Introduction: Temporal lobe epilepsy surgery represents the majority of surgical interventions in patients with refractory epilepsy. In consequence, knowledge of prognostic factors in this type of epilepsy surgery is of major importance. The objective of this study is to study series of prognostic factors in a group of patients who underwent temporal lobe epilepsy surgery and to correlate Engel's Classification of Postoperative Outcome, now used in most epilepsy centers, and the Proposal for New Classification in regards to Epileptic Seizures Following Epilepsy Surgery of the International League Against Epilepsy (ILAE).
Methods: We analyzed 41 consecutive patients who underwent temporal lobe epilepsy surgery in the Epilepsy Surgery Program of the Epilepsy Unit in the Fundación Jiménez Díaz. The following prognostic factors were analyzed: age at surgery, time since the first seizure (excluding febrile seizures), risk factors for the development of epilepsy, presence of simple partial seizures, presurgical complex partial seizure frequency, findings in brain magnetic resonance imaging, interictal and ictal electroencephalogram, neuropsychological assessment, Wada test and neuropathological study of the surgical specimen. Two outcome classifications were used: Engel's classification of postoperative outcome and the proposal for a new classification of outcome in regards to epileptic seizures following epilepsy surgery of the ILAE. Statistical analysis was performed using non-parametric tests.
Results: The presence of temporal unilateral interictal epileptiform activity and the presence of less than 20 seizures complex partial seizures per month before surgery were associated with a better prognosis using both classifications. The electronencephalographic unilateral temporal ictal onset recording was associated with a better prognosis using Engel's classification but not ILAE's outcome classification. The presence of febrile seizures was associated with a better prognosis in regards to ILAE's outcome classification but not in regards to Engel's classification. The remaining factors were not associated with outcome.
Conclusions: The following factors were associated with a good prognosis: presence of unilateral temporal interictal epileptiform activity, presurgery seizure frequency below 20 complex partial seizures per month, unilateral temporal ictal onset, and presence of febrile seizures. A good correlation was found between both outcome classifications in regards to most of the analyzed prognostic factors.