The comparative accuracy of the ROSA stereotactic robot across a wide range of clinical applications and registration techniques

Magnetoencephalographic detection of synchronized epileptic activity between the hippocampus and insular cortex

Most magnetoencephalographic signals are derived from synchronized activity in the brain surface cortex. By contrast, the contribution of synchronized activity in the deep brain to magnetoencephalography (MEG) has remained unclear. We compared stereotactic electroencephalography (sEEG) with simultaneous MEG findings in a patient with temporal lobe epilepsy to determine the conditions under which MEG could also detect sEEG findings. The synchrony and similarity of the waves were evaluated using visual inspection and wavelet coherence. A 45-year-old woman with intractable temporal lobe epilepsy underwent sEEG and MEG simultaneously to determine the laterality and precise location of the epileptic focus. When spike-and-waves were seen in the right hippocampal head alone, no distinct spike-and-waves were observed visually in the right temporal MEG. The seizure then spread to the right insula on sEEG with a rhythmic theta frequency while synchronous activity was observed in the right temporal MEG channels. When polyspikes appeared in the right hippocampus, the right temporal MEG showed electrical activity with relatively high similarity to that of the right hippocampal head and insular cortex but less similarity to that of the right lateral temporal lobe cortex. MEG might detect epileptic activity synchronized between the hippocampus and insular cortex.

Accuracy and efficiency using frameless transient fiducial registration in stereoelectroencephalography and deep brain stimulation

OBJECTIVE

Stereotactic surgical methods continue to advance technologically. Frameless transient fiducial registration (FTFR) systems have been developed and avoid the need to move or position a patient in a frame after already receiving registration imaging. One such system, Neurolocate, has recently become available as a robotic attachment for the Neuromate stereotactic robot. This study is the largest in the literature to evaluate the accuracy of frameless registration using Neurolocate versus frame-based registration (FBR) methods in both deep brain stimulation (DBS) and stereoelectroencephalography (SEEG). Additionally, the authors sought to reevaluate factors affecting accuracy in both procedures.

METHODS

This study was a retrospective chart and imaging review of 88 consecutive procedures (involving 621 electrodes) implanting either DBS or SEEG at the authors' institution over a 5-year period from March 2015 to March 2020. Registration duration, radial target entry point, and Euclidean target implantation accuracies, as well as factors affecting accuracy, were recorded for each patient.

RESULTS

SEEG procedures included 38 patients and 525 implanted electrodes (294 using FBR and 231 using FTFR). DBS procedures included 50 patients and 96 implanted electrodes (65 using FBR and 31 using FTFR). Overall, FTFR registration was significantly more accurate (median 0.1 mm, IQR 0-0.4 mm) compared with FBR (median 1.3 mm, IQR 0.9-1.5 mm; p = 0.04). Likewise, FTFR had a significantly shorter duration of registration (median 84 minutes, IQR 77.3-95.3 minutes) when compared with FBR (median 110.5 minutes, IQR 107.3-138 minutes; p = 0.02). No significant differences were found when examining the radial entry point and Euclidean target implantation errors of each method.

CONCLUSIONS

FTFR with the Neurolocate system represents a technique that may decrease operative time while maintaining the high accuracy previously demonstrated by other stereotactic methods, despite an initial surgeon learning curve. It should be investigated in future studies to continue to improve stereotactic accuracies in neurosurgery.

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.

Awake Deep Brain Stimulation Surgery Without Intraoperative Imaging Is Accurate and Effective: A Case Series

BACKGROUND

The success of deep brain stimulation (DBS) surgery depends on the accuracy of electrode placement. Several factors can affect this such as brain shift, the quality of preoperative planning, and technical factors. It is crucial to determine whether techniques yield accurate lead placement and effective symptom relief. Many of the studies establishing the accuracy of frameless techniques used intraoperative imaging to further refine lead placement.

OBJECTIVE

To determine whether awake lead placement without intraoperative imaging can achieve similar minimal targeting error while preserving clinical results.

METHODS

Eighty-two trajectories in 47 patients who underwent awake, frameless DBS lead placement with the Fred Haer Corporation STarFix system for essential tremor or Parkinson's disease were analyzed. Neurological testing during lead placement was used to determine appropriate lead locations, and no intraoperative imaging was performed. Accuracy data were compared with previously performed studies.

RESULTS

The Euclidean error for the patient cohort was 1.79 ± 1.02 mm, and the Pythagorean error was 1.40 ± 0.95 mm. The percentage symptom improvement evaluated by the Unified Parkinson's Disease Rating Scale for Parkinson's disease or the Fahn-Tolosa-Marin scale for essential tremor was similar to reported values at 58% ± 17.2% and 67.4% ± 24.7%, respectively. The operative time was 95.0 ± 30.3 minutes for all study patients.

