Safety and efficacy of frameless and frame-based intracranial biopsy techniques

The ClearPoint Array Frame: An MRI Compatible System that Supports Non-craniotomy, Multi-trajectory (NCMT) Stereotactic Procedures

BACKGROUND

With continued evolution in stereotactic techniques and an expanding armamentarium of surgical therapeutic options, non-craniotomy stereotactic procedures in neuro-oncology are becoming increasingly complex, often requiring multi-trajectory approaches. Here we demonstrate that the ClearPoint SmartFrame Array (Solana Beach, California, USA), a second-generation magnetic resonance imaging-compatible stereotactic frame, supports such non-craniotomy, multi-trajectory (NCMT) stereotactic procedures.

METHODS

We previously published case reports demonstrating the feasibility of NCMT through the ClearPoint SmartFrame Array. Here we prospectively followed the next 10 consecutive patients who underwent such multi-trajectory procedures to further establish procedural safety and clinical utility.

RESULTS

Ten patients underwent complex, multi-trajectory stereotactic procedures, including combinations of needle biopsy ± cyst drainage and laser interstitial thermal therapy targeting geographically distinct regions of neoplastic lesions under the same anesthetic event. The median maximal radial error of stereotaxis was 1.0 mm. In all cases, definitive diagnosis was achieved, and >90% of the intended targets were ablated. The average stereotaxis time for the multi-trajectory procedure was 119 ± 22.2 minutes, comparing favorably to our previously published results of single-trajectory procedures (80 ± 9.59 minutes, P = 0.125). There were no procedural complications. Post-procedure, the neurologic condition of 1 patient improved, while the remaining 9 patients remained stable. All patients were discharged home, with a median hospital stay of 1 day (range: 1-12 days). With a median follow-up of 376 days (range: 155-1438 days), there were no 30-day readmissions or wound complications.

CONCLUSIONS

Geographically distinct regions of brain cancer can be safely and accurately accessed through the ClearPoint Array frame in NCMT stereotactic procedures.

An accessible deep learning tool for voxel-wise classification of brain malignancies from perfusion MRI

Noninvasive differential diagnosis of brain tumors is currently based on the assessment of magnetic resonance imaging (MRI) coupled with dynamic susceptibility contrast (DSC). However, a definitive diagnosis often requires neurosurgical interventions that compromise patients' quality of life. We apply deep learning on DSC images from histology-confirmed patients with glioblastoma, metastasis, or lymphoma. The convolutional neural network trained on ∼50,000 voxels from 40 patients provides intratumor probability maps that yield clinical-grade diagnosis. Performance is tested in 400 additional cases and an external validation cohort of 128 patients. The tool reaches a three-way accuracy of 0.78, superior to the conventional MRI metrics cerebral blood volume (0.55) and percentage of signal recovery (0.59), showing high value as a support diagnostic tool. Our open-access software, Diagnosis In Susceptibility Contrast Enhancing Regions for Neuro-oncology (DISCERN), demonstrates its potential in aiding medical decisions for brain tumor diagnosis using standard-of-care MRI.

Safety and efficacy of frameless stereotactic robot-assisted intraparenchymal brain lesion biopsies versus image-guided biopsies: a bicentric comparative study

PURPOSE

User-friendly robotic assistance and image-guided tools have been developed in the past decades for intraparenchymal brain lesion biopsy. These two methods are gradually becoming well accepted and are performed at the discretion of the neurosurgical teams. However, only a few data comparing their effectiveness and safety are available.

METHODS

Population-based parallel cohorts were followed from two French university hospitals with different surgical methods and defined geographical catchment regions (September 2019 to September 2022). In center A, frameless robot-assisted stereotactic intraparenchymal brain lesion biopsies were performed, while image-guided intraparenchymal brain lesion biopsies were performed in center B. Pre-and postoperative clinical, radiological, and histomolecular features were retrospectively collected and compared.

RESULTS

Two hundred fifty patients were included: 131 frameless robot-assisted stereotactic intraparenchymal brain lesion biopsies in center A and 119 image-guided biopsies in center B. The clinical, radiological, and histomolecular features were comparable between the two groups. The diagnostic yield (96.2% and 95.8% respectively; p = 1.000) and the overall postoperative complications rates (13% and 14%, respectively; p = 0.880) did not differ between the two groups. The mean duration of the surgical procedure was longer in the robot-assisted group (61.9 ± 25.3 min, range 23-150) than in the image-guided group (47.4 ± 11.8 min, range 25-81, p < 0.001). In the subgroup of patients with anticoagulant and/or antiplatelet therapy administered preoperatively, the intracerebral hemorrhage > 10 mm on postoperative CT scan was higher in the image-guided group (36.8%) than in the robot-assisted group (5%, p < 0.001).

CONCLUSION

In our bicentric comparative study, robot-assisted stereotactic and image-guided biopsies have two main differences (shorter time but more frequent postoperative hematoma for image-guided biopsies); however, both techniques are demonstrated to be safe and efficient.

Comparison meta-analysis of intraoperative MRI-guided needle biopsy versus conventional stereotactic needle biopsies

Background

MRI-guided needle biopsy (INB) is an emerging alternative to conventional frame-based or frameless stereotactic needle biopsy (SNB). Studies of INB have been limited to select case series, and comparative studies between INB and SNB remain a missing gap in the literature. We performed a meta-analysis to compare INB and SNB literature in terms of diagnostic yield, surgical morbidity and mortality, tumor size, and procedural time.

Methods

We identified 36 separate cohorts in 26 studies of SNB (including both frameless and frame-based biopsies, 3374 patients) and 27 studies of INB (977 patients). Meta-regression and meta-analysis by proportions were performed.

Results

Relative to publications that studied SNB, publications studying INB more likely involved brain tumors located in the eloquent cerebrum (79.4% versus 62.6%, P = 0.004) or are smaller in maximal diameter (2.7 cm in INB group versus 3.6 cm in the SNB group, P = .032). Despite these differences, the pooled estimate of diagnostic yield for INB was higher than SNB (95.4% versus 92.3%, P = .026). The pooled estimate of surgical morbidity was higher in the SNB group (12.0%) relative to the INB group (6.1%) (P = .004). Mortality after the procedure was comparable between INB and SNB (1.7% versus 2.3%, P = .288). Procedural time was statistically comparable at 90.3 min (INB) and 103.7 min (SNB), respectively (P = .526).

Conclusions

Our meta-analysis indicates that, relative to SNB, INB is more often performed for the challenging, smaller-sized brain tumors located in the eloquent cerebrum. INB is associated with lower surgical morbidity and improved diagnostic yield.

Surgical Characteristics of Intracranial Biopsy Using a Frameless Stereotactic Robotic Platform: A Single-Center Experience

BACKGROUND AND OBJECTIVES

Cranial robotics are a burgeoning field of neurosurgery. To date, all cranial robotic systems described have been computerized, arm-based instruments that take up significant space in the operating room. The Medtronic Stealth Autoguide robot has a smaller operating room footprint and offers multiaxial, frame-based surgical targeting. The authors set out to define the surgical characteristics of a novel robotic platform for brain biopsy in a large patient cohort.

METHODS

Patients who underwent stereotactic biopsy using the Stealth Autoguide cranial robotic platform from July 2020 to March 2023 were included in this study. Clinical, surgical, and histological data were collected and analyzed.

RESULTS

Ninety-six consecutive patients (50 female, 46 male) were included. The mean age at biopsy was 53.7 ± 18.0 years. The mean target depth was 68.2 ± 15.3 mm. The biopsy diagnostic tissue acquisition rate was 100%. The mean time from incision to biopsy tissue acquisition was 15.4 ± 9.9 minutes. Target lesions were located throughout the brain: in the frontal lobe (n = 32, 33.3%), parietal lobe (n = 21, 21.9%), temporal lobe (n = 22, 22.9%), deep brain nuclei/thalamus (n = 13, 13.5%), cerebellum (n = 7, 7.3%), and brainstem (n = 1, 1.0%). Most cases were gliomas (n = 75, 78.2%). Patients were discharged home on postoperative day 0 or 1 in 62.5% of cases. A total of 7 patients developed postoperative complications (7.2%).

CONCLUSION

This cranial robotic platform can be used for efficient, safe, and accurate cranial biopsies that allow for reliable diagnosis of intracranial pathology in a minimally invasive setting.

5-aminolevulinic acid-guided endoscopic biopsy with violet light-emitting diode flashlight in malignant glioma: Technical note

Background

5-aminolevulinic acid (5-ALA) photodynamic diagnosis (PDD) has enabled better identification of malignant tumor cells and real-time intraoperative guidance. Here, we report a reasonable procedure for 5-ALA-guided endoscopic biopsy with a violet light-emitting diode (LED) flashlight for deep-seated malignant gliomas.

