Ictal and interictal electric source imaging in pre‐surgical evaluation: a prospective study

Sharma, Pawan Kumar; Scherg, Michael; Pinborg, Lars H.; Fabricius, Martin; Rubboli, Guido; Pedersen, Birthe; Leffers, Anne-Mette; Uldall, Peter; Jespersen, Bo; Brennum, Jannick; Henriksen, Otto Mølby; Beniczky, Sándor

doi:10.1111/ene.13676

Cited by 57 publications

(63 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…In another study based on low‐density EEG (19 channels), ESI reached a 65% concordance . Another study using also low‐density EEG obtained a localization accuracy of 51% and 62% using two different inverse solution methods, which was similar to other conventional neuroimaging methods (structural MRI, PET, and SPECT) . In our study, the percentage of concordance with the presumed EZ using ESI reached 90% in TLE and 57% in ETLE.…”

Section: Discussionsupporting

confidence: 79%

“…7 Another study using also low-density EEG obtained a localization accuracy of 51% and 62% using two different inverse solution methods, which was similar to other conventional neuroimaging methods (structural MRI, PET, and SPECT). 31 In our study, the percentage of concordance with the presumed EZ using ESI reached 90% in TLE and 57% in ETLE. The differences in the results may be explained by methodologic differences between the studies: different forward models (here, we used a sophisticated realistic head model including six compartments-scalp, bone, cerebral spinal fluid [CSF], gray matter, white matter, air) and inverse solutions.…”

Section: F I G U R Esupporting

confidence: 46%

See 1 more Smart Citation

Interictal epileptogenic zone localization in patients with focal epilepsy using electric source imaging and directed functional connectivity from low‐density EEG

et al. 2019

View full text Add to dashboard Cite

Summary Objective Electrical source imaging ( ESI ) is used increasingly to estimate the epileptogenic zone ( EZ ) in patients with epilepsy. Directed functional connectivity ( DFC ) coupled to ESI helps to better characterize epileptic networks, but studies on interictal activity have relied on high‐density recordings. We investigated the accuracy of ESI and DFC for localizing the EZ , based on low‐density clinical electroencephalography (EEG) . Methods We selected patients with the following: (a) focal epilepsy, (b) interictal spikes on standard EEG, (c) either a focal structural lesion concordant with the electroclinical semiology or good postoperative outcome. In 34 patients (20 temporal lobe epilepsy [TLE] , 14 extra‐TLE [ETLE ]), we marked interictal spikes and estimated the cortical activity during each spike in 82 cortical regions using a patient‐specific head model and distributed linear inverse solution. DFC between brain regions was computed using Granger‐causal modeling followed by network topologic measures. The concordance with the presumed EZ at the sublobar level was computed using the epileptogenic lesion or the resected area in postoperative seizure‐free patients. Results ESI, summed outflow, and efficiency were concordant with the presumed EZ in 76% of the patients, whereas the clustering coefficient and betweenness centrality were concordant in 70% of patients. There was no significant difference between ESI and connectivity measures. In all measures, patients with TLE had a significantly higher ( P < 0.05) concordance with the presumed EZ than patients with with ETLE. The brain volume accepted for concordance was significantly larger in TLE . Significance ESI and DFC derived from low‐density EEG can reliably estimate the EZ from interictal spikes. Connectivity measures were not superior to ESI for EZ localization during interictal spikes, but the current validation of the localization of connectivity measure is promising for other applications.

show abstract

Section: Discussionsupporting

confidence: 79%

Section: F I G U R Esupporting

confidence: 46%

Interictal epileptogenic zone localization in patients with focal epilepsy using electric source imaging and directed functional connectivity from low‐density EEG

et al. 2019

View full text Add to dashboard Cite

show abstract

“…Nevertheless, these results do not necessarily mean that imperfect spatial sampling precludes source localization. Even with < 32 electrodes, source localization allows to gain valuable insight about the underlying sources, particularly in applications with well-defined focal activity such as epileptic spikes (15, 58–60).…”

