Federico, PaoloMohammadi, Negar2018-09-272018-09-272018-09-18http://hdl.handle.net/1880/108693Simultaneous EEG-fMRI has been an effective technique for identification of the seizure onset zone (SOZ) in patients with refractory epilepsy. Recent studies have shown that using intracranial electrodes (iEEG) combined with fMRI offers unique insight into changes in blood oxygen-level dependent (BOLD) responses associated with interictal epileptiform discharges (IEDs). However, the concordance level between SOZ and IED-related BOLD clusters has not been quantitatively investigated for different brain structures. This thesis aims to identify patient-specific concordance levels between spike-associated BOLD clusters and IED/SOZ originating from temporal and extra-temporal structures. The distances between the BOLD clusters to IED/SOZ locations were measured for 15 patients with focal refractory epilepsy. The results showed that the spike-generating network was better delineated in patients with temporal discharges compared to those with extra-temporal discharges. Also, we observed shorter distances between the BOLD clusters and the SOZ for mesial temporal lobe seizures compared to frontal lobe seizures. Further investigation into the differences between mesial temporal and frontal structures showed that patients with focal impaired awareness seizures had significantly higher concordance for mesial temporal lobe seizures. This key finding suggests that mesial temporal structures limit spike-associated BOLD activation to the SOZ more than the frontal lobe in patients who have spread of ictal activity to subcortical arousal systems. This mechanistic difference was also complemented by our findings pertaining seizure frequency. Specifically, concordance levels in temporal lobe structures were significantly higher for patients with weekly seizures compared to extra-temporal structures. Based on these findings, we suggest that iEEG-fMRI is a useful technique for identifying seizure onset zone for patients with epileptic spikes and seizures originate in the mesial temporal structures. The work presented in this thesis may assist clinicians to better determine the seizure onset zone, guide epilepsy surgery, and improve post-surgical outcomes for epilepsy patients.engUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.EpilepsyClinical NeuroscienceEEG-fMRIEpileptiform dischargeBOLD responseBrain ImagingEducation--HealthNeuroscienceRadiologyPsychology--Clinicalmaster thesis10.11575/PRISM/33046