Comparison of epileptogenic focus localization using magnetoencephalography and video electroencephalogram
10.3969/j.issn.1673-8225.2009.35.043
- VernacularTitle:脑磁图与视频脑电图定位癫痫灶的结果比较
- Author:
Ping ZHANG
;
Ruoqiu WU
- Publication Type:Journal Article
- From:
Chinese Journal of Tissue Engineering Research
2009;13(35):6991-6994
- CountryChina
- Language:Chinese
-
Abstract:
BACKGROUND: A considerable number of epilepsy patients cannot be treated sufficiently by drug. Epilepsy surgery is a treatment option in these cases. However, precisely localizing epileptogenic zone in epileptic patients is a successful element of epilepsy surgery. Its goal is to remove a minimum volume to control the seizures without cognitive impairment. Presurgical evaluation typically involves electroencephalogram (EEG), video-EEG monitoring, magnetic resonance imaging (MRI), single photon emission computed tomography and neuropsychological testing. Magnetoencephalography (MEG) has been as a noninvasive technique to be used to epilepsy surgical planning and brain functional study in many countries.OBJECTIVE: To preoperatively localize epileptogenic zone in patients with lesion-associated epilepsy using magnetoencephalography, compare with noninvasive video-EEG, and assess its localizing value according to the surgical outcomes. DESIGN, TIME AND SETTING: A retrospective case analysis was performed at the Magnetoencephalography Laboratory, Guangdong 999 Brain Hospital, China between November 2001 and December 2005.PARTICIPANTS: A total of 618 epileptic patients undergoing magnetoencephalography. Spontaneous magnetic field signal was collected to analyze single dipole location. Of them, 149 patients with MRI-documented epilepsy underwent surgery. The history of disease was at least 2 years. The course of disease ranged 2-35 years, with an average of 9.5 years. METHODS: MEG was recorded by a 148-channels whole head type MEG system (Magnes WH2500, 4-D Neuroimaging, San Diego, CA, USA) in Magnetically Shielded Room (MSR, Germany). Sampling rate: 508.63 Hz, 30-minutes interictal MEG (Bandpass: 1.0-100 Hz). For magnetic source imaging, the nasion and preauricular points were applied as fiducials. Single equivalent current dipole (ECDs) and head sphere model were applied for analysis. Estimated ECDs were overlaid on T1-weighted MRI of each subject.MAIN OUTCOME MEASURES: Preoperative MEG, MRI, and video-EEG and postoperative follow-up were measured. RESULTS: The sensitivity of the interictal MEG for detecting epileptiform activity was found in 91% of the patient. In most cases, the equivalent dipoles were mainly distributed over the border and neighborhood of the structural lesions. By MEG, we were able to localize the resected region in a greater proportion of patients (62.4%, 93/149) than with noninvasive vedio-EEG (38.9%, 58/149) in all patients with MRI-documented lesions. A total of 89 patients were followed up from 3-35 months, averagely 9 months. Of the 89 patients, 72 patients (80.9%) had no postoperative seizures (EngelⅠ); 7 (7.9%) cases obtain Engel Ⅱ and Engel Ⅲ outcomes. Favorable outcomes were not seen in 10 patients (11.2%) cases (Engel Ⅳ and Engel Ⅴ). Total effective rate was 88.8% (EngelⅠ-Ⅲ). CONCLUSION: MEG is not only most useful for presurgical planning in epilepsy patients with MRI-documented lesions, but is also a noninvasive method to identify the spatial relationship between the lesion and epileptogenic zone, a precise localization of the epileptogenic zone is correlated to a favorable outcome.
