Interictal epileptiform discharges and epilepsy surgery outcome in extratemporal lobe epilepsy

Background: Video-EEG monitoring (v-EEG) is a basic procedure in evaluation of patients with refractory epilepsy who are candidate for epilepsy surgery. During this method seizure onset zone (SOZ) is commonly determined based on ictal EEG findings, but there are reports of favorable outcome of epilepsy surgery based on data extracted from interictal and MRI findings only and without any need to v-EEG in patients with temporal lobe epilepsy (TLE). There is no solid data about extra-temporal lobe epilepsy (ETLE) in this regard. This study aimed to investigate the prognostic effect of concordance of interictal findings with ictal and MRI data on post-surgical outcome of patients with ETLE. Methods: This retrospective study was conducted on 40 patients with refractory ETLE who undergone v-EEG as a part of pre-surgical evaluation. Conformity assessment was done comparing irritative zone (IZ) and SOZ and also IZ and MRI lesion and prognostic effect of concordance on surgical outcome was investigated in follow up visit based on Engel criteria. Findings: Regarding relevancy between IZ and SOZ, in 73.2% of patients, results were concordant and 26.8% had overlap. Discrepancy between IZ and SOZ was found in none of patient. Concordance between IZ and MRI lesion was found in 51.2% of patients while discordance was determined in 12.2% and overlap registered in 36.6%.We could not find any relation between the concordance of interictal findings and SOZ or MRI lesion and post-surgical outcome. Conclusion: Our study showed that concordance of IZ with SOZ and MRI has no independent effect on post-surgical outcome of patients with ETLE. We suggest that excluding exceptional cases, v-EEG should be considered as the mainstay of pre-surgical evaluation in this group of patients.

کلیدواژه ها:

Extra-temporal lobe epilepsy ، Electroencephalography ، Surgery ، Outcome