Clinical Assessment of SEEG-Based Source Localization
Abstract number :
3.171
Submission category :
3. Neurophysiology / 3G. Computational Analysis & Modeling of EEG
Year :
2021
Submission ID :
1826496
Source :
www.aesnet.org
Presentation date :
12/6/2021 12:00:00 PM
Published date :
Nov 22, 2021, 06:54 AM
Authors :
David Satzer, MD - University of Chicago; Yasar Esengul - Department of Neurology - University of Chicago; Peter Warnke - Department of Neurosurgery - University of Chicago; Naoum Issa - Department of Neurology - University of Chicago; Douglas Nordli - Section of Child Neurology, Department of Pediatrics - University of Chicago
Rationale: Conventional analysis of stereo-electroencephalography (SEEG) is prone to the streetlight effect and may not identify propagation or volume conduction if the epileptogenic zone is not directly implanted. Electrical source localization (ESL) models activity distant from electrodes. ESL with SEEG has been shown to be feasible in computational simulations but has not been clinically validated.
Methods: Interictal epileptiform discharges (IEDs) were identified on SEEG in patients who underwent SEEG followed by resection, ablation, or disconnection of the suspected epileptogenic zone. Equivalent current dipoles (ECD) and SWARM algorithm-based current density were determined from the half-rise time point of the averaged dominant IED using a finite element head model. Total treatment (resection, ablation, or disconnection) volume (TV) was determined on postoperative MRI and seizure freedom (Engel class 1 outcome) was assessed at last follow up.
Results: Of 26 patients, 73% had temporal lobe epilepsy, 38% had a solitary lesion, and 42% were seizure-free at last follow up (2.8±1.7 years after the most recent surgery). The fraction of current within the TV was greater (p=0.04) in seizure-free patients (median 71%, IQR 13-93%) than in non-seizure-free patients (median 16%, IQR 0-75%). The positive predictive value was 83% and the negative predictive value was 70% using a cutoff of 80% of current included within the TV. The distance between ECD and the TV did not differ (p=0.79) between seizure-free patients (median 9 mm, IQR 0-9 mm) and non-seizure-free patients (median 5 mm, IQR 3-19 mm).
Conclusions: ESL of IEDs from SEEG can distinguish between seizure-free and non-seizure-free patients, indicating that this technique is useful in corroborating the epileptogenic zone. Further work is necessary to evaluate the capability to localize distant IEDs and ictal discharges.
Funding: Please list any funding that was received in support of this abstract.: No funding was received in support of this abstract.
Neurophysiology