Rationale: To determine the contribution of stereo-EEG for localization purpose in patients with a visible lesion on MRI. Methods: All consecutive patients between February 2013 and May 2018 who met these criteria were included. We assessed the localization of the ictal onset and its relationship with the lesion. Clinical, radiological, and electrographic analyses were performed. Results: Stereo-EEG revealed an ictal onset with either partial or no overlap with the lesion seen on MRI in 42 (56%) of the 75 lesions included. Mesial temporal sclerosis was the only lesion type associated with an exclusively lesional ictal onset. Conclusions: These findings support the idea that a lesion is only part of a more complex epileptogenic network. Funding: Please list any funding that was received in support of this abstract.: None.
