Est-ce que l'eeg a toujours sa place en 2019? Thomas Bast Epilepsy Center Kork, Germany
Does EEG still play a role in 2019? What a question 7T-MRI, fmri, DTI, MEG, SISCOM, Of ieeg course! /HFO, Genetics EEG
What makes the surface EEG unique? Spatial resolution (mm) Invasiveness 14 12 EEG SPECT www.brightmindinstitue.com 10 8 6 4 2 MEG ieeg fmri PET 0 10-3 10-2 0.1 1 10 100 10 3 10 4 Time resolution (sec)
Surface EEG in clinical epilepsy research Electric source analysis in presurgical evaluation Functional connectivity studies
High-resolution EEG with up to 256 surface electrodes 14 Patients with FLE, 7 resective surgery 76 channel surface EEG vs. ieeg In comparison to conventional EEG, SISCOM Correct lateralization heeg 14/14, ceeg 9/14 Concordant to ieeg heeg 12/14 ceeg 3/14 SISCOM 3/12 Feyissa et al. High density scalp EEG in frontal lobe epilepsy. Epilepsy Res 2017
What is EEG source analysis? or Electric Source Imaging (ESI)? (Geneva) Visual inspection Pattern recognition Spikes are similar Maximum negativity FC5/F3/F7
What is EEG source analysis? Every EEG reviewer builds a hypothesis on the localization of the underlying cortical generator of interictal and/or ictal epileptic activity Quality of this hypothesis depends on experience Source analysis leads to more stable hypotheses and allows for better visualization by MRI co-registration Dipole model L2 minimum norm 8
Success of EEG source localization depends on Optimized individual head model
Success of EEG source localization depends on Optimized individual head model Number of electrodes High-resolution EEG (HR-EEG) or High-density EEG (HD-EEG) Seeck et al. Clin Neurophysiol 2017 Sohrabpour et al. Effect of EEG electrode number on epileptic source localization in pediatric patients. Clin Neurophysiol 201510
Success of EEG source localization depends on Optimized individual head model Number of electrodes High-resolution EEG (HR-EEG) or High-density EEG (HD-EEG) Analysis of spike onset instead of (potentially propagated) peak activity Averaging of similar spikes 11
EEG dipole localization depends on SNR Bast et al., J Clin Neurophysiol 2006
ESI in presurgical evaluation 152 patients, follow-up 1 year, MRI normal in 10 Brodbeck et al. Electroencephalographic source imaging: a prospective study of 152 operated epileptic patients. Brain 2011
ESI in presurgical evaluation Brodbeck et al. Electroencephalographic source imaging: a prospective study of 152 operated epileptic patients. Brain 2011
ESI in presurgical evaluation Brodbeck et al. Electroencephalographic source imaging: a prospective study of 152 operated epileptic patients. Brain 2011
ESI in presurgical evaluation Prospective study in 190 operated patients (TLE 154) Follow-up 1 year, 77.8% seizure free 58 underwent examinations with all methods Lascano et al. Yield of MRI, high-density electric source imaging (HD-ESI), SPECT and PET in epilepsy surgery candidates. Clin Neurophysiol 2016
Source analysis of ictal activity Mégevand & Seek. Electroencephalography, magnetoencephalography and source localization: their value in epilepsy. Curr Opin Neurol 2018
High-frequency oscillations (ripples, 80-250Hz) in 10-20- vs. HD-EEG Kuhnke et al. Brain Topogr 2018
High-frequency oscillations (ripples, 80-250Hz) in 10-20- vs. HD-EEG 13 patients 10-20 vs. 128 channel vs. ieeg 12/13 with ripples Kuhnke et al. High Frequency Oscillations in the Ripple Band (80-250 Hz) in Scalp EEG: Higher Density of Electrodes Allows for Better Localization of the Seizure Onset Zone. Brain Topogr 2018
Surface EEG in clinical epilepsy research Electric source analysis in presurgical evaluation Functional connectivity studies
Resting state functional connectivity - fmri Spontaneous brain activity ~ coherent and correlated fluctuations of activity in specific sets of brain areas Biswal, Yetkin, Haughton, & Hyde, 1995; Damoiseaux et al., 2006; Raichle et al., 2001 Resting state network = areas showing increased and correlated activations at rest ~ correspond spatially to networks associated with specific tasks areas (somatosensory, motor, visual, cognitive, ) ~ correlate with structural connectivity patterns Honey at al. 2009 Coito et al. Directed functional connections underlying spontaneous brain activity. Hum Brain Map 2018
Resting state functional connectivity - fmri Language network Auditory network Default Mode Network = mainly: Posterior cingulate cortex Medial prefrontal cortex Medial temporal regions Inferior parietal cortex Smitha et al. Resting state fmri: A review on methods in resting state connectivity analysis and resting state networks. Neuroradiol J 2017
