Objective: to present the postsurgical outcome of extratemporal epilepsy (ExTLE) patients submitted to preoperative multimodal evaluation and intraoperative sequential electrocorticography (ECoG). Subjects and methods: thirty-four pharmaco-resistant patients with lesional and non-lesional ExTLE underwent comprehensive pre-surgical evaluation including multimodal neuroimaging such as ictal and interictal perfusion single photon emission computed tomography (SPECT) scans, subtraction of ictal and interictal SPECT co-registered with magnetic resonance imaging (SISCOM) and electroencephalography (EEG) source imaging (ESI) of ictal epileptic activity. Surgical procedures were tailored by sequential intraoperative ECoG, and absolute spike frequency (ASF) was calculated in the pre- and post-resection ECoG. Postoperative clinical outcome assessment for each patient was carried out one year after surgery using Engel scores. Results: frontal and occipital resection were the most common surgical techniques applied. In addition, surgical resection encroaching upon eloquent cortex was accomplished in 41% of the ExTLE patients. Pre-surgical magnetic resonance imaging (MRI) did not indicate a distinct lesion in 47% of the cases. In the latter number of subjects, SISCOM and ESI of ictal epileptic activity made it possible to estimate the epileptogenic zone. After one- year follow up, 55.8% of the patients was categorized as Engel class I–II. In this study, there was no difference in the clinical outcome between lesional and non lesional ExTLE patients. About 43.7% of patients without lesion were also seizure- free, p = 0.15 (Fischer exact test). Patients with satisfactory seizure outcome showed lower absolute spike frequency in the pre-resection intraoperative ECoG than those with unsatisfactory seizure outcome, (Mann– Whitney U test, p = 0.005). Conclusions: this study has shown that multimodal pre-surgical evaluation based, particularly, on data from SISCOM and ESI alongside sequential intraoperative ECoG, allow seizure control to be achieved in patients with pharmacoresistant ExTLE epilepsy.

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Introduction: Drug-resistant extratemporal epilepsy is the second cause of referral to epilepsy surgery. Objectives: To identify factors associated with short-term seizure recurrence following extratemporal epilepsy surgery. Materials and Methods: We performed a retrospective study of 19 consecutive patients who underwent surgery for drug-resistant extratemporal epilepsy at the National Institute of Neurology and Neurosurgery of Havana, Cuba, from September 2014 to October 2019. All patients had at least one year of postoperative follow-up. Fisher's exact test was used to search for an association between dichotomous variables. A value of p≤0.05 was considered significant. Results: After one year of follow-up, seizure freedom reached 31.6% (Engel I) and 36.8% showed significant improvement in the number of seizures (Engel II). The frontal location (p=0.046) and incomplete resection of the epileptogenic zone (p=0.017), bilateral interictal discharges on the preoperative electroencephalogram (EEG) (p=0.017), the presence of epileptiform discharges on the postsurgical EEG (p=0.001), and the occurrence of seizures after the sixth month of surgery (p=0.001), were associated with seizures recurrence. Conclusions: After one year, 31.6% of patients operated on for extratemporal epilepsy were seizure-free. The incomplete resection of the epileptogenic zone and the presence of epileptogenic discharges in the postsurgical EEG, and the presence of seizures after the sixth month of surgery were the most significant factors of seizure recurrence.