CONCLUSION

Awake, frameless DBS surgery with the Fred Haer Corporation STarFix system does not require intraoperative imaging for stereotactic accuracy or clinical effectiveness.

Advances in human intracranial electroencephalography research, guidelines and good practices

Since the second-half of the twentieth century, intracranial electroencephalography (iEEG), including both electrocorticography (ECoG) and stereo-electroencephalography (sEEG), has provided an intimate view into the human brain. At the interface between fundamental research and the clinic, iEEG provides both high temporal resolution and high spatial specificity but comes with constraints, such as the individual's tailored sparsity of electrode sampling. Over the years, researchers in neuroscience developed their practices to make the most of the iEEG approach. Here we offer a critical review of iEEG research practices in a didactic framework for newcomers, as well addressing issues encountered by proficient researchers. The scope is threefold: (i) review common practices in iEEG research, (ii) suggest potential guidelines for working with iEEG data and answer frequently asked questions based on the most widespread practices, and (iii) based on current neurophysiological knowledge and methodologies, pave the way to good practice standards in iEEG research. The organization of this paper follows the steps of iEEG data processing. The first section contextualizes iEEG data collection. The second section focuses on localization of intracranial electrodes. The third section highlights the main pre-processing steps. The fourth section presents iEEG signal analysis methods. The fifth section discusses statistical approaches. The sixth section draws some unique perspectives on iEEG research. Finally, to ensure a consistent nomenclature throughout the manuscript and to align with other guidelines, e.g., Brain Imaging Data Structure (BIDS) and the OHBM Committee on Best Practices in Data Analysis and Sharing (COBIDAS), we provide a glossary to disambiguate terms related to iEEG research.

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.

Frameless Robot-Assisted vs Frame-Based Awake Deep Brain Stimulation Surgery: An Evaluation of Technique and New Challenges

BACKGROUND

Methodological approaches to deep brain stimulation (DBS) continue to evolve from awake frame-based to asleep frameless procedures with robotic assistance, primarily directed to optimize operative efficiency, lead accuracy, and patient comfort. Comparison between the 2 is scarce.

OBJECTIVE

To analyze the impacts of methodological differences on operative efficiency and stereotactic accuracy using a frame compared with a frameless robotic platform while maintaining the awake state and use of multiple microelectrode recording (MER) trajectories.

METHODS

Thirty-four consecutive patients who underwent bilateral awake frameless robot-assisted DBS were compared with a previous cohort of 30 patients who underwent frame-based surgery. Patient demographics, operative times, and MER data were collected for both cohorts. Two-dimensional radial errors of lead placements were calculated.

RESULTS

Preoperative setup, surgical, and total operating room times were all significantly greater for the robot-assisted cohort (P < .001). The need for computed tomography imaging when referencing the robotic fiducials led to increased setup duration because of patient transport, unnecessary for the frame-based cohort. Multiple simultaneous MER trajectories increased surgical time (mean 26 min) for the robot-assisted cohort only. The mean radial errors in the robot-assisted and frame cohorts were 0.98 ± 0.66 and 0.74 ± 0.49 mm (P = .03), respectively.

CONCLUSION

The use of a truly frameless robotic platform such as the Mazor Renaissance (Mazor Robotics Ltd) presented challenges when implementing techniques used during awake frame-based surgery. Maintaining good accuracy, intraoperative reference imaging, and limited MER trajectories will help integrate frameless robot assistance into the awake DBS surgical workflow.

Intraparenchymal hematoma and intraventricular catheter placement using robotic stereotactic assistance (ROSA): A single center preliminary experience

BACKGROUND

Large supratentorial intraparenchymal hemorrhages are managed emergently with image-guided catheters that aim to minimize injury to surrounding parenchyma. Robotic assistance may offer advantages for stereotactic guidance and placement of such catheters. We describe our center's experience with minimally invasive ROSA-assisted intraventricular and intraparenchymal hemorrhage catheter placement and delineate its safety and outcomes.

METHODS

A retrospective analysis was performed including all patients with intraparenchymal hematoma that underwent ROSA-assisted intraparenchymal and intraventricular catheter placement at the University of Pittsburgh Medical Center between 2017 and 2019. All patients received tissue plasminogen activator (tPA) through the intraparenchymal catheter. We performed a manual chart review of these patients. Pertinent clinical and radiological characteristics and patient outcomes were recorded and analyzed. Catheter trajectory was independently quantified and analyzed by two independent reviewers. Error between the planned trajectory and final position was calculated and analyzed.

