Objective To explore the value of afterdischarges monitoring for intraoperative electrical stimulation for brain mapping. Methods 34 patients received cerebral cortex electrical stimulation for brain mapping during operation of brain function area , afterdischarges were monitored simultaneously to determine the upper limit of stimulus intensity. Results 34 cases underwent electrical stimulation successfully , and received surgery without neurologic decline except 2 cases of hypokinesia. Conclusion After discharges monitoring improve the accuracy, reduce the risk of intraoperative cerebral cortex electrical stimulation.

Objective Introduce a technique for creating 3-dimensional (3D) brain models of subdural electrodes , ideal for demonstrating the space-relationship of seizure localization and eloquent cortices , and discuss its usefulness for presurgical evaluation of epileptic patients. Methods Patients with medically intractable epilepsy were underwent a thorough preoperative MR brain scan including a T1-weighted high-resolution 3D sequence. Intraoperative photographs were taken with the digital camera. After the surgical implantation of subdural electrodes for epileptic zone localization , the thin-slice CT scan of the electrodes were taken and coregistered to preoperative brain 3D MR images in the Medtronic StealthMerge software environment. After the iEEG monitoring , multiple habitual seizures were recorded , eloquent areas were also identified by electrical stimulation of the cortex. The epileptic zone and the eloquent areas were marked on the subdural electrodes respectively. Then, 3D tessellations of the epileptic zone and the eloquent areas were rendered. Results Six patients (4 male, 2 female) were enrolled in this study. The mean time of iEEG monitoring was 13.7 days. After the coregistration of postoperative CT with preoperative 3D MRI , the 3D stereoscopic reconstruction provided an accurate representation of the implanted electrodes with highly detailed visualization of the underlying anatomy. The visual comparison between 3D reconstructions and intraoperative photographs indicated a good correspondence. The patients were followed for 3 to 6 months after the secondary operation , and had continuing improvement in seizure control. Conclusions The results indicate that the 3D reconstruction of subdural electrodes can reveal the precise localization of subdural electrodes , and can be useful for the presurgical evaluation of epileptic patients.