DYNAMIC STATISTICAL PARAMETRIC MAPPING (dSPM) OF MEG IN EPILEPTIC PATIENTS OF ICTAL AND SUBCLINICAL DISCHARGES
Abstract number :
2.224
Submission category :
Year :
2003
Submission ID :
3679
Source :
www.aesnet.org
Presentation date :
12/6/2003 12:00:00 AM
Published date :
Dec 1, 2003, 06:00 AM
Authors :
H. Shiraishi, S. Knake, V.A. Carr, D.M. Foxe, K. Hara, P.E. Grant, E. Halgren, S.M. Stufflebeam Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital/ Harvard Medical School, Charlestown, MA; Department of Pediatrics, Teine K
Ictal recordings are crucial in the presurgical evaluation of patients with focal epilepsies. In MEG, interictal discharges (IIDs) are typically used for determining the irritative zone in these patients . Recent MEG studies have focused on ictal events using equivalent current dipoles (ECDs) fitting by analyzing only the beginning of the seizure. We previously presented a new MEG evaluation technique called dynamic statistical parametric mapping (dSPM) for the analysis for the patients with symptomatic localization related epilepsy (SLRE) at the AES in 2002 describing the use of dSPM to analyze the epileptic activity in patients with widespread spikes and slow waves. Furthermore, dSPM was used to present the propagation of the epileptic discharges with high spatial and temporal resolution.
In the current study, we present the dSPM analysis for ictal rhythmic spikes and subclinical discharges (SCDs) to visualize the propagation of activity during the events in the patients with SLRE.
MEG was collected with a whole head 306-channel helmet-shaped system (Vectorwiew system; Neuromag Inc., Helsinki, Finland) with simultaneous 64-channel EEG. We calculated dSPM to estimate the spatiotemporal cortical distribution of the ictal activity and the SCDs (Neuron 2000; 26: 55-67).
Four pediatric patients with SLRE were studied: three patients with frontal lobe epilepsy (FLE) and one patient with unclassified focal epilepsy (mean age: 21 years).
Case 1: 28-year-old female with FLE. ID on EEG at the beginning of seizure was described as recruiting rhythmic spikes at the posterior midline area. dSPM presents the ictal onset area at the right posterior cingulate gyrus with rapid propagation to the right lateral frontal lobe and left posterior cingulate region.
Case 2: 17-year-old male with FLE. SCD on EEG were described as bilateral diffuse poly-spike or poly-spike with slow wave. dSPM presents the onset at the right paracentral lobe (precentral gyrus) with rapid propagation to the whole right hemisphere.
Case 3: 21-year-old male with unclassified focal epilepsy. SCD on EEG were described as bilateral diffuse poly-spike burst. dSPM presents the onset of the SCD at the left fusiform gyrus showing rapid propagation to the right anterior cingulate gyrus and left fusiform gyrus within 12 msec.
Case 4: 18-year-old female patient with FLE. SCD on EEG were described as bilateral diffuse poly-spike burst and the seizure onset could not be delineated by EEG. dSPM showed that the onset of the ictal activity originated from the right superior frontal gyrus and rapidly spread to the ipsilateral lateral and medial frontal lobe.
dSPM is a promising new method for detecting the seizure onset even in patients with rapid generalization. dSPM is a useful tool for showing rapid propagation of ictal activity across lobes and it also provides other useful information for the presurgical evaluation.
[Supported by: The MIND Institute]