Clinical Application of Functional Brain Cortical Mapping Using Magnetoencephalography and Electroencephalography

我们开发了一种MRI连接的全头脑磁图(MEG)系统，作为一种非侵入性功能脑图的工具。采用头盔形66道脑磁图系统，对20例健康受试者、80例颅内结构病变患者和4例顽固性癫痫患者进行全头部磁场测量，首先测量体感诱发电场(SEF)、听觉诱发电场(AEF)和视觉诱发磁场(VEF)。我们使用多偶极子模型定位了上述大脑活动的生成器，每个受试者的头部都有一个最适合的球体。最后，将偶极子叠加在3D-MRI上。SEF用于正中神经和胫神经刺激定位对侧中央沟。声调的AEF定位于双侧上颞面。VEF定位于刺激半视野对侧的距骨裂。脑电地形图和脑电地形图分别测量了癫痫患者的发作间期放电，其中2例为双侧偶极子模式。这些偶极图案在中线上相互重叠。双偶极子模型估计了双侧新皮质、单侧新皮质和对侧内侧颞叶结构或双侧内侧颞叶结构中的“棘波”或“波状”偶极子。另2例仅在单侧大脑半球出现单偶极子图形，这些棘波或波状冬极子出现在一个叶内。整个头部脑磁图系统有助于定位多灶性癫痫放电，以及评估两个大脑半球之间的信号传播。综上所述，脑磁图以非侵入性的方式定位皮质功能，具有极高的空间分辨率，这一点得到了我们的MRI连接系统的证实。这项技术对常规神经外科和血管内神经外科以及立体定向放射外科很有用。

We developed a MRI-linked whole head magnetoencephalography (MEG) system as a tool of non-invasive functional brain mapping. In 20 healthy subjects, 80 patients with intracranial structural lesions and 4 patients with intractable seizures, neuromagnetic fields were measured over the entire head, using a helmet shaped 66 channel MEG system.First, we measured somatosensory evoked field (SEF), auditory evoked field (AEF), and visually evoked field (VEF). We localized generators of above brain activities, using a multiple dipole model with a best-fitting sphere for each subject's head. Finally, the dipoles were superimposed on 3-D MRI.SEF for median and tibial nerve stimuli localized the contralateral central sulcus. AEF for tones localized bilateral superior temporal planes. VEF localized calcarine fissure contralateral to the stimulated half visual field. Positions of the sources were precisely on the responsible cortical surface, with standard deviation of 2-4 mm, either with or without structural lesions.Second, in patients with epilepsy, interictal epileptic discharges were measured by means of both MEG and EEG.We observed two dipole patterns bilaterally in two cases. These dipolar patterns overlap each other across the midline. A two dipole model estimated "spike" or "wave" dipoles in bilateral neocortices, unilateral neocortex and contralateral mesial temporal structure, or bilateral mesial temporal structures. In the other 2 cases, single dipole pattern appeared on unilateral hemisphere only ; these spike or wave hipoles were estimated within one lobe. The whole head MEG system is useful to localize multifocal epileptic discharges, as well as to evaluate signal propagation between bilateral hemispheres.In summary, MEG localized cortical function non-invasively, with exceptionally high spatial resolution confirmed by our MRI-linked system. This technique was useful for conventional and intravascular neurosurgery, as well as for stereotaxic radiosurgery.