Prognostic Role of Ictal Electroencephalographic Patterns in Extratemporal Epilepsy Surgery

This study aimed to investigate the correlation of ictal onset patterns in scalp electroencephalography (EEG) in patients with refractory extratemporal lobe epilepsy with postsurgical outcome.
This was a retrospective cohort study conducted between 2011 and 2015 in Kashani Epilepsy Center, Isfahan, Iran, enrolling patients with refractory extratemporal epilepsy who underwent presurgical evaluation. Demographic, clinical, and imaging data, and also ictal findings during video-EEG monitoring were reviewed. The correlation between preoperative findings and 1-year postsurgical outcome was analyzed.
Findings: We reviewed 91 seizures of 27 patients. 49.5% of seizures were sleep-related. Secondary generalization occurred during 15.4% of seizures. The most common EEG pattern at ictal onset and the most frequent late pattern were rhythmic theta and rhythmic spike/sharp, respectively. Favorable 1-year outcome was observed in 74.1% of patients. Age of less than 35 years, lower number of antiepileptic drugs, and occurrence of EEG changes before clinical signs of seizure were more common in patients with favorable outcome. Secondary generalization and sleep-related seizures frequently associated with unfavorable postsurgical outcome.
Clinical and EEG findings during video-EEG monitoring can provide valuable information regarding postsurgical prognosis in patients with extratemporal lobe epilepsy. However, in order to reach a more accurate conclusion, intracranial monitoring and larger studies are required.