Effect of EEG electrode number on epileptic source localization in pediatric patients

Abstract

Objective To investigate the relationship between EEG source localization and the number of scalp EEG recording channels. Methods 128 EEG channel recordings of 5 pediatric patients with medically intractable partial epilepsy were used to perform source localization of interictal spikes. The results were compared with surgical resection and intracranial recordings. Various electrode configurations were tested and a series of computer simulations based on a realistic head boundary element model were also performed in order to further validate the clinical findings. Results The improvement seen in source localization substantially decreases as the number of electrodes increases. This finding was evaluated using the surgical resection, intracranial recordings and computer simulation. It was also shown in the simulation that increasing the electrode numbers could remedy the localization error of deep sources. A plateauing effect was seen in deep and superficial sources with further increasing the electrode number. Conclusion The source localization is improved when electrode numbers increase, but the absolute improvement in accuracy decreases with increasing electrode number. Significance Increasing the electrode number helps decrease localization error and thus can more ably assist the physician to better plan for surgical procedures.

Imaging brain source extent from EEG/MEG by means of an iteratively reweighted edge sparsity minimization (IRES) strategy

“…Additionally, it would be interesting to study the effect of electrode number on solution precision (within the new framework). While there are several studies suggesting that increasing the number of electrodes helps improve source localization results significantly (Brodbeck et al, 2011; Lantz et al, 2003; Michel et al, 2004a; Sohrabpour et al, 2015; Srinivasan et al, 1998), determining the relation between the number of electrodes and solution precision awaits future experimentation. Whether plateauing effects will be observed as suggested by Sohrabpour et al (Sohrabpour et al, 2015) or not, can only be determined after further investigations (specifically in clinical data).…”

Combined EMD-sLORETA Analysis of EEG Data Collected during a Contour Integration Task

“…Localization accuracy increases in a non-linear fashion with the number of electrodes, and estimates indicate that probably no less than 500 electrodes would be needed for an accurate sampling of the surface potential distribution [31, 32]. But it has also been pointed out recently that the absolute improvement in accuracy decreases with the number of electrodes [33]. Bayesian approaches, have been reviewed recently [34], allow to compare several models and indicate that spatial localization precision in the milimeter range can be achieved reliably.…”

High density EEG—What do we have to lose?

“…In this issue of Clinical Neurophysiology, Sohrabpour et al evaluate source localization accuracy of 4 electrode configurations in a case series of 5 pediatric patients with high density EEG and individual MRIs using electrocorticography recordings and surgical resections with good outcome to measure accuracy (Sohrabpour et al, 2014). These authors conclude that increasing electrode number decreases localization error, though this improvement plateaus.…”