Electrode placement accuracy in robot-assisted epilepsy surgery: A comparison of different referencing techniques including frame-based CT versus facial laser scan based on CT or MRI

Implantation accuracy of novel polyimide stereotactic electroencephalographic depth electrodes-a human cadaveric study

Introduction

Stereoelectroencephalography (sEEG) is a minimally invasive procedure that uses depth electrodes stereotactically implanted into brain structures to map the origin and propagation of seizures in epileptic patients. Implantation accuracy of sEEG electrodes plays a critical role in the safety and efficacy of the procedure. This study used human cadaver heads, simulating clinical practice, to evaluate (1) neurosurgeon's ability to implant a new thin-film polyimide sEEG electrode according to the instructions for use (IFU), and (2) implantation accuracy.

Methods

Four neurosurgeons (users) implanted 24 sEEG electrodes into two cadaver heads with the aid of the ROSA robotic system. Usability was evaluated using a questionnaire that assessed completion of all procedure steps per IFU and user errors. For implantation accuracy evaluation, planned electrode trajectories were compared with post-implantation trajectories after fusion of pre- and postoperative computer tomography (CT) images. Implantation accuracy was quantified using the Euclidean distance for entry point error (EPE) and target point error (TPE).

Results

All sEEG electrodes were successfully placed following the IFU without user errors, and post-implant survey of users showed favorable handling characteristics. The EPE was 1.28 ± 0.86 mm and TPE was 1.61 ± 0.89 mm. Long trajectories (>50 mm) had significantly larger EPEs and TPEs than short trajectories (<50 mm), and no differences were found between orthogonal and oblique trajectories. Accuracies were similar or superior to those reported in the literature when using similar experimental conditions, and in the same range as those reported in patients.

Discussion

The results demonstrate that newly developed polyimide sEEG electrodes can be implanted as accurately as similar devices in the marker without user errors when following the IFU in a simulated clinical environment. The human cadaver ex-vivo test system provided a realistic test system, owing to the size, anatomy and similarity of tissue composition to that of the live human brain.

Usefulness of Robotic Stereotactic Assistance (ROSA®) Device for Stereoelectroencephalography Electrode Implantation: A Systematic Review and Meta-analysis

The aim of this study was to systematically review and meta-analyze the efficiency and safety of using the Robotic Stereotactic Assistance (ROSA®) device (Zimmer Biomet; Warsaw, IN, USA) for stereoelectroencephalography (SEEG) electrode implantation in patients with drug-resistant epilepsy. Based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, a literature search was carried out. Overall, 855 nonduplicate relevant articles were determined, and 15 of them were selected for analysis. The benefits of the ROSA® device use in terms of electrode placement accuracy, as well as operative time length, perioperative complications, and seizure outcomes, were evaluated. Studies that were included reported on a total of 11,257 SEEG electrode implantations. The limited number of comparative studies hindered the comprehensive evaluation of the electrode implantation accuracy. Compared with frame-based or navigation-assisted techniques, ROSA®-assisted SEEG electrode implantation provided significant benefits for reduction of both overall operative time (mean difference [MD], -63.45 min; 95% confidence interval [CI] from -88.73 to -38.17 min; P < 0.00001) and operative time per implanted electrode (MD, -8.79 min; 95% CI from -14.37 to -3.21 min; P = 0.002). No significant differences existed in perioperative complications and seizure outcomes after the application of the ROSA® device and other techniques for electrode implantation. To conclude, the available evidence shows that the ROSA® device is an effective and safe surgical tool for trajectory-guided SEEG electrode implantation in patients with drug-resistant epilepsy, offering benefits for saving operative time and neither increasing the risk of perioperative complications nor negatively impacting seizure outcomes.

Safety, Accuracy, and Efficacy of Robot-Assisted Stereo Electroencephalography in Children of Different Ages

BACKGROUND AND OBJECTIVES

Aimed to investigate the safety, accuracy, and efficacy of stereo electroencephalography (SEEG) in children of various ages, with particular emphasis on those younger than 3 years. There is limited guidance regarding whether SEEG can conducted on very young children.

METHODS

This retrospective study was conducted between July 2018 and August 2022. It involved 88 patients who underwent 99 robot-assisted SEEG procedures at our center. The patients were categorized into 3 groups based on their age at the time of the robot-assisted SEEG procedures: group 1 (3 years and younger, n = 28), group 2 (age 3-6 years, n = 27), and group 3 (older than 6 years, n = 44). Clinical data, SEEG demographics, complications, and seizure outcomes were analyzed.

RESULTS

A total of 675 electrodes were implanted, with an average of 6.82 ± 3.47 (2.00-16.00) electrodes per patient (P = .052). The average target point error for the 675 electrodes was 1.93 ± 1.11 mm, and the average entry point error was 1.30 ± 0.97 mm (P = .536 and P = .549, respectively). The overall percentage of complications was 6.06% (P = .879). No severe or long-term neurologic impairment was observed. Of the total 99 procedures included in this study, 78 were admitted for epilepsy surgery for the first time, while 9 patients were treated twice and 1 patient was treated 3 times. There were 21 radiofrequency thermocoagulation and 78 second-stage resective procedures performed after SEEG. There was no statistically significant difference in Engel class I outcomes among the patients who underwent SEEG in the 3 age groups (P = .621).

CONCLUSION

Robot-assisted SEEG were demonstrated to be safe, accurate, and efficient across different age groups of children. This technique is suitable for children younger than 3 years who have indications for SEEG placement.

Learning Curve in Robotic Stereoelectroencephalography: Single Platform Experience

BACKGROUND

Learning curve, training, and cost impede widespread implementation of new technology. Neurosurgical robotic technology introduces challenges to visuospatial reasoning and requires the acquisition of new fine motor skills. Studies detailing operative workflow, learning curve, and patient outcomes are needed to describe the utility and cost-effectiveness of new robotic technology.

METHODS

A retrospective analysis was performed of pediatric patients who underwent robotic stereoelectroencephalography (sEEG) with the Medtronic Stealth Autoguide. Workflow, total operative time, and time per electrode were evaluated alongside target accuracy assessed via error measurements and root sum square. Patient demographics and clinical outcomes related to sEEG were also assessed.

