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，作为一种非侵入性脑功能制图工具。选取20例健康受试者、80例颅内结构性病变患者和4例难治性癫痫患者，采用头盔形66通道MEG系统测量全头部神经磁场。首先测量体感诱发场（SEF）、听觉诱发场（AEF）和视觉诱发场（VEF）。我们对上述大脑活动的产生器进行了定位，使用了一个多偶极子模型，并为每个受试者的头部提供了一个最合适的球体。最后，在三维MRI上叠加偶极子。SEF用于正中和胫骨神经刺激定位对侧中央沟。音调定位于双侧颞上平面的AEF。VEF将calcarine裂隙定位在受刺激的半视野的对侧。无论有无结构性病变，病灶的位置都精确地位于相应的皮质表面，标准差为2-4 mm。其次，在癫痫患者中，通过MEG和EEG同时测量癫痫发作间期放电。在两种情况下，我们观察到两种偶极子模式。这些偶极图案在中线上相互重叠。双偶极子模型估计双侧新皮层、单侧新皮层和对侧颞内侧结构或双侧颞内侧结构的“尖峰”或“波”偶极子。另外2例仅在单侧半球出现单偶极子模式；这些尖峰或波极是在一个叶内估计的。整个头部MEG系统可用于定位多灶性癫痫放电，以及评估双脑半球之间的信号传播。总之，我们的mri连接系统证实了MEG非侵入性定位皮质功能，具有异常高的空间分辨率。这项技术对常规和血管内神经外科手术以及立体定向放射外科手术都很有用。

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.