Methods

A 63-year-old man presented with a headache and left upper homonymous quadrantanopia. Imaging studies showed atypical lesions with non-significant and partial contrast enhancement in the right deep temporo-occipital lobe. An endoscopic biopsy was performed under the guidance of 5-ALA PDD with a violet LED flashlight.

Results

The tumor tissues, which were difficult to distinguish from normal brain parenchyma under white light, were positive for 5-ALA fluorescence. The histopathological diagnosis was astrocytoma (the World Health Organization grade 3). The patient underwent adjuvant chemoradiation therapy. Headache and anopia improved, and no recurrence was observed at 12 months follow-up.

Conclusion

This technique of neuroendoscopic biopsy guided by 5-ALA PDD fluorescence with a violet LED flashlight may allow a safe and accurate diagnosis of deep-seated malignant gliomas.

Hemorrhagic Complications After Brain Tumor Biopsy: Risk-Reduction Strategies Based on Safer Biopsy Targets and Techniques

OBJECTIVE

Brain tumor biopsies are essential for pathologic diagnosis. However, hemorrhagic complications after biopsies may occur, leading to suboptimal outcomes. This study aimed to evaluate the associated factors of hemorrhagic complications after brain tumor biopsies and propose countermeasures.

METHODS

We retrospectively collected data on 208 consecutive patients with brain tumors (malignant lymphoma or glioma) who underwent a biopsy from 2011-2020. We evaluated factors and microbleeds (MBs) in the tumor plus relative cerebral/tumoral blood flow (rCBF) at the biopsy site on preoperative magnetic resonance imaging (MRI).

RESULTS

Postoperative all and symptomatic hemorrhage occurred in 21.6% and 9.6% of patients. In univariate analysis, a needle biopsy was significantly associated with the risk of all and symptomatic hemorrhages compared to techniques that allow adequate hemostatic manipulation (i.e., open and endoscopic biopsies). Multivariate analyses revealed that a needle biopsy and gliomas of World Health Organization (WHO) grade III/IV were significantly associated with postoperative all and symptomatic hemorrhages. Multiple lesions were also an independent risk factor for symptomatic hemorrhages. On preoperative MRI, abundant MBs in the tumor and MBs at the biopsy sites, in addition to high rCBF, were significantly associated with postoperative all and symptomatic hemorrhages.

CONCLUSIONS

We recommend the following measures to prevent hemorrhagic complications: consider biopsy techniques that allow adequate hemostatic manipulation preferentially; perform more careful hemostasis in cases of suspected gliomas of WHO grade III/IV, multiple lesions, and abundant MBs in the tumors; and, if there are multiple candidate biopsy sites, select areas with lower rCBF and no MBs as a biopsy target.

Novel application of robot-guided stereotactic technique on biopsy diagnosis of intracranial lesions

Introduction

This study was performed to examine whether there is a link between the application of three types of robot-guided stereotactic biopsy techniques and the diagnostic rate of intracranial lesion biopsy.

Methods

The study involved 407 patients who underwent robot-guided stereotactic intracranial lesion biopsy at Xuanwu Hospital of Capital Medical University from January 2019 to December 2021. Age, sex, lesion characteristics, lesion distribution, surgical method, and target path depth were assessed for their impact on the biopsy diagnostic rate.

Results

The patients' mean age was 42.1 years (range, 6 months-82 years). All patients underwent robot-assisted stereotactic brain biopsy using one of three different systems: a ROSA robotic system (n=35), the CAS-R-2 (n=65), or the REMEBOT domestic robotic system (n=307). No significant difference was found in the diagnostic rate of positive histopathological findings or the mean time of surgery among the three biopsy modalities. The diagnostic rate was 93.86%. Multiple linear regression analysis showed that age, sex, and biopsy modality did not affect the diagnostic rate n>0.05), whereas enhancing lesions and smaller-volume lesions (≤l cm3) were significantly correlated with the diagnostic rate (p = 0.01). Lesions located in the suprasellar and pineal regions were significantly associated with the negative diagnostic rate (p<0.05).

Conclusion

The presence of enhancing lesions, lesion location, and lesion volume significantly affected the diagnostic rate of brain biopsy. Age, sex, lesion depth, and biopsy modality did not significantly affect the diagnostic rate. All three procedures had high safety and effectiveness.

Astrocytes in the central nervous system and their functions in health and disease: A review

Astrocytes are key cells in the central nervous system. They are involved in many important functions under physiological and pathological conditions. As part of neuroglia, they have been recognised as cellular elements in their own right. The name astrocyte was first proposed by Mihaly von Lenhossek in 1895 because of the finely branched processes and star-like appearance of these particular cells. As early as the late 19^th and early 20^th centuries, Ramon y Cajal and Camillo Golgi had noted that although astrocytes have stellate features, their morphology is extremely diverse. Modern research has confirmed the morphological diversity of astrocytes both in vitro and in vivo and their complex, specific, and important roles in the central nervous system. In this review, the functions of astrocytes and their roles are described.

Navigation Guided Biopsy Is as Effective as Frame-Based Stereotactic Biopsy

BACKGROUND

Stereotactic biopsy is a standard procedure for brain biopsy. However, with advances in technology, navigation-guided brain biopsy has become a well-established alternative. Previous studies have shown that frameless stereotactic brain biopsy is as effective and safe as frame-based stereotactic brain biopsy is. In this study, the authors evaluate the diagnostic yield and complication rate of frameless intracranial biopsy.

MATERIALS AND METHODS

We reviewed data from biopsy performed patients between March 2014 and April 2022. We retrospectively reviewed medical records, including imaging studies. Various intracerebral lesions were biopsied. Diagnostic yield and post-operative complications were compared with those of frame-based stereotactic biopsy.

RESULTS

Forty-two frameless navigation-guided biopsy were performed, and the most common pathology was primary central nervous system lymphoma (35.7%), followed by glioblastoma (33.3%), and anaplastic astrocytomas (16.7%), respectively. The diagnostic yield was 100%. Post-operative intracerebral hematoma occurred in 2.4% of cases, but it was not symptomatic. Thirty patients underwent frame-based stereotactic biopsy, and the diagnostic yield was 96.7%. There was no difference in diagnostic rates between two methods (Fisher's exact test, p = 0.916).

CONCLUSIONS

Frameless navigation-guided biopsy is as effective as frame-based stereotactic biopsy is, without causing further complications. We consider that frame-based stereotactic biopsy is no longer needed if frameless navigation-guided biopsy is used. A further study will be needed to generalize our results.

When to discharge patients following a neuronavigation-assisted brain biopsy for supratentorial lesion? A single-center experience

OBJECTIVE

Most brain biopsies are performed using the frame-based stereotactic technique and several studies describe the time taken and rate of complications, often allowing an early discharge. In comparison, neuronavigation-assisted biopsies are performed under general anesthesia and their complications have been poorly described. We examined the complication rate and determined which patients will worsen clinically.

METHODS

All adults who underwent a neuronavigation-assisted brain biopsy for a supratentorial lesion from Jan, 2015, to Jan, 2021, in the Neurosurgical Department of the University Hospital Center of Bordeaux, France, were analyzed retrospectively in accordance with the Strengthening the Reporting of Observational studies in Epidemiology (STROBE) statement. The primary outcome of interest was short-term (7 days) clinical deterioration. The secondary outcome of interest was the complication rate.

RESULTS

The study included 240 patients. The median postoperative Glasgow score was 15. Thirty patients (12.6 %) showed acute postoperative clinical worsening, including 14 (5.8 %) with permanent neurological worsening. The median delay was 22 h after the intervention. We examined several clinical combinations that allowed early postoperative discharge. A preoperative Glasgow prognostic score of 15, Charlson Comorbidity Index ≤ 3, preoperative World Health Organization Performance Status ≤ 1, and no preoperative anticoagulation or antiplatelet treatment predicted postoperative worsening (negative predictive value, 96.3 %).

CONCLUSION

Optical neuronavigation-assisted brain biopsies might require longer postoperative observation than frame-based biopsies. Based on strict preoperative clinical criteria, we consider to plan postoperative observation for 24 h a sufficient hospital stay for patients who undergo these brain biopsies.

Surgical management of Glioma Grade 4: technical update from the neuro-oncology section of the Italian Society of Neurosurgery (SINch®): a systematic review

PURPOSE

The extent of resection (EOR) is an independent prognostic factor for overall survival (OS) in adult patients with Glioma Grade 4 (GG4). The aim of the neuro-oncology section of the Italian Society of Neurosurgery (SINch®) was to provide a general overview of the current trends and technical tools to reach this goal.

METHODS

A systematic review was performed. The results were divided and ordered, by an expert team of surgeons, to assess the Class of Evidence (CE) and Strength of Recommendation (SR) of perioperative drugs management, imaging, surgery, intraoperative imaging, estimation of EOR, surgery at tumor progression and surgery in elderly patients.

