Abstracts

RATIONALE: We investigated the correlation of sharp waves in routine EEG six and twenty-four months after epilepsy surgery with regard to long-term seizure outcome.
METHODS: In 148 patients (74% TLE, 26% extratemporal) EEG results (SW present or absent) were correlated with the postoperative outcome using the Engel classification 6 and 24 months after resection (PO1 and PO2, respectively). Self- evaluation was conducted 3 and 5 years after resection (PO3 and PO5, respectively).
RESULTS: 91 patients (62%) were seizure-free 5 years after resection; 88% of them showed no SW in PO1. 28 patients (19%) displayed SW in routine EEG 6 months after resection, 61% of them had recurrent seizures in PO5, p=0,007. No SW in PO1 and PO2 correlate with a good outcome (73% seizure free), p=0,001.
Seizure-free patients (Engel I) and patients with a less favorable outcome (Engel III, IV) at PO1 and PO2 rarely changed the category of outcome during the following years, p=0,000. 50% of the patients with a favorable seizure reduction (Engel II) changed to seizure-free (Engel I) or to a worse outcome (Engel III, IV).
SW in PO1 were more predictive for a worse outcome in TLE than in extratemporal epilepsy (p=0,011) and in FCD compared to other etiologies (p=0,077).
CONCLUSIONS: Postoperative routine EEG is a good prognostic instrument for the prediction of long-term seizure outcome, especially for TLE and FCD. It predicts the running up/down of fits in patients with rare seizures (Engel II).