Performance Assessment of Presurgical Tests in Temporal Lobe Epileptic Patients

The performance of the presurgical test (preSurg) for temporal lobe epilepsy (TLE) was evaluated via video-electroencephalography (VEEG), electroencephalography (EEG), 99mTc-HmPAO single-photon emission tomography (SPECT) and 1.5 T magnetic resonance imaging (MRI) in a group of 112 men (37.0 ± 1.1 years) and 106 women (39.7 ± 1.1 years) operated on for TLE. The epileptic zone (EZ) was adequately identified to determine whether the patient reached an Engel I grade (EI) at least one-year postop. Accuracy was evaluated by the coefficient α, ranging from 3 (when result = EZ) to 2 (result in the same hemisphere as the EZ), 1 (noninformative result) or 0 (EZ in the contralateral hemisphere). The simplicity of diagnosis was defined as the number of preSurg surgeries needed to identify the EZ. EI was obtained in 85.8% of patients, even though 42.2% had noninformative MRI results. For preSurg α was higher for vEEG, followed by MRI and lower for EEG. The accuracy (combination of sensitivity and specificity) was calculated as follows: VEEG (0.797) > MRI (0.518) > EEG (0.446) > SPECT (0.360). The likelihood positive ratio was more significant, and the likelihood negative ratio was lower for VEEG. Both results indicated the highest discriminatory ability for this study. The most relevant factor for the regression model, in order to predict a good function post-surgical outcome were, from more to less relevant VEEG, MRI and EEG, and the factors were not significantly related to SPECT. EZs in EI patients with low simplicity were identified mainly by VEEG. A very good postoperative outcome can be obtained even in TLE patients with no lesions on MRI. This is a relevant idea, because, even patients without apparent lesions in imaging, should be referred to a specialized center to presurgical evaluation. The VEEG is the most reliable preSurg test and may be the only reliable test for patients with very low simplicity.