RESULTS

A total of 352 studies were identified, including 299 retrospective studies and 53 reviews/meta-analysis. The use of Dexamethasone and the avoidance of prophylaxis with anti-seizure medications reached a CE I and SR A. A preoperative imaging standard protocol was defined with CE II and SR B and usefulness of an early postoperative MRI, with CE II and SR B. The EOR was defined the strongest independent risk factor for both OS and tumor recurrence with CE II and SR B. For intraoperative imaging only the use of 5-ALA reached a CE II and SR B. The estimation of EOR was established to be fundamental in planning postoperative adjuvant treatments with CE II and SR B and the stereotactic image-guided brain biopsy to be the procedure of choice when an extensive surgical resection is not feasible (CE II and SR B).

CONCLUSIONS

A growing number of evidences evidence support the role of maximal safe resection as primary OS predictor in GG4 patients. The ongoing development of intraoperative techniques for a precise real-time identification of peritumoral functional pathways enables surgeons to maximize EOR minimizing the post-operative morbidity.

Commonly Overlooked Factors in Biocompatibility Studies of Neural Implants

Biocompatibility of cutting-edge neural implants, surgical tools and techniques, and therapeutic technologies is a challenging concept that can be easily misjudged. For example, neural interfaces are routinely gauged on how effectively they determine active neurons near their recording sites. Tissue integration and toxicity of neural interfaces are frequently assessed histologically in animal models to determine tissue morphological and cellular changes in response to surgical implantation and chronic presence. A disconnect between histological and efficacious biocompatibility exists, however, as neuronal numbers frequently observed near electrodes do not match recorded neuronal spiking activity. The downstream effects of the myriad surgical and experimental factors involved in such studies are rarely examined when deciding whether a technology or surgical process is biocompatible. Such surgical factors as anesthesia, temperature excursions, bleed incidence, mechanical forces generated, and metabolic conditions are known to have strong systemic and thus local cellular and extracellular consequences. Many tissue markers are extremely sensitive to the physiological state of cells and tissues, thus significantly impacting histological accuracy. This review aims to shed light on commonly overlooked factors that can have a strong impact on the assessment of neural biocompatibility and to address the mismatch between results stemming from functional and histological methods.

Augmented Reality in Stereotactic Neurosurgery: Current Status and Issues

Stereotactic neurosurgery is an established technique, but it has several limitations. In frame-based stereotaxy using a stereotactic frame, frame setting errors may decrease the accuracy of the procedure. Frameless stereotaxy using neuronavigation requires surgeons to shift their view from the surgical field to the navigation display and to advance the needle while assuming a physically uncomfortable position. To overcome these limitations, several researchers have applied augmented reality in stereotactic neurosurgery. Augmented reality enables surgeons to visualize the information regarding the target and preplanned trajectory superimposed over the actual surgical field. In frame-based stereotaxy, a researcher applies tablet computer-based augmented reality to check for the setting errors of the stereotactic frame, thereby improving the safety of the procedure. Several researchers have reported performing frameless stereotaxy guided by head-mounted-display-based augmented reality that enables surgeons to advance the needle at a more natural posture. These studies have shown that augmented reality can address the limitations of stereotactic neurosurgery. Conversely, they have also revealed the limited accuracy of current augmented reality systems for small targets, which indicates that further development of augmented reality systems is needed.

High intratumoral susceptibility signal grade on susceptibility-weighted imaging: a risk factor for hemorrhage after stereotactic biopsy

OBJECTIVE

This study aimed to examine the association of preoperative intratumoral susceptibility signal (ITSS) grade with hemorrhage after stereotactic biopsy (STB).

METHODS

The authors retrospectively reviewed 66 patients who underwent STB in their institution. Preoperative factors including age, sex, platelet count, prothrombin time-international normalized ratio, activated thromboplastin time, antiplatelet agent use, history of diabetes mellitus and hypertension, target location, anesthesia type, and ITSS data were recorded. ITSS was defined as a dot-like or fine linear low signal within a tumor on susceptibility-weighted imaging (SWI) and was graded using a 3-point scale: grade 1, no ITSS within the lesion; grade 2, 1-10 ITSSs; and grade 3, ≥ 11 ITSSs. Postoperative final tumor pathology was also reviewed. The association between preoperative variables and the size of postoperative hemorrhage was examined.

RESULTS

Thirty-four patients were men and 32 were women. The mean age was 66.6 years. The most common tumor location was the frontal lobe (27.3%, n = 18). The diagnostic yield of STB was 93.9%. The most common pathology was lymphoma (36.4%, n = 24). The ITSS was grade 1 in 37 patients (56.1%), grade 2 in 14 patients (21.2%), and grade 3 in 15 patients (22.7%). Interobserver agreement for ITSS was almost perfect (weighted kappa = 0.87; 95% CI 0.77-0.98). Age was significantly associated with ITSS (p = 0.0075). Postoperative hemorrhage occurred in 17 patients (25.8%). Maximum hemorrhage diameter (mean ± SD) was 1.78 ± 1.35 mm in grade 1 lesions, 2.98 ± 2.2 mm in grade 2 lesions, and 9.51 ± 2.11 mm in grade 3 lesions (p = 0.01). Hemorrhage > 10 mm in diameter occurred in 10 patients (15.2%), being symptomatic in 3 of them. Four of 6 patients with grade 3 ITSS glioblastomas (66.7%) had postoperative hemorrhages > 10 mm in diameter. After adjusting for age, ITSS grade was the only factor significantly associated with hemorrhage > 10 mm (p = 0.029). Compared with patients with grade 1 ITSS, the odds of postoperative hemorrhage > 10 mm in diameter were 2.57 times higher in patients with grade 2 ITSS (95% CI 0.31-21.1) and 9.73 times higher in patients with grade 3 ITSS (95% CI 1.57-60.5).

CONCLUSIONS

ITSS grade on SWI is associated with size of postoperative hemorrhage after STB.

Endoscopic Trans-Mini-Cylinder Biopsy for Intraparenchymal Brain Lesions

OBJECTIVE

The biopsy procedure is intended to obtain an adequate specimen volume from the targeted area while ensuring minimal damage to the normal brain. We performed navigation-guided endoscopic biopsy using a small-diameter cylinder to reduce the invasiveness of the biopsy procedure and ensure a sufficient amount of tissue is collected. We examined whether it is possible to reduce brain tissue injury by using a small-diameter cylinder and improve safety and effectiveness by using an endoscope to directly observe the lesion and achieve hemostasis.

METHODS

Patients who underwent endoscopic biopsy surgery using a 6-mm-diameter cylinder for intraparenchymal lesions were enrolled in this study. Postoperative hematoma formation and the extent of trajectory scarring were assessed.

RESULTS

Fifty-two procedures performed on 51 patients were analyzed in this study. Postoperative neurological deterioration was not observed in any patient. A pathological diagnosis was made for all patients. Postoperative computed tomography revealed no hematoma after 49 procedures and a small hematoma after 3 procedures, and no patients required additional treatment. A postoperative trajectory scar less than 5 mm in diameter was observed after 30 procedures, a scar of 5-10 mm was observed after 19 procedures, a scar larger than 10 mm was observed after 3 procedures at 1 week after surgery, and 40, 6 and 0 scars were observed at 3 months after surgery.

CONCLUSIONS

Endoscopic biopsy using a small-diameter cylinder is a possible alternative biopsy technique for intraparenchymal lesions. This surgical technique is useful, especially in patients at risk of hemorrhagic complications.

Patient Safety Comparison of Frameless and Frame-Based Stereotactic Navigation for Brain Biopsy-A Single Center Cohort Study

Leksell stereotactic system-based aspiration biopsy is a common procedure in the neurosurgical treatment of deep-seated or multiple brain lesions. This study aimed to evaluate the benefit of frameless biopsy using VarioGuide compared to frame-based biopsy using the Leksell stereotactic system (LSS). We analyzed all brain biopsies using VarioGuide or LSS at our neurooncological Department of Neurosurgery in the University Hospital of Bonn between January 2018 and August 2020. We analyzed demographic data, duration of surgery, size of lesion, localization, and early complications. Uni-variable analyses were carried out on data from both groups. In total, 109 biopsies were compared (40 VarioGuide vs. 69 LSS). Patients with VarioGuide were significant older (74 (62−80) years vs. 67 (57−76) years; p = 0.03) and had a shorter duration of general anesthesia (163 (138−194) min vs. 193 (167−215) min, p < 0.001). We found no significant differences in surgery duration (VarioGuide median 28 min (IQR 20−38); LSS: median 30 min (IQR 25−39); p = 0.1352) or in early complication rates (5% vs. 7%; p = 0.644). A slightly higher false negative biopsy rate was registered in the LSS group (3 vs. 1; p = 0.1347). The size of the lesions also did not differ significantly between the two groups (18.31 ± 26.35 cm3 vs. 12.63 ± 14.62; p = 0.15). Our data showed that biopsies performed using VarioGuide took significantly less time than LSS biopsies and did not differ in complication rates. Both systems offered a high degree of patient safety.

