The goal of this observational study is to evaluate the effectiveness of Magnetoencephalography (MEG) in the preoperative assessment of children with refractory epilepsy, particularly in identifying the seizure focus, and to compare it with the gold standard methods of Stereo-electroencephalography (SEEG) and Electrocorticography (ECoG). The main questions this study aims to answer are: 1. How consistent is MEG with SEEG/ECoG in locating the epileptic focus in children with refractory epilepsy? 2. What is the clinical efficacy of MEG in identifying epileptic foci? Participants will: 1. Be divided into 2 groups: the case group and the control group. Participants in the case group will undergo both MEG and SEEG/ECoG for preoperative assessment, while patients in the control group will undergo only SEEG/ECoG before surgery. 2. Be followed up at 1, 3, 6, and 12 months after surgery to assess seizure control, neurological function, and quality of life.