High-resolution electroencephalographic forward modeling in traumatic brain injury using the finite element method

Localization of electrical brain activity via electroencephalography (EEG) remains a challenging task in traumatic brain injury (TBI) patients, partly due to the complexity of structural brain changes resulting from neurological insult. When localizing EEG-recorded brain activity, the failure to account for pathology-related changes in tissue conductivities may cause forward model inaccuracies which translate into large localization errors. Here, the effects of TBI-related pathology upon the accuracy of the EEG forward matrix are explored in the context of a realistic finite element method (FEM) model of the head with 25 tissue types. It is found that the omission of TBI pathology from the anatomical model can lead to substantial inaccuracies in the calculation of the forward matrix, with EEG lead field focality being underestimated by as much as ~90% if TBI-related conductivity changes are ignored. Our study is the first to rigorously quantify the extent to which TBI-related pathology can affect forward EEG calculations.