Accuracy and safety of 101 consecutives neurosurgical procedures for newly diagnosed central nervous system lymphomas: a single-institution experience

INTRODUCTION

Brain surgery is required to ascertain the diagnosis of central nervous system lymphoma. We assessed the diagnostic yield and safety of the surgical procedures, the predictors of postoperative morbidity, and of overall survival.

METHODS

Observational single-institution retrospective cohort study (1992-2020) of 101 consecutive adult patients who underwent stereotactic biopsy, open biopsy, or resection for a newly diagnosed central nervous system lymphoma.

RESULTS

The diagnostic yield was 100% despite preoperative steroid administration in 48/101 cases (47.5%). A preoperative Karnofsky Performance Status score less than 70 (p = 0.006) was an independent predictor of a new postoperative focal neurological deficit (7/101 cases, 6.9%). A previous history of hematological malignancy (p = 0.049), age 65 years or more (p = 0.031), and new postoperative neurological deficit (p < 0.001) were independent predictors of a Karnofsky Performance Status score decrease 20 points or more postoperatively (13/101 cases, 12.9%). A previous history of hematological malignancy (p = 0.034), and preoperative Karnofsky Performance Status score less than 70 (p = 0.024) were independent predictors of postoperative hemorrhage (13/101 cases, 12.9%). A preoperative Karnofsky Performance Status score less than 70 (p = 0.019), and a previous history of hematological malignancy (p = 0.014) were independent predictors of death during hospital stay (8/101 cases, 7.9%). In the 82 immunocompetent patients harboring a primary central nervous system lymphoma, age 65 years or more (p = 0.044), and time to hematological treatment more than 21 days (p = 0.008), were independent predictors of a shorter overall survival. A dedicated hematological treatment (p < 0.001) was an independent predictor of a longer overall survival.

CONCLUSION

Brain biopsy is feasible with low morbidity for central nervous system lymphomas. Postoperatively, patients should be promptly referred for hematological treatment initiation.

Diagnostic Yield and Complication Rate of Stereotactic Biopsies in Precision Medicine of Gliomas

Background

An integrated diagnosis consisting of histology and molecular markers is the basis of the current WHO classification system of gliomas. In patients with suspected newly diagnosed or recurrent glioma, stereotactic biopsy is an alternative in cases in which microsurgical resection is deemed to not be safely feasible or indicated. In this retrospective study, we aimed to analyze both the diagnostic yield and the safety of a standardized biopsy technique.

Material and Methods

The institutional database was screened for frame-based biopsy procedures (January 2016 until March 2021). Only patients with a suspected diagnosis of glioma based on imaging were included. All tumors were classified according to the current WHO grading system. The clinical parameters, procedural complications, histology, and molecular signature of the tissues obtained were assessed.

Results

Between January 2016 and March 2021, 1,214 patients underwent a stereotactic biopsy: 617 (50.8%) for a newly diagnosed lesion and 597 (49.2%) for a suspected recurrence. The median age was 56.9 years (range 5 months−94.4 years). Magnetic resonance imaging (MRI)-guidance was used in 99.3% of cases and additional positron emission tomography (PET)-guidance in 34.3% of cases. In total, stereotactic serial biopsy provided an integrated diagnosis in 96.3% of all procedures. The most frequent diagnoses were isocitrate dehydrogenase (IDH) wildtype glioblastoma (n = 596; 49.2%), oligodendroglioma grade 2 (n = 109; 9%), astrocytoma grade 3 (n = 108; 8.9%), oligodendroglioma grade 3 (n = 76; 6.3%), and astrocytoma grade 2 (n = 66; 5.4%). A detailed determination was successful for IDH 1/2 mutation in 99.4% of cases, for 1p/19q codeletion in 97.4% of cases, for TERT mutation in 98.9% of cases, and for MGMT promoter methylation in 99.1% of cases. Next-generation sequencing was evaluable in 64/67 (95.5%) of cases and DNA methylome analysis in 41/44 (93.2%) of cases. Thirteen (1.1%) cases showed glial tumors that could not be further specified. Seventy-three tumors were different non-glioma entities, e.g., of infectious or inflammatory nature. Seventy-five out of 597 suspected recurrences turned out to be post-therapeutic changes only. The rate of post-procedural complications with clinical symptoms of the Common Terminology Criteria for Adverse Events (CTCAE) grade 3 or higher was 1.2% in overall patients and 2.6% in the subgroup of brainstem biopsies. There was no fatal outcome in the entire series.

Conclusion

Image-guided stereotactic serial biopsy enables obtaining reliable histopathological and molecular diagnoses with a very low complication rate even in tumors with critical localization. Thus, in patients not undergoing microsurgical resection, this is a valuable tool for precision medicine of patients with glioma.

Care of the Patient Undergoing Robotic-Assisted Brain Biopsy With Stereotactic Navigation: An Overview

Brain tumors can cause pressure, swelling, and functional changes to the surrounding tissue and lead to sensorimotor symptoms. Such tumors are either benign or malignant and their origin can be primary or metastatic. Although diagnostic studies (eg, computed tomography and magnetic resonance imaging) can reveal a mass and provide information on its location, size, and relationship to surrounding structures, the most definitive way to make a diagnosis requires a brain biopsy tissue sample. The robotic-assisted technique with stereotactic navigation allows the neurosurgeon to merge preoperative scans with a computer program to provide a map of the planned surgical trajectory and use the robot to obtain the biopsy. The robotic-assisted brain biopsy with navigation provides improved accuracy with small incisions that may not be possible using non-robotic-assisted techniques. This article provides background information and an overview of the nursing considerations for patients undergoing robotic-assisted brain biopsy procedures.

Feasability of a Frameless Brain Biopsy System for Companion Animals Using Cone-Beam CT-Based Automated Registration

The aim of the present study was to evaluate the use of a novel intraoperative cone-beam computed tomography (CBCT)-based automated registration system for frameless stereotactic brain biopsy in companion animals. An experimental cadaveric study evaluated thalamic and piriform lobe target site needle placement error in three dogs and three cats without a history of intracranial disease. Diagnostic accuracy and diagnostic yield were prospectively evaluated in twenty-four client-owned dogs and four cats with intracranial disease. Twenty-one procedures were performed post mortem (eighteen dogs and three cats), and seven biopsy procedures were performed in alive patients (six dogs and one cat). Procedural duration was evaluated in ten post mortem and four living patients. Outcome was evaluated in six dogs and one cat. In dogs, the calculated median needle placement error was 1.8 mm (range 0.71–2.84 mm) and 1.53 mm (range 1.45–1.99 mm) for piriform lobe and thalamus target sites, respectively. In cats, the calculated median needle placement error was 0.79 mm (range 0.6–1.91 mm) for the piriform lobe target site and 1.29 mm (range 0.47–2.69 mm) for the thalamic target site. The diagnostic yield was 96.4% (95% CI 0.81–0.99), the diagnostic accuracy was 94.4% (95% CI 0.72–0.99). Median total procedural duration for post mortem biopsies was 57.5 min (range 41–69 min). Median total procedural duration for intra vitam biopsies was 122.5 min (range 103–136 min). Three dogs were discharged 1 day after biopsy and one dog after 6 days. Two dogs and one cat were euthanized 24 and 48 h after biopsy. Intraoperative CBCT-based automated image registration for frameless stereotactic biopsies in companion animals is capable of providing diagnostic brain biopsy specimens independent of skull size and morphology with diagnostic yield and accuracy comparable to published values for diverse frameless and frame-based stereotaxy systems used in veterinary medicine. Duration of the procedure is not negatively affected and within the published range with other systems. Mobile intraoperative CBCT-based registration combined with neuronavigation delivers diagnostic brain biopsies in companion animals.

OCT-Guided Surgery for Gliomas: Current Concept and Future Perspectives

Optical coherence tomography (OCT) has been recently suggested as a promising method to obtain in vivo and real-time high-resolution images of tissue structure in brain tumor surgery. This review focuses on the basics of OCT imaging, types of OCT images and currently suggested OCT scanner devices and the results of their application in neurosurgery. OCT can assist in achieving intraoperative precision identification of tumor infiltration within surrounding brain parenchyma by using qualitative or quantitative OCT image analysis of scanned tissue. OCT is able to identify tumorous tissue and blood vessels detection during stereotactic biopsy procedures. The combination of OCT with traditional imaging such as MRI, ultrasound and 5-ALA fluorescence has the potential to increase the safety and accuracy of the resection. OCT can improve the extent of resection by offering the direct visualization of tumor with cellular resolution when using microscopic OCT contact probes. The theranostic implementation of OCT as a part of intelligent optical diagnosis and automated lesion localization and ablation could achieve high precision, automation and intelligence in brain tumor surgery. We present this review for the increase of knowledge and formation of critical opinion in the field of OCT implementation in brain tumor surgery.

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.

