Functional and structural brain networks during epileptic spikes in human brain

© 2020 Magdalena Alicja KowalczykAccurate localisation of the brain region responsible for the seizure onset is a critical step for refractory epilepsy patients to gain access to surgical treatment. In this work, EEG, functional MRI and diffusion-weighted MRI were used to enhance the current understanding of functional and structural properties of brain networks involved in epileptic activity in patients with refractory focal epilepsy. The findings of the studies included in this thesis support the view that epilepsy is a network disorder, and epileptic activity is organised in a complex network. This work showed that results from simultaneous EEG-fMRI studies can have a critical impact on patient management, including influencing the decision for targeted surgical resection, with good subsequent seizure outcomes. Preforming EEG-fMRI studies in patients with frequent spikes during inpatient video-EEG monitoring, while on reduced or withdrawn antiepileptic medications, may lead to a much higher proportion of successful cases. Similarly, automatic spike detection method can improve detection of epileptic spikes in scalp EEG recordings, significantly shorten the analysis time, and enhance the statistical power of EEG-fMRI analysis, revealing additional elements of the patient’s epileptic networks. This work proved that the addition of spike variability information into standard fMRI analysis of the EEG-fMRI data allows for better localisation of the origin of epileptic activity and its spread across the network. In addition, investigating the structural connections that may underlie functional networks can enhance the current understanding of the propagation pathways used by epileptic activity. This work demonstrated the utility of advanced analysis methods in the investigation of refractory epilepsy. Advanced neuroimaging techniques can better localise the epileptic onset and propagation of epileptic activity. Combination of information from different diagnostic modalities bridges the gap between neurophysiology (EEG) and imaging (MRI) of epilepsy and may be a useful adjunct to the presurgical assessment of refractory epilepsy