Authors :
Presenting Author: Nathan Evans, MPhys – Newcastle University
Sarah Gascoigne, BSc, PGDip – Newcastle University; Fahmida Chowdhury, Bsc, MRCP, PhD – National Hospital for Neurology and Neurosurgery; Jane de Tisi, Ba, Dip – UCL IRIS; Beate Diehl, PhD – UCL Queen Square Institute of Neurology; John Duncan, BM BCh, MA, DM – National Hospital for Neurology and Neurosurgery; Andrew McEvoy, MB BS, BSc Hons, MD – National Hospital for Neurology and Neurosurgery; Anna Miserocchi, MD – Cleveland Clinic London Hospital; Christopher Thornton, PhD – Newcastle University; Peter Taylor, PhD – Newcastle University; Yujiang Wang, PhD – Newcastle University
Rationale:
In focal epilepsy, a holy grail is to identify epileptogenic areas of the brain in each patient. The seizure onset zone (SOZ) has been an accepted proxy for the epileptogenic areas. However, to date, a systematic quantitative analysis of the spatial patterns in SOZs across a range of seizures in each patient is lacking.
Methods:
Diffusion MRI (dMRI) and intracranial EEG (27 subjects, 388 seizures) were retrospectively analyzed. Ictal activity was algorithmically determined using a seizure imprint algorithm (see Gascoigne et al., 2023), from which we defined the spatial patterns of onset for each seizure. White matter connections were calculated from dMRI in subject space. For each subject and seizure, we tested if onset regions are contiguous in terms of grey matter, or connected through a white matter connection.
Results:
Seizure onsets are shown to be contiguous in grey matter only in a minority of subjects (5/27), whilst additionally integrating white matter connections connects all onset regions for all seizures in more than half of the subjects (16/27).
Additionally, the mean percentage of connected seizure onset regions for each subject was increased from 68% when only using contiguous in grey matter links to 94% by combining grey and white matter connections.
Conclusions:
We have shown that spatial patterns of onset are often linked across both grey and white matter. Neither can account for spatial patterns of onset when used in isolation. These findings are significant as they highlight the necessity of combining different types of neural connections when defining seizure onsets.
Funding: Epilepsy Research UK, UKRI fellowship