RESULTS

Four patients (2 males and 2 females, mean age of 64 years) with deep brain large volume intraparenchymal hemorrhages were treated with catheter evacuation with robotic assistance. For 2 of the 4 patients, thin-cut CT imaging allowed for the real trajectory of the catheter to be compared to the targeted trajectory to calculate error. The mean error of catheter placement was 3.48 mm. ROSA-assisted catheter placement achieved up to 95% reduction of intraparenchymal hematoma volume with a statistically significant decrease following catheter drainage (pre- 51.8 ± 19.1 cc vs. post- 13.0 ± 14.4; p < 0.01).

CONCLUSION

Robotic stereotactic assistance offers a safe and sufficiently accurate technique for intraparenchymal hematoma and intraventricular catheter placement.

Robotic guidance platform for laser interstitial thermal ablation and stereotactic needle biopsies: a single center experience

While laser ablation has become an increasingly important tool in the neurosurgical oncologist's armamentarium, deep seated lesions, and those located near critical structures require utmost accuracy during stereotactic laser catheter placement. Robotic devices have evolved significantly over the past two decades becoming an accurate and safe tool for stereotactic neurosurgery. Here, we present our single center experience with the MedTech ROSA ONE Brain robot for robotic guidance in laser interstitial thermal therapy (LITT) and stereotactic biopsies. We retrospectively analyzed the first 70 consecutive patients treated with ROSA device at a single academic medical center. Forty-three patients received needle biopsy immediately followed by LITT with the catheter placed with robotic guidance and 27 received stereotactic needle biopsy alone. All the procedures were performed frameless with skull bone fiducials for registration. We report data regarding intraoperative details, mortality and morbidity, diagnostic yield and lesion characteristics on MRI. Also, we describe the surgical workflow for both procedures. The mean age was 60.3 ± 15 years. The diagnostic yield was positive in 98.5% (n = 69). Sixty-three biopsies (90%) were supratentorial and seven (10%) were infratentorial. Gliomas represented 54.3% of the patients (n = 38). There were two postoperative deaths (2.8%). No permanent morbidity related to surgery were observed. We did not find intraoperative technical problems with the device. There was no need to reposition the needle after the initial placement. Stereotactic robotic guided placement of laser ablation catheters and biopsy needles is safe, accurate, and can be implemented into a neurosurgical workflow.

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.

Robot-Assisted Stereotactic Shunting as a Novel Treatment for Pontine Glioependymal Cysts

In this case report, the authors describe the first case of a glioependymal cyst of the brainstem managed by robot-assisted, stereotactic, cysto-ventricular shunting. Glioependymal cysts are rare congenital cystic lesions that are thought to form by displacement of ependymal cells during the embryonal period. Glioependymal cysts have been reported in a variety of different locations within the central nervous system. However, glioependymal cysts of the brainstem have only been described once before. Here, we report the case of a 53-year-old man who was referred to our department due to hemiparesis, hemihypesthesia, and hemidysesthesia, as well as facial and abducens nerve palsy. A large pontine glioependymal cyst was confirmed via magnetic resonance imaging (MRI) scans. The cyst was subsequently decompressed by connecting the cyst with the fourth ventricle via robot-assisted stereotactic shunt placement. In the postoperative course, the patient made a quick recovery and did not report any permanent neurologic deficits.

Development of a fluoroscopically guided robotic assistant for instrument placement in pelvic trauma surgery

Purpose: A method for fluoroscopic guidance of a robotic assistant is presented for instrument placement in pelvic trauma surgery. The solution uses fluoroscopic images acquired in standard clinical workflow and helps avoid repeat fluoroscopy commonly performed during implant guidance. Approach: Images acquired from a mobile C-arm are used to perform 3D-2D registration of both the patient (via patient CT) and the robot (via CAD model of a surgical instrument attached to its end effector, e.g; a drill guide), guiding the robot to target trajectories defined in the patient CT. The proposed approach avoids C-arm gantry motion, instead manipulating the robot to acquire disparate views of the instrument. Phantom and cadaver studies were performed to determine operating parameters and assess the accuracy of the proposed approach in aligning a standard drill guide instrument. Results: The proposed approach achieved average drill guide tip placement accuracy of 1.57 ± 0.47    mm and angular alignment of 0.35 ± 0.32    deg in phantom studies. The errors remained within 2 mm and 1 deg in cadaver experiments, comparable to the margins of errors provided by surgical trackers (but operating without the need for external tracking). Conclusions: By operating at a fixed fluoroscopic perspective and eliminating the need for encoded C-arm gantry movement, the proposed approach simplifies and expedites the registration of image-guided robotic assistants and can be used with simple, non-calibrated, non-encoded, and non-isocentric C-arm systems to accurately guide a robotic device in a manner that is compatible with the surgical workflow.

