Disparate properties of afterdischarges elicited by electric cortical stimulation in MRI lesional epilepsy patients with different surgical outcomes.

ABSTRACT

PURPOSE: The purpose of this study was to demonstrate the prognostic value of afterdischarges(ADs) on surgical outcome by comparing the disparate properties in epilepsy patients with different surgical outcomes METHODS: 27 lesional epilepsy patients were retrospectively analyzed. The brain region covered by subdural electrodes in each patient was dichotomized into the area of the brain lobe(s) where the MRI lesion is located (region ML) and other brain areas (region nML). The occurrence of ADs and ADs evolving into clinical seizure, ADs threshold and ADs duration in region ML and nML were compared between seizure-free (SF) and non-seizure-free (nSF) patients. RESULTS: A total of 2535 contacts were analyzed, and the total occurrence of ADs was 18.6% (471/2535). The overall occurrence of ADs in region ML (24.8%) was significantly higher than that in region nML (10.3%) (P < 0.001). In region ML, compared with SF patients, nSF patients had a lower occurrence of ADs (19.2% vs. 31.2%, P < 0.001), a higher occurrence of ADs evolves into clinical seizure (8.7% vs. 2.4%, P = 0.006), a higher ADs threshold (12.8 ± 4.1 mA vs. 11.0 ± 3.7 mA, P < 0.001) and a shorter ADs duration (15.3 ± 14.2 s vs. 20.6 ± 17.0 s, P < 0.001). However, in region nML, there was no significant difference in properties of ADs between SF and nSF patients. CONCLUSION: Higher occurrence of ADs in region ML might predict a good outcome, whereas higher occurrence of ADs evolving into clinical seizure, higher ADs threshold and shorter ADs duration might predict an unfavorable surgical outcome. ADs might help predict surgical outcomes in epilepsy patients.