脑磁图与视频脑电图定位癫痫灶的结果比较

背景: 多数癫痫患者的癫痫发作经药物治疗可得到控制,但对于难治性癫痫患者来说,手术可能是一种治疗选择,正确定位癫痫患者的致痫灶是癫痫手术成功的基础.癫痫患者的术前评估包括视频脑电图、MRI、正电子发射计算机体层摄影/单光子发射计算机体层摄影和神经心理测试等.脑磁图作为一种新的无创性术前检测技术,已被许多国家用于癫痫外科手术计划和大脑功能的研究.目的:术前采用磁源成像技术进行对手术治疗的难治性癫痫患者进行致痫灶定位,并与无创性视频脑电图对比,参考手术效果,评估其定位价值.设计、时间及地点:回顾性病例分析,于2001-11/2005-12在广东三九脑科医院脑磁图室完成.对象:选择进行脑磁图检查618例的癫痫患者,采集其自发磁场信号进行单偶极子定位分析诊断.对其中149例MRI检查有结构改变、病史在2年以上者进行了手术治疗,病程2～35年,平均9.5年.方法:用148通道全头型脑磁系统(Magnes WH2500, 4-D Neuroimaging, San Diego, CA, USA)在磁屏蔽室采集脑自发磁场,采样频率为508.63 Hz,带通为1.0～100 Hz,采集30 min发作间歇期的自发脑磁,采用单个等效电流偶极子进行数据分析.分析结果最后重叠在MRI-T1加权像上,形成磁源成像.主要观察指标:术前视频脑电图、MRI和脑磁图结果及术后随访结果.结果:30 min发作间期的脑磁图检测到明显的癫痫样活动的敏感度为91%,并且大部分患者,其等效偶极子主要分布于结构性异常的边缘和邻近区域.与无创性视频脑电图(38.9%,58/149)相比,利用脑磁图可以对大部分MRI上有病变的患者(62.4%,93/149)进行精确定位并且能够确定切除区域.对资料完整的89 例患者进行了3～35个月的随访,平均随访9个月.89例患者中有72例(80.9%)术后未出现癫痫发作(EngelⅠ);7例(7.9%)癫痫发作极少或癫痫发作频率减少90%以上(Engel Ⅱ和 Engel Ⅲ);10例(11.2%)癫痫发作频率无明显减少(Engel Ⅳ和Engel Ⅴ),总有效率达88.8%(EngelⅠ～Ⅲ).结论:与无创性视频脑电图相比,利用脑磁图可以对大部分MRI上出现结构性病变的癫痫患者致痫灶进行精确定位,并且能够确定切除区域.

Comparison of epileptogenic focus localization using magnetoencephalography and video electroencephalogram

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.