Pushing the boundaries of accuracy and reliability during stereotactic procedures: A prospective study on 526 biopsies comparing the frameless robotic and Image-Guided Surgery systems

INTRODUCTION

A 12-year long, prospective, single center study was conducted, comparing two frameless systems for brain biopsies: ROSA robotic-assisted stereotaxy and BrainLab Varioguide image-guided stereotaxy (Image Guided Surgery, IGS).

METHOD

All consecutive adult and pediatric patients undergoing frameless brain biopsies were included. Successfully achieving diagnosis was the primary endpoint, analysis of all periprocedural complications was the secondary endpoint, and the tertiary endpoint was the length of the procedure, with the aim of assessing of the learning curve for each operator over time. The results for the ROSA robot and the Varioguide system were compared and benchmarked to data from the literature.

RESULTS

We performed 526 on 516 patients, 314 with the ROSA robot (Group A) and 212 with the IGS Varioguide (Group B). Histological diagnosis was achieved in 97.4% of cases in Group A, versus 93.3% in Group B (p < 0.05). No statistically significant difference was found for secondary and tertiary endpoints. The complication rate appeared similar between the 2 frameless systems, with a hemorrhagic complications rate of 3.5% in Group A and 4.7% in Group B. Permanent neurological deterioration was only recorded in 0.8% of cases from Group B. Mortality was recorded in 0.3% in Group A and 0.4% in Group B.

CONCLUSION

This study provides evidence to confirm that robotic surgery lives up to its promises of increased safety, accuracy, and reliability.

Neurosurgical Approaches to Brain Tissue Harvesting for the Establishment of Cell Cultures in Neural Experimental Cell Models

In recent decades, cell biology has made rapid progress. Cell isolation and cultivation techniques, supported by modern laboratory procedures and experimental capabilities, provide a wide range of opportunities for in vitro research to study physiological and pathophysiological processes in health and disease. They can also be used very efficiently for the analysis of biomaterials. Before a new biomaterial is ready for implantation into tissues and widespread use in clinical practice, it must be extensively tested. Experimental cell models, which are a suitable testing ground and the first line of empirical exploration of new biomaterials, must contain suitable cells that form the basis of biomaterial testing. To isolate a stable and suitable cell culture, many steps are required. The first and one of the most important steps is the collection of donor tissue, usually during a surgical procedure. Thus, the collection is the foundation for the success of cell isolation. This article explains the sources and neurosurgical procedures for obtaining brain tissue samples for cell isolation techniques, which are essential for biomaterial testing procedures.

Related factors with diagnostic yield and intracranial hemorrhagic complications in frame-based stereotactic biopsy. Review

The frame-based stereotactic biopsy is a minimally invasive technique that allows us to obtain a sample of brain tissue for subsequent diagnosis and treatment. The scope of this article is to review the published data related to the factors that could condition its diagnostic yield, and the appearance of post-biopsy hemorrhagic complications. PubMed search, last updated June 2020, was conducted using the terms "stereotactic biopsy", "diagnostic yield" and "intracranial post-biopsy hemorrhage". A total of 38 studies, that showed descriptive or analytical results, were included, and reviewed. Our literature review show that some characteristics of the lesion and surgical procedure peculiarities are significantly related with the effectiveness and safety of the technique. In this way, they must be taken into account in order to optimize its results.

Fusion of Preoperative and Postoperative Imaging May Predict the Diagnostic Yield of Stereotactic Needle Brain Biopsies

BACKGROUND

Stereotactic needle brain biopsy is a commonly used neurosurgical procedure. However, up to 15% of biopsies result in undiagnostic pathology reports. Repeat biopsy or continued management without a diagnosis are often considered after undiagnostic biopsies. There have been no reports about the role of postoperative imaging in predicting the diagnostic yield of stereotactic biopsies.

METHODS

We retrospectively assessed all stereotactic biopsies performed over an 11-year period. We performed fusion of immediate postoperative computed tomography (CT) with preoperative MRI, to document whether the air bubble in the postoperative CT was located within the targeted lesion. We then evaluated the association of this fusion-based accuracy assessment with the diagnostic yield of the biopsy.

RESULTS

Fewer than 5% of biopsies did not have an air bubble on postoperative CT. A total of 226 biopsies were performed for 219 patients. In our sample, 213 of 226 biopsies were accurate (94.2% accuracy rate), and 203 of 226 biopsies gave a definitive diagnosis (89.8% diagnostic rate). In those cases where the fusion was accurate, the diagnostic rate was 93.9%. When the fusion was inaccurate, the diagnostic rate was only 23.1% (odds ratio 51.5, 95% confidence interval 12.6-210.44, P < 0.001). Of all patient, imaging, surgical, and admission parameters, the only parameter that correlated with diagnostic outcome of the biopsy was the fusion construct accuracy.

CONCLUSIONS

Fusion of immediate postoperative CT with preoperative imaging is predictive of the diagnostic rate. In cases where the pathology report following a biopsy is not diagnostic, this fusion may be useful in making decisions regarding repeat biopsy or considering other diagnostic options.

A Comparative Scientometric Analysis of the 100 Most Cited Articles of Acta Neurochirurgica (Wien) and World Neurosurgery

BACKGROUND

Acta Neurochirurgica (ANCH) and World Neurosurgery (WN), are 2 journals of significant importance in the neurosurgical community and have been associated with international federations. These journals carry a similar impact factor. The difference is the years they have been active (ANCH starting publication in 1973 and WN in 2010). This factor allows for a unique opportunity to delve deep into comparative, scientometric parameters, to understand the evolution of neurosurgical research.

METHODS

A title-specific search of the Web of Science database using the keywords "Acta Neurochirurgica," "Acta," "Neurochirurgica," "World Neurosurgery," "World," and "Neurosurgery" was performed and arranged according to number of citations. The title of the articles, authors, corresponding authors, country of origin, journal of publication, year of publication, citation count. and journal impact factor were assessed.

RESULTS

The average citation for ANCH was 170.1 citations, most being original articles (83/100). The articles of WN garnered nearly 70.48 citations, averaging 8.3 citations per publication. Most corresponding authors in ANCH originated from Germany with neuro-oncology, followed by neurotrauma and vascular as subjects. In contrast, the United States followed by China were the most common countries of origin for WN, with endoscopy and skull base being the topics achieving high impact.

CONCLUSIONS

Neurotrauma and consensus guidelines have been shown to have maximal citations for ANCH whereas endoscopy and skull base lesions garnered the most for WN. Author subspecialization and increased collaboration across specialties with more articles on refinement of technique and outcome have emerged as recent trends.

Factors affecting diagnostic yield in stereotactic biopsy for brain lesions: a 5-year single-center series

The objective of this study is to determine the factors that are associated with the diagnostic yield of stereotactic brain biopsy. A retrospective analysis was performed on 50 consecutive patients who underwent stereotactic brain biopsies in a single institute from 2014 to 2019. Variables including age, gender, lesion topography and characteristics, biopsy methods, and surgeon's experience were analyzed along with diagnostic rate. This study included 31 male and 19 female patients with a mean age of 48.4 (range: 1-76). Of these, 25 underwent frameless brain-suite stereotactic biopsies, 15 were frameless Portable Brain-lab® stereotactic biopsies and 10 were frame-based CRW® stereotactic biopsies. There was no statistical difference between the diagnostic yield of the three methods. The diagnostic yield in our series was 76%. Age, gender, and biopsy methods had no impact on diagnostic yield. Periventricular and pineal lesion biopsies were significantly associated with negative diagnostic yield (p = 0.01) whereas larger lesions were significantly associated with a positive yield (p = 0.01) with the mean volume of lesions in the positive yield group (13.6 cc) being higher than the negative yield group (7 cc). The diagnostic yields seen between senior and junior neurosurgeons in the biopsy procedure were 95% and 63%, respectively (p = 0.02). Anatomical location of the lesion, volume of the lesion, and experience of the surgeon have significant impacts on the diagnostic yield in stereotactic brain biopsy. There was no statistical difference between the diagnostic yield of the three methods, age, gender, and depth of lesion.

Augmented reality navigation for cranial biopsy and external ventricular drain insertion

OBJECTIVE

The aim of this study was to evaluate the accuracy (deviation from the target or intended path) and efficacy (insertion time) of an augmented reality surgical navigation (ARSN) system for insertion of biopsy needles and external ventricular drains (EVDs), two common neurosurgical procedures that require high precision.

METHODS

The hybrid operating room-based ARSN system, comprising a robotic C-arm with intraoperative cone-beam CT (CBCT) and integrated video tracking of the patient and instruments using nonobtrusive adhesive optical markers, was used. A 3D-printed skull phantom with a realistic gelatinous brain model containing air-filled ventricles and 2-mm spherical biopsy targets was obtained. After initial CBCT acquisition for target registration and planning, ARSN was used for 30 cranial biopsies and 10 EVD insertions. Needle positions were verified by CBCT.

