Spatio-temporal spike dynamics predict surgical outcome in adult focal epilepsy

Objective: We hypothesized that spatio-temporal dynamics of interictal spikes reflect the extent and stability of epileptic sources and determine surgical outcome.Methods: We studied 30 consecutive patients (14 good outcome). Spikes were detected in prolonged stereo-electroencephalography recordings. We quantified the spatio-temporal dynamics of spikes using the variance of the spike rate, line length and skewness of the spike distribution, and related these features to outcome. We built a logistic regression model, and compared its performance to traditional markers.Results: Good outcome patients had more dominant and stable sources than poor outcome patients as expressed by a higher variance of spike rates, a lower variance of line length, and a lower variance of positive skewness (ps < 0.05). The outcome was correctly predicted in 80% of patients. This was better or non-inferior to predictions based on a focal lesion (p = 0.016), focal seizure-onset zone, or complete resection (ps > 0.05). In the five patients where traditional markers failed, spike distribution predicted the outcome correctly. The best results were achieved by 18-h periods or longer.Conclusions: Analysis of spike dynamics shows that surgery outcome depends on strong, single and stable sources.Significance: Our quantitative method has the potential to be a reliable predictor of surgical outcome.(c) 2021 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.

Automated summary

The spatio-temporal dynamics of interictal spikes are closely related to the extent and stability of epileptic sources, and can determine the surgical outcome. By analyzing the variance of spike rates, line length, and skewness of the spike distribution, it is possible to predict the outcome of patients more accurately.