Background and Objectives: As brain lesions present complex diagnostic challenges, accurate tissue sampling via biopsy is critical for effective treatment planning. Traditional frame-based stereotactic biopsy has been complemented by navigated biopsy techniques, leveraging advancements in imaging and navigation technology. This study aims to compare the navigated and frame-based stereotactic biopsy methods in a clinical setting, evaluating their efficacy, safety, and diagnostic outcomes to determine the optimal approach for precise brain lesion targeting. Materials and Methods: retrospective analysis was conducted on patients who underwent brain biopsies between January 2017 and August 2023 at an academic medical center. Data on patient demographics, clinical characteristics, biopsy technique (navigated vs. frame-based), and outcomes including accuracy, complications, and hospital stay duration were analyzed. Results: The cohort comprised 112 patients, with no significant age or gender differences between groups. Symptoms leading to biopsy were predominantly diminished muscle strength (42.0%), cognitive issues (28.6%), and aphasia (24.1%). Tumors were most common in the deep hemisphere (24.1%). The median hospital stay was 5 days, with a rehospitalization rate of 27.7%. Complications occurred in 4.47% of patients, showing no significant difference between biopsy methods. However, navigated biopsies resulted in fewer samples (p < 0.001) but with comparable diagnostic accuracy as frame-based biopsies. Conclusions: Navigated and frame-based stereotactic biopsies are both effective and safe, with comparable accuracy and complication rates. The choice of technique should consider lesion specifics, surgeon preference, and technological availability. The findings highlight the importance of advanced neurosurgical techniques in enhancing patient care and outcomes.

UNASSIGNED: The Dual Shell Encompass Fibreplast™ System (DS-Encompass) by CQ Medical™ is validated for frameless immobilization in stereotactic brain radiotherapy. An alternative mask model has been proposed with the rear shell replaced by a Moldcare® cushion (M-Encompass). To validate the use of this model in our cranial stereotactic workflow method including HyperArc™, we performed a prospective randomized study comparing inter-and intrafractional motion and patients comfort between both masks.
UNASSIGNED: A prospective randomized study between DS-Encompass and M-Encompass was conducted involving 60 participants. Stratification between DS-Encompass and M-Encompass was carried out based on the fractionation scheme. Treatment plans were created with HyperArc™. During treatment, surface guidance was used for patient positioning and monitoring. A pre-treatment cone-beam CT (CBCT) was acquired to correct interfractional motion and a post-treatment CBCT was acquired to quantify the intrafractional motion. Patients reported comfort was analyzed with a Likert-scale at the end of the treatment. Unpaired t-tests were conducted to determine the level of significance.
UNASSIGNED: No significant difference in interfractional translations is present. A significant difference is revealed in roll-axis rotation, where DS-Encompass allows for smaller deviations. Since interfractional motion can be corrected through daily CBCT-scans and 6D-couch corrections, they are clinically irrelevant. Intrafractional motion does not differ significantly and remains below 0.5 mm and 0.5° for both systems. There is no statistical difference in patient-reported comfort.
UNASSIGNED: We conclude that Encompass with Moldcare offers a safe alternative to Duall Shell Encompass for non-coplanar stereotactic brain radiotherapy. There is no significant difference in intrafractional motion nor difference in comfort levels.

Successful surgery for epilepsy hinges on identification of the epileptogenic focus. Stereoelectroencephalography (sEEG) is the most effective way to identify most seizure foci. There are multiple methods of inserting depth electrodes, including frame-based, frameless, and robot-assisted techniques. Studies have shown the accuracy of frame-based and robotic-assisted techniques to be statistically similar, while only one study has detailed the frameless sEEG insertion technique.
Patients underwent placement of sEEG depth electrodes using frameless stereotaxy from September 2019 to September 2021 at Geisinger Medical Center by a single surgeon. Seizure history, electrode placement accuracy relative to the planned trajectories, surgical times, success rate of identifying the epileptogenic focus, and subsequent seizure control rates after surgical treatment were documented.
Data were available for 21 patients and 181 electrodes inserted using the VarioGuide frameless stereotactic system. Each insertion took an average of 14.5 minutes per lead. Average entry variance was 2.7 mm with an average target variance of 4.6 mm. The epileptogenic focus was identified in 19 of 21 patients, and further surgical treatment was performed in 18 of 21 patients (85.7%).
VarioGuide frameless stereotaxy for sEEG placement is comparable to frame-based and robotic-assisted techniques with statistically similar rates of epileptic focus identification. Lead placement accuracy is slightly lower and time per lead is slightly higher relative to robot-assisted surgeries. When a robot system is unavailable, surgeons can consider using a frameless stereotactic technique for sEEG insertion, allowing patients to benefit from a similarly high rate of epileptic zone identification.

