Pre-Operative Interictal Discharge Patterns and Magnetic Resonance Imaging Findings Affect Prognosis of Temporal Lobe Epilepsy Surgery

Abstract

Objective: This study investigated whether pre-operative interictal discharge patterns detected by electroencephalogram (EEG) and magnetic resonance imaging (MRI) findings affect the surgical prognosis in temporal lobe epilepsy (TLE) patients. Methods: A retrospective analysis of 115 cases of patients with refractory TLE was carried out from October 2010 to 2014 based on the classification of pre-operative interictal discharge patterns in EEG and MRI findings. The patients were followed up for 4 years after surgery. The ILAE method was used to assess differences in seizure-free rate among different types of interictal discharge pattern as well as in MRI findings. Results: A total of 115 cases were classified according to interictal discharge patterns in EEG, including normal cases, unilateral anterior discharge, unilateral multi-region discharge, and bilateral discharge. MRI findings were classified into negative results and positive results. Unilateral anterior and bilateral discharges showed statistically significant differences in post-operative seizure-free rates (p< 0.001). MRI-positive cases showed good overall post-operative outcome, irrespective of interictal discharge pattern in the EEG, whereas MRI-negative cases showed good overall prognosis if the interictal discharge pattern in EEG occurred in the unilateral anterior region. Conclusion: If the pre-operative interictal discharge pattern in EEG is confined to the unilateral anterior region, prognosis is good. If there are abnormalities in MRI findings, post-operative prognosis is good, regardless of pre-operative interictal discharge patterns in EEG. Surgical intervention is highly recommended for TLE patients with normal MRI findings and interictal discharge confined to the unilateral anterior region.