Cortico-cortical Evoked Potential Methodology Affects the Outcome of Analysis in Pediatric Patients
Abstract number :
2.168
Submission category :
3. Neurophysiology / 3E. Brain Stimulation
Year :
2024
Submission ID :
44
Source :
www.aesnet.org
Presentation date :
12/8/2024 12:00:00 AM
Published date :
Authors :
Presenting Author: Rudy Whitney, BS/MS candidate – Children's Hospital of Philadelphia
Samuel Tomlinson, MD – University of Pennsylvania
Benjamin Kennedy, MD – Children's Hospital of Philadelphia
Sudha Kilaru Kessler, MD – Children's Hospital of Philadelphia
Erin Conrad, MD – University of Pennsylvania
Eric Marsh, MD PhD – Children's Hospital of Philadelphia
Caren Armstrong, MD, PhD – University of California, Davis
Rationale: Cortico-cortical evoked potentials (CCEPs), using low frequency cortical stimulation, can be used to probe functional connectivity and seizure onset networks during intracranial EEG. CCEP analysis approaches have not been standardized, with numerous methods used, leading to varying results suggesting that a unified approach may be needed to best utilize information from CCEPs.
Methods: The Children’s Hospital of Philadelphia (CHOP) institutional review board approved this study and informed consent and assent (when applicable) was obtained from legal guardians and subjects undergoing stereoelectroencephalographic (sEEG) monitoring for epilepsy. Stimulation consisted of sequential 30s trains of 1Hz biphasic stimulation in bipolar configuration across adjacent electrode contacts, pulse width 300-500us and amplitude 2-8mA (charge density 12-59µC/cm2).
An automated pipeline synchronized sweeps, removed artifact, and generated an average waveform for each response channel. Reconstructions from pre and post implant images were generated using GARDEL software. Electrode locations were mapped to a standardized atlas using Freesurfer. The accuracy of peak amplitudes and latencies were compared by calculating positive and negative predictive values (PPV/NPV) by visual review of a random sample of 25 kept and 25 rejected traces for each patient by a board-certified epileptologist.
Results: Fourty-six patients aged 1.8-23 (mediatn 13.5) years participated. Detection in bipolar montage had a 94% PPV and 84% NPV. This was higher than in machine reference montage (PPV 86% NPV 72%). The relative amplitude of N1 was higher and N2 was lower in reference (N1 Z score bipolar 14.75, reference 17.3, p=0.001, N2 Z score bipolar 21.3, reference 17.7, p< 0.0001), and latency was longer for both N1 and N2 in reference (bipolar N1 47.4ms N2 263.4ms, reference N1 70.7ms N2 354.7ms, p< 0.0001 for each). When adjusted for distance from stimulation site, both amplitude and latency decrease with patient age in bipolar (amplitude N1 r2= 0.20, p=0.002 & N2 r2= 0.17, p=0.004; latency N1 r2= 0.19, p=0.002 & N2 r2= 0.14, p=0.010) but do not correlate with patient age in reference (amplitude N1 r2= 0.004, p=0.66; N1 r2= 0.005, p=0.64; latency N1 r2< 0.001, p=0.90; N1 r2< 0.001, p=0.95). In a subset of patients, additional stimulation parameters (charge density 24 to 55 µC/cm
Neurophysiology