Section: Number and Positioning Of The Electrodesmentioning

confidence: 99%

“…On the other hand, if too many dipoles are assumed, spurious sources will be introduced. Nevertheless, dipole source localization can produce reasonable results under some particular conditions (12), in particular in localizing the irritative zone in focal epilepsy (13–15) or the localization of primary sensory areas in evoked potentials, such as the sensorimotor cortex in surgical candidates (16). Dipole source localization is still widely used in the MEG community for these clinical applications (17).…”

Section: Introductionmentioning

confidence: 99%

EEG Source Imaging: A Practical Review of the Analysis Steps

2019

View full text Add to dashboard Cite

The electroencephalogram (EEG) is one of the oldest technologies to measure neuronal activity of the human brain. It has its undisputed value in clinical diagnosis, particularly (but not exclusively) in the identification of epilepsy and sleep disorders and in the evaluation of dysfunctions in sensory transmission pathways. With the advancement of digital technologies, the analysis of EEG has moved from pure visual inspection of amplitude and frequency modulations over time to a comprehensive exploration of the temporal and spatial characteristics of the recorded signals. Today, EEG is accepted as a powerful tool to capture brain function with the unique advantage of measuring neuronal processes in the time frame in which these processes occur, namely in the sub-second range. However, it is generally stated that EEG suffers from a poor spatial resolution that makes it difficult to infer to the location of the brain areas generating the neuronal activity measured on the scalp. This statement has challenged a whole community of biomedical engineers to offer solutions to localize more precisely and more reliably the generators of the EEG activity. High-density EEG systems combined with precise information of the head anatomy and sophisticated source localization algorithms now exist that convert the EEG to a true neuroimaging modality. With these tools in hand and with the fact that EEG still remains versatile, inexpensive and portable, electrical neuroimaging has become a widely used technology to study the functions of the pathological and healthy human brain. However, several steps are needed to pass from the recording of the EEG to 3-dimensional images of neuronal activity. This review explains these different steps and illustrates them in a comprehensive analysis pipeline integrated in a stand-alone freely available academic software: Cartool. The information about how the different steps are performed in Cartool is only meant as a suggestion. Other EEG source imaging software may apply similar or different approaches to the different steps.

show abstract

“…Scalp EEG recordings, using the standard 25-electrode array of the International Federation of Clinical Neurophysiology [ 5 ] showed build-up of rhythmic 4–5 Hz ictal activity in the basal temporal area, 8–37 s after the clinical onset. Both interictal and ictal EEG source imaging, using the methodology previously validated in a large prospective study [ 6 ] localised to the left antero-mesial temporal area ( Fig. 1 A).…”

Section: Case Reportmentioning

confidence: 99%

Somatosensory phenomena elicited by electrical stimulation of hippocampus: Insight into the ictal network

Merinder

Rásonyi

Tsiropoulos

et al. 2020

Epilepsy & Behavior Reports

View full text Add to dashboard Cite

Up to 11% of patients with mesial temporal lobe epilepsy experience somatosensory auras, although these structures do not have any somatosensory physiological representation. We present the case of a patient with left mesial temporal lobe epilepsy who had somatosensory auras on the right side of the body. Stereo-EEG recording demonstrated seizure onset in the left mesial temporal structures, with propagation to the sensory cortices, when the patient experienced the somatosensory aura. Direct electrical stimulation of both the left amygdala and the hippocampus elicited the patient's habitual, somatosensory aura, with afterdischarges propagating to sensory cortices. These unusual responses to cortical stimulation suggest that in patients with epilepsy, aberrant neural networks are established, which have an essential role in ictogenesis.

show abstract

Ictal and interictal electric source imaging in pre‐surgical evaluation: a prospective study

Abstract: The II-ESI and IC-ESI of LTM data have high feasibility and their localization accuracy is similar to that of conventional neuroimaging methods.

Cited by 57 publications

References 25 publications

Interictal epileptogenic zone localization in patients with focal epilepsy using electric source imaging and directed functional connectivity from low‐density EEG

Interictal epileptogenic zone localization in patients with focal epilepsy using electric source imaging and directed functional connectivity from low‐density EEG

EEG Source Imaging: A Practical Review of the Analysis Steps

Somatosensory phenomena elicited by electrical stimulation of hippocampus: Insight into the ictal network

Contact Info

Product

Resources

About