Functional connectivity analysis: Default Mode Network 5 healthy subjects, 256 channel EEG (204 included), 1000 Hz sampling, 60 * 1 sec. epochs simplified realistic head model (3D-T1) linear distributed inverse solution: LAURA = local auto-regressive averages 82 ROI each subject mean spectral power, normalization (0 1) across regions, time and frequencies (1 40 Hz) by subtracting the minimum power and dividing by the range Estimation of the directed functional connections between source regions by PDC= partial directed coherence Investigation of the directionality of functional brain connections in the frequency domain by Granger-causality approach = weighted PDC Coito et al. Directed functional connections underlying spontaneous brain activity. Hum Brain Map 2018
Functional connectivity analysis: Default Mode Network Coito et al. Directed functional connections underlying spontaneous brain activity. Hum Brain Map 2018
Functional connectivity analysis: Default Mode Network PCC = strongest driver (highest integration and segregation importance), 2 nd = mtl regions Coito et al. Hum Brain Map 2018
Functional connectivity analysis in epilepsy 20 LTLE, 20 RTLE, 20 controls Resting-state HD-EEG recording 96-256 channels, 250-1000Hz in the absence of ED Methods ~ Coito et al. Hum Brain Map 2018 Coito et al. Altered directed functional connectivity in temporal lobe epilepsy in the absence of interictal spikes: A high density EEG study. Epilepsia 2016
Functional connectivity analysis in epilepsy Coito et al. Altered directed functional connectivity in temporal lobe epilepsy in the absence of interictal spikes: A high density EEG study. Epilepsia 2016
Functional connectivity analysis in epilepsy Coito et al. Altered directed functional connectivity in temporal lobe epilepsy in the absence of interictal spikes: A high density EEG study. Epilepsia 2016
Functional connectivity analysis in epilepsy 20 LTLE, 20 RTLE, 20 controls Resting-state HD-EEG recording 96-256 channels, 250-1000Hz in the absence of ED Methods ~ Coito et al. Hum Brain Map 2018 RTLE: epilepsy duration ~ less driving from ipsilateral and contralateral mesiolimbic structures Learning defects or depression ~ lower outflow from anterior cingulum Coito et al. Altered directed functional connectivity in temporal lobe epilepsy in the absence of interictal spikes: A high density EEG study. Epilepsia 2016
Functional connectivity analysis in epilepsy 30 TLE, 31 ETLE, 31 controls MEG global functional connectivity maps Englot et al. Global and regional functional connectivity maps of neural oscillations in focal epilepsy. Brain 2015
Functional connectivity analysis in epilepsy Englot et al. Global and regional functional connectivity maps of neural oscillations in focal epilepsy. Brain 2015
Functional connectivity analysis in epilepsy Englot et al. Global and regional functional connectivity maps of neural oscillations in focal epilepsy. Brain 2015
Functional connectivity analysis in epilepsy 30 TLE, 31 ETLE, 31 controls MEG global functional connectivity maps regional functional connectivity maps at the region of resection compared to the homotopic non-epileptogenic region in the contralateral hemisphere Englot et al. Global and regional functional connectivity maps of neural oscillations in focal epilepsy. Brain 2015
Functional connectivity analysis in epilepsy 111 seizures in 27 patients with postoperative outcome Engel 1 ( 1y) 24h-EEG, 27-32 electrodes ESI plus functional connectivity LORETA, spectrum-weighted Adaptive Directed Transfer Function Staljanssens et al. EEG source connectivity to localize the seizure onset zone with drug resistant epilepsy. Neuroimage Clin 2017
Siniatchkin & Capovilla. Functional neuroimaging in epileptic encephalopathies Epilepsia 2013
Networks in West syndrome Japaridze et al. Neuronal Networks in West Syndrome as Revealed by Source Analysis and Renormalized Partial Directed Coherence. Brain Topogr 2013
Networks in West syndrome Japaridze et al. Neuronal Networks in West Syndrome as Revealed by Source Analysis and Renormalized Partial Directed Coherence. Brain Topogr 2013
CSWS networks Japaridze et al. Neuronal networks in epileptic encephalopathies with CSWS. Epilepsia 2016
CSWS networks Mean follow-up 3 years CSWS resolved Persisting CSWS Japaridze et al. Neuronal networks in epileptic encephalopathies with CSWS. Epilepsia 2016
Summary EEG is THE important diagnostic tool in the management of epilepsy Availability, repeatability High temporal resolution Satisfying spatial resolution Long-term recordings Source analysis of interictal and ictal epileptiform activity is an additional diagnostic tool in presurgical evaluation. The combination with functional connectivity analysis may improve the accuracy. These functional studies can improve our understanding of the pathophysiology of different epileptic syndromes.
tbast@epilepsiezentrum.de