RESULTS

Robot-assisted sEEG was performed in 12 pediatric patients. Comparison of cases over time demonstrated a mean operative time of 363.3 ± 109.5 minutes for the first 6 cases and 256.3 ± 59.1 minutes for the second 6 cases, with reduced operative time per electrode (P = 0.037). Mean entry point error, target point error, and depth point error were 1.82 ± 0.77 mm, 2.26 ± 0.71 mm, and 1.27 ± 0.53 mm, respectively, with mean root sum square of 3.23 ± 0.97 mm. Error measurements between magnetic resonance imaging and computed tomography angiography found computed tomography angiography to be more accurate with significant differences in mean entry point error (P = 0.043) and mean target point error (P = 0.035). The epileptogenic zone was identified in 11 patients, with therapeutic surgeries following in 9 patients, of whom 78% achieved an Engel class I.

CONCLUSIONS

This study demonstrated institutional workflow evolution and learning curve for the Autoguide in pediatric sEEG, resulting in reduced operative times and increased accuracy over a small number of cases. The platform may seamlessly and quickly be incorporated into clinical practice, and the provided workflow can facilitate a smooth transition.

Robotic-Assisted Stereoelectroencephalography: A Systematic Review and Meta-Analysis of Safety, Outcomes, and Precision in Refractory Epilepsy Patients

Robotic assistance in stereoelectroencephalography (SEEG) holds promising potential for enhancing accuracy, efficiency, and safety during electrode placement and surgical procedures. This systematic review and meta-analysis, following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and International Prospective Register of Systematic Reviews (PROSPERO) registration, delves into the latest advancements and implications of robotic systems in SEEG, while meticulously evaluating outcomes and safety measures. Among 855 patients suffering from medication-refractory epilepsy who underwent SEEG in 29 studies, averaging 24.6 years in age, the most prevalent robots employed were robotic surgical assistant (ROSA) (450 patients), Neuromate (207), Sinovation (140), and ISys1 (58). A total of 8,184 electrodes were successfully implanted, with an average operative time of 157.2 minutes per procedure and 15.1 minutes per electrode, resulting in an overall mean operative time of 157.7 minutes across all studies. Notably, the mean target point error (TPE) stood at 2.13 mm, the mean entry point error (EPE) at 1.48 mm, and postoperative complications occurred in 7.69% of robotically assisted (RA) SEEG cases (60), with 85% of these complications being asymptomatic. This comprehensive analysis underscores the safety and efficacy of RA-SEEG in patients with medication-refractory epilepsy, characterized by low complication rates, reduced operative time, and precise electrode placement, supporting its widespread adoption in clinical practice, with no discernible differences noted among the various robotic systems.

The accuracy of a novel self-tapping bone fiducial marker for frameless robot-assisted stereo-electro-encephalography implantation and registration techniques

BACKGROUND

We aimed to evaluate the accuracy and safety of a novel self-tapping bone fiducial as a registration technique for stereoelectroencephalography (SEEG) implantation.

METHODS

Each patient was installed with five bone fiducial markers. All procedures were performed using the same Sinovation robot system. The accuracy was determined by calculating the target point error (TPE) and the entry point error (EPE) of electrodes.

RESULTS

Fourteen patients underwent SEEG implantation surgery; and the average installation time of the markers per patient was 86.1 s. In the operating theatre, the average registration time was 206.6 s, and the average registration error was 0.18 mm. The average TPE of 174 electrodes was 1.98 mm and the average EPE was 0.88 mm.

CONCLUSION

Our study provided a bone fiducial marker installation and registration technique that was convenient and fast, highly accurate in registration, and highly tolerated by patients.

A Method of Intraoperative Registration Verification to Prevent Accuracy Errors in Robot-Assisted Stereotactic Electroencephalography Electrode Placement

BACKGROUND

Robotic-assisted stereotactic electroencephalography (sEEG) electrode placement is increasingly common at specialized epilepsy centers. High accuracy and low complication rates are essential to realizing the benefits of sEEG surgery. The aim of this study was to describe for the first time in the literature a method for a stereotactic registration checkpoint to verify intraoperative accuracy during robotic-assisted sEEG and to report our institutional experience with this technique.

METHODS

All cases performed with this technique since the adoption of robotic-assisted sEEG at our institution were retrospectively reviewed.

RESULTS

In 4 of 111 consecutive sEEG operations, use of the checkpoint detected an intraoperative registration error, which was addressed before completion of sEEG electrode placement.

CONCLUSIONS

The use of a registration checkpoint in robotic-assisted sEEG surgery is a simple technique that can prevent electrode misplacement and improve the safety profile of this procedure.

Recent developments in stereo electroencephalography monitoring for epilepsy surgery

Recently the utilization of the stereo electroencephalography (SEEG) method has exploded globally. It is now the preferred method of intracranial monitoring for epilepsy. Since its inception, the basic tenet of the SEEG method remains the same: strategic implantation of intracerebral electrodes based on a hypothesis grounded on anatomo-electroclinical correlation, interpretation of interictal and ictal abnormalities, and formation of a surgical plan based on these data. However, there are recent advancements in all these domains-electrodes implantations, data interpretation, and therapeutic strategy- that can make the SEEG a more accessible and effective approach. In this narrative review, these newer developments are discussed and summarized. Regarding implantation, efficient commercial robotic systems are now increasingly available, which are also more accurate in implanting electrodes. In terms of ictal and interictal abnormalities, newer studies focused on correlating these abnormalities with pathological substrates and surgical outcomes and analyzing high-frequency oscillations and cortical-subcortical connectivity. These abnormalities can now be further quantified using advanced tools (spectrum, spatiotemporal, connectivity analysis, and machine learning algorithms) for objective and efficient interpretation. Another aspect of recent development is renewed interest in SEEG-based electrical stimulation mapping (ESM). The SEEG-ESM has been used in defining epileptogenic networks, mapping eloquent cortex (primarily language), and analyzing cortico-cortical evoked potential. Regarding SEEG-guided direct therapeutic strategy, several clinical studies evaluated the use of radiofrequency thermocoagulation. As the emerging SEEG-based diagnosis and therapeutics are better evolved, treatments aimed at specific epileptogenic networks without compromising the eloquent cortex will become more easily accessible to improve the lives of individuals with drug-resistant epilepsy (DRE).

