Magnetoencephalography Guides Proton Magnetic Resonance Spectroscopy to Areas of Metabolite Abnormalities in Frontal Lobe Epilepsy
Abstract number :
1.237
Submission category :
Year :
2001
Submission ID :
2005
Source :
www.aesnet.org
Presentation date :
12/1/2001 12:00:00 AM
Published date :
Dec 1, 2001, 06:00 AM
Authors :
J.J. Shih, M.D., Neurology, University of New Mexico, Albuquerque, NM; M.P. Weisend, Ph.D., Radiology, VA Medical Center, Albuquerque, NM; R.R. Lee, M.D., Radiology, VA Medical Center, Albuquerque, NM
RATIONALE: Magnetoencephalography (MEG) can detect interictal spike foci. We have previously shown in patients with temporal lobe epilepsy that these spike foci indicate areas of neuronal cell loss or dysfunction as demonstrated by proton magnetic resonance spectroscopy (MRS). We report our preliminary experience using MEG to guide proton MRS to areas of neuronal dysfunction in frontal lobe epilepsy (FLE).
METHODS: Power analysis suggests nineteen subjects are needed to detect a statistical difference in metabolite ratios. Our preliminary analysis consists of fifteen consecutive patients meeting inclusion criteria. Inclusion criteria include seizure semiology consistent with FLE, MRI documenting the absence of structural lesions outside the frontal lobes, and concordant EEG findings. Patients were studied with a whole-head 122-channel biomagnetometer. Interictal spikes were identified by offline analysis, with realistic head model algorithms used for spike localization. Single-voxel proton MRS obtained metabolite ratios in the MEG spike zone and the contralateral homologous region. Statistical analysis used paired T-tests.
RESULTS: Ten patients had lower N-acetylaspartate (NAA)/(choline(cr) + creatine (cr)) ratios in the MEG spike zones when compared to the contralateral homologous region. The NAA/(cho+cr) ratio was 0.95 [plusminus] 0.19 for the MEG spikes zones and 1.11 [plusminus] 0.28 for the contralateral homologous regions (p=0.09).
CONCLUSIONS: Our preliminary data shows a trend for MEG spike foci to identify areas of significant neuronal loss or dysfunction in frontal lobe epilepsy.
Support: NIH/NCRR 3 M01 RR00997-25S3.