Robotic Navigated Laser Craniotomy for Depth Electrode Implantation in Epilepsy Surgery: A Cadaver Lab Study

Abstract

Objective Depth electrode implantation for invasive monitoring in epilepsy surgery has become a standard procedure. We describe a new frameless stereotactic intervention using robot-guided laser beam for making precise bone channels for depth electrode placement. Methods A laboratory investigation on a head cadaver specimen was performed using a CT scan planning of depth electrodes in various positions. Precise bone channels were made by a navigated robot-driven laser beam (erbium:yttrium aluminum garnet [Er:YAG], 2.94-μm wavelength,) instead of twist drill holes. Entry point and target point precision was calculated using postimplantation CT scans and comparison to the preoperative trajectory plan. Results Frontal, parietal, and occipital bone channels for bolt implantation were made. The occipital bone channel had an angulation of more than 60 degrees to the surface. Bolts and depth electrodes were implanted solely guided by the trajectory given by the precise bone channels. The mean depth electrode length was 45.5 mm. Entry point deviation was 0.73 mm (±0.66 mm SD) and target point deviation was 2.0 mm (±0.64 mm SD). Bone channel laser time was ∼30 seconds per channel. Altogether, the implantation time was ∼10 to 15 minutes per electrode. Conclusion Navigated robot-assisted laser for making precise bone channels for depth electrode implantation in epilepsy surgery is a promising new, exact and straightforward implantation technique and may have many advantages over twist drill hole implantation.

Navigated, Robot-Driven Laser Craniotomy for SEEG Application Using Optical Coherence Tomography in an Animal Model

“…Recent studies that perform osteotomies with Er.YAG lasers observed difficulties with depth control as visual inspection is limited ( Stübinger et al, 2009 ; Stübinger et al, 2010 ). Air bone transition signals recorded with OCT in this study were comparable to the ex vivo model with the same device, meaning that it is possible to detect cutting depth in real time and operate in remaining bone thickness mode ( Roessler et al, 2020 ). This excludes the erroneous detection of inflowing liquid surfaces originating either from cerebrospinal fluid or blood during the procedure.…”

“…The tested device using Er:YAG laser in this study has been successfully investigated in oral and maxillofacial surgery as the first autonomous, contact-free osteotomy device ( Baek et al, 2015 ; Augello et al, 2018b ). This device was already tested in an ex vivo study for craniotomies ( Roessler et al, 2020 ).…”

“…Building the drill hole is one of the crucial surgical steps for the implantation of depth electrodes for invasive monitoring in epilepsy surgery. An electric power drill is used for this in frameless procedures ( Ortler et al, 2011 ; Roessler et al, 2020 ). However, small deviations in drilling may cause large deviations in target point accuracy.…”

“…We recently introduced a navigated robot-driven laser beam in an ex vivo study, replacing the role of a hand-held electric power drill ( Roessler et al, 2020 ). The purpose of this in vivo pilot study was to acquire data for this device’s depth control unit.…”

Advanced cutting strategy for navigated, robot-driven laser craniotomy for stereoelectroencephalography: An in Vivo non-recovery animal study

“…We recently introduced a navigated, robot-driven laser for implantation of cranial depth electrodes as an alternative to frame-based procedures ( Spire et al, 2008 ; Cardinale et al, 2013 ; Berg et al, 2019 ; Roessler et al, 2021 ). This method was proven accurate and feasible in previous cadaver and in vivo non-recovery studies ( Roessler et al, 2021 ; Winter et al, 2021 ). However, cut-through could not be reliably detected with neither optical coherence tomography (OCT) signals nor the coaxial camera system.…”