Robot-Assisted Deep Brain Stimulation: High Accuracy and Streamlined Workflow

BACKGROUND

A number of stereotactic platforms are available for performing deep brain stimulation (DBS) lead implantation. Robot-assisted stereotaxy has emerged more recently demonstrating comparable accuracy and shorter operating room times compared with conventional frame-based systems.

OBJECTIVE

To compare the accuracy of our streamlined robotic DBS workflow with data in the literature from frame-based and frameless systems.

METHODS

We retrospectively reviewed 126 consecutive DBS lead placement procedures using a robotic stereotactic platform. Indications included Parkinson disease (n = 94), essential tremor (n = 21), obsessive compulsive disorder (n = 7), and dystonia (n = 4). Procedures were performed using a stereotactic frame for fixation and the frame pins as skull fiducials for robot registration. We used intraoperative fluoroscopic computed tomography for registration and postplacement verification.

RESULTS

The mean radial error for the target point was 1.06 mm (SD: 0.55 mm, range 0.04-2.80 mm) on intraoperative fluoroscopic computed tomography. The mean operative time for an asleep, bilateral implant without implantable pulse generator placement was 238 minutes (SD: 52 minutes), and skin-to-skin procedure time was 116 minutes (SD: 42 minutes).

CONCLUSION

We describe a streamlined workflow for DBS lead placement using robot-assisted stereotaxy with a comparable accuracy profile. Obviating the need for checking and switching coordinates, as is standard for frame-based DBS, also reduces the chance for human error and facilitates training.

Pilot study of a new type of machine vision-assisted stereotactic neurosurgery for EVD placement

BACKGROUND

The usage of machine vision technologies for image-based analysis and inspection is increasing. With the advent of the ability to process high-dimension data instantly, the possibilities of machine vision multiply exponentially. Robots now use this technology to assist in surgery.

OBJECTIVE

The aim of this study is to explore the efficacy of Surgical Navigation Robot NaoTrac (Brain Navi Biotechnology Co., Ltd.), which utilizes machine vision-inspired technology for patient registration and stereotactic external ventricular drainage (EVD) by the robotic arm.

METHODS

Preoperative and postoperative computed tomography (CT) scans were acquired for each case. The surgeons planned the targets and trajectories with the preoperative CT images. The postoperative CT images were utilized in the accuracy measurements.

RESULTS

All 14 cases had cerebrospinal fluid drained through the catheter. The NaoTrac placed the catheter into the frontal horn in one attempt in 13 cases and was able to drain CSF in 12 cases. Not a single case had any bleeding or intraoperative complications. The average time spent on the patient registration was 142.8 s. The mean target deviation was 1.68 mm, and the mean angular deviation was 1.99°, all within the accepted tolerance for minimal tissue damage.

CONCLUSION

The results of this report demonstrate that machine vision-inspired patient registration is feasible and fast. NaoTrac has demonstrated its accuracy and safety in performing frameless catheter placement in 13 clinical cases. Other stereotactic neurosurgical operations such as stereotactic biopsy, depth electrode placement, deep brain stimulation electrode positioning, and neuroendoscopy may also be benefited from the assistance of NaoTrac.

Accuracy of Robotic and Frame-Based Stereotactic Neurosurgery in a Phantom Model

Background

The development of robotic systems has provided an alternative to frame-based stereotactic procedures. The aim of this experimental phantom study was to compare the mechanical accuracy of the Robotic Surgery Assistant (ROSA) and the Leksell stereotactic frame by reducing clinical and procedural factors to a minimum.

Methods

To precisely compare mechanical accuracy, a stereotactic system was chosen as reference for both methods. A thin layer CT scan with an acrylic phantom fixed to the frame and a localizer enabling the software to recognize the coordinate system was performed. For each of the five phantom targets, two different trajectories were planned, resulting in 10 trajectories. A series of five repetitions was performed, each time based on a new CT scan. Hence, 50 trajectories were analyzed for each method. X-rays of the final cannula position were fused with the planning data. The coordinates of the target point and the endpoint of the robot- or frame-guided probe were visually determined using the robotic software. The target point error (TPE) was calculated applying the Euclidian distance. The depth deviation along the trajectory and the lateral deviation were separately calculated.

Results

Robotics was significantly more accurate, with an arithmetic TPE mean of 0.53 mm (95% CI 0.41–0.55 mm) compared to 0.72 mm (95% CI 0.63–0.8 mm) in stereotaxy (p < 0.05). In robotics, the mean depth deviation along the trajectory was −0.22 mm (95% CI −0.25 to −0.14 mm). The mean lateral deviation was 0.43 mm (95% CI 0.32–0.49 mm). In frame-based stereotaxy, the mean depth deviation amounted to −0.20 mm (95% CI −0.26 to −0.14 mm), the mean lateral deviation to 0.65 mm (95% CI 0.55–0.74 mm).

Conclusion

Both the robotic and frame-based approach proved accurate. The robotic procedure showed significantly higher accuracy. For both methods, procedural factors occurring during surgery might have a more relevant impact on overall accuracy.

FreeSurfer and 3D Slicer-Assisted SEEG Implantation for Drug-Resistant Epilepsy

Objective

Our study aimed to develop an approach to improve the speed and resolution of cerebral-hemisphere and lesion modeling and evaluate the advantages and disadvantages of robot-assisted surgical planning software.

Methods

We applied both conventional robot planning software (method 1) and open-source auxiliary software (FreeSurfer and 3D Slicer; method 2) to model the brain and lesions in 19 patients with drug-resistant epilepsy. The patients' mean age at implantation was 21.4 years (range, 6–52 years). Each patient received an average of 12 electrodes (range, 9–16) between May and November 2021. The electrode-implantation plan was designed based on the models established using the two methods. We statistically analyzed and compared the duration of designing the models and planning the implantation using these two methods and performed the surgeries with the implantation plan designed using the auxiliary software.

