Stereoelectroencephalography (sEEG) is a diagnostic procedure for a patient with refractory focal epilepsy that is performed to localize and define the epileptogenic zone. In contrast to grid electrodes, sEEG electrodes are implanted using minimal invasive operation techniques without large craniotomies. Stereoelectroencephalography is one of the intraoperative EEG techniques currently used in the presurgical work-up, and it is well-distinguished from other invasive techniques, such as subdural grids and strips.
Stereoelectroencephalography (SEEG) was originally developed by Jean Talairach and Bancaud.
Many SEEG depth electrode implantation techniques involve the use of extensive technological equipment and shaving of the patient's entire head before electrode implantation 1).
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.
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.
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.
SEEG-interventions were associated, at least, non-inferiorly, with seizure-freedom compared with SDG-monitors in temporal, lesional and overall subgroups 2).