The etiological spectrum of multiple ring-enhancing lesions of the brain: a systematic review of published cases and case series.

OBJECTIVE: Multiple ring-enhancing lesions of the brain are enigmatic neuroimaging abnormality. In this systematic review, we evaluated the etiological spectrum of these lesions. METHODS: This systematic review adhered to the PRISMA guidelines. We searched PubMed, Embase, Scopus, and Google Scholar up until 15 June 2023. We included case reports and case series. Quality evaluation of each case was based on selection, ascertainment, causality, and reporting. The extracted information included demographic characteristics, clinical features, type and number of multiple enhancing brain lesions, diagnostic procedures, final diagnoses, treatments, and patient outcomes. PROTOCOL REGISTRATION: PROSPERO CRD42023437081. RESULTS: We analyzed 156 records representing 161 patients, 60 of whom were immunocompromised. The mean age was 42.6 years, and 67% of patients experienced symptoms for up to 1 month. A higher proportion of immunocompromised patients (42% vs. 30%) exhibited encephalopathy. Chest or CT thorax abnormalities were reported in 27.3% of patients, while CSF abnormalities were found in 31.7%, more frequently among the immunocompromised. Definitive diagnoses were established via brain biopsy, aspiration, or autopsy in 60% of cases, and through CSF examination or other ancillary tests in 40% of cases. Immunocompromised patients had a higher incidence of Toxoplasma gondii infection and CNS lymphoma, while immunocompetent patients had a higher incidence of Mycobacterium tuberculosis infection and immune-mediated and demyelinating disorders. The improvement rate was 74% in immunocompetent patients compared to 52% in the immunocompromised group. CONCLUSION: Multiple ring-enhancing lesions of the brain in immunocompromised patients are more frequently caused by Toxoplasma gondii infections and CNS lymphoma. Conversely, among immunocompetent patients, Mycobacterium tuberculosis infection and immune-related demyelinating conditions are common.

To scan or not to scan? A retrospective cohort study analysing the efficacy of routine post-operative CT after brain biopsy.

PURPOSE: Postoperative management following elective cranial surgery, particularly after biopsy procedures, varies significantly across neurosurgical centres. Routine postoperative head CT scans, traditionally performed to detect complications such as intracranial bleeding or cerebral oedema, lack substantial evidence supporting their necessity. METHODS: This study is a retrospective cohort analysis conducted at a regional neurosurgical department of 236 patients who underwent brain biopsies between 2018 and 2022. Patient data, including demographics, surgical details, and postoperative outcomes, were collected and analysed. The outcomes investigated were the incidence and impact of postoperative CT scans on time to discharge, management changes, and the influence of preoperative anticoagulation. RESULTS: Out of 236 patients, 205 (86.86%) underwent postoperative CT scans. There was no significant relationship between postoperative hematoma, as detected on a CT scan, and neurological deficit (p = 0.443), or between preoperative anticoagulation and postoperative bleeding on CT scans (p = 0.464). Patients who had postoperative CT scans had a significantly longer length of stay (LOS) compared to those who did not (p < 0.001). Intraoperative bleeding was a predictor of hematoma on postoperative CT (p = 0.017) but not of postoperative neurological deficit. The routine postoperative CT scan showed limited predictive value for symptomatic deficits, with a positive predictive value of 6.67% and a negative predictive value of 96.88%. CONCLUSIONS: Routine postoperative CT scans after brain biopsies do not significantly impact management or improve patient outcomes but are associated with longer hospital stays. CT scans should be reserved for patients showing clinical signs of complications rather than used as a routine procedure after a brain biopsy.

Primary angiitis of the central nervous system.

Primary angiitis of the central nervous system (CNS) is an uncommon inflammatory disorder, with highly variable clinical presentation. It needs to be differentiated from several mimickers, such as CNS involvement in systemic vasculitides, connective tissue disorders, infectious disease, and leukodystrophy as well as neoplastic diseases. The diagnosis requires a combination of clinical and laboratory investigations, multimodal imaging, and histopathological examination, which should be available for confirmation. In the present paper, the histopathological features of primary angiitis of the CNS are described and highlighted to help pathologists avoid misdiagnosis of a treatable acquired disease.

Small vessel childhood primary angiitis of the central nervous system with positive anti-glial fibrillary acidic protein antibodies: a case report and review of literature.

