Project 463540

Approximately 80,000 Canadians suffer from epilepsy with uncontrolled seizures that medication is unable to prevent. Their best chance at attaining seizure freedom is the identification and surgical removal of the brain areas generating the seizures. To identify these areas, the current clinical gold standard is scalp or intracranial EEG, which use scalp or implanted electrodes to measure epileptic discharges in the brain during a lengthy hospitalization lasting days to weeks. However, as scalp or implanted electrodes can only detect epileptic discharges in very limited areas of the brain, these techniques often fail to delineate the full extent of seizure-generating brain areas, leading to poor surgical success. Thus, there is a pressing need for better diagnostic tools to localize seizure-generating brain areas, ideally without requiring a costly long-term hospitalization. One such promising technique is resting-state fMRI, which can map activity across the whole brain in a single scanning session. We have observed that the measured fMRI activity in epilepsy patients dynamically fluctuates when epileptic discharges occur and thus propose to use these fluctuations to differentiate seizure-generating brain areas from healthy tissue. We will study 60 epilepsy patients undergoing intracranial EEG as part of the standard clinical investigation to identify a surgical target. By acquiring resting-state fMRI concurrently with intracranial EEG, we will be able to demonstrate that the observed dynamic fMRI fluctuations are indeed linked with the occurrence of epileptic discharges and therefore that they are good diagnostic indicators of epileptic brain areas. This proposal will establish resting-state fMRI as a time- and cost-effective method to delineate brain areas generating epileptic seizures. This method will be widely applicable in other centres, leading to better future outcomes for epilepsy patients.