Significance of postoperative electroencephalograms in patients with extratemporal lesional epilepsy

We retrospectively studied EEGs performed 1 week, 3 months, and 1 year after surgery (lesionectomy or lesion resection with corticectomy) in 24 patients with extratemporal lesional epilepsy who had a mean duration of follow-up of 2.5 years. All patients had intractable partial seizures and underwent a comprehensive presurgical evaluation including long-term EEG monitoring. Twenty of the 24 patients had interictal epileptiform activity (IEA) identified on the preoperative sleep and awake EEG recordings. The presence of IEA 1 year after surgery was associated with recurrent seizure activity (p < 0.05). The postoperative EEG recordings, however, revealed no IEA in the two patients with persistent seizures who had no epileptiform abnormality on the preoperative study. The extent of cortical resection appeared to have no significant effect on the recording of IEA after surgery. One-year postoperative EEG recordings are prognostically useful in patients with extratemporal lesional epilepsy who undergo surgical treatment.