The aim of the article is to introduce a novel laser-based frameless stereotactic device that can locate intracranial lesions quickly and with computed tomograph (CT)/magnetic resonance imaging (MRI) films. Preliminary experiences of application in 416 cases are also summarized.
From August in 2020 to October in 2022, a total of 416 cases of new minimalist laser stereotactic surgery have been performed on 415 patients. Of the 415 patients, 377 had intracranial hematomas, while the remaining cases were brain tumors or brain abscesses. Postoperative CT was used to evaluate the accuracy of catheterization of 405 patients according to the MISTIE study. The duration time of locating was recorded. Rebleeding refers to the definition: Compared with preoperative CT, the relative volume of postoperative hematoma increases by >33% or absolute volume increase >12.5 mL.
According to postoperative CT, the accuracy of 405 stereotactic catheterization cases was good in 346 cases (85.4%) and suboptimal in 59 cases (14.6%), with no poor results. Postoperative rebleeding occurred in 4 spontaneous cerebral hemorrhage cases and 1 brain biopsy case. The average localization time of supratentorial lesions was 13.2 minutes in the supine position, 21.5 minutes in the lateral position, and 27.6 minutes in the prone position.
The new laser-based frameless stereotactic device is simple in principle and convenient in positioning operation of brain hematoma and abscess puncture, brain biopsy and tumor surgery, and appropriate to the precision requirements in most craniocerebral surgery.

Awake craniotomies are often performed with rigid pin fixation to support optical neuronavigation. Newer electromagnetic (EM) neuronavigation technology now enables unpinned cranial neurosurgery while maintaining robust intraoperative image guidance. Here, we share technical nuances, operative pearls, and lessons learned from our institutional experience using Curve EM neuronavigation during awake, unpinned craniotomies.
We describe our process for patient positioning, instrumentation setup, system registration, intraoperative navigation, and surgical adjunct use (e.g., intraoperative neuromonitoring and intraoperative magnetic resonance imaging) in detail. At each step, we provide pearls for success and tips for pitfall avoidance based on our experience.
Ten patients underwent awake pinless intra-axial tumor resection using Curve EM neuronavigation from May 2021 to August 2022 with a single surgeon. Postoperative transient neurological deficits were seen in 8 of 10 cases (80.0%), as all resections were taken to functional margins. Of the 9 patients with a 3-month follow-up visit at the time of publication, all 9 (100%) had improved or stable preoperative symptoms. No surgical complications, clinically appreciable inaccuracies, intraoperative losses of registration, unexpected postoperative magnetic resonance imaging findings, or errors related to the use of EM neuronavigation occurred.
The technical pearls outlined here will help interested neurosurgeons integrate EM neuronavigation into awake craniotomies. In our experience, using unpinned neuronavigation during awake cases provides many advantages to the patient, surgeon, and entire operative team. It has thus become the standard practice at our institution.

BACKGROUND: This purpose of this work is to give a detailed description of a surgical technique for frameless robot-assisted asleep deep brain stimulation (DBS) of the centromedian thalamic nucleus (CMT) in drug-resistant epilepsy (DRE).
METHODS: Ten consecutively enrolled patients who underwent CMT-DBS were included in the study. The FreeSurfer \"Thalamic Kernel Segmentation\" module and experience target coordinates were used for locating the CMT, and quantitative susceptibility mapping (QSM) images were used to check the target. The patient\'s head was secured with a head clip, and electrode implantation was performed with the assistance of the neurosurgical robot Sinovation®. After opening the dura, the burr hole was continuously flushed with physiological saline to stop air from entering the skull. All procedures were performed under general anesthesia without intraoperative microelectrode recording (MER).
RESULTS: The mean age of the patients at surgery and onset of seizures was 22 years (range 11-41 years) and 11 years (range 1-21 years), respectively. The median duration of seizures before CMT-DBS surgery was 10 years (2-26 years). CMT was successfully segmented, and its position was verified by experience target coordinates and QSM images in all ten patients. The mean surgical time for bilateral CMT-DBS in this cohort was 165 ± 18 min. The mean pneumocephalus volume was 2 cm3. The median absolute errors in the x-, y-, and z-axes were 0.7 mm, 0.5 mm, and 0.9 mm, respectively. The median Euclidean distance (ED) and radial error (RE) was 1.3 ± 0.5 mm and 1.0 ± 0.3 mm, respectively. No significant difference was found between right- and left-sided electrodes regarding the RE nor the ED. After a mean 12-month follow-up, the average reduction in seizures was 61%, and six patients experienced a ≥ 50% reduction in seizures, including one patient who had no seizures after the operation. All patients tolerated the anesthesia operation, and no permanent or serious complications were reported.
CONCLUSIONS: Frameless robot-assisted asleep surgery is a precise and safe approach for placing CMT electrodes in patients with DRE, shortening the surgery time. The segmentation of the thalamic nuclei enables the precise location of the CMT, and the flow of physiological saline to seal the burr holes is a good way to reduce the influx of air. CMT-DBS is an effective method to reduce seizures.

