Abstracts

RATIONALE: Depth electrodes are useful in the identification of deep epileptogenic foci. CT, MR and angiography-guided frame-based techniques are safe and accurate, but require 4-point rigid skull fixation that can limit cranial access for placement of additional grids and strips. We designed and implemented a custom-built adaptor for use with the StealthStation Frameless Neuronavigation System.
METHODS: A slotted, custom-designed adaptor was built (Ad-Tech, Racine WI) to interface with the StealthStation Guide Frame - DT and 960-525 Stealth Fighter.(Medtronic, Louisville, CO). ). The Mach 4.0 Cranial Navigation Software was used to plan the trajectory and entry site based on a preoperative SPGR MRI. Anatomic accuracy was assessed based on whether the electrode was 1) within, 2) touching or 3) outside of the target tissue. Physiologic accuracy was assessed based on whether adequate recordings were obtained.
RESULTS: Sixteen depth electrodes were placed into 20 targets in 7 patients. Eight electrodes were placed laterally though a craniotomy into the hippocampus and amygdala. Four electrodes were placed through occipital burr holes along the length of the hippocampus into the amygdala. Four electrodes were placed into targets deep in the frontal lobe. Of 20 targets, 19 (95%) had electrode contacts either within or touching the target, 18 of which (90%) provided adequate recordings. There were no complications.
CONCLUSIONS: Depth electrodes can be placed safely and accurately using a commercially-available frameless stereotactic navigation system and a custom-made adaptor.