Robot-assisted transcerebellar stereotactic approach to the posterior fossa in pediatric patients: a technical note.

PURPOSE: During the last decade, there has been renewed interest in stereotactic approaches to diffuse intrinsic pontine gliomas (DIPGs) in children, due to the development of new concepts in molecular biology and management, and subsequent need for tissue sampling. Stereotactic frame-based and robot-assisted techniques are associated with reduced target error and have been incorporated into standard practice at our institution. METHODS: Four children (age 2-7 years) underwent a robot-assisted frame-based transcerebellar approach using the Leksell G frame coupled with Renishaw's neuromate® stereotactic robot. The procedures included 3 biopsies (two brainstem tumors and one cerebellar hemispheric lesion) and 1 depth electrode implantation into a low-grade tumor remnant (ganglioglioma) of the middle cerebellar peduncle causing drug-resistant epilepsy in a young girl. Targeting was based on MRI, and in one case, 18F-FET-PET was coregistered to MRI to improve sampling accuracy. The frame was applied 180° rotated compared to standard orientation, and patients were positioned prone during surgery and stereotactic preoperative CT scan. Postoperative CT scan ruled out complications and was coregistered to preoperative MRI to check the target accuracy. RESULTS: No complications occurred, and targeting was accurate in all cases. All tissue samplings provided proper histology; depth electrode EEG exploration was diagnostic and led subsequent resective surgery. CONCLUSIONS: According to our experience, the transcerebellar frame-based robotic stereotactic approach to the cerebellum and the brainstem is feasible, safe, and effective even in young children.

Accuracy and Workflow Improvements for Responsive Neurostimulation Hippocampal Depth Electrode Placement Using Robotic Stereotaxy.

Background: Robotic stereotaxy is increasingly common in epilepsy surgery for the implantation of stereo-electroencephalography (sEEG) electrodes for intracranial seizure monitoring. The use of robots is also gaining popularity for permanent stereotactic lead implantation applications such as in deep brain stimulation and responsive neurostimulation (RNS) procedures. Objective: We describe the evolution of our robotic stereotactic implantation technique for placement of occipital-approach hippocampal RNS depth leads. Methods: We performed a retrospective review of 10 consecutive patients who underwent robotic RNS hippocampal depth electrode implantation. Accuracy of depth lead implantation was measured by registering intraoperative post-implantation fluoroscopic CT images and post-operative CT scans with the stereotactic plan to measure implantation accuracy. Seizure data were also collected from the RNS devices and analyzed to obtain initial seizure control outcome estimates. Results: Ten patients underwent occipital-approach hippocampal RNS depth electrode placement for medically refractory epilepsy. A total of 18 depth electrodes were included in the analysis. Six patients (10 electrodes) were implanted in the supine position, with mean target radial error of 1.9 ± 0.9 mm (mean ± SD). Four patients (8 electrodes) were implanted in the prone position, with mean radial error of 0.8 ± 0.3 mm. The radial error was significantly smaller when electrodes were implanted in the prone position compared to the supine position (p = 0.002). Early results (median follow-up time 7.4 months) demonstrate mean seizure frequency reduction of 26% (n = 8), with 37.5% achieving ≥50% reduction in seizure frequency as measured by RNS long episode counts. Conclusion: Prone positioning for robotic implantation of occipital-approach hippocampal RNS depth electrodes led to lower radial target error compared to supine positioning. The robotic platform offers a number of workflow advantages over traditional frame-based approaches, including parallel rather than serial operation in a bilateral case, decreased concern regarding human error in setting frame coordinates, and surgeon comfort.

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.