Combining Non-Invasive Procedures for Presurgical Focus Localisation in Epilepsy.
Abstract number :
3.179
Submission category :
Year :
2001
Submission ID :
276
Source :
www.aesnet.org
Presentation date :
12/1/2001 12:00:00 AM
Published date :
Dec 1, 2001, 06:00 AM
Authors :
R. Wiest, MD, Neurology; K. Schindler, MD, PhD, Neurology; D. Hubl, MD, Psychiatric Neurophysiology; M. Wissmeyer, MD, Nuclear Medicine; M. Kollar, REEGT, Neurology; K. Loevblad, MD, Neuroradiology; T. Dierks, MD, PhD, Psychiatric Neurophysiology; F. Dona
RATIONALE: During the last decade, functional imaging techniques have become powerful tools to precisely localise an epileptogenic focus. Ictal SPECT studies co-registered to structural MRI (SISCOM) may help to enhance the sensitivity of focus localisation. Furthermore, if interictal spikes are recorded with scalp EEG, detection of local changes in blood oxygenation by EEG-triggered functional MRI (fMRI) and 3D-EEG source localisation provide additional non-invasive information about the epileptogenic focus. In this study, we investigated the combined use of SISCOM, fMRI and 3-D-EEG in the presurgical evaluation of patients with partial epilepsies.
METHODS: We have evaluated 9 patients with refractory partial epilepsies originating from the temporal lobe (7 pts.), frontal lobe (1 pt.) and occipital lobe(1 pt.) MRI revealed no structural abnormalities in 4 patients, 3 patients showed mesiotemporal sclerosis, 1 patient posttraumatic damage of the anterior temporal lobe, and 1 patient nodular heterotopia in the temporooccipital region. All 9 patients received detailed neurological evaluation, structural MRI, video-EEG monitoring, ictal and interictal CBF-SPECT using Tc-99m-ECD. 6 patients underwent semiinvasive foramen ovale (Fo) EEGs. In 2 patients who displayed interictal epileptiform activity during seizure-free epochs, we performed EEG-correlated functional MRI imaging (multi single slice echoplanar imaging) and 3D-EEG source localisation (low resolution tomography, LORETA with 32-channel EEG). SPECT co-registration to MRI and fMRI data analysis was performed using the brain voyager 2000 software package (Brain Innovation), normalisation of the SPECT data was done with MATLAB (Mathworks Inc.).
RESULTS: In 7 patients with ictal tracer injection SISCOM localised the epileptogenic focus concordant with standard EEGs and semi-invasive Fo-EEGs. In one patient SISCOM failed due to postictal injection. The regions of hyperperfusion during SPECT analysis in 2 patients (one with true ictal SPECT and one with interictal SPECT vs. baseline paradigm) correlated with the region of focal BOLD signal changes in fMRI and the 3D distribution in LORETA. The results were supported by the semi-invasive Fo- and video-EEG analysis.
CONCLUSIONS: Functional imaging methods (SISCOM and fMRI) may provide helpful information about the localisation of an epileptogenic focus in partial epilepsies. Hyperperfusion during ictal and spike-related SPECT studies correlate with the BOLD signal changes in fMRI in selected patients.
Support: This work was partially supported by the Swiss National Foundation for Science SNF No 31-55298.98