BACKGROUND: Small vessel childhood primary angiitis of the central nervous system (SV-cPACNS) is a rare disease characterized by inflammation within small vessels such as arterioles or capillaries. CASE PRESENTATION: We report a case of SV-cPACNS in an 8-year-old boy confirmed by brain biopsy. This patient was also incidentally found to have anti-glial fibrillary acidic protein (GFAP) antibodies in the cerebrospinal fluid (CSF) but had no evidence of antibody-mediated disease on brain biopsy. A literature review highlighted the rarity of SV-cPACNS and found no prior reports of CSF GFAP-associated SV-cPACNS in the pediatric age group. CONCLUSION: We present the first case of biopsy proven SV-cPACNS vasculitis associated with an incidental finding of CSF GFAP antibodies. The GFAP antibodies are likely a clinically insignificant bystander in this case and possibly in other diseases with CNS inflammation. Further research is needed to determine the clinical significance of newer CSF autoantibodies such as anti-GFAP before they are used for medical decision-making in pediatrics.

Post-malaria neurological syndrome (PMNS): a rare case report with brain biopsy findings.

Post-malaria neurological syndrome (PMNS) is a rare, self-limiting condition that presents with a wide range of neurological manifestations after clearance of malarial infection, especially 𝘗𝘭𝘢𝘴𝘮𝘰𝘥𝘪𝘶𝘮 f𝘢𝘭𝘤𝘪𝘱𝘢𝘳𝘶𝘮, most patients recover without residual deficits. Here we present a case of a 29-year-old, male with a recent history of malaria treated successfully, who presented due to a generalized tonic-clonic seizure, without any other neurological symptoms, the examination and labs were unremarkable, he underwent a computer tomography (CT) scan and Magnetic resonant imaging (MRI) which both showed two areas of vasogenic edema involving the subcortical white matter of left frontal and right posterior parasagittal regions, all autoimmune screens, infection workup from blood and CSF were negative, he underwent a brain biopsy that showed intense perivascular inflammation with neuronal loss and gliosis, findings are nonspecific and can be seen in a variety of condition. The patient's condition improved, and he was discharged without any complications.

Fluorescein sodium fluorescence: role in stereotactic brain biopsy.

BACKGROUND: Stereotactic brain biopsy for eloquent area brain tumours is associated with complications like hemorrhage due to multiple sampling and increased operative time due to dependence on neuropathologist for frozen section assessment. In order to curb these limitations, we investigated the use of Fluorescein sodium fluorescence in confirming pathological tissue samples in stereotactic brain biopsy of gadolinium-enhancing tumours. METHODS: This prospective observational study included 23 consecutive patients who underwent stereotactic biopsy of gadolinium-contrast-enhancing brain lesions with intravenous fluorescein sodium administration. 93 specimens were obtained and examined for the presence of fluorescence using a microscope with fluorescence visualisation capability. Later the nature of the samples was confirmed on histopathology. The sensitivity and specificity of flourescein sodium fluorescence were calculated based on histopathological confirmation. RESULTS: 58 (62.3%) fluorescent and 35 (37.6%) nonfluorescent samples were obtained. All fluorescent specimens contained diagnostic tissue appropriate for tumor grading. Of 35 nonfluorescent specimens, 12 (34.3%) did not contain tumor, 11 (31.4%) contained minor hypercellularity or gliosis, and 12 (34.3%) contained tumor with a high proportion of necrosis. The sensitivity and specificity for fluorescein fluorescence were 83% and 100%, respectively. CONCLUSIONS: Fluorescein fluorescence is a handy tool to detect the pathological tissue in stereotactic brain biopsy and may improve its diagnostic accuracy and expedite the procedure.

Epileptic seizures in patients with primary central nervous system lymphoma: A systematic review.