Results

A significantly longer time was needed to reconstruct a cerebral-hemisphere model using method 1 (mean, 206 s) than using method 2 (mean, 20 s) (p < 0.05). Both methods identified a mean of 1.4 lesions (range, 1–5) in each patient. Overall, using method 1 required longer (mean, 130 s; range, 48–436) than using method 2 (mean, 68.1 s; range, 50–104; p < 0.05). In addition, the clarity of the model based on method 1 was lower than that based on method 2. To devise an electrode-implantation plan, it took 9.1–25.5 min (mean, 16) and 6.6–14.8 min (mean, 10.2) based on methods 1 and 2, respectively (p < 0.05). The average target point error of 231 electrodes amounted to 1.90 mm ± 0.37 mm (range, 0.33–3.61 mm). The average entry point error was 0.89 ± 0.26 mm (range, 0.17–1.67 mm). None of the patients presented with intracranial hemorrhage or infection, and no other serious complications were observed.

Conclusions

FreeSurfer and 3D Slicer-assisted SEEG implantation is an excellent approach to enhance modeling speed and resolution, shorten the electrode-implantation planning time, and boost the efficiency of clinical work. These well-known, trusted open-source programs do not have explicitly restricted licenses. These tools, therefore, seem well suited for clinical-research applications under the premise of approval by an ethics committee, informed consent of the patient, and clinical judgment of the surgeon.

Rediscovery of the transcerebellar approach: improving the risk-benefit ratio in robot-assisted brainstem biopsies

OBJECTIVE

Conventional frame-based stereotaxy through a transfrontal approach (TFA) is the gold standard in brainstem biopsies. Because of the high surgical morbidity and limited impact on therapy, brainstem biopsies are controversial. The introduction of robot-assisted stereotaxy potentially improves the risk-benefit ratio by simplifying a transcerebellar approach (TCA). The aim of this single-center cohort study was to evaluate the risk-benefit ratio of transcerebellar brainstem biopsies performed by 2 different robotic systems. In addition to standard quality indicators, a special focus was set on trajectory selection for reducing surgical morbidity.

METHODS

This study included 25 pediatric (n = 7) and adult (n = 18) patients who underwent 26 robot-assisted biopsies via a TCA. The diagnostic yield, complication rate, trajectory characteristics (i.e., length, anatomical entry, and target-point location), and skin-to-skin (STS) time were evaluated. Transcerebellar and hypothetical transfrontal trajectories were reconstructed and transferred into a common MR space for further comparison with anatomical atlases.

RESULTS

Robot-assisted, transcerebellar biopsies demonstrated a high diagnostic yield (96.2%) while exerting no surgical mortality and no permanent morbidity in both pediatric and adult patients. Only 3.8% of cases involved a transient neurological deterioration. Transcerebellar trajectories had a length of 48.4 ± 7.3 mm using a wide stereotactic corridor via crus I or II of the cerebellum and the middle cerebellar peduncle. The mean STS time was 49.5 ± 23.7 minutes and differed significantly between the robotic systems (p = 0.017). The TFA was characterized by longer trajectories (107.4 ± 11.8 mm, p < 0.001) and affected multiple eloquent structures. Transfrontal target points were located significantly more medial (−3.4 ± 7.2 mm, p = 0.042) and anterior (−3.9 ± 8.4 mm, p = 0.048) in comparison with the transcerebellar trajectories.

CONCLUSIONS

Robot-assisted, transcerebellar stereotaxy can improve the risk-benefit ratio of brainstem biopsies by avoiding the restrictions of a TFA and conventional frame-based stereotaxy. Profound registration and anatomical-functional trajectory selection were essential to reduce mortality and morbidity.

Frame-based and robot-assisted insular stereo-electroencephalography via an anterior or posterior oblique approach

OBJECTIVE

There is an increasing interest in stereo-electroencephalography (SEEG) for invasive evaluation of insular epilepsy. The implantation of insular SEEG electrodes, however, is still challenging due to the anatomical location and complex functional segmentation in both an anteroposterior and ventrodorsal (i.e., superoinferior) direction. While the orthogonal approach (OA) is the shortest trajectory to the insula, it might insufficiently cover these networks. In contrast, the anterior approach (AOA) or posterior oblique approach (POA) has the potential for full insular coverage, with fewer electrodes bearing a risk of being more inaccurate due to the longer trajectory. Here, the authors evaluated the implantation accuracy and the detection of epilepsy-related SEEG activity with AOA and POA insular trajectories.

METHODS

This retrospective study evaluated the accuracy of 220 SEEG electrodes in 27 patients. Twelve patients underwent a stereotactic frame-based procedure (frame group), and 15 patients underwent a frameless robot-assisted surgery (robot group). In total, 55 insular electrodes were implanted using the AOA or POA considering the insular anteroposterior and ventrodorsal functional organization. The entry point error (EPE) and target point error (TPE) were related to the implantation technique (frame vs robot), the length of the trajectory, and the location of the target (insular vs noninsular). Finally, the spatial distribution of epilepsy-related SEEG activity within the insula is described.

RESULTS

There were no significant differences in EPE (mean 0.9 ± 0.6 for the nonsinsular electrodes and 1.1 ± 0.7 mm for the insular electrodes) and TPE (1.5 ± 0.8 and 1.6 ± 0.9 mm, respectively), although the length of trajectories differed significantly (34.1 ± 10.9 and 70.1 ± 9.0 mm, repsectively). There was a significantly larger EPE in the frame group than in the robot group (1.5 ± 0.6 vs 0.7 ± 0.5 mm). However, there was no group difference in the TPE (1.5 ± 0.8 vs 1.6 ± 0.8 mm). Epilepsy-related SEEG activity was detected in 42% (23/55) of the insular electrodes. Spatial distribution of this activity showed a clustering in both anteroposterior and ventrodorsal directions. In purely insular onset cases, subsequent insular lesionectomy resulted in a good seizure outcome.

CONCLUSIONS

The implantation of insular electrodes via the AOA or POA is safe and efficient for SEEG implantation covering both anteroposterior and ventrodorsal functional organization with few electrodes. In this series, there was no decrease in accuracy due to the longer trajectory of insular SEEG electrodes in comparison with noninsular SEEG electrodes. The results of frame-based and robot-assisted implantations were comparable.

