VISUALIZATION OF INTERICTAL SPIKES AS MEASURED WITH SUBDURAL EEG ELECTRODES USING FUNCTIONAL MAGNETIC IMAGING ( fMRI)
Abstract number :
1.239
Submission category :
Year :
2002
Submission ID :
1458
Source :
www.aesnet.org
Presentation date :
12/7/2002 12:00:00 AM
Published date :
Dec 1, 2002, 06:00 AM
Authors :
Stephan Arnold, L. Jaeger, M. Reiser, Peter Winkler, Soheyl Noachtar. Neurology, University of Munich, Munich, Germany; Radiology, University of Munich, Munich, Germany; Neurosurgery, University of Munich, Munich, Germany
RATIONALE: Functional Magnetic resonance Imaging (fMRI) using Echo-planar imaging (EPI) and the BOLD effect can detect regional activation during interictal spikes in focal epilepsy. We investigated whether interictal activity as documented by subdural EEG electrodes but not detected by concomitant surface EEG electrodes can elicit regional BOLD activation.
METHODS: Three patients with temporal lobe epilepsies were investigated prior to resective epilepsy surgery. All patients had subdural electrodes covering the temporal lobe of seizure onset and additional surface electrodes. EEG was recorded using the [dsquote]EMR[dsquote] EEG amplifier (Schwarzer GmbH, Munich, Germany) and BrainLab software (OSG, Rumst, Belgium). EEG-artefacts due to MRI aquisition were eliminated based on MATLAB software (Math Works, Inc., Natrick, Massachusetts). MRI was performed using a 1.5 T whole body MR system (`Vision`, Siemens, Erlangen, Germany). Images were obtained during [dsquote]baseline[dsquote] (without interictal temporal spikes recorded on subdural or surface electrodes) and during interictal spiking as documented by subdural EEG. The interictal activity was not detected at the surface electrodes in all patients. The localization and frequency of interictal spikes before and during MRI aquisition was registered using offline artefact-elimination and analysis. Only episodes without additional spiking during MRI aquisition periods were used for further analysis using the `Analysis of Functional NeuroImages` (AFNI) software.
RESULTS: Activation maps revealed significant regional hyperperfusion of 8 % corresponding to the localization of the temporal lobe spikes in two of the three patients.
CONCLUSIONS: We demonstrate that interictal epileptiform discharges recorded with subdural EEG electrodes but not detected by concomitant surface electrodes are sufficient to elicit regional fMRI activation.