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.

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.

Frameless stereotactic brain biopsy: A prospective study on robot-assisted brain biopsies performed on 32 patients by using the RONNA G4 system

BACKGROUND

We present a novel robotic neuronavigation system (RONNA G4), used for precise preoperative planning and frameless neuronavigation, developed by a research group from the University of Zagreb and neurosurgeons from the University Hospital Dubrava, Zagreb, Croatia. The aim of study is to provide comprehensive error measurement analysis of the system used for the brain biopsy.

METHODS

Frameless stereotactic robot-assisted biopsies were performed on 32 consecutive patients. Post-operative CT and MRI scans were assessed to precisely measure and calculate target point error (TPE) and entry point error (EPE).

RESULTS

The application accuracy of the RONNA system for TPE was 1.95 ± 1.11 mm, while for EPE was 1.42 ± 0.74 mm. The total diagnostic yield was 96.87%. Linear regression showed statistical significance between the TPE and EPE, and the angle of the trajectory on the bone.

CONCLUSION

The RONNA G4 robotic system is a precise and highly accurate autonomous neurosurgical assistant for performing frameless brain biopsies.

A body-mounted device for MRI-guided spinal therapy

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease with no cure and limited treatment options. Recent studies have shown that delivering cellular therapeutics to the ventral horn of the spinal cord can effectively halt neurodegeneration associated with ALS in small animal models.

METHODS

We developed a robotic system that assists with MRI-guided percutaneous injections to the spinal cord. The needle positioning robot consists of two linear axes with motorised translational sleds for two-degree-of-freedom (2-DOF) needle translation and a radial template for 2-DOF discrete rotation.

RESULTS

The robot's targeting capability, evaluated using phantom models and swine cadavers, showed mean targeting errors of 0.48 and 2.84 mm, respectively. The duration of the targeting procedure is approximately 60 min, with an extra 10 min for each additional injection.

CONCLUSIONS

The presented robot does not affect imaging quality during MRI-guided procedures, and it enables a simplified workflow for MRI-guided spinal therapy.

Fluoroscopic Guidance of a Surgical Robot: Pre-clinical Evaluation in Pelvic Guidewire Placement

PURPOSE

A method and prototype for a fluoroscopically-guided surgical robot is reported for assisting pelvic fracture fixation. The approach extends the compatibility of existing guidance methods with C-arms that are in mainstream use (without prior geometric calibration) using an online calibration of the C-arm geometry automated via registration to patient anatomy. We report the first preclinical studies of this method in cadaver for evaluation of geometric accuracy.

METHODS

The robot is placed over the patient within the imaging field-of-view and radiographs are acquired as the robot rotates an attached instrument. The radiographs are then used to perform an online geometric calibration via 3D-2D image registration, which solves for the intrinsic and extrinsic parameters of the C-arm imaging system with respect to the patient. The solved projective geometry is then be used to register the robot to the patient and drive the robot to planned trajectories. This method is applied to a robotic system consisting of a drill guide instrument for guidewire placement and evaluated in experiments using a cadaver specimen.

RESULTS

Robotic drill guide alignment to trajectories defined in the cadaver pelvis were accurate within 2 mm and 1° (on average) using the calibration-free approach. Conformance of trajectories within bone corridors was confirmed in cadaver by extrapolating the aligned drill guide trajectory into the cadaver pelvis.

CONCLUSION

This study demonstrates the accuracy of image-guided robotic positioning without prior calibration of the C-arm gantry, facilitating the use of surgical robots with simpler imaging devices that cannot establish or maintain an offline calibration. Future work includes testing of the system in a clinical setting with trained orthopaedic surgeons and residents.

MRI-guided stereotactic laser corpus callosotomy for epilepsy: distinct methods and outcomes

OBJECTIVE

Several small series have described stereotactic MRI-guided laser interstitial thermal therapy for partial callosotomy of astatic and generalized tonic-clonic (GTC) seizures, especially in association with Lennox-Gastaut syndrome. Larger case series and comparison of distinct stereotactic methods for stereotactic laser corpus callosotomy (SLCC), however, are currently lacking. The objective of this study was to report seizure outcomes in a series of adult patients with epilepsy following anterior, posterior, and complete SLCC procedures and to compare the results achieved with a frameless stereotactic surgical robot versus direct MRI guidance frames.

METHODS

The authors retrospectively reviewed sequential adult epilepsy surgery patients who underwent SLCC procedures at a single institution. They describe workflows, stereotactic errors, percentage disconnection, hospitalization durations, adverse events, and seizure outcomes after performing anterior, posterior, and complete SLCC procedures using a frameless stereotactic surgical robot versus direct MRI guidance platforms.

