Diffusion Tensor Imaging in Epilepsy With Continuous Spikes and Waves During Sleep

Continuous Spikes and Waves during Sleep (CSWS) is a rare paediatric epileptic encephalopathy. Even if the correlation between the severity of the epilepsy and the cognitive consequences is well established, the mechanisms involved in epileptic cognitive degradation are complex and poorly understood. In CSWS, there are many arguments for the implication of cortical and subcortical cerebral structures. Among them the thalamus seems to play a crucial role. In fact it is strongly implicated in the sleep and this function is determining for learning. Moreover, it is part of the propagation pathway of generalized forms of epilepsy like absences in animal studies. Unfortunately there is no animal model for CSWS to confirm this theory. In human studies, few cases are caused by thalamic injuries but most of the time conventional MRI is normal. Despite few literature on CSWS, some studies reported abnormal functional connectivity especially in the thalamus. The investigators hypothesize that the first utilisation of diffusion tensor imaging (DTI) and tractography will be useful in CSWS to confirm the implication of a cortico-thalamo-cortical network showing an abnormal structural connectivity. The investigators will try to determinate if a particular thalamic nucleus is concerned and demonstrate a link between the disease severity (duration and cognitive consequences) and the importance of structural abnormalities. Using resting state functional MRI (fMRI), the investigators will also try to investigate the default mode network. Its implication was also suggested in the literature.