An Improved Neurosurgical Planning Method for Focal Epileptic Seizure Surgery using Stereo-EEG-Based Source...

Refractory Focal Epilepsy can be treated by the surgical resection of the Seizure Onset Zone (SOZ), the region in the brain from which seizures originate. To remove the SOZ, precise localization must be performed to identify this region, and to minimize the risk of removing eloquent cortex. StereoEEG is a valuable method to localize the SOZ, by recording the propagation of epileptic signals using a series of implanted depth electrodes. This allows the origin of the seizure signals to be determined based on the time at which they are detected at known electrode contact coordinates along the implanted electrodes. The automation of the localization of the SOZ using stereo-EEG, CT and MRI data is becoming increasingly relevant in the neurosurgical literature, as it offers an opportunity for increased accuracy and efficiency. This study proposes a novel method to localize the SOZ by using multimodal image processing. The method allows a statistical representation of the SOZ to be constructed on the cortical surface model, by using a series of spatial transformations. In a clinical case of MRI-positive focal epilepsy, the proposed pipeline was able to correctly identify the SOZ whilst using electrophysiological input from distant electrodes with 80-90% of the pipeline's result being within the resection cavity. In an MRI-negative patient's result, 60-75% of the SOZ determination was also within the resective cavity. In both cases, the pipeline showed greater than 50% reduction in SOZ volume determination. Such precise localization may allow for smaller resection volumes to achieve seizure freedom and reduce neurological complications. This method may therefore offer a more accurate solution to SOZ localization with a reduced clinical workload.