RESULTS

Thirteen patients underwent 15 SLCC procedures. The median age at surgery was 29 years (range 20-49 years), the median duration of epilepsy was 21 years (range 9-48 years), and median postablation follow-up was 20 months (range 4-44 months). Ten patients underwent anterior SLCC with a median 73% (range 33%-80%) midsagittal length of callosum acutely ablated. Following anterior SLCC, 6 of 10 patients achieved meaningful (> 50%) reduction of target seizures. Four patients underwent posterior (completion) SLCC following prior anterior callosotomy, and 1 patient underwent complete SLCC as a single procedure; 3 of these 5 patients experienced meaningful reduction of target seizures. Overall, 8 of 10 patients in whom astatic seizures were targeted and treated by anterior and/or posterior SLCC experienced meaningful improvement. SLCC procedures with direct MRI guidance (n = 7) versus a frameless surgical robot (n = 8) yielded median radial accuracies of 1.1 mm (range 0.2-2.0 mm) versus 2.4 mm (range 0.6-6.1 mm; p = 0.0011). The most serious adverse event was a clinically significant intraparenchymal hemorrhage in a patient who underwent the robotic technique.

CONCLUSIONS

This is the largest reported series of SLCC for epilepsy to date. SLCC provides seizure outcomes comparable to open surgery outcomes reported in the literature. Direct MRI guidance is more accurate, which has the potential to reduce the risks of SLCC. Methodological advancements and larger studies are needed.

Frameless Robot-Assisted Deep Brain Stimulation Surgery: An Initial Experience

BACKGROUND

Modern robotic-assist surgical systems have revolutionized stereotaxy for a variety of procedures by increasing operative efficiency while preserving and even improving accuracy and safety. However, experience with robotic systems in deep brain stimulation (DBS) surgery is scarce.

OBJECTIVE

To present an initial series of DBS surgery performed utilizing a frameless robotic solution for image-guided stereotaxy, and report on operative efficiency, stereotactic accuracy, and complications.

METHODS

This study included the initial 20 consecutive patients undergoing bilateral robot-assisted DBS. The prior 20 nonrobotic, frameless cohort of DBS cases was sampled as a baseline historic control. For both cohorts, patient demographic and clinical data were collected including postoperative complications. Intraoperative duration and number of Microelectrode recording (MER) and final lead passes were recorded. For the robot-assisted cohort, 2D radial errors were calculated.

RESULTS

Mean case times (total operating room, anesthesia, and operative times) were all significantly decreased in the robot-assisted cohort (all P-values < .02) compared to frameless DBS. When looking at trends in case times, operative efficiency improved over time in the robot-assisted cohort across all time assessment points. Mean radial error in the robot-assisted cohort was 1.40 ± 0.11 mm, and mean depth error was 1.05 ± 0.18 mm. There was a significant decrease in the average number of MER passes in the robot-assisted cohort (1.05) compared to the nonrobotic cohort (1.45, P < .001).

CONCLUSION

This is the first report of application of frameless robotic-assistance with the Mazor Renaissance platform (Mazor Robotics Ltd, Caesarea, Israel) for DBS surgery, and our findings reveal that an initial experience is safe and can have a positive impact on operative efficiency, accuracy, and safety.

Oblique trajectory angles in robotic stereo-electroencephalography

OBJECTIVE

Traditional stereo-electroencephalography (sEEG) entails the use of orthogonal trajectories guided by seizure semiology and arteriography. Advances in robotic stereotaxy and computerized neuronavigation have made oblique trajectories more feasible and easier to implement without formal arteriography. Such trajectories provide access to components of seizure networks not readily sampled using orthogonal trajectories. However, the dogma regarding the relative safety and predictability of orthogonal and azimuth-based trajectories persists, given the absence of data regarding the safety and efficacy of oblique sEEG trajectories. In this study, the authors evaluated the relative accuracy and efficacy of both orthogonal and oblique trajectories during robotic implantation of sEEG electrodes to sample seizure networks.

METHODS

The authors performed a retrospective analysis of 150 consecutive procedures in 134 patients, accounting for 2040 electrode implantations. Of these, 837 (41%) were implanted via oblique trajectories (defined as an entry angle > 30°). Accuracy was calculated by comparing the deviation of each electrode at the entry and the target point from the planned trajectory using postimplantation imaging.

RESULTS

The mean entry and target deviations were 1.57 mm and 1.89 mm for oblique trajectories compared with 1.38 mm and 1.69 mm for orthogonal trajectories, respectively. Entry point deviation was significantly associated with entry angle, but the impact of this relationship was negligible (-0.015-mm deviation per degree). Deviation at the target point was not significantly affected by the entry angle. No hemorrhagic or infectious complications were observed in the entire cohort, further suggesting that these differences were not meaningful in a clinical context. Of the patients who then underwent definitive procedures after sEEG, 69 patients had a minimum of 12 months of follow-up, of whom 58 (84%) achieved an Engel class I or II outcome during a median follow-up of 27 months.

