Authors :
Presenting Author: Kristen Scheitler, MD – Mayo Clinic Rochester
Benjamin Brinkmann, PhD – Mayo Clinic Rochester; David Burkholder, MD – Neurology – Mayo Clinic Rochester; Nicholas Gregg, MD, PhD – Neurology – Mayo Clinic Rochester; Brian Lundstrom, MD, PhD – Neurology – Mayo Clinic Rochester; Kai Miller, MD, PhD – Mayo Clinic Rochester; Cindy Nelson, R. EEG T. – Mayo Clinic Rochester; Jamie Van Gompel, MD – Neurologic Surgery – Mayo Clinic Rochester
Rationale:
Intracranial stereotactic electroencephalography (sEEG) is a key tool in seizure onset localization for medically refractory epilepsy. Prior to surgical implantation of sEEG electrodes, a multidisciplinary team plans desired electrode trajectories that target the area(s) of interest while minimizing risk of damage to nearby anatomic structures.
At the time of sEEG explantation, intracranial leads may by observed to have migrated from their original position as documented by post-implant CT, the clinical implications of which are currently unclear but theoretically include incorrect seizure localization or inaccurate recordings. The migration of intracranial sEEG electrodes between the time of implantation and the time of explantation is not well described. Herein, we present a retrospective review of patients at our institution for whom immediate post-implant and immediate pre-explant CT head imaging were directly compared for changes in lead position.
Methods:
A retrospective review of the electronic medical records was performed. Patients undergoing sEEG implantation with both immediate post-sEEG-implantation CT head imaging and immediate pre-sEEG-explantation CT head imaging were identified. CT imaging was performed using high-resolution, thin-cut processing to ensure minimization of radiographic lead artifact. For each patient, the original lead trajectory plans (created using StealthStation Application 2.0.1, Medtronic, Minneapolis, MN) were used to correctly identify each lead on the post-implant CT using standard sEEG nomenclature. This post-implant CT was then merged with the pre-explant CT to measure changes in lead position for each lead.
Results:
Fifteen patients were identified (n = 15). The average number of days between lead implantation and explantation was 7.2 (median 7, range 3-12). Seven patients had bilateral leads. The average total number of leads per patient was 14.3 (median 14, range 11-16). The total number of leads placed for all patients was 215. Comparison of CT imaging demonstrated that all fifteen patients had radiographic evidence of intracranial lead migration. The total number of leads that demonstrated non-zero migration was 183 out of 215 (85%), and amount of migration in millimeters (mm) ranged from 0.1 to 12.1 mm. One lead came out completely during hospital admission. The most commonly migrated leads were those in the hippocampus or anterior thalamus. Lead migration on pre-implant CT was only correctly identified by radiologists for four of the fifteen patients.
Conclusions:
Direct comparison of post-implant CT head imaging and pre-explant CT head imaging using stereotactic software identified intracranial lead migration in all patients undergoing sEEG monitoring. Leads that migrated the farthest distances were most commonly in the hippocampus or anterior thalamus. Future studies are needed to clarify the predisposing factors for lead migration and the clinical implications of a migrated lead on EEG accuracy.
Funding: None