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

Current state of the art of traditional and minimal invasive epilepsy surgery approaches

Introduction

Open resective surgery remains the main treatment modality for refractory epilepsy, but is often considered a last resort option due to its invasiveness.

Research question

This manuscript aims to provide an overview on traditional as well as minimally invasive surgical approaches in modern state of the art epilepsy surgery.

Materials and methods

This narrative review addresses both historical and contemporary as well as minimal invasive surgical approaches in epilepsy surgery. Peer-reviewed published articles were retrieved from PubMed and Scopus. Only articles written in English were considered for this work. A range of traditional and minimally invasive surgical approaches in epilepsy surgery were examined, and their respective advantages and disadvantages have been summarized.

Results

The following approaches and techniques are discussed: minimally invasive diagnostics in epilepsy surgery, anterior temporal lobectomy, functional temporal lobectomy, selective amygdalohippocampectomy through a transsylvian, transcortical, or subtemporal approach, insulo-opercular corticectomies compared to laser interstitial thermal therapy, radiofrequency thermocoagulation, stereotactic radiosurgery, neuromodulation, high intensity focused ultrasound, and disconnection surgery including callosotomy, hemispherotomy, and subpial transections.

Discussion and conclusion

Understanding the benefits and disadvantages of different surgical approaches and strategies in traditional and minimal invasive epilepsy surgery might improve the surgical decision tree, as not all procedures are appropriate for all patients.

Automation in Dentistry with Mechanical Drills and Lasers for Implant Osteotomy: A Narrative-Scoping Review

The popularity of implants is increasing with the aging population requiring oral-dental rehabilitation. There are several critical steps in the implant workflow, including case selection, implant design, surgical procedure, biological tissue responses, and functional restoration. Among these steps, surgical osteotomy procedures are a crucial determinant of clinical success. This brief review was aimed at outlining the current state of the field in automation-assisted implant surgical osteotomy technologies. A broad search of the literature was performed to identify current literature. The results are outlined in three broad categories: semi-automated static (image-guided) or dynamic (navigation-assisted) systems, and fully-automated robotic systems. As well as the current mechanical rotary approaches, the literature supporting the use of lasers in further refinement of these approaches is reviewed. The advantages and limitations of adopting autonomous technologies in practical clinical dental practices are discussed. In summary, advances in clinical technologies enable improved precision and efficacious clinical outcomes with implant dentistry. Hard-tissue lasers offer further advancements in precision, improved biological responses, and favorable clinical outcomes that require further investigation.

Robotic calvarial bone sampling

The aim of this study was to assess the feasibility of complex unicortical calvarial harvesting by using the Cold Ablation Robot-Guided Laser Osteotome (CARLO® primo+). A cadaveric study was performed with a progressive complexity of the bone harvesting. This preliminary study on the cadaveric cranial vault area examined the tracking precision, the strategies, settings and durations of harvesting, the accuracy of the unicortical bone cutting, and the risk of dura exposition. All sampling was realised with no more difficulty than that experienced during the standard procedure. No bicortical cutting occurred during CARLO® primo + robot-guided laser cutting. During the second sampling, dura was partially exposed due to improper angulation of the curved osteotome during harvesting. Complex unicortical calvarial harvesting using robot-guided laser appears to be feasible and safe. In the future, robotic approaches will probably replace current surgical techniques using cutting guides and help reduce intraoperative inaccuracies due to the human factor.

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

Objectives: In this study we aimed to present an updated cutting strategy and updated hardware for a new camera system that can increase cut-through detection using a cold ablation robot-guided laser osteotome.

Methods: We performed a preoperative computed tomography scan of each animal. The laser was mounted on a robotic arm and guided by a navigation system based on a tracking camera. Surgery was performed with animals in the prone position. A new cutting strategy was implemented consisting of two circular paths involving inner (full cylindric) and outer (hollow cylindric) sections, with three different ablation phases. The depth electrodes were inserted after cut-through detection was confirmed on either the coaxial camera system or optical coherence tomography signal.

Results: A total of 71 precision bone channels were cut in four pig specimens using a robot-guided laser. No signs of hemodynamic or respiratory irregularities were observed during anesthesia. All bone channels were created using the advanced cutting strategy. The new cutting strategy showed no irregularities in either cylindrical (parallel walled; n = 38, 45° = 10, 60° = 14, 90° = 14) or anticonical (walls widening by 2 degrees; n = 33, 45° = 11, 60° = 13, 90° = 9) bone channels. The entrance hole diameters ranged from 2.25–3.7 mm and the exit hole diameters ranged from 1.25 to 2.82 mm. Anchor bolts were successfully inserted in all bone channels. 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 angulated cylindrical and anti-conical bone channels in this large, in vivo non-recovery animal study. Our findings indicate that the coaxial camera system is feasible for cut-through detection.

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

Objectives: We recently introduced a navigated, robot-driven laser beam craniotomy for use with stereoelectroencephalography (SEEG) applications. This method was intended to substitute the hand-held electric power drill in an ex vivo study. The purpose of this in vivo non-recovery pilot study was to acquire data for the depth control unit of this laser device, to test the feasibility of cutting bone channels, and to assess dura perforation and possible cortex damage related to cold ablation.

Methods: Multiple holes suitable for SEEG bone channels were planned for the superior portion of two pig craniums using surgical planning software and a frameless, navigated technique. The trajectories were planned to avoid cortical blood vessels using magnetic resonance angiography. Each trajectory was converted into a series of circular paths to cut bone channels. The cutting strategy for each hole involved two modes: a remaining bone thickness mode and a cut through mode (CTR). The remaining bone thickness mode is an automatic coarse approach where the cutting depth is measured in real time using optical coherence tomography (OCT). In this mode, a pre-set measurement, in mm, of the remaining bone is left over by automatically comparing the bone thickness from computed tomography with the OCT depth. In the CTR mode, the cut through at lower cutting energies is managed by observing the cutting site with real-time video.

Results: Both anesthesia protocols did not show any irregularities. In total, 19 bone channels were cut in both specimens. All channels were executed according to the planned cutting strategy using the frameless navigation of the robot-driven laser device. The dura showed minor damage after one laser beam and severe damage after two and three laser beams. The cortex was not damaged. As soon as the cut through was obtained, we observed that moderate cerebrospinal fluid leakage impeded the cutting efficiency and interfered with the visualization for depth control. The coaxial camera showed a live video feed in which cut through of the bone could be identified in 84%.

Conclusion: Inflowing cerebrospinal fluid disturbed OCT signals, and, therefore, the current CTR method could not be reliably applied. Video imaging is a candidate for observing a successful cut through. OCT and video imaging may be used for depth control to implement an updated SEEG bone channel cutting strategy in the future.