BACKGROUND: Primary central nervous system lymphoma (PCNSL) accounts for less than 5% of primary brain tumors. Epileptic seizures are a common manifestation of brain tumors; however, literature on the prevalence, characteristics, and oncological implications of seizures in patients with PCNSL is limited, and the management of antiepileptic drugs (AEDs) is unclear. This review aimed to summarize the existing knowledge on seizures in PCNSL, their potential association with surgery, oncological treatment, survival rates, and management of AEDs. METHODS: A systematic review was performed according to the PRISMA recommendations and included articles published between 1953 and 2023 describing seizures in patients with PCNSL. RESULTS: The search identified 282 studies, of which 21 were included. Up to 33% of patients with PCNSL developed seizures, mostly at the initial presentation. Little information was found on changes in seizure incidence through the course of the disease, and no details were found on seizure frequency, the percentage of treatment-resistant patients, or the evolution of seizures at remission. Younger age, cortical location, and immunodeficiency have been identified as potential risk factors for seizures, but evidence is very limited. The growing use of vigorous treatments including intensive chemotherapy with autologous stem cell transplantation and immunotherapy with CAR-T cells is associated with a higher incidence of seizures. The association between seizure development and patient mortality in PCNSL remains unknown. There are no data on AED prophylaxis or the use of specific AEDs in PCNSL. CONCLUSIONS: Further studies are needed to investigate seizures in larger cohorts of PCNSL, to clarify their prevalence, better characterize them, identify risk factors, analyze survival rates, and make recommendations on AED management. We recommend following general practice guidelines for seizures symptomatic of brain tumors and not to prescribe AED prophylaxis in PCNSL.

[Sporadic Creutzfeldt-Jakob Disease With Slow Progression:Report of One Case].

Sporadic Creutzfeldt-Jakob disease(sCJD)is a prion-caused degenerative disease of the central nervous system,with the typical clinical manifestation of rapidly progressive dementia.The course of disease is less than 1 year in most patients and more than 2 years in only 2% to 3% patients.We reported a case of sCJD with expressive language disorder and slow progression in this paper.By summarizing the clinical manifestations and the electroencephalograhpy,MRI,and pathological features,we aimed to enrich the knowledge about the sCJD with slow progression.

Lymphomatosis cerebri: a rare diffuse leukoencephalopathy you should never miss.

INTRODUCTION: Lymphomatosis cerebri (LC) is a rare variant of primary central nervous system lymphoma that diffusely involves throughout the brain. In recent years, increasingly reported cases have notably broadened the spectrum of clinical and radiological features; however, it remains a great diagnostic challenge. CASE REPORT: We reported an atypical case of LC presented with subacute onset of focal neurological deficits and diffuse T2 hyperintensities without contrast enhancement on magnetic resonance imaging. He was initially considered as inflammatory leukoencephalopathy and received empirical corticosteroids, showing a dramatically clinical response. Three months later, the patient relapsed with deteriorating symptoms and enlarged brain lesions with mass-like enhancement. A diagnosis of LC was finally established according to the radiological and pathological findings. DISCUSSION: Though rare, LC should always be kept as a differential diagnosis of diffuse leukoencephalopathy. Neurologists should be aware of every detailed information about LC to avoid a delay of diagnostic biopsy in clinical practice.

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.

Advances, technological innovations, and future prospects in stereotactic brain biopsies.

Stereotactic brain biopsy is one of the most frequently performed brain surgeries. This review aimed to expose the latest cutting-edge and updated technologies and innovations available to neurosurgeons to safely perform stereotactic brain biopsy by minimizing the risks of complications and ensuring that the procedure is successful, leading to a histological diagnosis. We also examined methods for improving preoperative, intraoperative, and postoperative workflows. We performed a comprehensive state-of-the-art literature review. Intraoperative histology, fluorescence, and imaging techniques appear as smart tools to improve the diagnostic yield of biopsy. Constant innovations such as optical methods and augmented reality are also being made to increase patient safety. Robotics and integrated imaging techniques provide an enhanced intraoperative workflow. Patients' management algorithms based on early discharge after biopsy optimize the patient's personal experience and make the most efficient possible use of the available hospital resources. Many new trends are emerging, constantly improving patient care and safety, as well as surgical workflow. A parameter that must be considered is the cost-effectiveness of these devices and the possibility of using them on a daily basis. The decision to implement a new instrument in the surgical workflow should also be dependent on the number of procedures per year, the existing stereotactic equipment, and the experience of each center. Research on patients' postbiopsy management is another mandatory approach to enhance the safety profile of stereotactic brain biopsy and patient satisfaction, as well as to reduce healthcare costs.

Diagnosis, treatment, and outcome of primary CNS lymphoma-a single-center experience.

