Comment: Debate on That Epilepsy Surgery Should Be Offered Early Even to Patients with Non-lesional Mri Scans

There is inherent difficulty in identifying the epileptogenic zone in nonlesional epilepsy, which leads to the incomplete resection. However, with careful interpretation of other studies including functional neuroimaging results, surgical treatment can benefit selected patients with nonlesional on MRI. There are two important issues regarding epilepsy surgery for these patients. One issue is when we can define the true intractability. Another issue is success rate of epilepsy surgery performed on these patients. Increasing medical costs with advancing age and high mortality associated with refractory seizures should also be considered. Concordance with two or more presurgical evaluations among interictal EEG, ictal EEG, FDG-PET, and ictal SPECT was significantly related to a seizure-free outcome in these patients. Intracranial EEG is one of the most important procedures in planning surgery and achieving a good surgical outcome. Careful placement of intracranial electrodes based on the results of presurgical evaluations should be needed. Resection that includes more electrodes with ictal rhythm or interictal abnormalities predicts a good surgical outcome. In conclusion, early application of epilepsy surgery for nonlesional patients can be considered case by case. The strong hypothesis based on the results of non-invasive evaluation is a key to successful epilepsy surgery. Introduction Neocortical epilepsy has comprised only a minor portion of epilepsy surgical series until now (1). It has not homogenous clinical manifestations. Widely different seizure semiologies could be found depending on the location of the epileptogenic foci. Clear understanding of epileptogenic network has not been possible. Scalp EEG often misleads or falsely localizes the ictal onset zone due to inaccessible location or widespread ictal onset. A focal structural lesion on MRI is a usually reliable indicator of the seizure onset (2-4). Concordant results of electrophysiological studies and MRI findings have high predictive value for good surgical outcome (5,6). However, MRI is ineffective in many partial epilepsy patients, even patients with cortical dysplasia. Multimodal evaluations are mandatory for the successful epilepsy surgery in these patients. Intracranial recording is also indispensable role for these patients. Surgical outcome has usually been known to be less well satisfactory (1,7,8). In the context of all these issues, determining the prognostic factors for good surgical outcome and suggesting the guideline of successful epilepsy surgery is very important for the this special group of patients. Prognostic factors in neocortical epilepsy surgery Although extratemporal resections are known to be generally less successful than are temporal lobe resections, the recent series suggested …