BACKGROUND: Brainstem tumors are rare and extremely heterogeneous and present significant challenges in surgical treatment. Thus, biopsies often set the foundation for the diagnosis of brainstem tumors. Multimodal, image-guided, robot-assisted frameless stereotactic biopsies are increasingly popular in neurosurgery centers. This study aimed to compare the safety, efficacy, and duration of the Remebot robot-assisted (Remebot) frameless brainstem tumor biopsy versus those of frame-based stereotactic biopsy.
METHODS: A retrospective analysis of 33 patients with brainstem tumors who underwent stereotactic brainstem biopsies in the department of neurosurgery from January 2016 to January 2021 was conducted. The patients were divided into two groups: the Remebot group (n = 22) and the frame-based group (n = 11). The clinical characteristics, trajectory strategy, duration of procedure, diagnostic yielding, histopathological diagnosis, and postoperative complications were retrospectively analyzed and compared between the groups.
RESULTS: More pediatric patients performed Remebot frameless brainstem tumor biopsy than frame-based biopsy, with a mean age of 17.3 ± 18.7 vs. 32.8 ± 17.1 (p = 0.027). The diagnostic yield had no significant difference in the two groups, with the diagnostic yield of frame-based biopsy and Remebot frameless brain biopsy being 90.9% and 95.5%, respectively. The time of the total process was 124.5 min for the frame-based biopsy and 84.7 min for the Remebot frameless brain biopsy (p < 0.001). There were no significant differences with respect to the occurrence of complication or the duration of the operation between the two groups.
CONCLUSIONS: Remebot frameless stereotactic brainstem biopsy is as safe and efficacious as frame-based stereotactic biopsy. However, Remebot frameless biopsy can reduce the total duration of the procedure and has better application in young pediatric patients. Remebot frameless stereotactic biopsies can be a better option towards the safe and efficient treatment of brainstem tumors.

Stereotactic radiosurgery (SRS) with >5 fraction (fr) has been increasingly adopted for brain metastases (BMs), given the current awareness of limited brain tolerance for ≤5 fr. The target volume/configuration change and/or deviation within the cranium during fractionated SRS can be unpredictable and critical uncertainties affecting treatment accuracy, plus the effect of these events on the long-term outcome remains uncertain. Herein, we describe a case of two challenging BMs treated by 10 fr SRS with a unique dose-gradient optimization strategy, in which the large cystic tumor revealed an intriguing correlation of such inter-fractional change with late radiographic sequela, suggesting a dose threshold for attaining long-term local tumor control and being immune to symptomatic brain necrosis. A 63-year-old man presented with two cystic lesions located in the left parietal lobe (19.9 cm3) and pons (1.1 cm3) one month after surgery for esophageal squamous cell carcinoma. The principles for 10 fr SRS were as follows: (1) very inhomogeneous gross tumor volume (GTV) dose covered by 53 Gy, biologically effective dose with an alpha/beta ratio of 10 (BED10) of ≥80 Gy; (2) moderate dose spillage margin outside the GTV boundary: 2-2.5 mm outside the GTV margin was covered by 37 Gy, BED10 of ≈50 Gy; (3) concentrically-laminated, steep dose increase inside the GTV boundary: 2 mm inside the GTV margin was covered by ≥62 Gy, BED10 of ≥100 Gy. At the completion of SRS, the parietal lesion showed significant shrinking and dorsomedial shifting with slight evisceration of the GTV, followed by marked regression of the parietal lesion within four months. At 13.5 months, a cystic change was noted at the dorsal part of the remnant. At 16.7 months, ventral enhancement gradually expanded without enlargement of the dorsal cystic component. On the T2-weighted images, the dorsal low-intensity remnant and ventral iso-intensity blurry-demarcated component were contrasting. Pathological examinations during and after lesionectomy at 17.4 months revealed necrosis only. At 30.5 months, the patient had a left visual field defect without recurrence. In contrast, the pons lesion showed no notable change during 10 fr SRS and nearly complete remission over six months with its sustainment without radiation injury at 30.5 months. Taken together, 10 fr SRS with a sufficient BED10 can provide superior tumor response and safety for BM that is not amenable to ≤5 fr SRS. Although a very inhomogeneous GTV dose can contribute to early and adequate tumor shrinkage and subsequent local tumor eradication, significant tumor shrinkage during fractionated SRS (fSRS) inevitably results in unnecessary higher dose exposure to the surrounding brain, which could lead to late radiation injury requiring intervention. The optimum dose should be determined through further investigation, in consideration of the dynamic and unpredictable nature of the actual absorbed doses to both the tumor and the surrounding brain.