BACKGROUND: Primary CNS lymphoma (PCNSL) is a highly aggressive non-Hodgkin lymphoma (NHL) that occurs in the CNS (e.g. brain, meninges, spinal cord, cerebrospinal fluid, or intraocular involvement) in the absence of systemic NHL. Tumor resection does not improve survival, and neurosurgical intervention is generally limited to stereotactic biopsy to provide a histopathological diagnosis. OBJECTIVE: The objective of this single-center study was to evaluate the management and outcome of PCNSL patients diagnosed by biopsy, using overall survival and progression-free survival as endpoints. METHODS: At our department of neurosurgery, 140 patients were diagnosed with PCNSL by biopsy between January 1, 2009, and December 31, 2018. Of these, 37 patients were included in the study and were divided into three groups according to their postoperative therapy. RESULTS: Median OS was 35.7 months for the intensive treatment group, 29.5 months for the moderate treatment group, and 8.6 months for the palliative treatment group. The intensive and moderate treatment groups had similar progression-free survival, while the palliative treatment group had poor overall and progression-free survival. Six patients were long-term survivors (> 80 months). Age under 65 years was the main significant parameter affecting overall survival. CONCLUSION: In this cohort, patients with PCNSL had an overall fair prognosis if they (1) were under 65 years old, (2) had a performance score < 2 at the time of diagnosis, and (3) received either intensive or moderate chemotherapeutic treatment. Biopsy is still the primary diagnostic tool; other methods have been investigated but are not yet recommended.

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.

Motor deficits at presentation and predictors of overall survival in central nervous system lymphomas.

PURPOSE: Central nervous system lymphomas (CNSL) can present with motor and non-motor symptoms. In many central nervous system tumors, motor deficits are associated with significant morbidity and functional impairment, and correlate with worse prognosis. CNSLs however, often exhibit remarkable response to chemotherapy and radiotherapy with corresponding symptom improvement. We investigate the survival outcomes and trajectories of motor and functional recovery in a cohort of patients presenting with and without initial motor deficits. METHODS: Patients who underwent biopsy and with a histologically confirmed CNSL between 2008 and 2019 were retrospectively identified. Baseline demographic variables, comorbidities, presenting symptoms, histological type, neuroimaging features (location and number of lesions), and treatment administered (pre- and post-operative steroid use and chemotherapy regime) were recorded. Dates of death were obtained from the National Registry of Births and Deaths. Motor power and performance status at admission, 1 month and 6 months were determined. RESULTS: We identified 119 patients, of whom 34% presented with focal motor deficits. The median overall survival (OS) was 26.6 months. Those with focal motor deficits had longer OS (median 42.4 months) than those without (median 23.3 months; p = 0.047). In multivariate Cox analysis, age (HR 1.04 per year; p = 0.003), CCI (HR 1.31 per point; p < 0.001), leptomeningeal/ependymal involvement (HR 2.53; p = 0.016), thalamus involvement (HR 0.34; p = 0.019), neutrophil:lymphocyte ratio (HR 1.06 per point; p = 0.034), positive HIV status (HR 5.31; p = 0.003), preoperative steroids use (HR 0.49; p = 0.018), postoperative high-dose steroids (HR 0.26; p < 0.001) and postoperative low-dose steroids (HR 0.28; p = 0.010) were significant predictors of OS. By one month, 43% of surviving patients had full power, increasing to 61% by six months. CONCLUSION: A significant proportion of patients with initial motor deficits recovered in motor strength by six months. In our population, those presenting with motor deficits had paradoxically better overall survival.

Mobile intraoperative CT-assisted frameless stereotactic biopsies achieved single-millimeter trajectory accuracy for deep-seated brain lesions in a sample of 7 patients.

