onset to postictal DWMRI was 81 min. Regions of interest (ROI) were selected in both the cortex, which was believed to be the ictal onset zone, and the corresponding anatomical region of the contralateral hemisphere in the postictal and interictal DWMRI. The mean ADC measured from all ROIs was compared. Ictal onset zones were determined by ictal electroencephalography (EEG) and seizure semiology.


RESULTS
On visual inspection of postictal and interictal DWMRI, signal changes in the ictal onset zone could be identified in only one patient with medial TLE. The mean ADC values from the ictal onset zones were not significantly different from those of the corresponding contralateral regions of the cortices in both postictal and interictal DWMRI. However, the postictal ADC values of the epileptogenic foci of neocortical epilepsy or neocortical temporal portion of TLE without hippocampal sclerosis were decreased compared with interictal ones in whom both interictal and postictal DWMRIs were obtained (P = 0.028).


CONCLUSIONS
Our results demonstrate that water diffusion can change even after a single seizure in non-lesional neocortical epilepsy.
Department of Neurology, Seoul National University Hospital, 28 Yongon-dong, Chongno-gu, Seoul, South Korea.
Jong-Bai
JB
Oh
Sang Kun
SK
Lee
Kwang-Ki
KK
Kim
In Chan
IC
Song
Kee-Hyun
KH
Chang
D000293:Adolescent; D000328:Adult; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D004569:Electroencephalography / Q000379:methods; D017034:Epilepsy, Frontal Lobe / Q000175:diagnosis* / Q000473:pathology; D004833:Epilepsy, Temporal Lobe / Q000175:diagnosis* / Q000473:pathology; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged