Mapping of Seizure Networks

Intracranial electroencephalography (iEEG) is used to localize the seizure onset zone (SOZ) and connected neuronal networks in surgical candidates suffering from intractable focal epilepsy. Identification of the SOZ is usually based on visual inspection of iEEG signals, but new computer-based quantitative iEEG analyses are being developed to improve and expedite SOZ detection. Two main questions arise. First, which signal features are the best proxys to identify the SOZ and the propagation pathways constituting epileptic networks? Second, how can the results of data analysis be represented in a clinically useful and meaningful manner? This chapter adopts an epileptogenicity mapping approach based on maps of ictal high-frequency oscillations superimposed on neuroanatomy and illustrates the main concepts underlying mapping of seizure networks. Future quantitative iEEG approaches should complete and operationalize understanding of seizure networks. Quantitative neuroimaging of iEEG features of seizures should help provide better presurgical assessment of patients undergoing resective surgery.