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Abteilung Prächirurgische Epilepsiediagnostik – EpilepsiezentrumKlinik für Neurochirurgie

Source imaging of epileptic activity

Source imaging aims at reconstructing the electromagnetic brain activity that gives rise to recordable electrical potentials fields at electrodes of scalp EEG or magnetic fields to be picked up by ultra-sensitive coils of magnetocephalography systems. Conductivity profiles based on the patient’s individual anatomy, recording systems with a high spatial sensor density and modern approaches to model focal and distributed generators made source reconstruction of epileptic activity a valuable asset in presurgical epilepsy diagnostics.

High-density scalp recordings with up to 256 channels prior to the intracranial EEG diagnostics are the basis for high accuracy source reconstruction of epileptic spikes with established and novel inverse modelling algorithms e.g. methods that are able to reconstruct the spatial extent of epileptic activity.

Acquisition of brain activity with intracranial electrodes offers unique opportunities for the validation of source imaging results. They are further extended by simultaneous acquisition of scalp EEG. A one by one analysis of scalp and intracranial EEG signals in brain regions that contain generators of epileptic activity opens an optimal environment for mutual validation studies.

Within the European Reference Network Epicare we further participate in the PROMAESIS trial (PI: Sandor Beniczky, Epilepsy Center Dianalund, Denmark) that prospectively evaluates automatic source imaging algorithms of interictal and ictal epileptic activity.

Current lines of research:

Extension of source localization approaches from scalp EEG to ECoG recordings at the brain surface

Ramantani G, Cosandier-Rimélé D, Schulze-Bonhage A, Maillard L, Zentner J, Dümpelmann M. Source reconstruction based on subdural EEG recordings adds to the presurgical evaluation in refractory frontal lobe epilepsy. Clinical Neurophysiology 124 (2013): 481–491.

Dümpelmann M., Ball T and Schulze-Bonhage, A, sLORETA allows reliable distributed source reconstruction based on subdural strip and grid recordings. Human Brain Mapping. 2012; 33:1172–1188.

Dümpelmann M, Fell J, Wellmer J, Urbach H, Elger CE. 3D source localization derived from subdural strip and grid electrodes: A simulation study. Clin Neurophysiol. 2009, 120(6):1061-9.

 

Mutimodal simulation, imaging and inverse modelling

Cosandier-Rimélé D, Ramantani G, Zentner J, Schulze-Bonhage A, Dümpelmann M. A realistic multimodal modeling approach for the evaluation of distributed source analysis: application to sLORETA. Journal of Neural Engineering, (2017) Oct;14(5):056008.

Heers M, Hedrich T, An D, Dubeau F, Gotman J, Grova C, Kobayashi E. Spatial correlation of hemodynamic changes related to interictal epileptic discharges with electric and magnetic source imaging. Hum Brain Mapp. 2014 Sep;35(9):4396-414. doi: 10.1002/hbm.22482. Epub 2014 Feb 24.

 

Reconstructing the spatial extent of epileptic activity

Heers M, Chowdhury RA, Hedrich T, Dubeau F, Hall JA, Lina JM, Grova C, Kobayashi E. Localization Accuracy of Distributed Inverse Solutions for Electric and Magnetic Source Imaging of Interictal Epileptic Discharges in Patients with Focal Epilepsy. Brain Topogr. 2016 Jan;29(1):162-81. doi: 10.1007/s10548-014-0423-1. Epub 2015 Jan 22.

 

Source imaging of seizure activity

Epitashvili N, Schulze-Bonhage A, Dümpelmann M. Localization accuracy of ictal source reconstruction investigated with scalp EEG and validated by simultaneous iEEG. 2016 American Epilepsy Society Annual Meeting, Houston, TX, USA.

Epitashvili N, Schulze-Bonhage A, Dümpelmann M. Source localization of ictal epileptic activity in patients with focal epilepsy validated with invasive EEG. Poster Award: 12th European Congress on Epileptology, Prague, Czech Republic, 2016.

To learn more about source imaging in epilepsy:

https://neuroimage.usc.edu/brainstorm/Tutorials/Epilepsy

Abteilung Prächirurgische Epilepsiediagnostik

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Ärztlicher Leiter:
Prof. Dr. Schulze-Bonhage
Breisacher Str. 64
D-79106 Freiburg
Telefon: 0761 270 53660
Telefax: 0761 270 50030
E-Mail: epilepsiezentrum@uniklinik-freiburg.de