Brainmapping Neuronal Networks in Children with Continuous Spikes and Waves during Slow Sleep as revealed by DICS and RPDC
CSWS is an age-related epileptic encephalopathy consisting of the triad of seizures, neuropsychological impairment and a specific EEG-pattern. This EEG-pattern is characterized by spike-and-wave-discharges emphasized during non-REM sleep. Until now, little has been known about the pathophysiologic processes. So far research approaches on the underlying neuronal network have been based on techniques with a good spatial but poor temporal resolution like fMRI and FDG-PET. In this study the search for sources participating in the neuronal network of CSWS is done by processing EEG-data with high temporal resolution. This allows not only interferences on the location of the individual sources but also on the direction of information flow between them. DICS is applied to the data to solve the inverse problem in the frequency domain. Afterwards RPDC, based on Granger causality, is implemented to reveal effective connectivity between the sources. 12 patients suffering from CSWS without any proof for macroscopic cerebral pathologies in a T1-MRI were investigated at two points of time, before and after treatment. All results are compared to other studies on the neuronal network of CSWS, to knowledge about genesis of epileptic activity in general and to knowledge about the pathogenesis of related psychiatric syndromes. During the active phase of CSWS the thalamus represents the central hub of the neuronal network, and also the cerebellum and key nodes of the DMN contribute to it. Therefore the results are concordant to the ones of former studies and to assumptions on the genesis of epileptic activity. In addition, pathogenetic parallels are found to autism, ADHD and memory-impairment. After cessation of CSWS, the network consists of exclusively cortical sources. In addition to the SWI the mean absolute source power, the mean coherence strength and the mean RPDC strength could be revealed as reliable indicators for the severity of the encephalopathy.