Abstract: Objective To investigate the value of synthetic aperture magnetometry (SAM) in localizing motor cortex and epileptogenic focus for brain lesions near the central sulcus and to clear its advantage in the localization. Methods 12 patients (6 patients with epilepsy) were enrolled in this study. Before the operation, the patients were all taken Karnofsky Performance Status Score (KPS), examined with MEG by SAM technique in the localization of motor cortex and epileptogenic focus to determine their position relationship, and guide the scheme of surgery programme. During the operation, the location of hand-motor functional area were identified with evoked potential monitoring awaking test, and epileptogenic focus with electrocorticogram (ECoG) monitoring. The accuracy of location was assessed with the hand movement and KPS score, and the epileptic attack were evaluated with Engel curative effect grading. They were followed up for 2 years. Results The motor cortex of all the patients were located near the precentral gyrus with SAM and the localization of epileptogenic focus in 6 patients by SAM was consistent with that by ECoG. All the operations were based on and guided by the SAM. After the operations, the motor function and KPS score of 8 patients improved. No extra functional lesions happened in all patients. Epilepsy was well controlled in 5 cases. Conclusion SAM can correctly localize the motor cortex and epileptogenic focus. Meanwhile position relationship between the intracranial lesions and motor functional areas and epileptic focus can be clear. It is a valuable method for surgical planning and epilepsy controlling and will decrease the occurrence of neurological deficits after operation.

Key words: magnetoencephalography, synthetic aperture magnetometry, motor cortex, epilepsy, epileptogenic focus