title: Pre-ictal BOLD alterations: Two cases of patients with focal epilepsy.
abstract: The pre-ictal state is of interest for better understanding pathophysiological processes leading up to seizures and for identifying potential biomarkers for the prediction of these events. We present two cases of patients with focal epilepsy (occipital, insular) who had seizures during functional magnetic resonance imaging (fMRI) scans. Interictal (>30min pre-seizure) control data was available for one participant. The location and timing of pre-ictal blood oxygenation-level dependent (BOLD) signal alterations were examined along with changes in pre-ictal functional connectivity. BOLD signal increases were seen at/close to the seizure onset zone and in/near a contralateral homologous region for both patients. In one patient, BOLD signal decreases were also observed distant from the seizure onset zone. The BOLD signal changes began 11 to 3min prior to seizure onset. These findings add to a growing number of cases of pre-ictal hemodynamic alterations. The significant BOLD signal increases seen in/near the homologous region contralateral to the seizure onset zone in both patients suggests that this area may play a critical role in the pre-ictal state, perhaps functioning to inhibit the seizure onset zone, or alternatively, to be directly involved in seizure generation. Pre-ictal functional connectivity, using a seed at the presumed seizure onset zone, demonstrated increases in connectivity with regions near the contralateral homologous region prior to seizures. Alterations in connectivity were also observed and characterized in interictal data, highlighting the importance of future research in determining if the observed pre-ictal changes are specific indicators for impending seizures.
authors.affiliation: Hotchkiss Brain Institute, University of Calgary, Health Research Innovation Centre, Room 1A10, 3330 Hospital Drive NW, Calgary, Alberta, T2N 4N1, Canada; Seaman Family MR Research Centre, University of Calgary, Foothills Medical Centre, 1403-29 Street NW, Calgary, Alberta, T2N 2T9, Canada; Department of Neuroscience, University of Calgary, Health Sciences Centre G-329, Calgary, Alberta, T2N 4N1, Canada.
authors.forename: Sarah A
authors.initials: SA
authors.lastname: Vinette
authors.affiliation: Hotchkiss Brain Institute, University of Calgary, Health Research Innovation Centre, Room 1A10, 3330 Hospital Drive NW, Calgary, Alberta, T2N 4N1, Canada; Seaman Family MR Research Centre, University of Calgary, Foothills Medical Centre, 1403-29 Street NW, Calgary, Alberta, T2N 2T9, Canada.
authors.forename: Shahleen
authors.initials: S
authors.lastname: Premji
authors.affiliation: Hotchkiss Brain Institute, University of Calgary, Health Research Innovation Centre, Room 1A10, 3330 Hospital Drive NW, Calgary, Alberta, T2N 4N1, Canada; Seaman Family MR Research Centre, University of Calgary, Foothills Medical Centre, 1403-29 Street NW, Calgary, Alberta, T2N 2T9, Canada; Department of Neuroscience, University of Calgary, Health Sciences Centre G-329, Calgary, Alberta, T2N 4N1, Canada.
authors.forename: Craig A
authors.initials: CA
authors.lastname: Beers
authors.affiliation: Hotchkiss Brain Institute, University of Calgary, Health Research Innovation Centre, Room 1A10, 3330 Hospital Drive NW, Calgary, Alberta, T2N 4N1, Canada; Seaman Family MR Research Centre, University of Calgary, Foothills Medical Centre, 1403-29 Street NW, Calgary, Alberta, T2N 2T9, Canada.
authors.forename: Ismael
authors.initials: I
authors.lastname: Gaxiola-Valdez
authors.affiliation: Hotchkiss Brain Institute, University of Calgary, Health Research Innovation Centre, Room 1A10, 3330 Hospital Drive NW, Calgary, Alberta, T2N 4N1, Canada; Seaman Family MR Research Centre, University of Calgary, Foothills Medical Centre, 1403-29 Street NW, Calgary, Alberta, T2N 2T9, Canada.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Pittman
authors.affiliation: Hotchkiss Brain Institute, University of Calgary, Health Research Innovation Centre, Room 1A10, 3330 Hospital Drive NW, Calgary, Alberta, T2N 4N1, Canada; Seaman Family MR Research Centre, University of Calgary, Foothills Medical Centre, 1403-29 Street NW, Calgary, Alberta, T2N 2T9, Canada; Department of Neuroscience, University of Calgary, Health Sciences Centre G-329, Calgary, Alberta, T2N 4N1, Canada.
authors.forename: Edward G
authors.initials: EG
authors.lastname: Slone
authors.affiliation: Hotchkiss Brain Institute, University of Calgary, Health Research Innovation Centre, Room 1A10, 3330 Hospital Drive NW, Calgary, Alberta, T2N 4N1, Canada; Department of Clinical Neurosciences, University of Calgary, Foothills Medical Centre, Room 1195, 1403-29 Street NW, Calgary, Alberta, T2N 2T9, Canada; Seaman Family MR Research Centre, University of Calgary, Foothills Medical Centre, 1403-29 Street NW, Calgary, Alberta, T2N 2T9, Canada; Department of Radiology, University of Calgary, Foothills Medical Centre, Room 813, North Tower, 1403-29 Street NW, Calgary, Alberta, T2N 2T9, Canada; Department of Psychiatry, University of Calgary, 1403-29 Street NW, Calgary, Alberta, T2N 2T9, Canada.
authors.forename: Bradley G
authors.initials: BG
authors.lastname: Goodyear
authors.affiliation: Hotchkiss Brain Institute, University of Calgary, Health Research Innovation Centre, Room 1A10, 3330 Hospital Drive NW, Calgary, Alberta, T2N 4N1, Canada; Department of Clinical Neurosciences, University of Calgary, Foothills Medical Centre, Room 1195, 1403-29 Street NW, Calgary, Alberta, T2N 2T9, Canada; Seaman Family MR Research Centre, University of Calgary, Foothills Medical Centre, 1403-29 Street NW, Calgary, Alberta, T2N 2T9, Canada; Department of Neuroscience, University of Calgary, Health Sciences Centre G-329, Calgary, Alberta, T2N 4N1, Canada; Department of Radiology, University of Calgary, Foothills Medical Centre, Room 813, North Tower, 1403-29 Street NW, Calgary, Alberta, T2N 2T9, Canada. Electronic address: pfederic@ucalgary.ca.
authors.forename: Paolo
authors.initials: P
authors.lastname: Federico
mesh_terms: D000293:Adolescent; D000328:Adult; D001921:Brain / Q000098:blood supply / Q000000981:diagnostic imaging / Q000503:physiopathology*; D001931:Brain Mapping; D002560:Cerebrovascular Circulation / Q000502:physiology; D004569:Electroencephalography; D004828:Epilepsies, Partial / Q000000981:diagnostic imaging / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D010100:Oxygen / Q000097:blood; D012640:Seizures / Q000000981:diagnostic imaging / Q000503:physiopathology*
chemical_list: D010100:Oxygen
keywords: Epilepsy; Functional magnetic resonance imaging (fMRI); Hemodynamic; Pre-ictal; Seizures