Mapping hemodynamic correlates of seizures using fMRI: A review

Abstract

Functional magnetic resonance imaging (fMRI) is able to detect changes in blood oxygenation level associated with neuronal activity throughout the brain. For more than a decade, fMRI alone or in combination with simultaneous EEG recording (EEG-fMRI) has been used to investigate the hemodynamic changes associated with interictal and ictal epileptic discharges. This is the first literature review to focus on the various fMRI acquisition and data analysis methods applied to map epileptic seizure-related hemodynamic changes from the first report of an fMRI scan of a seizure to the present day. Two types of data analysis approaches, based on temporal correlation and data driven, are explained and contrasted. The spatial and temporal relationship between the observed hemodynamic changes using fMRI and other non-invasive and invasive electrophysiological and imaging data is considered. We then describe the role of fMRI in localizing and exploring the networks involved in spontaneous and triggered seizure onset and propagation. We also discuss that fMRI alone and combined with EEG hold great promise in the investigation of seizure-related hemodynamic changes non-invasively in humans. We think that this will lead to significant improvements in our understanding of seizures with important consequences for the treatment of epilepsy.

Altered brain rhythms and functional network disruptions involved in patients with generalized fixation-off epilepsy

“…These same areas have been found negatively correlated with alpha and beta in control subjects (Laufs 2008;Mantini et al 2007). This result is not surprising taking into account that this patient has absences related to 3Hz-spike and waves discharges, which have been related in the literature with deactivation of default mode network (Chaudhary et al 2013). It is also interesting to mention that the pattern of and through single-ICA in patient 1 (middle row) and patient 2 (bottom row).…”

Altered physiological brain variation in drug‐resistant epilepsy

“…For epilepsy patients, functional magnetic resonance imaging (fMRI) has been used to localize language areas in the brain via task activations studies and imaging at resting state as well as to evaluate surgical outcomes (Chaudhary, Duncan, & Lemieux, 2013; Constable et al., 2013; van Graan, Lemieux, & Chaudhary, 2015; Lee, Smyser, & Shimony, 2013; Pittau, Ferri, Fahoum, Dubeau, & Gotman, 2017; Proulx et al., 2014; Robinson et al., 2017; Tracy & Doucet, 2015). FMRI combined with simultaneous electroencephalography (EEG‐fMRI) has become a useful tool in mapping frequent epileptiform activity in the form of spikes and seizure activity (Abela et al., 2013; Gotman, 2008; Jacobs et al., 2009; Moeller et al., 2009; Pittau et al., 2017).…”

Epileptic network of hypothalamic hamartoma: An EEG-fMRI study

“…In addition, it possibly predicts postsurgical outcome non-invasively although its clinical utility in comparison with other techniques, e.g. ictal SPECT, has been not determined (Chaudhary et al, 2013). With these in mind, we expected EEG-fMRI to clarify the common brain networks associated with subcortical epileptogenesis/encephalopathy in HH patients.…”