RESULTS

The mean accuracy of the biopsy needle insertions (n = 30) was 0.8 mm ± 0.43 mm. The median path length was 39 mm (range 16-104 mm) and did not correlate to accuracy (p = 0.15). The median device insertion time was 149 seconds (range 87-233 seconds). The mean accuracy for the EVD insertions (n = 10) was 2.9 mm ± 0.8 mm at the tip with a 0.7° ± 0.5° angular deviation compared with the planned path, and the median insertion time was 188 seconds (range 135-400 seconds).

CONCLUSIONS

This study demonstrated that ARSN can be used for navigation of percutaneous cranial biopsies and EVDs with high accuracy and efficacy.

Prognostic factors in Tumefactive demyelinating lesions: A retrospective study

INTRODUCTION

Demyelinating lesions occasionally present as mass-like lesions on imaging, raising concern for malignancy. The disease course of such tumefactive demyelinating lesions (TDLs) is still being defined.

METHODS

We retrospectively analyzed 21 patients with new-onset neurologic symptoms and mass-like lesions on brain magnetic resonance imaging (MRI), which resulted in biopsy-proven diagnoses of demyelination. 18 patients had a median follow-up of 52 months. The clinical, radiologic and histologic features were associated with disease course.

RESULTS

An aggressive disease course (ADC) was noted in 33% of the patients and was associated with an initial largest lesion size ≥35 mm (p = 0.0007), mass effect (p = 0.01) and perilesional edema (p = 0.01) on MRI. Age 30 years and older, at presentation (p = 0.05), as well as the absence of a prior tonsillectomy (p = 0.0128) were also associated with an ADC.

CONCLUSIONS

We identified several factors, including initial larger lesion size, mass effect and perilesional edema on MRI, presentation after 30 years of age and the absence of a prior tonsillectomy, that predict an ADC in patients presenting with TDLs. These predictors of disease course can help guide patient follow-up and stratification for intervention.

Clinical outcomes as a function of the number of samples taken during stereotactic needle biopsies: a meta-analysis

BACKGROUND

Stereotactic needle biopsy remains the cornerstone for tissue diagnosis for tumors located in regions of the brain that are difficult to access through open surgery.

OBJECTIVE

We perform a meta-analysis of the literature to examine the relation between number of samples taken during biopsy and diagnostic yield, morbidity and mortality.

METHODS

We identified 2416 patients from 28 cohorts in studies published in PubMed database that studied stereotactic needle biopsies for tumor indications. Meta-analysis by proportions and meta-regression analyses were performed.

RESULTS

On meta-analysis, the morbidity profile of the published needle biopsy studies clustered into three groups: studies that performed < 3 samples (n = 8), 3-6 samples (n = 13), and > 6 samples during biopsy (n = 7). Pooled estimates for biopsy related morbidity were 4.3%, 16.3%, and 17% for studies reporting < 3, 3-6, and > 6 biopsy samples, respectively. While these morbidity estimates significantly differed (p < 0.001), the diagnostic yields reported for studies performing < 3 biopsies, 3-6 samples, and > 6 samples were comparable. Pooled estimates of diagnostic yield for these three groups were 90.4%, 93.8%, and 88.1%, respectively. Mortality did not significantly differ between studies reporting differing number of samples taken during biopsy.

CONCLUSIONS

Our meta-analysis suggests that morbidity risk in needle biopsy is non-linearly associated with the number of samples taken. There was no association between the number of biopsies taken, and diagnostic yield or mortality.

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.

Application of multimodal MRI and radiologic features for stereotactic brain biopsy: insights from a series of 208 patients

OBJECTIVES

We reviewed our institutional experience during a 10-year period for improvement of safety and efficacy of stereotactic biopsy procedures.

METHODS

We performed a retrospective review of inpatient summaries, stereotactic worksheets and radiologic investigations of 208 consecutive patients, who underwent MRI-guided stereotactic biopsies between March 2010 and March 2020.

RESULTS

The overall diagnostic yield was 96.2%. CT-confirmed intracranial hemorrhage occurred in 17 patients (8.2%), and the overall mortality rate was 0.5%. Combined MRS and PWI helped target selection in 27 cases (13.0%), the diagnostic yield was 100%. The results of the regression analysis revealed that non-diagnostic biopsy specimen significantly correlated with the cystic trait (p<.01) and edema of lesions (p<.05). Enhancement (p<.01) is shown to be an important factor for obtaining a diagnostic biopsy. Furthermore, the edema trait of lesions (p<.01) showed the important factors of hemorrhage.

CONCLUSIONS

The radiological features of lesions and use of the most suitable MRI sequences during biopsy planning are recommended ways to improve the diagnostic yield and safety of this technique.

Frame-based versus frameless stereotactic brain biopsies: A systematic review and meta-analysis

Background:

Stereotactic brain biopsy techniques have been a focus of rapid technological innovation. The recent advent of frameless stereotaxy has invited the question of whether it can provide the same diagnostic yield as frame-based techniques, without increasing risk of harm to patients. The goal of this meta-analysis was to compare each of these techniques in terms of yield and safety.

Methods:

We independently searched four databases for English studies comparing frameless and frame-based stereotactic brain biopsies. Our primary outcome was biopsy diagnostic yield. Our secondary outcomes included mortality, morbidity (e.g., symptomatic postbiopsy intracranial hemorrhage, asymptomatic postbiopsy intracranial hemorrhage, new postbiopsy neurological deficit, and postbiopsy seizure), and frequency of repeat biopsy. We calculated pooled estimates and relative risks for dichotomous outcomes using Review Manager 5.3, with corresponding 95% confidence intervals.

Results:

A total of 3256 stereotactic brain biopsies (2050 frame based and 1206 frameless), from 20 studies, were included in our final analysis. The results did not demonstrate any significant difference between the two stereotactic systems in terms of diagnostic yield (risk ratio [RR] 1.00, 95% confidence interval [CI] 0.99–1.02, P = 0.64, I² = 0%). The only significant difference was the increased frequency of asymptomatic hemorrhages in the frameless group (RR 1.37, 95% CI 1.06–1.75, P = 0.01, I² = 0%). Application of Grading of Recommendations Assessment, Development, and Evaluation to the results yielded very low quality of all outcomes.

Conclusion:

Based on very low-quality evidence, both frame-based and frameless stereotaxy are safe and effective for biopsy of intracranial tumors. Further study of patient preference and cost comparing analysis is required to identify if either modality should be preferred.

Longitudinal Assessment of Enhancing Foci of Abnormal Signal Intensity in Neurofibromatosis Type 1

BACKGROUND AND PURPOSE

Patients with neurofibromatosis 1 are at increased risk of developing brain tumors, and differentiation from contrast-enhancing foci of abnormal signal intensity can be challenging. We aimed to longitudinally characterize rare, enhancing foci of abnormal signal intensity based on location and demographics.

MATERIALS AND METHODS

A total of 109 MR imaging datasets from 19 consecutive patients (7 male; mean age, 8.6 years; range, 2.3-16.8 years) with neurofibromatosis 1 and a total of 23 contrast-enhancing parenchymal lesions initially classified as foci of abnormal signal intensity were included. The mean follow-up period was 6.5 years (range, 1-13.8 years). Enhancing foci of abnormal signal intensity were followed up with respect to presence, location, and volume. Linear regression analysis was performed.

RESULTS

Location, mean peak volume, and decrease in enhancing volume over time of the 23 lesions were as follows: 10 splenium of the corpus callosum (295 mm³, 5 decreasing, 3 completely resolving, 2 surgical intervention for change in imaging appearance later confirmed to be gangliocytoma and astrocytoma WHO II), 1 body of the corpus callosum (44 mm³, decreasing), 2 frontal lobe white matter (32 mm³, 1 completely resolving), 3 globus pallidus (50 mm³, all completely resolving), 6 cerebellum (206 mm³, 3 decreasing, 1 completely resolving), and 1 midbrain (34 mm³). On average, splenium lesions began to decrease in size at 12.2 years, posterior fossa lesions at 17.1 years, and other locations at 9.4 years of age.

CONCLUSIONS

Albeit very rare, contrast-enhancing lesions in patients with neurofibromatosis 1 may regress over time. Follow-up MR imaging aids in ascertaining regression. The development of atypical features should prompt further evaluation for underlying tumors.

Pseudoprogression versus true progression in glioblastoma patients: A multiapproach literature review. Part 2 - Radiological features and metric markers

After chemoradiotherapy for glioblastoma, pseudoprogression can occur and must be distinguished from true progression to correctly manage glioblastoma treatment and follow-up. Conventional treatment response assessment is evaluated via conventional MRI (contrast-enhanced T1-weighted and T2/FLAIR), which is unreliable. The emergence of advanced MRI techniques, MR spectroscopy, and PET tracers has improved pseudoprogression diagnostic accuracy. This review presents a literature review of the different imaging techniques and potential imaging biomarkers to differentiate pseudoprogression from true progression.

