Concordant interictal stereoelectroencephalographic high-frequency oscillations and magnetoencephalography predict...

This study was undertaken to investigate the concordance between magnetoencephalographic (MEG) and interictal stereoelectroencephalographic (SEEG) high-frequency oscillations (HFOs) and their impact on surgical outcomes.

Thirty focal epilepsy patients who underwent SEEG and resection surgery were selected for HFO time-lag analysis. HFOs were automatically extracted from SEEG recordings to determine their time stamps. The difference of first HFO stamp between each channel was calculated, and a matrix was built based on the time differences. Channels with time differences exceeding the threshold were defined as HFO source channels. The threshold was set as the mean plus .5 times the SD via time-lag network analysis. Next, 40 independent patients who underwent MEG and SEEG monitoring followed by surgery at our center were included. MEG dipoles were calculated using a single equivalent current dipole model based on interictal spikes. HFO source channels were identified using the abovementioned analysis. Concordance between MEG and SEEG was examined. Chi-squared test and logistic regression were used to explore relationships among concordance, dipole/HFO source channel resection rate, and surgical outcomes.

For concordance analysis, 28 patients (70.0%) had concordant/partially concordant MEG and HFO localization. Patients with concordant MEG-SEEG locations (p = .01) and higher dipole resection rates (p = .02) were more likely to be postoperatively seizure-free. High dipole resection rate was more likely to be associated with seizure freedom in patients with superficial seizure onset zone (p = .01). Logistic regression based on all features achieved an area under the curve of .81. Concordant dipole and HFO locations played a crucial role in the regression (odds ratio = 6.27, 95% confidence interval = 1.16-40.93, p = .04).

Good concordance between interictal MEG and SEEG, as well as a higher resection rate of dipoles, suggests a higher chance of achieving seizure freedom. The regression model based on MEG-SEEG concordance, and dipole and HFO source channel resection rate, could predict postoperative prognosis with an area under the curve of .81.