The BOLD effect of interictal spike activity in childhood occipital lobe epilepsy.
OBJECTIVE
Occipital lobe epilepsy (OLE) presents in childhood with different manifestations, age of onset and EEG features that form distinct syndromes. The ictal clinical symptoms are difficult to correlate with onset in particular areas in the occipital lobes, and the EEG recordings have not been able to overcome this limitation. The mapping of epileptogenic cortical regions in OLE remains therefore an important goal in our understanding of these syndromes.


METHODS
In this work, three patients with two types of idiopathic childhood OLE were studied with EEG source analysis and also with mapping of the BOLD effect associated with spikes in simultaneous EEG/fMRI recordings.


RESULTS
Two patients with late onset OLE provided EEG source localizations in the lateral parietal cortex and in the medial occipital areas. The BOLD activations were more consistent and restricted to the medial parietal-occipital cortex in both cases. One patient with photosensitive idiopathic OLE presented with dipole sources in the medial parietal cortex, but the BOLD activations were widespread over inferior and bilateral occipital areas and also posterior temporal ones. There was little spatial overlap between the EEG and BOLD results, but the localizations suggested by the latter are more consistent with the ictal clinical manifestations of each type of epileptic syndrome.


CONCLUSIONS
Overall, the BOLD effect associated with interictal spikes maps epileptogenic areas to different localizations than the ones suggested by EEG source analysis. These maps are similar in two patients with late onset idiopathic OLE, but different from a case of photosensitive idiopathic OLE.
Leal
Alberto
A
Department of Neurophysiology, Hospital Júlio de Matos, Lisbon, Portugal. a.leal@netcabo.pt
Dias
Ana
A
Vieira
José P
JP
Secca
Mário
M
Jordão
Constança
C
D000293:Adolescent; D017668:Age of Onset; D001931:Brain Mapping / Q000379:methods; D002540:Cerebral Cortex / Q000503:physiopathology*; D002648:Child; D004569:Electroencephalography / Q000379:methods / Q000706:statistics & numerical data*; D004828:Epilepsies, Partial / Q000097:blood / Q000175:diagnosis / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods / Q000706:statistics & numerical data*; D008297:Male; D009778:Occipital Lobe / Q000503:physiopathology; D010100:Oxygen / Q000097:blood*; D010296:Parietal Lobe / Q000503:physiopathology; D013702:Temporal Lobe / Q000503:physiopathology
D010100:Oxygen