Neural Fragility of the Intracranial EEG Network Decreases after Surgical Resection of the Epileptogenic Zone

Abstract

Over 15 million patients with epilepsy worldwide do not respond to medical therapy and may benefit from surgical treatment. In cases of focal epilepsy, surgical treatment requires complete removal or disconnection of the epileptogenic zone (EZ). However, despite detailed multimodal pre-operative assessment, surgical success rates vary and may be as low as 30% in the most challenging cases. Here we demonstrate that neural fragility, a proposed dynamical networked-system biomarker of epileptogenicity decreases following successful surgical resection. Moreover, neural fragility increases or does not change when seizure-freedom is not achieved. We demonstrate this in a virtual patient with epilepsy using the Virtual Brain neuroinformatics platform, and then subsequently on six children with epilepsy with pre- and post-resection intra-operative recordings. Furthermore, we provide a theoretical analysis of neural fragility. Finally, we compare neural fragility as a putative biomarker of epileptogenicity against established spectral metrics, such as high frequency oscillations and find that neural fragility is a superior biomarker of epileptogencity.

Diagnosing Epilepsy with Normal Interictal EEG Using Dynamic Network Models

“…Both methods were validated across multiple epilepsy centers and developed in the Sarma lab. 24,25,32…”

“…Both methods were validated across multiple epilepsy centers and developed in the Sarma lab. 24,25,32 Neural fragility is a concept related to the underlying dynamics of epileptic networks and the emergence of seizures. Specifically, it suggests that the onset of focal seizures may be related to the presence of a few fragile nodes, which render the epileptic network unstable and susceptible to seizure activity.…”