BACKGROUND: Brain biopsies are crucial diagnostic interventions, providing valuable information for treatment and prognosis, but largely depend on a high accuracy and precision. We hypothesized that through the combination of neuronavigation-based frameless stereotaxy and MRI-guided trajectory planning with intraoperative CT examination using a mobile unit, one can achieve a seamlessly integrated approach yielding optimal target accuracy. METHODS: We analyzed a total of 7 stereotactic biopsy trajectories for a variety of deep-seated locations and different patient positions. After rigid head fixation, an intraoperative pre-procedural scan using a mobile CT unit was performed for automatic image fusion with the planning MRI images and a peri-procedural scan with the biopsy cannula in situ for verification of the definite target position. We then evaluated the radial trajectory error. RESULTS: Intraoperative scanning, surgery, computerized merging of MRI and CT images as well as trajectory planning were feasible without difficulties and safe in all cases. We achieved a radial trajectory deviation of 0.97 ± 0.39 mm at a trajectory length of 60 ± 12.3 mm (mean ± standard deviation). Repositioning of the biopsy cannula due to inaccurate targeting was not required. CONCLUSION: Intraoperative verification using a mobile CT unit in combination with frameless neuronavigation-guided stereotaxy and pre-operative MRI-based trajectory planning was feasible, safe and highly accurate. The setting enabled single-millimeter accuracy for deep-seated brain lesions and direct detection of intraoperative complications, did not depend on a dedicated operating room and was seamlessly integrated into common stereotactic procedures.

The role of surgical resection in primary central nervous system lymphoma: a single-center retrospective analysis of 70 patients.

BACKGROUND: The aim of this study was to evaluate the effect of surgical resection and stereotactic biopsy on the complication rate, progression-free survival (PFS) and overall survival (OS) of 70 patients diagnosed at a single institution with primary central nervous system lymphoma (PCNSL) and to explore the predictors of selection for resection and the prognostic factors of PCNSL. METHODS: A retrospective analysis was performed of 70 patients with PCNSL that was diagnosed by surgical resection or stereotactic brain biopsy in our department from January 2013 to May 2019. We divided the patients into two groups: a resection group (n = 28) and a stereotactic biopsy group (n = 42). Data on clinical characteristics, imaging findings, complication rates, PFS and OS were retrospectively reviewed and compared between these two groups. We also analysed the predictors of selection for resection and prognostic factors of PCNSL by multivariate analysis. RESULTS: The median age was 53.3 ± 14.3 years, and there was a male predominance with a sex ratio of 1.33:1. The most common clinical manifestation was a headache. The complication rate in the resection group was 10.7% versus 7.1% in the stereotactic biopsy group, and there was no statistically significant difference. The rate of improvement in symptoms of the resection group was significantly higher than that of the stereotactic biopsy group. Multivariable analysis identified a single tumour and not involving deep structures as predictors of selection for resection. With a median follow-up of 30 months (range 1-110), the mean OS and PFS of all patients were 16.1 months and 6.2 months, respectively. Patients who underwent surgical resection had a mean OS of 23.4 months and PFS of 8.6 months versus 11.2 months and 4.6 months for those who had a brain biopsy performed. In addition, multivariable analysis showed that not involving deep structures and resection were favourable prognostic factors for PCNSL. CONCLUSIONS: The outcomes of patients with PCNSL treated in our cohort are still poor. In our series, surgical resection might play a role in significantly improving OS and PFS compared with stereotactic biopsy in a subset of patients. The type of surgery and tumour location are prognostic factors for PCNSL.

Late-onset acute disseminated encephalomyelitis followed by optic neuritis without anti-myelin oligodendrocyte glycoprotein antibodies: a biopsied case report.

BACKGROUND: Acute disseminated encephalomyelitis (ADEM) followed by optic neuritis (ADEM-ON) is characterized by the following features: early onset, monophasic or multiphasic ADEM followed by one or more episodes of ON, and the presence of serum anti-myelin oligodendrocyte glycoprotein (MOG) antibodies. CASE REPORT: We report a case of ADEM-ON without anti-MOG antibodies in a 78-year-old woman. The patient developed acute-onset neurological findings and was diagnosed with ADEM. She was treated with intravenous methylprednisolone (IVMP), and oral corticosteroids. Her clinical symptoms and MRI findings subsequently improved. Left optic neuritis emerged 6 months later, and we made a diagnosis of ADEM-ON. A brain biopsy performed during the acute phase of ADEM showed perivascular infiltration of macrophages with demyelination. CONCLUSION: The majority of the reported ADEM-ON cases are pediatric cases with serum anti-MOG antibodies, but our patient was the elderly, without anti-MOG antibodies. Moreover, the pathological features of our case were similar to those observed in patients with typical ADEM and in patients with anti-MOG antibody-positive ADEM. Although ADEM-ON is related to the presence of anti-MOG antibodies, factors other than anti-MOG antibodies could contribute to the development of ADEM-ON.

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.

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.