Three Dimensional Brain Reconstruction Optimizes Surgical Approaches and Medical Education in Minimally Invasive Neurosurgery for Refractory Epilepsy

Epilepsy is a prevalent condition that affects 1–3% of the population or about 50–65 million people worldwide (WHO estimates) and about 3.5 million people in the USA alone (CDC estimates). Refractory epilepsy refers to patients that respond inadequately to medical management alone (at least two anti-seizure medications at appropriate doses) and are appropriate candidates for other interventions such as brain surgery or the use of neurostimulators for their epilepsy. Minimally invasive techniques like stereotactic EEG electrodes offer excellent investigational abilities to study the diagnostic attributes of the seizure networks, while therapies like laser ablations and neurostimulators permit intervention and modulation of these networks to offer seizure control with minimal cognitive compromise and surgical morbidity. The accuracy of these techniques is highly contingent on precise anatomical correlation between the location of the electrodes and their proximity to relevant structures of the brain. Ensuring good anatomical correlation using 3-dimensional (3D) reconstructions would permit precise localization and accurate understanding of the seizure networks. Accurate localization of stereotactic electrodes would enable precise understanding of the electrical networks and identify vital nodes in the seizure network. These reconstructions would also permit better understanding of the proximity of these electrodes to each other and help confirm arrangement of neurostimulators to maximize modulatory effects on the networks. Such reconstructions would enable better understanding of neuroanatomy and connectivity to improve knowledge of brain structures and relations in neurological conditions. These methods would enable medical students and doctors-in-training to better their understanding of neurological disease and the necessary interventions.

Cranial neurosurgical robotics

OBJECT

The purpose of this review is to highlight the major factors limiting the progress of robotics development in the field of cranial neurosurgery.

METHODS

A literature search was performed focused on published reports of any Neurosurgical technology developed for use in cranial neurosurgery. Technology was reviewed and assessed for strengths and weaknesses, use in patients and whether or not the project was active or closed.

RESULTS

Published reports of 24 robots are discussed going back to 1985. In total, there were 9 robots used in patients (PUMA, Robot Hand, EXPERT, Neuromate, Evolution 1, ROSA, iSYS1, NeuroArm and NeuRobot) and only 2 active today (ROSA, NeuroArm). Of all clinically active systems, only three were used in more than 30 patients (ROSA, iSYS1 & NeuroArm). Projects were limited by cost, technology adoption, and clinical utility to actually improve workflow. The most common use of developed robots is for Stereotaxis.

CONCLUSIONS

There is a clear void in the area of cranial neurosurgery regarding robotics technology despite success in other fields of surgery. Significant factors such as cost, technology limitations, market size and regulatory pathway all contribute to a steep gradient for success.

Robot-assisted stereoelectroencephalography electrode placement in twenty-three pediatric patients: a high-resolution analysis of individual lead placement time and accuracy at a single institution

PURPOSE

We describe a detailed evaluation of predictors associated with individual lead placement efficiency and accuracy for 261 stereoelectroencephalography (sEEG) electrodes placed for epilepsy monitoring in twenty-three children at our institution.

METHODS

Intra- and post-operative data was used to generate a linear mixed model to investigate predictors associated with three outcomes (lead placement time, lead entry error, lead target error) while accounting for correlated observations from the same patients. Lead placement time was measured using electronic time-stamp records stored by the ROSA software for each individual electrode; entry and target site accuracy was measured using postoperative stereotactic CT images fused with preoperative electrode trajectory planning images on the ROSA computer software. Predictors were selected from a list of variables that included patient demographics, laterality of leads, anatomic location of lead, skull thickness, bolt cap device used, and lead sequence number.

RESULTS

Twenty-three patients (11 female, 48%) of mean age 11.7 (± 6.1) years underwent placement of intracranial sEEG electrodes (median 11 electrodes) at our institution over a period of 1 year. There were no associated infections, hemorrhages, or other adverse events, and successful seizure capture was obtained in all monitored patients. The mean placement time for individual electrodes across all patients was 6.56 (± 3.5) min; mean target accuracy was 4.5 (± 3.5) mm. Lesional electrodes were associated with 25.7% (95% CI: 6.7-40.9%, p = 0.02) smaller target point errors. Larger skull thickness was associated with larger error: for every 1-mm increase in skull thickness, there was a 4.3% (95% CI: 1.2-7.5%, p = 0.007) increase in target error. Bilateral lead placement was associated with 26.0% (95% CI: 9.9-44.5%, p = 0.002) longer lead placement time. The relationship between placement time and lead sequence number was nonlinear: it decreased consistently for the first 4 electrodes, and became less pronounced thereafter.

CONCLUSIONS

Variation in sEEG electrode placement efficiency and accuracy can be explained by phenomena both within and outside of operator control. It is important to keep in mind the factors that can lead to better or worse lead placement efficiency and/or accuracy in order to maximize patient safety while maintaining the standard of care.

Comparison of frame-less robotic versus frame-based stereotactic biopsy of intracranial lesions

OBJECTIVE

Robotic guidance might be an alternative to classic stereotaxy for biopsies of intracranial lesions. Both methods were compared regarding time efficacy, histopathological results and complications.

METHODS

A retrospective analysis enrolling all patients undergoing robotic- or stereotactic biopsies between 01/2015 and 12/2018 was conducted. Trajectory planning was performed on magnetic resonance imaging (MRI). With the Robotic Surgery Assistant (ROSA), patient registration was accomplished using a facial laser scan in the operating room (OR), immediately followed by biopsy. In stereotaxy, patients were transported to the CT for Leksell Frame registration, followed by biopsy in the OR.

RESULTS

The average overall procedure time amounted in robotics to 169 min and in stereotaxy to 179 min (p = 0.005). The difference was greatest for temporal targets, amounting in robotics to 161 min and in stereotaxy to 188 min (p = 0,0007). However, the average time spent purely in the OR amounted in robotics to 140 min and in stereotaxy to 113 min (p < 0.001). In 150 robotic biopsies, diagnostic yield amounted to 98%, in 266 stereotactic biopsies to 91%. Symptomatic postoperative hemorrhages were observed in 3 patients (2%) in robotic biopsy and 7 patients (2,7%) in stereotactic biopsy.

