Introduction: Implantation of depth electrodes to localize epileptogenic foci in patients with drug-resistant epilepsy can be accomplished by frame-based, frameless, and robotic stereotactic systems. We aim to evaluate the accuracy of electrode implantation using the FHC microTargeting platform without use of a rigid insertion cannula.
Methods: A total of 147 depth electrodes were implanted in eleven patients who underwent stereoelectroencephalography (SEEG) for drug-resistant epilepsy using the microTargeting platform and Ad-Tech depth electrodes without rigid guide cannula. MATLAB was utilized to evaluate targeting accuracy. Two manual coordinate measurements were averaged with minimal inter-rater reliability.
Results: Patients were predominantly male (91%) with average age 35.3 (SD 11.1, range 21-57) and average age of epilepsy onset at 14.1 (SD 7.6, range 3-26). On MRI, 27.3% were noted to have structural abnormalities and 18.2% to have hippocampal sclerosis. 27.3% of patients underwent depth electrode placement due to bilateral ictal scalp EEG activity, 27.3% due to delay or absence of EEG activity following clinical manifestation, and 36.4% due to competing potential seizure foci. A mean of 13.5 electrodes were implanted (range 10-16). Mean operative time was 146 minutes (range 104 to 176). One patient developed a post-operative complication. Location of onset was identified in all patients, though one patient required implantation of an additional electrode. Mean lateral entry point localization error was 1.78 mm (sd 3.23) and mean lateral target point localization error was 2.45 mm (sd 1.79). Following monitoring, 63.6% underwent RNS placement, 27.3% underwent temporal lobectomy, and 9.1% underwent other focal resection. At follow up (mean 4.6 months, range 1.7-9.8), 54.5% of patients demonstrate an Engel class I outcome.
Conclusions: Utilization of the FHC microTargeting platform without the use of insertion cannulae is safe, effective and accurate. Localization of seizure foci was accomplished in all patients and accuracy of depth electrode placement was satisfactory.
Patient Care: Use of the FHC microTargeting platform without rigid insertion cannula is accurate and efficient, providing for better surgical care of patients who require intracranial monitoring for seizure activity.
Learning Objectives: By the conclusion of this session, participants should be able to 1) Discuss the options for intracranial seizure monitoring 2) Describe the value of utilizing the FHC microTargeting platform without rigid insertion cannula