Pediatric brainstem lesions are diagnoses that require tissue sampling to advance our understanding of them and their management. Frameless, robot-assisted biopsy of these lesions has emerged as a novel, viable biopsy approach. Correspondingly, the aim of this study was to quantitively and qualitatively summarize the contemporary literature regarding the likelihood of achieving tumor diagnosis and experiencing any postoperative complications.
Searches of 7 electronic databases from inception to September 2022 were conducted following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Articles were screened against prespecified criteria. Outcomes were pooled by random-effects meta-analyses of proportions where possible.
A total of 8 cohort studies satisfied all criteria. They described 99 pediatric patients with brainstem lesions in whom frameless, robot-assisted biopsy was involved in their work-up. There were 62 (63%) male and 37 (37%) female patients with a median age of 9 years at time of biopsy. Overall, all patients had sufficient tissue obtained by initial biopsy for evaluation. Pooled estimate of achieving tumor diagnosis was 100% (95% confidence interval [CI] 97%-100%) across all studies with a high degree of certainty. Across all studies, there were no cases of procedure-related mortality. The pooled estimates of transient and permanent complications after biopsy were 10% (95% CI 4%-19%) and 0% (95% CI 0%-2%), respectively, of very low and low degrees of certainty each.
The contemporary metadata demonstrates the frameless, robot-assisted biopsy of pediatric brainstem lesions is both effective and safe when performed in an experienced setting. Further research is needed to augment robot and automated technologies into workup algorithms.

OBJECTIVE: Given its high spatial resolution and vasculature selectivity, the cone-beam computed tomography (CT) angiography (CBCTA) image acquired by selective 3D rotational angiography (3DRA) is the most suitable 3D image for the target definition of stereotactic radiosurgery (SRS) for intracranial arteriovenous malformations (AVMs) and dural arteriovenous fistulas (DAVFs). Furthermore, the relatively low temporal resolution of 3DRA-based CBCTA can be complemented by the stereotactic co-registration of orthogonally paired 2D dynamic digital subtraction angiography (2D-DSA). The integration of 2D-DSA, which is usually limited to one or a few frames for each projection, into CBCTA and/or planning CT can be achieved only by catheter-directed angiography on the day of SRS via a dedicated image localizer under rigid frame fixation to the skull, which imposes substantial burdens on patients. This study aimed to demonstrate a novel, convenient, and significantly less invasive method for the frameless co-registration of biplane 2D-DSA whole frames and CBCTA on commercially available dedicated software, namely, Brainlab® Elements (Brainlab AG, Munich, Germany), and present its prerequisite for successful image fusion. Technical Report: Elements have afforded the following functionality: A 3D vasculature image is automatically extracted as a floating image from any 3D image series containing vascular details and then subsequently co-registered manually and automatically to a selected frame pair of 2D-DSA with a six-degree-of-freedom rigid registration. As a preclinical feasibility study, two anonymous image datasets from patients harboring cerebral AVM and transverse-sigmoid (TS) DAVF were used to verify the accuracy and practicality of Elements for the frameless co-registration of 2D/3D vascular images, particularly on the assumption of clinical workflow for the target delineation of SRS planning. The use of ordinary unsubtracted CBCTA resulted in the insufficient extraction of abutting vessels or vessels that are in close proximity to bony structures, particularly in the case of TS-DAVF, where the fistulous pouch and the affected venous sinuses were adjacent to the cranial bone. By contrast, the amount and selectivity of vasculatures and the accuracy of subsequent image fusion were significantly improved from the subtracted CBCTA. The integration of CBCTA into dynamic 2D-DSA allowed the simultaneous review of both image information by sharing any concerning point and 2D or 3D structures under a common 3D coordinate.
CONCLUSIONS: Elements enable the clinically useful frameless co-registration of biplane 2D-DSA whole frames into CBCTA, for which the routine acquisition of both subtracted and unsubtracted CBCTA axial images for ordinary diagnostic purposes is an indispensable prerequisite for successful image fusion and further widespread application. This frameless integration of the 2D/3D angiogram would dramatically enhance both the frame-based and frameless SRS workflow and circumstances by allowing users to forward SRS planning well in advance before SRS, along with the omission of invasive angiography on the day of SRS, and would broaden the implementation of frameless SRS. Furthermore, the comprehensive alternating interactive review of the 2D/3D integrated angiogram leads to a more in-depth quasi-4D understanding of the affected angioarchitectures compared with the separate viewing of each image.