CONCLUSION

Robotics showed a shorter overall procedure time as there is no need for a transport to the CT whereas the pure OR time was shorter in stereotaxy due to skipping the laser registration process. Diagnostic yield was higher in robotics, most likely due to case selection, complication rates were equal.

Patient-to-robot registration: The fate of robot-assisted stereotaxy

BACKGROUND

Robot-assisted stereotaxy (RAS) promises higher stereotactic accuracy (SA) and time efficiency (TE) than frame-based stereotaxy. However, both aspects are attributed to the problem of patient-to-robot registration.

OBJECTIVE

To examine different registration techniques regarding their SA and TE.

METHODS

This study enrolled 57 patients undergoing RAS with bone fiducial registration (BFR) or laser surface registration (LSR). SA was measured by the entry point error (EPE). Additionally, predictors of SA (registration error [RegE], distance-to-registration plane [DTC]) and TE (imaging, skin-to-skin) were assessed.

RESULTS

The mean SA was 1.0 ± 0.8 mm. BFR increased SA by reducing RegE and DTC. In LSR, EPE depended on DTC (face and forehead) with highest accuracy for DTC ≤100 mm. CT-based LSR exerted a higher SA than MR-based LSR. In BFR, TE was confined by the additional imaging.

CONCLUSION

Every registration technique counteracts one of the promises of RAS. New solutions are needed to increase the acceptance of RAS in neurosurgery.

THE SAFETY AND EFFICACY OF ROBOT-ASSISTED STEREOTACTIC BIOPSY FOR BRAIN GLIOMA: EARLIEST INSTITUTIONAL EXPERIENCES AND EVALUATION OF LITERATURE

Robot-assisted brain tumor biopsy is becoming one of the most important innovative technologies in neurosurgical practice. The idea behind its engagement is to advance the safety and efficacy of the biopsy procedure, which is much in demand when planning the management of endocranial tumor pathology. Herein, we provide our earliest institutional experiences in utilizing this mesmerizing technology. Cranial robotic device was employed for stereotactic robot-assisted brain glioma biopsy in three consecutive patients from our series: an anaplastic isocitrate dehydrogenase (IDH) negative astrocytoma (WHO grade III) located in the right trigone region of the periventricular white matter; a low grade diffuse astrocytoma (WHO grade II) of bilateral thalamic region spreading into the right mesencephalic area; and an IDH-wildtype glioblastoma (WHO grade IV) of the right frontal lobe producing a contralateral midline shifting. Robot-assisted tumor biopsy was successfully performed to get tissue samples for histopathologic and immunohistochemical analysis. The adjacent tissue iatrogenic damage of the eloquent cortical areas was minimal, while the immediate postoperative recovery was satisfactory in all patients. In conclusion, considering the preliminary results of our early experiences, robot-assisted tumor biopsy was proven to be a feasible and accurate procedure when surgery for brain glioma was not an option. It may increase safety and precision, without expanding surgical time, being similarly effective when compared to standard stereotactic and manual biopsy. Using this method to provide accurate sampling for histopathologic and immunohistochemical analysis is a safe and easy way to determine management strategies and outcome of different types of brain glioma.

VarioGuide® frameless neuronavigation-guided stereoelectroencephalography in adult epilepsy patients: technique, accuracy and clinical experience

Background

Stereoelectroencephalography (SEEG) allows the identification of deep-seated seizure foci and determination of the epileptogenic zone (EZ) in drug-resistant epilepsy (DRE) patients. We evaluated the accuracy and treatment-associated morbidity of frameless VarioGuide® (VG) neuronavigation-guided depth electrode (DE) implantations.

Methods

We retrospectively identified all consecutive adult DRE patients, who underwent VG-neuronavigation DE implantations, between March 2013 and April 2019. Clinical data were extracted from the electronic patient charts. An interdisciplinary team agreed upon all treatment decisions. We performed trajectory planning with iPlan® Cranial software and DE implantations with the VG system. Each electrode’s accuracy was assessed at the entry (EP), the centre (CP) and the target point (TP). We conducted correlation analyses to identify factors associated with accuracy.

Results

The study population comprised 17 patients (10 women) with a median age of 32.0 years (range 21.0–54.0). In total, 220 DEs (median length 49.3 mm, range 25.1–93.8) were implanted in 21 SEEG procedures (range 3–16 DEs/surgery). Adequate signals for postoperative SEEG were detected for all but one implanted DEs (99.5%); in 15/17 (88.2%) patients, the EZ was identified and 8/17 (47.1%) eventually underwent focus resection. The mean deviations were 3.2 ± 2.4 mm for EP, 3.0 ± 2.2 mm for CP and 2.7 ± 2.0 mm for TP. One patient suffered from postoperative SEEG-associated morbidity (i.e. conservatively treated delayed bacterial meningitis). No mortality or new neurological deficits were recorded.

Conclusions

The accuracy of VG-SEEG proved sufficient to identify EZ in DRE patients and associated with a good risk-profile. It is a viable and safe alternative to frame-based or robotic systems.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00701-021-04755-w.

Robot-Assisted Stereotaxy Reduces Target Error: A Meta-Analysis and Meta-Regression of 6056 Trajectories

BACKGROUND

The pursuit of improved accuracy for localization and electrode implantation in deep brain stimulation (DBS) and stereoelectroencephalography (sEEG) has fostered an abundance of disparate surgical/stereotactic practices. Specific practices/technologies directly modify implantation accuracy; however, no study has described their respective influence in multivariable context.

OBJECTIVE

To synthesize the known literature to statistically quantify factors affecting implantation accuracy.

METHODS

A systematic review and meta-analysis was conducted to determine the inverse-variance weighted pooled mean target error (MTE) of implanted electrodes among patients undergoing DBS or sEEG. MTE was defined as Euclidean distance between planned and final electrode tip. Meta-regression identified moderators of MTE in a multivariable-adjusted model.