CONCLUSIONS

The magnitude of stereotactic errors in this study falls squarely within the range reported in the sEEG literature, which primarily features orthogonal trajectories. The patient outcomes reported in this study suggest that seizure foci are well localized using oblique trajectories. Thus, the selective use of oblique trajectories in the authors' cohort was associated with excellent safety and efficacy, with no patient incidents, and the findings support the use of oblique trajectories as an effective and safe means of investigating seizure networks.

Role of 3D intraoperative imaging in orthopedic and trauma surgery

Intraoperative three-dimensional (3D) imaging is now feasible because of recent technological advances such as 3D cone-beam CT (CBCT) and flat-panel X-ray detectors (FPDs). These technologies reduce the radiation dose to the patient and surgical team. The aim of this study is to review the advantages of 3D intraoperative imaging in orthopedic and trauma surgery by answering the following 5 questions: What are its technical principles? CBCT with a FPD produces non-distorted digital images and frees up the surgical field. The high quality of these 3D intraoperative images allows them to be integrated into surgical navigation systems. Human-robot comanipulation will likely follow soon after. Conventional multislice CT technology has also improved to the point where it can be used in the operating room. What can we expect from 3D intraoperative imaging and which applications have been validated clinically? We reviewed the literature on this topic for the past 10 years. The expected benefits were determined during the implantation of pedicular screws: more accurate implantation, fewer surgical revisions and time savings. There are few studies in trauma or arthroplasty cases, as robotic comanipulation is a more recent development. What is the tolerance for irradiation to the patient and surgical team? The health drawbacks are the harmful radiation-induced effects. The deterministic effects that we will develop are correlated to the absorbed dose in Gray units (Gy). The stochastic and carcinogenic effects are related to the effective dose in milliSievert (mSv) of linear evolution without threshold. The International Commission on Radiological Protection (ICRP) states that irradiation for medical purposes with risk of detriment is acceptable if it is justified by an optimization attempt. The radioprotection limits must be known but do not constitute opposable restrictions. The superiority of intraoperative 3D imaging over fluoroscopy has been demonstrated for spine surgery and sacroiliac screw fixation. How does the environment need to be adapted? The volume, access, wall protection and floor strength of the operating room must take into account the features of each machine. The instrumentation implants and need for specialized staff result in additional costs. Not every system can track movements during the CBCT acquisition thus transient suspension of assisted ventilation may be required. Is it financially viable? This needs to be calculated based on the expected clinical benefits, which mainly correspond to the elimination of expenses tied to surgical revisions. Our society's search for safety has driven the investments in this technology. LEVEL OF EVIDENCE: V, Expert opinion.

Robot-assisted versus manual navigated stereoelectroencephalography in adult medically-refractory epilepsy patients

OBJECTIVE

Stereoelectroencephalography (SEEG) has experienced a recent growth in adoption for epileptogenic zone (EZ) localization. Advances in robotics have the potential to improve the efficiency and safety of this intracranial seizure monitoring method. We present our institutional experience employing robot-assisted SEEG and compare its operative efficiency, seizure reduction outcomes, and direct hospital costs with SEEG performed without robotic assistance using navigated stereotaxy.

METHODS

We retrospectively identified 50 consecutive adult SEEG cases at our institution in this IRB-approved study, of which 25 were navigated with image guidance (hereafter referred to as "navigated") (02/2014-10/2016) and 25 were robot-assisted (09/2016-12/2017). A thorough review of medical/surgical history and operative records with imaging and trajectory plans was done for each patient. Direct inpatient costs related to each technique were compared.

RESULTS

Most common seizure etiologies for patients undergoing navigated and robot-assisted SEEG included non-lesional and benign temporal lesions. Despite having a higher mean number of leads-per-patient (10.2 ± 3.5 versus 7.2 ± 2.6, P = 0.002), robot-assisted cases had a significantly shorter mean operative time than navigated cases (125.5±48.5 versus 173.4±84.3 min, P = 0.02). Comparison of robot-assisted cases over the study interval revealed no significant difference in mean operative time (136.4±51.4 min for the first ten cases versus 109.9±75.8 min for the last ten cases, P = 0.25) and estimated operative time-per-lead (13.4±6.0 min for the first ten cases versus 12.9±7.7 min for the last ten cases, P = 0.86). The mean depth, radial, target, and entry point errors for robot-assisted cases were 2.12±1.89, 1.66±1.58, 3.05±2.02 mm, and 1.39 ± 0.75 mm, respectively. The two techniques resulted in equivalent EZ localization rate (navigated 88 %, robot-assisted 96 %, P = 0.30). Common types of epilepsy surgery performed consisted of implantation of responsive neurostimulation (RNS) device (56 %), resection (19.1 %), and laser ablation (23.8 %) for navigated SEEG. For robot-assisted SEEG, either RNS implantation (68.2 %) or laser ablation (22.7 %) were performed or offered. A majority of navigated and robot-assisted patients who underwent epilepsy surgery achieved either Engel Class I (navigated 36.8 %, robot-assisted 31.6 %) or II (navigated 36.8 %, robot-assisted 15.8 %) outcome with no significant difference between the groups (P = 0.14). Direct hospital cost for robot-assisted SEEG was 10 % higher than non-robotic cases.

