John Libbey Eurotext

Understanding the pathophysiology of reflex epilepsy using simultaneous EEG-fMRI Volume 16, issue 1, March 2014

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Authors
1 Cognitive Neuroscience Center, National Institute of Mental Health, Neuro Science (NIMHANS)
2 Dept of Neuroimaging and Interventional Radiology, National Institute of Mental Health and Neuro Science (NIMHANS)
3 Dept of Neurology, National Institute of Mental Health and Neuro Science (NIMHANS), Bangalore, India
* Correspondence: Rose Dawn Bharath Cognitive Neuroscience Center and Dept of Neuroimaging and Interventional Radiology, National Institute of Mental Health and Neuro Science (NIMHANS), Hosur Road, Bangalore 560029, India

Measuring neuro-haemodynamic correlates in the brain of epilepsy patients using EEG-fMRI has opened new avenues in clinical neuroscience, as these are two complementary methods for understanding brain function. In this study, we investigated three patients with drug-resistant reflex epilepsy using EEG-fMRI. Different types of reflex epilepsy such as eating, startle myoclonus, and hot water epilepsy were included in the study. The analysis of EEG-fMRI data was based on the visual identification of interictal epileptiform discharges on scalp EEG. The convolution of onset time and duration of these epilepsy spikes was estimated, and using these condition-specific effects in a general linear model approach, we evaluated activation of fMRI. Patients with startle myoclonus epilepsy experienced epilepsy in response to sudden sound or touch, in association with increased delta and theta activity with a spike-and-slow-wave pattern of interictal epileptiform discharges on EEG and fronto-parietal network activation pattern on SPECT and EEG-fMRI. Eating epilepsy was triggered by sight or smell of food and fronto-temporal discharges were noted on video-EEG (VEEG). Similarly, fronto-temporo-parietal involvement was noted on SPECT and EEG-fMRI. Hot water epilepsy was triggered by contact with hot water either in the bath or by hand immersion, and VEEG showed fronto-parietal involvement. SPECT and EEG fMRI revealed a similar fronto-parietal-occipital involvement. From these results, we conclude that continuous EEG recording can improve the modelling of BOLD changes related to interictal epileptic activity and this can thus be used to understand the neuro-haemodynamic substrates involved in reflex epilepsy.