MAGNETOENCEPHALOGRAPHY IN EPILEPTIC PATIENTS WITH WIDESPREAD SPIKE OR SLOW WAVE ACTIVITY
Abstract number :
3.195
Submission category :
Year :
2002
Submission ID :
3402
Source :
www.aesnet.org
Presentation date :
12/7/2002 12:00:00 AM
Published date :
Dec 1, 2002, 06:00 AM
Authors :
Hideaki Shiraishi, Seppo P. Ahlfors, Steven M. Stufflebeam, Kyoko Takako, Susanne Knake, Shinji Saitoh, Eric Halgren. Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital/Harvard Medical School, Charlestown, MA; Department o
RATIONALE: Epilepsy can manifest itself as a focal or diffuse discharge. Traditionally, epileptic discharges are modeled as single equivalent current dipole (ECD) with EEG or magnetoencephalography (MEG). This model, however, fails to characterize diffuse discharges. We examined whether widespread iterictal discharges (IIDs) of epileptic patients can be adequately mapped using a new analysis technique, dynamic statistical parametric mapping (dSPM), from MEG recordings, thereby extending the applicability of MEG to a larger population of epileptic patients.
METHODS: MEG was collected with a 204-channel helmet-shaped system (Vectorwiew system; 4-D Neuroimaging Inc., San Diego, CA) with simultaneous EEG. We made dynamic statistical parametric maps to estimate the cortical distribution of IIDs (Neuron 2000; 26: 55-67).
We also underwent single-photon emission CT (SPECT) in interictal period using 99mTc-HMPAO with a triple detector gamma camera (GCA-9300; Toshiba Medical Inc., Tokyo, Japan).
RESULTS: We studied two pediatric patients with symptomatic localization-related epilepsy. One patient had widespread spikes at Fp1, F3, C3, F8, Fz, and Cz as IIDs in EEG with complex gestural automatism seizure with a post-operative scar from a resection of a brain tumor in the left frontal lobe. The other had widespread left hemispheric slow-wave activity as IIDs in EEG with complex partial seizure accompanied by sensory auras in right arm and leg. In the patient with widespread spikes, the major activity at the peak of the spikes occurred at the vicinity of the post-operative scar in the left frontal lobe on dSPM. In the patient with hemispheric slow waves, the most active area was located in the left parietal lobe and additional activity was seen in the ipsilateral temporal and frontal lobes. The source estimates correlated well with the ictal clinical manifestation and interictal SPECT findings for this patient.
CONCLUSIONS: We suggest that by means of dSPM, MEG is useful as a diagnostic tool, not only for patients with localized epileptiform activity, but also for patients with widespread spikes or slow waves.
[Supported by: The MIND Institute]