The Dynamic BOLD Signal Changes During Children Absence Seizures

Object:Our research investigated the dynamic BOLD signal changes of children patients suffering from classical absence seizures when their brain network switches from a normal EEG background to the highly synchronized activity pattern, to illustrate the common trends of the process of dynamic BOLD signal changes, and further, to investigate the foundational mechanism of classical absence epilepsy.Methods:In this study, we analyzed the temporal-spatial profile during absence seizure in seven drug-naive absence epilepsy patients using EEG-fMRI technique. Combining with their clinical manifests to mark the time point of onset and ending of three per second GSWDs, then to profile the event-related BOLD signal in the whole brain temporally.Results:Our seven patients were all observed classical absence seizures during EEG-fMRI scanning. After statistical analysis, when plotted against time, our limited time course analysis showed that the BOLD response in the involved network started to increase at least8s before the onset of GSW. The peak of BOLD signal increase was within2s prior to GSW onset, within consideration of the normal delay between the neuronal discharge and the hemodynamic response. During three per second GSW paroxysms, bilateral negative BOLD signal changes were seen in most of the involved regions. Then, during2,4,6s after GSW, no BOLD signal changes was observed in the brain map. Meanwhile, variable cortex, basal ganglia and thalamus are involved in the absence network, and the activations of cortex and basal ganglia are earlier than that of thalamus.Conclusions:According to our researches, the BOLD signal preceding electric discharges represents that there is a hemodynamic transitional period in the cortical-thalamo-ganglia network as it changes from normal physiologic state to neurologic dysfunction. The concurrently involvement of multiple structures suggests a systemic mechanism for the initialization of absence seizures.