This chapter highlights the importance of the revised analysis of electroencephalography (EEG) and magnetoencephalography (MEG) spike source estimation based on comprehensive case conference discussion. It discusses two typical cases of localization-related epilepsy: case 1 as a simple situation and case 2 as a complicated situation. No “gold standard” for epileptic spike analysis in EEG or MEG has been established, so several methods must be adopted to achieve the most reasonable interpretation. However, such intense and revisional analyses may be too time-consuming in clinical settings and result in arbitrary conclusions. Therefore, the authors currently use a simple method first, that is, a single dipole model for the peak or preceding upward slope of unaveraged single spikes. In the following case conference, EEG and MEG data are reviewed with seizure semiology, anatomical magnetic resonance imaging (MRI), and 18F-fluorodeoxyglucose positron emission tomography (FDG-PET). If all the findings almost agree, the clinical decision can be easily made. If not, revisional analysis of EEG/MEG is recommended using averaged spikes and principal component analysis models as well as distributed source models. In addition to EEG/MEG, the authors often order revisional analysis and additional MRI and FDG-PET studies after the conference. Even further history taking will be recommended if necessary.