Between-hospital variation in rates of complications and decline of patient performance after glioblastoma surgery in the dutch Quality Registry Neuro Surgery

Introduction

For decisions on glioblastoma surgery, the risk of complications and decline in performance is decisive. In this study, we determine the rate of complications and performance decline after resections and biopsies in a national quality registry, their risk factors and the risk-standardized variation between institutions.

Methods

Data from all 3288 adults with first-time glioblastoma surgery at 13 hospitals were obtained from a prospective population-based Quality Registry Neuro Surgery in the Netherlands between 2013 and 2017. Patients were stratified by biopsies and resections. Complications were categorized as Clavien-Dindo grades II and higher. Performance decline was considered a deterioration of more than 10 Karnofsky points at 6 weeks. Risk factors were evaluated in multivariable logistic regression analysis. Patient-specific expected and observed complications and performance declines were summarized for institutions and analyzed in funnel plots.

Results

For 2271 resections, the overall complication rate was 20 % and 16 % declined in performance. For 1017 biopsies, the overall complication rate was 11 % and 30 % declined in performance. Patient-related characteristics were significant risk factors for complications and performance decline, i.e. higher age, lower baseline Karnofsky, higher ASA classification, and the surgical procedure. Hospital characteristics, i.e. case volume, university affiliation and biopsy percentage, were not. In three institutes the observed complication rate was significantly less than expected. In one institute significantly more performance declines were observed than expected, and in one institute significantly less.

Conclusions

Patient characteristics, but not case volume, were risk factors for complications and performance decline after glioblastoma surgery. After risk-standardization, hospitals varied in complications and performance declines.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11060-021-03697-8.

Hemorrhagic Attitude in Frameless and Frame-Based Stereotactic Biopsy for Deep-Seated Primary Central Nervous System Lymphomas in Immunocompetent Patients: A Multicentric Analysis of the Last Twenty Years

BACKGROUND

Primary central nervous system lymphoma (PCNSL) is a rare manifestation of aggressive extranodal non-Hodgkin lymphoma. In patients with deep-seated lesions, stereotactic brain biopsy (SBB) is an accepted diagnostic procedure to obtain histopathologic confirmation.

OBJECTIVE

The aim of this study was to assess the feasibility, diagnostic yield, safety, and complications of stereotactic procedures in midline and deep-seated PCNSLs.

METHODS

Patients selected had received a histopathologic diagnosis of PCNSL localized in deep-seated midline structures, obtained by SBB. The intraoperative frozen section was executed as an integral part of the procedure. Computed tomography scan was performed after surgery.

RESULTS

A total of 476 SBBs were performed between January 2000 and December 2019 . Of these SBBs, 91 deep-seated lesions had a histologic diagnosis of PCNSL. A significant increase of the incidence of PCNSL compared with all other diseases was observed (P < 0.0001). Eight patients (8.7%) showed a symptomatic hemorrhage, 4 of whom required craniotomy. There were 4 deaths and 2 cases of permanent morbidity. The hemorrhage risk in the PCNSL group was statistically significant (P = 0.0003) compared with other histotypes.

CONCLUSIONS

In suspected cases of PCNSL, a histopathologic diagnosis is necessary to distinguish it from glioblastoma or other, nonmalignant conditions. Deep-seated PCNSLs present a higher risk of biopsy-related morbidity and mortality. Intraoperative frozen section increases the diagnostic yield and reduces the number of sampling procedures. Postoperative computed tomography seems to be warranted in patients with suspected PCNSL.

A single-centre study of frame-based stereotactic brain biopsies

OBJECTIVE

We aimed to evaluate the concordance between the image-based and the tissue-based diagnosis using frame-based stereotactic biopsy.

MATERIALS AND METHODS

Medical records of biopsy procedures from 2000 to 2017 were reviewed. The radiologists' preoperative reports, biopsy procedures and postoperative histopathological diagnoses were retrieved. We compared the preoperative image-based diagnosis with the final histopathological diagnosis.

RESULTS

We identified 125 biopsy procedures performed in 123 patients. The concordance between image-based and histopathological diagnoses varied between 53.3% and 87.5%. The concordance of diagnosis concerning both tumor entity (i.e. cell type) and WHO grade was 54.6%. The diagnostic yield was 95.2%. There was overall morbidity of 10.4%, and a mortality rate of 0.8%. Minor complications occurred in 4.0% of the cases, while clinically significant complications occurred in 6.4% of the cases.

CONCLUSIONS

There was suboptimal concordance between radiological and histopathological diagnosis. Also, there was a tendency of histopathological undergrading. We confirm that frame-based stereotactic biopsies have a high diagnostic yield and a low rate of clinically significant complications and mortality.

Related factors with diagnostic yield and intracranial hemorrhagic complications in frame-based stereotactic biopsy. Review

The frame-based stereotactic biopsy is a minimally invasive technique that allows us to obtain a sample of brain tissue for subsequent diagnosis and treatment. The scope of this article is to review the published data related to the factors that could condition its diagnostic yield, and the appearance of post-biopsy hemorrhagic complications. PubMed search, last updated June 2020, was conducted using the terms "stereotactic biopsy", "diagnostic yield" and "intracranial post-biopsy hemorrhage". A total of 38 studies, that showed descriptive or analytical results, were included, and reviewed. Our literature review show that some characteristics of the lesion and surgical procedure peculiarities are significantly related with the effectiveness and safety of the technique. In this way, they must be taken into account in order to optimize its results.

Postoperative intracerebral haematomas following stereotactic biopsies: Poor planning or poor execution?

BACKGROUND

Postoperative intracerebral haematomas represent a serious complication following stereotactic biopsy. We investigated the possible underlying causes - poor planning or poor execution - of postoperative intracerebral haematomas following stereotactic biopsies.

METHODS

We performed a technical investigation using a retrospective single-centre consecutive series of robot-assisted stereotactic biopsies for a supratentorial diffuse glioma in adults. Each actual biopsy trajectory was reviewed to search for a conflict with an anatomical structure at risk.

RESULTS

From 379 patients, 12 (3.2%) presented with a postoperative intracerebral haematoma ≥20 mm on postoperative CT-scan (3 requiring surgical evacuation); 11 of them had available intraoperative imaging (bi-planar stereoscopic teleangiography x-rays at each biopsy site). The actual biopsy trajectory was similar to the planned biopsy trajectory in these 11 cases. In 72.7% (8/11) of these cases, the actual biopsy trajectory was found to contact a structure at risk (blood vessel and cerebral sulcus) and identified as the intracerebral haematoma origin.

CONCLUSIONS

Robot-assisted stereotactic biopsy is an accurate procedure. Postoperative intracerebral haematomas mainly derive from human-related errors during trajectory planning.

A Simple Modified Technique for Frameless Brain Lesion Biopsy

Published articles pertaining to possible ways to increase the accuracy of image-guided frameless surgery are abundant in the literature. Accurate target localization is dependent on many factors, of which noteworthy is the meticulous registration and constant fixation of instruments during the procedure. Frequent changing of instruments’ application or inadvertent destabilization of its fixation during surgery after registration might disrupt the preset navigation measurements, leading to inaccurate targeting. Technical wise, we managed to avoid the drawback of moving the aiming device repeatedly during the procedure, as we will discuss later.

This retrospective study aims to evaluate the feasibility and reliability of a simple frameless technique we used in navigation-guided brain biopsy and to show how it refines the accuracy of frameless biopsy procedures. All procedures were performed at our institution in the period from 2018 to 2019 and included 10 patients with different brain lesions. The mean operative time using our technique was noticeably short (18 minutes) and the standard deviation was 2.1. The used technique was easy, undemanding, and reliable in obtaining samples from brain tumors, guaranteeing more precision by applying an all-time fixed and stable navigation reference hardware.

Orally Administered 5-aminolevulinic Acid for Isolation and Characterization of Circulating Tumor-Derived Extracellular Vesicles in Glioblastoma Patients

Background: In glioblastoma (GB), tissue is required for accurate diagnosis and subtyping. Tissue can be obtained through resection or (stereotactic) biopsy, but these invasive procedures provide risks for patients. Extracellular vesicles (EVs) are small, cell-derived vesicles that contain miRNAs, proteins, and lipids, and possible candidates for liquid biopsies. GB-derived EVs can be found in the blood of patients, but it is difficult to distinguish them from circulating non-tumor EVs. 5-aminolevulinic acid (5-ALA) is orally administered to GB patients to facilitate tumor visualization and maximal resection, as it is metabolized to fluorescent protoporphyrin IX (PpIX) that accumulates in glioma cells. In this study, we assessed whether PpIX accumulates in GB-derived EVs and whether these EVs could be isolated and characterized to enable a liquid biopsy in GB. Methods: EVs were isolated from the conditioned media of U87 cells treated with 5-ALA by differential ultracentrifugation. Blood samples were collected and processed from healthy controls and patients undergoing 5-ALA guided surgery for GB. High-resolution flow cytometry (hFC) enabled detection and sorting of PpIX-positive EVs, which were subsequently analyzed by digital droplet PCR (ddPCR). Results: PpIX-positive EVs could be detected in conditioned cell culture media as well as in patient samples after administration of 5-ALA. By using hFC, we could sort the PpIX-positive EVs for further analysis with ddPCR, which indicated the presence of EVs and GB-associated miRNAs. Conclusion: GB-derived EVs can be isolated from the plasma of GB patients by using 5-ALA induced fluorescence. Although many challenges remain, our findings show new possibilities for the development of blood-based liquid biopsies in GB patients.

