COMPARISON OF INTERICTAL MEG AND ICTAL SPECT IN THE PRESURGICAL EPILEPSY EVALUATION
Abstract number :
2.220
Submission category :
Year :
2003
Submission ID :
479
Source :
www.aesnet.org
Presentation date :
12/6/2003 12:00:00 AM
Published date :
Dec 1, 2003, 06:00 AM
Authors :
Dalia Miller, Jorge Burneo, Roy C. Martin, Avinash Prasad, R. Edward Faught, Richard Morawetz, Ruben I. Kuzniecky, Robert C. Knowlton Department of Neurology, University of Alabama, Birmingham, AL; Division of Neurosurgery, University of Alabama, Birmingh
Patients without an unequivocal epileptogenic lesion identified on MRI remain a large challenge in presurgical epilepsy evaluations. Ictal single photon emission computed tomography (SPECT) and magnetoencephalography (MEG) are both established interictal noninvasive neuroimaging tools that can aid the goal of localization for surgery. However, the value of these imaging modalities in patients with non-localizing MRI (normal, questionable or ambiguous abnormalities) is unclear.
Thirty consecutive patients with refractory partial epilepsy and non-localizing MRI were evaluated between September 2001 and January 2003 as part of a presurgical evaluation at the University of Alabama at Birmingham Epilepsy Center. MEG was recorded with a 148 channel whole-head system with simultaneous scalp EEG using the standard International System of electrode placement. Epileptiform spikes and sharp waves were analyzed with a single equivalent current dipole model. Ictal SPECT was performed with injections (within 30 seconds of seizure onset) of 20-40 mCi of 99mTc-hexylmethylene phenyloxaloacetae (HMPAO).
The mean age of the patients was 20 years (range: 1.4 to 48 years, 13 female). Concordance information regarding localization was obtained in 17 patients for both interictal MEG and ictal SPECT. Negative interictal MEG results (no epileptiform discharges recorded) were present in seven cases, and ictal SPECT studies were reported as normal in three patients. Discordant information regarding lateralization was found in three patients. In 22 patients interictal MEG, and in 26 patients ictal SPECT, localized the epileptogenic focus.
Interictal MEG can provide reliable non-invasive localization data when MRI is non-localizing and ictal SPECT cannot be obtained.
[Supported by: NIH K-23 NS02218-01, RCK
EFA Clinical Epilepsy Fellowship, JB]