The role of hybrid FDG-PET/MRI on decision-making in presurgical evaluation of drug-resistant epilepsy.

BACKGROUND: When MRI fails to detect a potentially epileptogenic lesion, the chance of a favorable outcome after epilepsy surgery becomes significantly lower (from 60 to 90% to 20-65%). Hybrid FDG-PET/MRI may provide additional information for identifying the epileptogenic zone. We aimed to investigate the possible effect of the introduction of hybrid FDG-PET/MRI into the algorithm of the decision-making in both lesional and non-lesional drug-resistant epileptic patients. METHODS: In a prospective study of patients suffering from drug-resistant focal epilepsy, 30 nonlesional and 30 lesional cases with discordant presurgical results were evaluated using hybrid FDG-PET/MRI. RESULTS: The hybrid imaging revealed morphological lesion in 18 patients and glucose hypometabolism in 29 patients within the nonlesional group. In the MRI positive group, 4 patients were found to be nonlesional, and in 9 patients at least one more epileptogenic lesion was discovered, while in another 17 cases the original lesion was confirmed by means of hybrid FDG-PET/MRI. As to the therapeutic decision-making, these results helped to indicate resective surgery instead of intracranial EEG (iEEG) monitoring in 2 cases, to avoid any further invasive diagnostic procedures in 7 patients, and to refer 21 patients for iEEG in the nonlesional group. Hybrid FDG-PET/MRI has also significantly changed the original therapeutic plans in the lesional group. Prior to the hybrid imaging, a resective surgery was considered in 3 patients, and iEEG was planned in 27 patients. However, 3 patients became eligible for resective surgery, 6 patients proved to be inoperable instead of iEEG, and 18 cases remained candidates for iEEG due to the hybrid FDG-PET/MRI. Two patients remained candidates for resective surgery and one patient became not eligible for any further invasive intervention. CONCLUSIONS: The results of hybrid FDG-PET/MRI significantly altered the original plans in 19 of 60 cases. The introduction of hybrid FDG-PET/MRI into the presurgical evaluation process had a potential modifying effect on clinical decision-making. TRIAL REGISTRATION: Trial registry: Scientific Research Ethics Committee of the Medical Research Council of Hungary. TRIAL REGISTRATION NUMBER: 008899/2016/OTIG . Date of registration: 08 February 2016.

Surgical outcomes related to invasive EEG monitoring with subdural grids or depth electrodes in adults: A systematic review and meta-analysis.

PURPOSE: Resective epilepsy surgery based on an invasive EEG-monitors performed with subdural grids (SDG) or depth electrodes (stereo-electroencephalography, SEEG) is considered to be the best option towards achieving seizure-free state in drug-resistant epilepsy. The authors present a meta-analysis, due to the lack of such a study focusing on surgical outcomes originating from SDG- or SEEG-monitors. METHOD: English-language studies published until May 2018, highlighting surgical outcomes were reviewed. Outcome measures including total number of SDG- or SEEG-monitors and resective surgeries; consecutively followed surgical cases; surgical outcomes classified by Engel in overall, temporal/extratemporal and lesional/nonlesional subgroups were analyzed. RESULTS: 19 articles containing 1025 SDG-interventions and 16 publications comprising 974 SEEG-monitors were researched. The rate of resective surgery deriving from SDG-monitoring hovered at 88.8% (95%CI:83.3-92.6%) (I2 = 77.0%;p < 0.001); in SEEG-group, 79.0% (95%CI:70.4-85.7%) (I2 = 72.5%;p < 0.001) was measured. After SDG-interventions, percentage of post-resective follow-up escalated to 96.0% (95%CI:92.0-98.1%) (I2 = 49.1%;p = 0.010), and in SEEG-group, it reached 94.9% (95%CI:89.3-97.6%) (I2 = 80.2%;p < 0.001). In SDG-group, ratio of seizure-free outcomes reached 55.9% (95%CI:50.9-60.8%) (I2 = 54.47%;p = 0.002). Using SEEG-monitor, seizure-freedom occurred in 64.7% (95%CI:59.2-69.8%) (I2 = 11.9%;p = 0.32). Assessing lesional cases, likelihood of Engel I outcome was found in 57.3% (95%CI:48.7%-65.6%) (I2 = 69.9%;p < 0.001), using SDG; while in SEEG-group, it was 71.6% (95%CI:61.6%-79.9%) (I2 = 24.5%;p = 0.225). In temporal subgroup, ratio of seizure-freedom was found to be 56.7% (95%CI:51.5%-61.9%) (I2 = 3.2%;p = 0.412) in SDG-group; whereas, SEEG-group reached 73.9% (95%CI:64.4%-81.6%); (I2 = 0.00%;p = 0.45). Significant differences between seizure-free outcomes were found in overall (p = 0.02), lesional (p = 0.031), and also, temporal (p = 0.002) comparisons. CONCLUSIONS: SEEG-interventions were associated, at least, non-inferiorly, with seizure-freedom compared with SDG-monitors in temporal, lesional and overall subgroups.