Stereotactic Brain Biopsy in Eloquent Areas Assisted by Navigated Transcranial Magnetic Stimulation: a Technical Case Report

BACKGROUND AND IMPORTANCE

Stereotactic brain biopsy (SB) is an important part of the neurosurgical armamentarium, with the possibility of achieving histopathological diagnosis in otherwise inaccessible lesions of the brain. Nevertheless, the procedure is not without the risk of morbidity, which is especially true for lesions in eloquent parts of the brain, where even a minor adverse event can result in significant deficits. Navigated transcranial magnetic stimulation (nTMS) is widely used to chart lesions in eloquent areas, successfully guiding maximal safe resection, while its potential role in aiding with the planning of a stereotactic biopsy is so far unexplored.

CLINICAL PRESENTATION

Magnetic resonance imaging of a 67-yr-old woman presenting with dysphasia revealed a noncontrast enhancing left-sided lesion in the frontal and parietal pars opercularis. Due to the location of the lesion, nTMS was used to chart both primary motor and language cortex, utilizing this information to plan a safe SB trajectory and sampling area according to the initial work-up recommendations from the multidisciplinary neuro-oncology board. The SB was uneventful, with histology revealing a ganglioglioma, WHO I. The patient was discharged the following day, having declined to proceed with tumor resection (awake surgery) due to the non-negligible risk of morbidity. Upon 1- and 3-mo follow-up, she showed no signs of any procedure-related deficits.

CONCLUSION

nTMS can be implemented to aid with the planning of a stereotactic biopsy procedure in eloquent areas of the brain, and should be considered part of the neurosurgical armamentarium.

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.

Comparing Fiducial-Based and Intraoperative Computed Tomography-Based Registration for Frameless Stereotactic Brain Biopsy

OBJECTIVE

The aim of this work was to compare fiducial-based and intraoperative computed tomography (iCT)-based registration for frameless stereotactic brain biopsy.

METHODS

Of 50 frameless stereotactic biopsies with the VarioGuide, 30 cases were registered as iCT based and 20 as fiducial based. Statistical analysis of the target registration error (TRE), dose length product, effective radiation dose (ED), operation time, and diagnostic yield was performed.

RESULTS

The mean TRE was significantly lower using iCT-based registration (mean ± SD: 0.70 ± 0.32 vs. 2.43 ± 0.73 mm, p < 0.0001). The ED was significantly lower when using iCT-based registration compared to standard navigational CT (mean ± SD: 0.10 ± 0.13 vs. 2.23 ± 0.34 mSv, p < 0.0001). Post-biopsy iCT was associated with a significant lower (p < 0.0001) ED compared to standard CT (mean ± SD: 1.04 ± 0.18 vs. 1.65 ± 0.26 mSv). The mean surgical time was shorter using iCT-based registration, although the mean total operating room (OR) time did not differ significantly. The diagnostic yield was 96.7% (iCT group) versus 95% (fiducial group). Post-biopsy imaging revealed severe bleeding in 3.3% (iCT group) versus 5% (fiducial group).

CONCLUSION

iCT-based registration for frameless stereotactic biopsies increases the accuracy significantly without negative effects on the surgical time or the overall time in the OR. Appropriate scan protocols in iCT registration contribute to a significant reduction of the radiation exposure. The high accuracy of the iCT makes it the more favorable registration strategy when taking biopsies of small tumors or lesions near eloquent brain areas.

Evaluation of 311 contemporary cases of stereotactic biopsies in patients with neoplastic and non-neoplastic lesions-diagnostic yield and management of non-diagnostic cases

Stereotactic biopsies are an established tool for obtaining diagnosis of unclear brain lesions. However, non-diagnostic biopsies still occur. We aimed to analyze the contemporary diagnostic yield of stereotactic biopsies, predictors for non-diagnostic biopsies, outcome, and follow-up strategy after non-diagnostic biopsy. We conducted a single-center retrospective study of 311 adult patients undergoing stereotactic biopsies due to a newly diagnosed lesion at our department between 2012 and 2018. Patient data regarding comorbidities, presenting symptoms, imaging features, and non-invasive diagnostic procedures were obtained. The overall diagnostic yield was 86.2% and differed significantly between the various suspected diagnosis groups and was the highest when suspecting primary brain tumor compared with non-neoplastic lesions (91.2% vs. 73.3%, p > 0.001). Predicators for non-diagnostic biopsies were small lesion size, lack of contrast-enhancement, presence of sepsis, or underlying hemato-oncological disease. In case of non-diagnostic biopsy, a re-biopsy was performed in 12 cases, revealing a final diagnosis in 75%. In 16 cases, empiric therapy was started based on the suspected underlying disease. Close follow-up was performed in the remaining 15 cases. We showed that stereotactic biopsy is a safe procedure with reasonable diagnostic yield even for non-neoplastic lesions, when non-invasive diagnostic was inconclusive. In addition, we developed treatment recommendations for cases of non-diagnostic biopsies.

Stereotactic Brain Biopsy Hemorrhage Risk Factors and Implications for Postoperative Care at a Single Institution: An Argument For Postoperative Imaging

OBJECTIVE

To determine preoperative factors contributing to postoperative hemorrhage after stereotactic brain biopsy (STB), clinical implications of postoperative hemorrhage, and the role of postoperative imaging in clinical management.

METHODS

Retrospective review of STB (2005-2018) across 2 institutions including patients aged >18 years undergoing first STB. Patients with prior craniotomy, open biopsy, or prior STB were excluded. Preoperative variables included age, sex, neurosurgeon seniority, STB method. Postoperative variables included pathology, postoperative hemorrhage on computed tomography, immediate and 30-day postoperative seizure, infection, postoperative hospital stay duration, and 30-day return to operating room (OR). Analysis used the Fisher exact tests for categorical variables.

RESULTS

Overall, 410 patients were included. Average age was 56.5 (±16.5) years; 60% (n = 248) were men. The majority of biopsies were performed by senior neurosurgeons (66%, n = 270); frontal lobe (42%, n = 182) and glioblastoma (45%, n = 186) were the most common location and pathology. Postoperative hemorrhage occurred in 28% (114) of patients with 20% <0.05 cm³ and 8% >0.05 cm³. Postoperative hemorrhage of any size was associated with increased rate of postoperative deficit within both 24 hours and 30 days, postoperative seizure, and length of hospital stay when controlling for pathology. Hemorrhages >0.05 cm³ had a 16% higher rate of return to the OR for evacuation, due to clinical deterioration as opposed to radiographic progression.

CONCLUSIONS

Postbiopsy hemorrhage was associated with higher risk of immediate and delayed postoperative deficit and seizure. Postoperative computed tomography should be used to determine whether STB patients can be discharged same day or admitted for observation; clinical evaluation should determine return to OR for evacuation.

A comparison of the efficacy, safety, and duration of frame-based and Remebot robot-assisted frameless stereotactic biopsy

OBJECTIVE

The aim of this study was to compare the efficacy, safety, and duration of Remebot robot-assisted frameless brain biopsy with those of standard frame-based stereotactic biopsy.

PATIENTS AND METHODS

A retrospective analysis of 66 patients undergoing stereotactic brain biopsy in our department from January 2015 to January 2019 was performed. We divided the patients into two groups: the frame-based group (n = 35) and the Remebot robot group (n = 31). Data on clinical characteristics, total procedure length, overall discomfort, diagnostic yield, complications, and postoperative length of hospital stay were retrospectively reviewed and compared between these two groups.

RESULTS

No significant difference in diagnostic yield was detected in the two groups, with frame-based biopsy having a diagnostic yield of 91.4% and Remebot robot-assisted frameless brain biopsy having a diagnostic yield of 93.5%. The duration of the total procedure was 116.5 min for the frame-based biopsy and 80.1 min for the Remebot robot-assisted frameless brain biopsy (p < 0.001). There were no statistically significant differences in complication rate or postoperative duration of hospitalization between the two groups. The overall patient discomfort in the frame-based group was significantly greater than that in the Remebot robot group (visual analog scale score 2.7 ± 1.2 versus 1.5 ± 0.7, p = 0.001).

CONCLUSIONS

Remebot robot-assisted frameless brain biopsy was as efficacious and safe as standard stereotactic frame-based biopsy. However, frameless biopsy can alleviate the suffering of the patient and reduce the total duration of the procedure. Remebot robot-assisted frameless brain biopsy is easy to use and better accepted by patients than frame-based biopsy.