Abstracts

Rationale: The SEEG implantation procedures still represent a challenge due to the intrinsic complexity of the method and the number of the depth electrodes required. Methods: We have designed a custom stereotactic fixture based on the STarFix technology (FHC Inc, ME) that allows implantation of depth electrodes used in presurgical evaluation of patients with focal pharmacoresistant epilepsy. We used the traditional orthogonal approach, but oblique trajectories are supported as well. The fixture is built using 3D laser sintering technology based on a computer-generated model to fit each patient's anatomy. Fiducial markers that also serve as anchors for the fixture are implanted into patient's skull prior to the surgery. The 3D fixture model is designed to align with the patient's anatomy (AC-PC and mid-plane points), such that the frame coordinates are identical to the anatomical coordinates, making targeting of individual structures more intuitive and consistent across patients. A rectangular grid of guides orthogonal to the sagittal plane and centered on the mid-commissural point (MCP) can be accommodated in the platform design, allowing an arbitrary selection of orthogonal trajectories. The frame has no adjustable parts, reducing the risk of inaccurate coordinate settings. Due to this feature, the procedure time is significantly reduced. Results: We have used the fixture for the implantation of depth electrodes for presurgical evaluation of a patient with temporal lobe epilepsy, with an overall two-fold reduction of the time required for planning and implantation. Conclusions: The custom stereotactic fixture design greatly simplifies the planning procedure, significantly reduces the OR time while maintaining a high accuracy.