Combining magnetic resonance imaging and electroencephalography in the investigation of interictal epileptic spikes

Interictal spikes are spontaneous neuronal discharges that occur between epileptic seizures, and that constitute a specific marker of epilepsy. The topic of our doctoral research is to localize in a noninvasive manner the regions of the brain responsible for generating the spikes. Such information is of great interest in the presurgical evaluation for pharmacoresistant epilepsy.In this context, we have studied the possibility of using a combination of two techniques, namely electroencephalography (EEG) and magnetic resonance imaging (MRI). Specifically, we have investigated three tracks for the combination of EEG and MRI.First, anatomical information from MRI can be used for improving EEG source localization. Our example is the modelling of postsurgical brain and skull defects, which affect the conductive properties of the head.Second, the EEG can be recorded inside the MR scanner and thereby allows the investigation of spontaneous epileptic spikes with functional MRI (fMRI). We evaluated the quality of EEG within the scanner, and measured the spatial and temporal fMRI response to spikes.Third, the information from the two modalities can be combined in order to benefit from both the good spatial resolution of fMRI and the excellent temporal resolution of EEG. We have proposed to build statistical maps for EEG source localization in order to identify common areas of activation in EEG and fMRI