RESULTS

A total of 37 eligible studies were identified from a search return of 2,901 potential articles (2002-2018) - 27 DBS and 10 sEEG. Random-effects pooled MTE = 1.91 mm (95% CI: 1.7-2.1) for DBS and 2.34 mm (95% CI: 2.1-2.6) for sEEG. Meta-regression identified study year, robot use, frame/frameless technique, and intraoperative electrophysiologic testing (iEPT) as significant multivariable-adjusted moderators of MTE (P < .0001, R2 = 0.63). Study year was associated with a 0.92-mm MTE reduction over the 16-yr study period (P = .0035), and robot use with a 0.79-mm decrease (P = .0019). Frameless technique was associated with a mean 0.50-mm (95% CI: 0.17-0.84) increase, and iEPT use with a 0.45-mm (95% CI: 0.10-0.80) increase in MTE. Registration method, imaging type, intraoperative imaging, target, and demographics were not significantly associated with MTE on multivariable analysis.

CONCLUSION

Robot assistance for stereotactic electrode implantation is independently associated with improved accuracy and reduced target error. This remains true regardless of other procedural factors, including frame-based vs frameless technique.

Time Efficiency in Stereotactic Robot-Assisted Surgery: An Appraisal of the Surgical Procedure and Surgeon's Learning Curve

BACKGROUND

Frame-based stereotactic procedures are still the gold standard in neurosurgery. However, there is an increasing interest in robot-assisted technologies. Introducing these increasingly complex tools in the clinical setting raises the question about the time efficiency of the system and the essential learning curve of the surgeon.

METHODS

This retrospective study enrolled a consecutive series of patients undergoing a robot-assisted procedure after first system installation at one institution. All procedures were performed by the same neurosurgeon to capture the learning curve. The objective read-out were the surgical procedure time (SPT), the skin-to-skin time, and the intraoperative registration time (IRT) after laser surface registration (LSR), bone fiducial registration (BFR), and skin fiducial registration (SFR), as well as the quality of the registration (as measured by the fiducial registration error [FRE]). The time measures were compared to those for a patient group undergoing classic frame-based stereotaxy.

RESULTS

In the first 7 months, we performed 31 robot-assisted surgeries (26 biopsies, 3 stereotactic electroencephalography [SEEG] implantations, and 2 endoscopic procedures). The SPT was depending on the actual type of surgery (biopsies: 85.0 ± 36.1 min; SEEG: 154.9 ± 75.9 min; endoscopy: 105.5 ± 1.1 min; p = 0.036). For the robot-assisted biopsies, there was a significant reduction in SPT within the evaluation period, reaching the level of frame-based surgeries (58.1 ± 17.9 min; p < 0.001). The IRT was depending on the applied registration method (LSR: 16.7 ± 2.3 min; BFR: 3.5 ± 1.1 min; SFR: 3.5 ± 1.6 min; p < 0.001). In contrast to BFR and SFR, there was a significant reduction in LSR time during that period (p = 0.038). The FRE differed between the applied registration methods (LSR: 0.60 ± 0.17 mm; BFR: 0.42 ± 0.15 mm; SFR: 2.17 ± 0.78 mm; p < 0.001). There was a significant improvement in LSR quality during the evaluation period (p = 0.035).

CONCLUSION

Introducing stereotactic, robot-assisted surgery in an established clinical setting initially necessitates a prolonged intraoperative preparation time. However, there is a steep learning curve during the first cases, reaching the time level of classic frame-based stereotaxy. Thus, a stereotactic robot can be integrated into daily routine within a decent period of time, thereby expanding the neurosurgeons' armamentarium, especially for procedures with multiple trajectories.

Surgical Robot-Enhanced Implantation of Intracranial Depth Electrodes for Single Neuron Recording Studies in Patients with Medically Refractory Epilepsy: A Technical Note

OBJECTIVE

Single neuron or unit recording enables researchers to measure the electrophysiologic responses of single neurons using a microelectrode system. This approach is widely used in cognitive science and has become more widespread in humans with the use of hybrid (micro-within-macrowire) depth electrodes that enable the implantation of microwires into the brain parenchyma.

METHODS

The authors describe their surgical technique in a total of 7 patients with intractable epilepsy who underwent robot-enhanced stereoencephalography in which both standard (nonhybrid) and hybrid depth electrodes were used for invasive chronic monitoring.

RESULTS

The technique and accuracy of the procedure were evaluated with a total of 84 depth electrodes (46 hybrid, 38 standard) in 7 patients. No major complications, such as intracranial hemorrhage, infection or cerebrospinal fluid leakage, occurred regardless of the type of electrode used.

CONCLUSIONS

The addition of hybrid depth electrodes for the purpose of in vivo single neuron recording in robot-enhanced stereoencephalography procedures is safe and does not impact the accuracy of targeting or patient safety.

Indications, Techniques, and Outcomes of Robot-Assisted Insular Stereo-Electro-Encephalography: A Review

Stereo-electro-encephalography (SEEG) is an invasive, surgical, and electrophysiological method for three-dimensional registration and mapping of seizure activity in drug-resistant epilepsy. It allows the accurate analysis of spatio-temporal seizure activity by multiple intraparenchymal depth electrodes. The technique requires rigorous non-invasive pre-SEEG evaluation (clinical, video-EEG, and neuroimaging investigations) in order to plan the insertion of the SEEG electrodes with minimal risk and maximal recording accuracy. The resulting recordings are used to precisely define the surgical limits of resection of the epileptogenic zone in relation to adjacent eloquent structures. Since the initial description of the technique by Talairach and Bancaud in the 1950's, several techniques of electrode insertion have been used with accuracy and relatively few complications. In the last decade, robot-assisted surgery has emerged as a safe, accurate, and time-saving electrode insertion technique due to its unparalleled potential for orthogonal and oblique insertion trajectories, guided by rigorous computer-assisted planning. SEEG exploration of the insular cortex remains difficult due to its anatomical location, hidden by the temporal and frontoparietal opercula. Furthermore, the close vicinity of Sylvian vessels makes surgical electrode insertion challenging. Some epilepsy surgery teams remain cautious about insular exploration due to the potential of neurovascular injury. However, several authors have published encouraging results regarding the technique's accuracy and safety in both children and adults. We will review the indications, techniques, and outcomes of insular SEEG exploration with emphasis on robot-assisted implantation.