CONCLUSION

This single-institutional study suggests that robotic assistance can enhance efficiency of SEEG without compromising safety or precision when compared to image guidance only. Adoption of this technique with uniform safety and efficacy over a short period of time is feasible with favorable epilepsy outcomes.

A Novel Robotic-Assisted Technique to Implant the Responsive Neurostimulation System

BACKGROUND

The responsive neurostimulation system (RNS) (NeuroPace Inc, Mountain View, California) was approved as an adjunctive therapy for medically refractory focal epilepsy. RNS detects epileptiform patterns and delivers electrical stimulation to abort seizures.

OBJECTIVE

To describe a novel technique of RNS lead implantation using robotic-assisted targeting of ictal-onset zones based on stereoelectroencephalography (sEEG) localization. Secondary objectives are to report the accuracy of robotic-assisted lead implantation using the ROSA robot as well as to report the clinical outcome achieved after RNS implantation by this method.

METHODS

A total of 16 patients with medically refractory focal epilepsy underwent sEEG implantation for ictal-onset localization followed by robotic RNS implantation. The electrode most correlative with ictal onset on sEEG was chosen as the target for the RNS electrode. Seizure control was measured at 6-mo and 1-yr follow-up. Ictal-onset electrocorticography (ECoG) data from RNS were compared with ictal onset from sEEG leads based on calculations of lead target to actual lead location from the ROSA robot.

RESULTS

At 6-mo follow-up, the average percent seizure reduction was 82% based upon self-reported seizure diaries. At 1-yr follow-up, 8 patients had an average of 90% seizure reduction. The location of seizure onset from ECoG data show similar onset from sEEG leads within 0.165-mm discrepancy.

CONCLUSION

The ROSA robot provides an ideal method for targeting subcortical ictal-onset zones. This method of RNS lead implantation achieves high accuracy and is associated with favorable clinical outcomes.

Robot-guided pediatric stereoelectroencephalography: single-institution experience

OBJECTIVEStereoelectroencephalography (SEEG) has increased in popularity for localization of epileptogenic zones in drug-resistant epilepsy because safety, accuracy, and efficacy have been well established in both adult and pediatric populations. Development of robot-guidance technology has greatly enhanced the efficiency of this procedure, without sacrificing safety or precision. To date there have been very limited reports of the use of this new technology in children. The authors present their initial experience using the ROSA platform for robot-guided SEEG in a pediatric population.METHODSBetween February 2016 and October 2017, 20 consecutive patients underwent robot-guided SEEG with the ROSA robotic guidance platform as part of ongoing seizure localization and workup for medically refractory epilepsy of several different etiologies. Medical and surgical history, imaging and trajectory plans, as well as operative records were analyzed retrospectively for surgical accuracy, efficiency, safety, and epilepsy outcomes.RESULTSA total of 222 leads were placed in 20 patients, with an average of 11.1 leads per patient. The mean total case time (± SD) was 297.95 (± 52.96) minutes and the mean operating time per lead was 10.98 minutes/lead, with improvements in total (33.36 minutes/lead vs 21.76 minutes/lead) and operative (13.84 minutes/lead vs 7.06 minutes/lead) case times/lead over the course of the study. The mean radial error was 1.75 (± 0.94 mm). Clinically useful data were obtained from SEEG in 95% of cases, and epilepsy surgery was indicated and performed in 95% of patients. In patients who underwent definitive epilepsy surgery with at least a 3-month follow-up, 50% achieved an Engel class I result (seizure freedom). There were no postoperative complications associated with SEEG placement and monitoring.CONCLUSIONSIn this study, the authors demonstrate that rapid adoption of robot-guided SEEG is possible even at a SEEG-naïve institution, with minimal learning curve. Use of robot guidance for SEEG can lead to significantly decreased operating times while maintaining safety, the overall goals of identification of epileptogenic zones, and improved epilepsy outcomes.

