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Title: Haemodynamic correlates of interictal and ictal epileptic discharges and ictal semiology using simultaneous scalp video-EEG-fMRI and intracranial EEG-fMRI
Author: Chaudhary, U. J.
Awarding Body: University College London (University of London)
Current Institution: University College London (University of London)
Date of Award: 2013
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Interictal and ictal epileptic discharges are produced by focal and widespread dysfunctional neuronal networks. Identification and characterization of epileptic discharges underlie the diagnosis and the choice of treatment for epilepsy patients. A better knowledge of the generation, propagation and localisation of epileptic discharges, and their interaction with the physiological and pathological brain networks can be very helpful in planning epilepsy surgery and minimizing the risk of damaging the physiological brain networks. This work describes a number of methodological developments and novel applications investigating the epileptic networks in humans using EEG-fMRI. First, I implemented synchronized video recording inside the MRI-scanner during simultaneous EEG-fMRI studies, which did not deteriorate the imaging and EEG data quality. Secondly, I used video recordings to identify physiological activities to be modelled as confounds in the functional imaging data analysis for interictal activity, thus increasing the sensitivity of video-EEG-fMRI. Thirdly, I applied this modelling approach to investigate seizure related functional networks in patients with focal epilepsy. Video recordings allowed partitioning seizures into phases separating the ictal onset related functional networks from propagation related networks. Localisation of the ictal onset related networks may be useful in the planning for epilepsy surgery in a selected group of patients, as demonstrated by their comparison with intracranial-EEG recordings. Further, I investigated haemodynamic changes during preictal period which suggested recruitment of an inhibitory followed by an excitatory network prior to the ictal onset on scalp EEG. In the next step, I used simultaneous intracranial-EEG-fMRI in patients undergoing invasive evaluation, demonstrating that local and remote networks associated with very focal interictal discharges recorded on intracranial-EEG may predict the surgical outcome. Finally, I investigated the interaction of epileptic discharges with the working memory, using scalp video-EEG-fMRI, showing that the presence of epileptic activity may alter the working memory related networks. Methodological constraints, clinical applications and future perspectives are discussed.
Supervisor: Lemieux, L. ; Duncan, J. S. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available