Abstracts

Rationale: Epilepsy represents a network disorder of the brain. Seizures are driven from the primary epileptic focus, and epileptic activities are transported to the vicinity or far remote structures, resulting in evolution of seizures. Existing brain networks contribute to this “transportation” system. Epilepsy clinicians should thus understand the anatomical and physiological connections between structures with which clinical expressions are associated. However, the brain has abundant neuronal fibers and complicated connections between multiple structures. Individual neuronal systems such as somatosensory, language, and memory circuits do not exist independently, but interact with each other. For these reasons, clinical physicians who are not experts in neuroanatomy or neurophysiology simply look for isolated epileptic foci, but may not interpret the entire network involved in seizure activities. In addition, medical students and beginners in neurology may avoid learning about epilepsy because of such difficult-to-understand features of neuronal networks and mechanisms. Illustration-based description may facilitate a good understanding of such complicated networks. Just like a metropolitan transportation map that people use to find their way to a destination, readily accessible material would be helpful to interpret the brain network disorders of epilepsy. The present project focuses on reviewing and understanding anatomical and functional connections between structures associated with symptoms of seizures, and creating an easy-to-grasp connection map in the epileptic brain similar to a subway map of a metropolitan city (Subway map of Epileptogeni-City).Methods: We selected and plotted responsible brain structures and functional systems involved in some specific seizure patterns, such as limbic seizures, sensori-motor seizures, and parieto-occipital seizures, on a blank brain map. Those structures/systems were then connected by lines from anatomical and clinical perspectives. Individual structures/systems corresponded to names of a station/hub, and connection lines were called “seizure lines” on the subway map if multiple stations were linked with a single line, suggesting a specific seizure pattern.Results: For example, limbic seizures can be called the “Limbic line”, consisting of stations named “Hippocampus”, “Amygdala”, “Parahippocampal Gyrus”, “Entorhinal Cortex”, “Cingulate Gyrus”, etc. Seizures often involve multiple networks, resulting in transformation of clinical symptoms. For instance, autonomic or visceral sensations are typically followed by motor symptoms (e.g., asymmetric dystonic postures) in temporal lobe epilepsy. A transition of seizure symptoms can be defined as a transfer from the “Limbic line” to the “Sensori-motor line” on the map, where “Putamen”, “Thalamus”, and “Cingulate Cortex” are indicated as transfer-available stations.Conclusions: At this time, we have only described a limited number of major “seizure lines” and “stations” on the map. In the future, the map will be filled out and revised with new information. The complete form of the map should prove helpful in clinical application, as well as for educational purposes.