NEURONAL COMPLEXITY LOSS IN INTERICTAL EEG RECORDED WITH FOREMEN OVALE ELECTRODES PREDICTS SIDE OF PRIMARY EPILEPTOGENIC AREA IN TEMPORAL-LOBE EPILEPSY - A REPLICATION STUDY

Purpose: To investigate whether a correct lateralization of the primar y epileptogenic area by means of neuronal complexity loss analysis can be obtained from interictal EEG recordings using semi-invasive forame n ovale electrodes. in a previous study with recordings from intrahipp ocampal depth and subdural strip electrodes it was shown that the dyna mics of the primary epileptogenic area can be characterized by an incr eased loss of neuronal complexity in patients with unilateral temporal lobe epilepsy (TLE). Methods: Neuronal complexity loss analysis was a pplied. This analysis method is derived from the theory of nonlinear d ynamics and provides a topological diagnosis even in cases where no ac tual seizure activity can be recorded. We examined interictal EEG reco rded intracranially from multipolar foramen ovale electrodes in 19 pat ients with unilateral TLE undergoing presurgical evaluation. Results: The primary epileptogenic area was correctly lateralized in 16 of the 19 investigated patients. The misclassification of the side of seizure onset in three patients might be attributed to the larger distance be tween the foramen ovale electrodes and the mesial temporal structures as compared to intrahippocampal depth electrodes. Conclusions: Our res ults confirm the previous findings and provide further evidence for th e usefulness of nonlinear time-series analysis for the characterizatio n of the spatiotemporal dynamics of the primary epileptogenic area in mesial temporal lobe epilepsy.