title: Postoperative routine EEG correlates with long-term seizure outcome after epilepsy surgery.
abstract: We investigated the correlation of interictal epileptiform discharges (IED) in routine EEG 6 and 24 months after epilepsy surgery with regard to long-term seizure outcome. In 148 patients (74% temporal lobe epilepsy (TLE), 26% extratemporal epilepsy) EEG results (IED present or absent) were correlated with the postoperative outcome using the Engel classification 6 and 24 months after resection (PO6m and PO2y, respectively). Self-evaluation was conducted 3 and 5 years after resection (PO3y and PO5y, respectively). Ninety-one patients (62%) were seizure-free 5 years after resection; 88% of them showed no IED in PO6m. Twenty-eight patients (19%) displayed IED in routine EEG 6 months after resection; 61% of them had recurrent seizures at PO5y, whereas of 120 patients without IED only 33% had recurrent seizures at PO5y; p=0.01. Absence of IED in PO6m and PO2y correlated with good outcome: 71% without IED remained seizure-free, whereas only 25% with IED at PO6m and PO2y remained seizure-free; p=0.001. Seizure-free patients (Engel 1) and patients with less favourable outcome (Engel 3-4) at PO6m and PO2y rarely changed categories of outcome during the following years (p<0.001). Half of the patients with favourable seizure reduction (Engel 2) changed to seizure-free (Engel 1) or to a worse outcome category (Engel 3-4). Postoperative routine EEG is a good prognostic instrument for the prediction of long-term seizure outcome, especially for TLE. It predicts the running up and down of fits in patients with rare seizures (Engel 2).
authors.affiliation: Friedrich-Alexander University, Department of Neuropathology, Erlangen, Germany.
authors.forename: Michelle
authors.initials: M
authors.lastname: Hildebrandt
authors.forename: Reinhard
authors.initials: R
authors.lastname: Schulz
authors.forename: Matthias
authors.initials: M
authors.lastname: Hoppe
authors.forename: Theodor
authors.initials: T
authors.lastname: May
authors.forename: Alois
authors.initials: A
authors.lastname: Ebner
mesh_terms: D000293:Adolescent; D000328:Adult; D004569:Electroencephalography; D004827:Epilepsy / Q000145:classification / Q000503:physiopathology* / Q000601:surgery*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D012189:Retrospective Studies; D013223:Statistics as Topic; D013997:Time Factors; D016896:Treatment Outcome