Robotic Navigated Laser Craniotomy for Depth Electrode Implantation: Results from an in-vivo non-recovery animal study.

Abstract-Text (inklusive Referenzen und Bildunterschriften)

Background: We previously published a new frameless stereotactic method using a robotic guided laser beam for depth electrode placement in a cadaver study. This study tested the feasibility of a new cutting strategy for angulated precision bone channels as well as improved cut-through detection in an in vivo animal study.

Methods: Preoperative CT scans were performed to plan trajectories for bone channels angulated 45, 60, and 90 degrees. The animals were prepared under general anesthesia by a trained veterinarian conforming European requirements and Good Laboratory Practice regulations. A new cutting strategy was implemented consisting of two circular paths, an inner section and outer section, and three different ablation phases. After cut-through detection bolts and depth electrodes were inserted to confirm cut-through and feasibility.

Results: 71 robotic guided laser beam precision bone channels were cut in four pig specimens. Bolts and depth electrodes were implanted solely guided by the trajectory given by the laser precision channels. The new cutting strategy showed no irregularities for either cylindrical (n=38, 45°=10, 60°14, 90°=14) or anti-conical (n=33, 45°=11, 60°=13, 90°=9) bone channels. Entrance hole diameters were 2.25-3.7mm, exit hole diameters 1.25-2.82mm. Hole diameters were larger with holes angulated either 45 or 60 degrees compared to 90 degrees. Angulation and cutting depth showed no significant difference between cylindrical and anti-conical cutting strategies. The updated co-axial camera live video feed in addition to OCT reliably detected cut-through. Insertion of bolts was achieved in all bone channels. All four anesthesia protocols showed no irregularities. Importantly, no unintended damage to the cortex was detected after laser guided craniotomy.

Conclusion: The new cutting strategy showed promising results in more than 70 precision bone channels for angulated cylindrical and anti-conical channels in a large in-vivo non-recovery animal study. OCT signal and a new co-axial camera proved its feasibility for cut-through detection.