Extrastriate visual cortex in idiopathic occipital epilepsies: The contribution of retinotopic areas to spike generation.
To provide insight into the pathophysiology of idiopathic childhood occipital epilepsies (ICOEs), by mapping the contribution of retinotopic visual areas to the generation and sustainment of epileptic activity.



Thirteen patients affected by ICOEs (mean age = 10.9 years) underwent a video electroencephalography-functional magnetic resonance imaging (EEG-fMRI) study. A flexible-related fMRI analysis was applied to estimate the shape of the blood oxygen level-dependent (BOLD) response in each patient. Second-level analysis was performed using the interictal EEG discharge (IED)-specific response shape for the ICOE group. The resulting fMRI t-maps were warped to the Population-Average, Landmark- and Surface-based (PALS)-B12 atlas in Caret. For localization purposes, functional results were plotted and compared against 19 retinotopic areas for each hemisphere. A correlation analysis was performed between the hemodynamic maps and electroclinical variables.



The shape of the group-averaged hemodynamic response in ICOE patients showed an earlier time-to-peak and a more pronounced undershoot than the canonical hemodynamic response function (HRF). The random-effect analysis showed positive hemodynamic changes in the bilateral temporooccipital network. With regard to the retinotopic subdivision of the visual cortex, the primary visual area was consistently spared. Conversely, an extensive involvement of the occipitotemporal cortex, including the fusiform gyrus, and the occipitoparietal areas was observed. Moreover, a linear relationship was detected between the occipital spike-density and BOLD increases at the postcentral gyrus and temporooccipital cortex.



Our data indicate that both the ventral and dorsal visual pathways are involved in spike generation in ICOEs, to extents that vary between patients, and reinforce the concept of benign childhood seizure susceptibility syndrome as a substrate for ICOEs. Finally, these results underscore the need for appropriate neuropsychological testing in these children, aimed at revealing selective impairments in functions subserved by both visual pathways.
Department of Biomedical, Metabolic, and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy.|Neurology Unit, NOCSAE Hospital, AUSL Modena, Modena, Italy.
Stefano
S
Meletti
Department of Biomedical, Metabolic, and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy.
Andrea
A
Ruggieri
Department of Neuroscience, University of Parma, Parma, Italy.
Pietro
P
Avanzini
Pediatric Neurology Unit, Policlinico Hospital, Modena, Italy.
Elisa
E
Caramaschi
Child Neuropsychiatry Unit, IRCCS, Institute of Neurological Sciences, Bellaria Hospital, Bologna, Italy.
Melissa
M
Filippini
Pediatric Neurology Unit, Policlinico Hospital, Modena, Italy.
Patrizia
P
Bergonzini
Department of Biomedical, Metabolic, and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy.|Neurology Unit, NOCSAE Hospital, AUSL Modena, Modena, Italy.
Giulia
G
Monti
Department of Health Sciences, University of Milano, Milano, Italy.
Aglaia
A
Vignoli
Brain and Behavior Department, University of Pavia, Pavia, Italy.
Sara
S
Olivotto
Pediatric Neurology Unit, V. Buzzi Hospital, Milano, Italy.
Massimo
M
Mastrangelo
IRCCS Institute of Neurological Sciences, Bellaria Hospital, AUSL of Bologna, Bologna, Italy.|Department of Biomedical and Neuromotor Science, University of Bologna, Bologna, Italy.
Margherita
M
Santucci
Child Neuropsychiatry Unit, IRCCS, Institute of Neurological Sciences, Bellaria Hospital, Bologna, Italy.
Giuseppe
G
Gobbi
Brain and Behavior Department, University of Pavia, Pavia, Italy.|Department of Child Neurology and Psychiatry C. Mondino, National Neurological Institute, University of Pavia, Pavia, Italy.
Pierangelo
P
Veggiotti
Department of Biomedical, Metabolic, and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy.|Neurology Unit, NOCSAE Hospital, AUSL Modena, Modena, Italy.
Anna Elisabetta
AE
Vaudano
D000293:Adolescent; D001931:Brain Mapping; D058256:Brain Waves / Q000502:physiology*; D002648:Child; D004569:Electroencephalography; D004828:Epilepsies, Partial / Q000000981:diagnostic imaging / Q000473:pathology* / Q000503:physiopathology; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D010100:Oxygen / Q000097:blood; D013223:Statistics as Topic; D014793:Visual Cortex / Q000000981:diagnostic imaging / Q000503:physiopathology*; D014795:Visual Pathways / Q000502:physiology*
D010100:Oxygen
Childhood; EEG-fMRI; Extrastriate visual cortex; Idiopathic childhood occipital epilepsies; Panayiotopoulos syndrome; Retinotopic map