Abstracts

Rationale: Alterations to structural and functional brain networks have been reported across many neurological conditions. However, the relationship between structure and function—their coupling—is relatively unexplored, particularly in the context of an intervention. Epilepsy surgery alters the brain structure and networks to control the functional abnormality of seizures. Given that surgery is a structural modification aiming to alter the function, we hypothesized that stronger structure-function coupling, in the area to be resected, preoperatively is associated with a greater chance of post-operative seizure control._x000D_ _x000D_ Methods: We constructed structural and functional brain networks in 39 subjects with medication- resistant focal epilepsy using multimodal data from intracranial EEG (iEEG) recordings (pre-surgery), structural MRI (pre-and post-surgery), and diffusion-weighted MRI (pre-surgery). We investigated pre- operative structure-function coupling at two spatial scales: (a) at the global iEEG network level and (b) at the resolution of individual iEEG electrode contacts using “virtual surgeries.” By incorporating these structure-function coupling metrics and routine clinical variables in a cross-validated predictive model, we benchmarked their added value to predict seizure outcomes._x000D_ _x000D_ Results: At a global network level, seizure-free individuals had stronger structure-function coupling pre- operatively than those that were not seizure-free regardless of the choice of interictal segment or frequency band. At the resolution of individual iEEG contacts, the virtual surgery approach provided complementary information to localize epileptogenic tissues. In predicting seizure outcomes, structure- function coupling measures were more important than clinical attributes, and together they predicted seizure outcomes with an accuracy of 85% and sensitivity of 87%._x000D_ _x000D_ Conclusions: The underlying assumption that the structural changes induced by surgery translate to the functional level to control seizures is valid when the structure-functional coupling is strong. Mapping the regions that contribute to structure-functional coupling using virtual surgeries may help aid surgical planning._x000D_ _x000D_ Funding: NS acknowledges funding from NINDS R01NS116504 and Research Excellence Academy, Newcastle University, UK. PNT was supported by the Wellcome Trust (105617/Z/14/Z and 210109/Z/18/Z) and UKRI Future Leaders Fellowship (MR/T04294X/1). YW was supported by the Wellcome Trust (208940/Z/17/Z) and UKRI Future Leaders Fellowship (MR/V026569/1). KD acknowledges funding from NINDS R01NS116504. JD and SBV were funded by the UCLH NIHR BRC. Scan acquisition and GPW were supported by the MRC (G0802012, MR/M00841X/1). We acknowledge support from the Epilepsy Society. This work was supported by the National Institute for Health Research University College London Hospitals Biomedical Research Centre. The authors acknowledge the facilities and scientific and technical assistance of the National Imaging Facility, a National Collaborative Research Infrastructure Strategy (NCRIS) capability, at the Centre for Microscopy, Characterisation, and Analysis, the University of Western Australia.