Innovations in the Neurosurgical Management of Epilepsy

Technical limitations and clinical challenges have historically limited the diagnostic tools and treatment methods available for surgical approaches to the management of epilepsy. By contrast, recent technological innovations in several areas hold significant promise in improving outcomes and decreasing morbidity. We review innovations in the neurosurgical management of epilepsy in several areas, including wireless recording and stimulation systems (particularly responsive neurostimulation [NeuroPace]), conformal electrodes for high-resolution electrocorticography, robot-assisted stereotactic surgery, optogenetics and optical imaging methods, novel positron emission tomography ligands, and new applications of focused ultrasonography. Investigation into genetic causes of and susceptibilities to epilepsy has introduced a new era of precision medicine, enabling the understanding of cell signaling mechanisms underlying epileptic activity as well as patient-specific molecularly targeted treatment options. We discuss the emerging path to individualized treatment plans, predicted outcomes, and improved selection of effective interventions, on the basis of these developments.

Robotic Surgical Assistant (ROSA™) Rehearsal: Using 3-Dimensional Printing Technology to Facilitate the Introduction of Stereotactic Robotic Neurosurgical Equipment

BACKGROUND

The use of frameless stereotactic robotic technology has rapidly expanded since the Food and Drug Administration's approval of the Robotic Surgical Assistant (ROSA™) in 2012. Although the safety and accuracy of the ROSA platform has been well-established, the introduction of complex robotic technology into an existing surgical practice poses technical and logistical challenges particular to a given institution.

OBJECTIVES

To better facilitate the integration of new surgical equipment into the armamentarium of a thriving pediatric neurosurgery practice by describing the use of a three-dimensional (3D)-printed patient model with in situ 3D-printed tumor for presurgical positioning and trajectory optimization in the stereotactic biopsy of a pontine lesion in a pediatric patient.

METHODS

A 3D model was created with an added silicone mock tumor at the anatomical position of the lesion. In a preoperative rehearsal session, the patient model was pinned and registered using the ROSA platform, and a mock biopsy was performed targeting the in Situ silicone tumor.

RESULTS

Utilization of the 3D-printed model enabled workflow optimization and increased staff familiarity with the logistics of the robotic technology. Biopsy trajectory successfully reached intralesional tissue on the 3D-printed model. The rehearsal maneuvers decreased operative and intubation time for the patient and improved operative staff familiarity with the robotic setup.

CONCLUSION

Use of a 3D-printed patient model enhanced presurgical positioning and trajectory planning in the biopsy of a difficult to reach pontine lesion in a pediatric patient. The ROSA rehearsal decreased operative time and increased staff familiarity with a new complex surgical equipment.

How technology is driving the landscape of epilepsy surgery

This article emphasizes the role of the technological progress in changing the landscape of epilepsy surgery and provides a critical appraisal of robotic applications, laser interstitial thermal therapy, intraoperative imaging, wireless recording, new neuromodulation techniques, and high-intensity focused ultrasound. Specifically, (a) it relativizes the current hype in using robots for stereo-electroencephalography (SEEG) to increase the accuracy of depth electrode placement and save operating time; (b) discusses the drawback of laser interstitial thermal therapy (LITT) when it comes to the need for adequate histopathologic specimen and the fact that the concept of stereotactic disconnection is not new; (c) addresses the ratio between the benefits and expenditure of using intraoperative magnetic resonance imaging (MRI), that is, the high technical and personnel expertise needed that might restrict its use to centers with a high case load, including those unrelated to epilepsy; (d) soberly reviews the advantages, disadvantages, and future potentials of neuromodulation techniques with special emphasis on the differences between closed and open-loop systems; and (e) provides a critical outlook on the clinical implications of focused ultrasound, wireless recording, and multipurpose electrodes that are already on the horizon. This outlook shows that although current ultrasonic systems do have some limitations in delivering the acoustic energy, further advance of this technique may lead to novel treatment paradigms. Furthermore, it highlights that new data streams from multipurpose electrodes and wireless transmission of intracranial recordings will become available soon once some critical developments will be achieved such as electrode fidelity, data processing and storage, heat conduction as well as rechargeable technology. A better understanding of modern epilepsy surgery will help to demystify epilepsy surgery for the patients and the treating physicians and thereby reduce the surgical treatment gap.

Robotic Surgical Assistant Rehearsal: Combining 3-Dimensional-Printing Technology With Preoperative Stereotactic Planning for Placement of Stereoencephalography Electrodes

BACKGROUND

The use of frameless stereotactic robotic technology has rapidly expanded since the Food and Drug Administration's approval of the Robotic Surgical Assistant (ROSA) in 2012. Although the use of the ROSA robot has greatly augmented stereotactic placement of intracerebral stereoelectroencephalography (sEEG) for the purposes of epileptogenic focus identification, the preoperative planning stages remain limited to computer software.

OBJECTIVE

To describe the use of a 3-dimensionally (3D)-printed patient model in the preoperative planning of ROSA-assisted depth electrode placement for epilepsy monitoring in a pediatric patient.

METHODS

An anatomically accurate 3D model was created and registered in a preoperative rehearsal session using the ROSA platform. After standard software-based electrode trajectory planning, sEEG electrodes were sequentially placed in the 3D model.

RESULTS

Utilization of the 3D-printed model enabled workflow optimization and increased staff familiarity with the logistics of the robotic technology as it relates to depth electrode placement. The rehearsal maneuvers enabled optimization of patient head positioning as well as identification of physical conflicts between 2 electrodes. This permitted revision of trajectory planning in anticipation of the actual case, thereby improving patient safety and decreasing operative time.

CONCLUSION

Use of a 3D-printed patient model enhanced presurgical positioning and trajectory planning in the placement of stereotactic sEEG electrodes for epilepsy monitoring in a pediatric patient. The ROSA rehearsal decreased operative time and increased efficiency of electrode placement.