Expanding the Spectrum of Robotic Assistance in Cranial Neurosurgery

BACKGROUND

Robotic automation and haptic guidance have multiple applications in neurosurgery.

OBJECTIVE

To define the spectrum of cranial procedures potentially benefiting from robotic assistance in a university hospital neurosurgical practice setting.

METHODS

Procedures utilizing robotic assistance during a 24-mo period were retrospectively analyzed and classified as stereotactic or endoscopic based on the mode utilized in the ROSA system (Zimmer Biomet, Warsaw, Indiana). Machine log file data were retrospectively analyzed to compare registration accuracy using 3 different methods: (1) facial laser scanning, (2) bone fiduciary, or (3) skin fiduciary.

RESULTS

Two hundred seven cranial neurosurgical procedures utilizing robotic assistance were performed in a 24-mo period. One hundred forty-five procedures utilizing the stereotactic mode included 33% stereotactic biopsy, 31% Stereo-EEG electrode insertion, 20% cranial navigation, 7% stereotactic catheter placement, 6% craniofacial stereotactic wire placement, 2% deep brain stimulation lead placement, and 1% stereotactic radiofrequency ablation. Sixty-two procedures utilizing the haptic endoscope guidance mode consisted of 48% transnasal endoscopic, 29% ventriculoscopic, and 23% endoport tubular access. Statistically significant differences in registration accuracies were observed with 0.521 ± 0.135 mm (n = 132) for facial laser scanning, 1.026 ± 0.398 mm for bone fiduciary (n = 22), and 1.750 ± 0.967 mm for skin fiduciary (n = 30; ANOVA, P < .001).

CONCLUSION

The combination of accurate, automated stereotaxy with image and haptic guidance can be applied to a wide range of cranial neurosurgical procedures. The facial laser scanning method offered the best registration accuracy for the ROSA system based on our retrospective analysis.

Robot-Assisted Responsive Neurostimulator System Placement in Medically Intractable Epilepsy: Instrumentation and Technique

BACKGROUND

The management of medically refractory epilepsy patients who are not surgical candidates has remained challenging. Closed loop—or responsive—neurostimulation (RNS) is now an established therapy for the treatment of epilepsy with specific indications. The RNS® system (NeuroPace Inc, Mountainview, California) has recently been shown to be effective in reducing the seizure frequency of partial onset seizures. The electrode design consists of either intracerebral depth electrodes or subdural strip electrodes, and stereotaxis is typically used to guide placement into the EZ. Details on the operative techniques used to place these electrodes have been lacking.

OBJECTIVE

To address the advantage of using a robotic-assisted technique to place depth electrodes for RNS® system placement compared to the typical frame-based or frameless stereotactic systems.

METHODS

We retrospectively reviewed our single center, technical operative experience with RNS® system placement using robotic assistance from 2014 to 2016 via chart review.

RESULTS

Twelve patients underwent RNS® system placement using robotic assistance. Mean operative time was 121 min for a median of 2 depth electrodes with mean deviation from intended target of ∼3 mm in x, y, and z planes. Two patients developed wound infections, 1 of whom was reimplanted. Seizures were reduced by ∼40% at 2 yr, similar to the results seen in the open label portion of the pivotal RNS trial.

CONCLUSION

Robotic-assisted stereotaxis can be used to provide a stable and accurate stereotactic platform for insertion of intracerebral RNS electrodes, representing a safe, efficient and accurate procedure.

Robotic drill guide positioning using known-component 3D-2D image registration

A method for x-ray image-guided robotic instrument positioning is reported and evaluated in preclinical studies of spinal pedicle screw placement with the aim of improving delivery of transpedicle K-wires and screws. The known-component (KC) registration algorithm was used to register the three-dimensional patient CT and drill guide surface model to intraoperative two-dimensional radiographs. Resulting transformations, combined with offline hand-eye calibration, drive the robotically held drill guide to target trajectories defined in the preoperative CT. The method was assessed in comparison with a more conventional tracker-based approach, and robustness to clinically realistic errors was tested in phantom and cadaver. Deviations from planned trajectories were analyzed in terms of target registration error (TRE) at the tooltip (mm) and approach angle (deg). In phantom studies, the KC approach resulted in [Formula: see text] and [Formula: see text], comparable with accuracy in tracker-based approach. In cadaver studies with realistic anatomical deformation, the KC approach yielded [Formula: see text] and [Formula: see text], with statistically significant improvement versus tracker ([Formula: see text] and [Formula: see text]). Robustness to deformation is attributed to relatively local rigidity of anatomy in radiographic views. X-ray guidance offered accurate robotic positioning and could fit naturally within clinical workflow of fluoroscopically guided procedures.