Intracranial electroencephalography @entity410 onset patterns and surgical outcomes in nonlesional XXXX .

@entity1 @entity410 @entity302
OBJECT: @entity1 with normal MR imaging (nonlesional) findings and medically refractory @entity302 make up a disproportionate number of nonexcellent outcomes after @entity302 surgery. In this paper, the authors investigated the usefulness of intracranial electroencephalography (iEEG) in the identification of surgical candidates. METHODS: Between 1992 and 2002, 51 consecutive @entity1 with normal MR imaging findings and @entity302 underwent intracranial electrode monitoring. The implantation of intracranial electrodes was determined by @entity410 semiology, interictal and ictal scalp EEG, SPECT, and in some @entity1 PET studies. The demographics of @entity1 at the time of surgery, lobar localization of electrode implantation, duration of follow-up, and Engel outcome score were abstracted from the Mayo Rochester Epilepsy Surgery Database. A blinded independent review of the iEEG records was conducted for this study. RESULTS: Thirty-one (61%) of the 51 @entity1 who underwent iEEG ultimately underwent resection for their @entity302 . For 28 (90.3%) of the 31 @entity1 who had @entity302 surgery, adequate information regarding follow-up (> 1 year), @entity410 frequency, and iEEG recordings was available. Twenty-six (92.9%) of 28 @entity1 had frontal lobe resections, and 2 had parietal lobe resections. The most common iEEG pattern at @entity410 onset in the surgically treated group was a focal high-frequency discharge (in 15 [53.6%] of 28 @entity1 ). Ten (35.7%) of the 28 surgically treated @entity1 were @entity410 free. Fourteen (50%) had Engel Class I outcomes, and overall, 17 (60.7%) had significant improvement (Engel Class I and IIAB with > or =80% @entity410 reduction). Focal high-frequency oscillation at @entity410 onset was associated with Engel Class I surgical outcome (12 [85.7%] of 14 @entity1 , p = 0.02), and it was uncommon in the nonexcellent outcome group (3 [21.4%] of 14 @entity1 ). CONCLUSIONS: A focal high-frequency oscillation (> 20 Hz) at @entity410 onset on iEEG may identify @entity1 with nonlesional @entity302 who are likely to have an Engel Class I outcome after @entity302 surgery. The prospect of excellent outcome in nonlesional extratemporal lobe @entity302 prior to intracranial monitoring is poor (14 [27.5%] of 51 @entity1 ). However, iEEG can further stratify @entity1 and help identify those with a greater likelihood of Engel Class I outcome after surgery.
