Frontiers in Neurology (Dec 2016)
Spatiotemporal mapping of interictal spike propagation: a novel methodology applied to pediatric intracranial EEG recordings.
Abstract
Synchronized cortical activity is implicated in both normative cognitive functioning andmany neurological disorders. For epilepsy patients with intractable seizures, irregular patterns ofsynchronization within the epileptogenic zone (EZ) is believed to provide the network substratethrough which seizures initiate and propagate. Mapping the EZ prior to epilepsy surgery is critical fordetecting seizure networks in order to achieve post-surgical seizure control. However, automatedtechniques for characterizing epileptic networks have yet to gain traction in the clinical setting.Recent advances in signal processing and spike detection have made it possible to examine thespatiotemporal propagation of interictal spike discharges across the epileptic cortex. In this study, wepresent a novel methodology for detecting, extracting, and visualizing spike propagation anddemonstrate its potential utility as a biomarker for the epileptogenic zone. Eighteen pre-surgicalintracranial EEG recordings were obtained from pediatric patients ultimately experiencing favorable(i.e., seizure-free, n = 9) or unfavorable (i.e., seizure-persistent, n = 9) surgical outcomes. Novelalgorithms were applied to extract multi-channel spike discharges and visualize their spatiotemporalpropagation. Quantitative analysis of spike propagation was performed using trajectory clusteringand spatial autocorrelation techniques. Comparison of interictal propagation patterns revealed anincrease in trajectory organization (i.e., spatial autocorrelation) among Sz-Free patients compared toSz-Persist patients. The pathophysiological basis and clinical implications of these findings areconsidered.
Keywords
