Stereo-electro-encephalography and epilepsy surgery in patients with temporal lobe epilepsy and normal Magnetic Resonance Imaging
Clinical Series, 13 - 21Tag this article
Object: To retrospectively analyze a consecutive series of patients with MRI-negative temporal lobe epilepsy (TLE) who underwent epilepsy surgery after stereo-electro-encephalography (SEEG). To define the role of SEEG in this population and to identify factors associated to postoperative seizure outcome among several presurgical, surgical and postsurgical variables. Methods: Clinical records of 866 patients who received temporal lobe resections and with a minimum follow-up of 12 months were retrospectively searched for MRI-negative cases that underwent SEEG evaluation before surgery. Anamnestic, clinical, neurophysiological, surgical, histopathological and postsurgical data were collected. Seizure outcome was categorized as favourable (Engel’s class I) and unfavourable (Engel’s classes II-IV). Univariate statistical analysis was performed to identify variables with a significant association to seizure outcome. Results: Twenty-six patients matched the inclusion criteria. Histology was unremarkable in 18 (69.2%) cases, revealed type I FCD in 6 cases, type II FCD in 1 case and HS in 1 case. Fifteen (57.7%) patients were in Engel’s class I after a mean follow- up of 71.6 months (SD ±74.2; range 12-242). Univariate analysis indicated contralateral diffusion of the discharge, secondary generalization and falls as factors significantly associated with an unfavourable outcome. Conclusions: Surgery is an effective treatment option for MRI-negative TLE, even in particularly complex cases requiring SEEG evaluation. SEEG and surgery should be considered with caution in patients with electroclinical features which are more likely associated to an unfavourable postoperative outcome. The presented data help optimizing the selection of patients with MRI-negative TLE with good chances to benefit from SEEGguided surgery.
KEY WORDS: temporal lobe epilepsy, stereo-electro- encephalography, epilepsy surgery, negative magnetic resonance imaging, seizure outcome.