**2.6 SEEG signal recording and stimulation**

Post-operative CT scan would be fused to the preoperative MRI. First, we assess the accuracy of electrodes placement. Second, the electrodes are segmented, and the anatomical position of different contacts are marked. SEEG signals would be recorded by 4–5 days. By then stimulation might be performed. On one hand seizure events

#### **Figure 12.**

*Electrodes are ready for connection to EEG montage. Betadine-soaked dressing is applied.*

could be triggered to give clinicians a hint on the location of the ictal onset zone. Yet, the events might be unhabitual. On the other hand, some eloquent areas might be located by the stimulation. Concerning the stimulation technique, low frequency stimulation (1 Hz frequency, 0.5-4 mA pulse intensity, 0.5-3 ms pulse width, 20–60s duration) is suitable for areas of low after-discharge threshold such as primary auditory cortex, primary motor cortex, hippocampus, and areas with focal cortical dysplasia. High frequency stimulation (50 Hz, 0.5-5 mA, 0.5-1 ms, 3–8 s) would be suitable to areas elsewhere [18]. Stimulation might be helpful for clinicians to understand the epileptic network better (**Figure 13**).
