Next-generation agents for fluorescence-guided glioblastoma surgery.

Glioblastoma is a fast-growing and aggressive form of brain cancer. Even with maximal treatment, patients show a low median survival and are often subjected to a high recurrence incidence. The currently available treatments require multimodal management, including maximal safe surgical resection, followed by radiation and chemotherapy. Because of the infiltrative glioblastoma nature, intraoperative differentiation of cancer tissue from normal brain parenchyma is very challenging, and this accounts for the low rate of complete tumor resection. For these reasons, clinicians have increasingly used various intraoperative adjuncts to improve surgical results, such as fluorescent agents. However, most of the existing fluorophores show several limitations such as poor selectivity, photostability, photosensitization and high costs. This could limit their application to successfully improve glioblastoma resection. In the present perspective, we highlight the possibility to develop next-generation fluorescent tools able to more selectively label cancer cells during surgical resection.

Integrative approaches in spinal cord stimulation: Neuropathic pain management and motor recovery in spinal cord injury. A narrative review.

Introduction: Spinal cord stimulation is a widespread treatment of chronic neuropathic pain from different conditions. Several novel and improving technologies have been recently developed to increase the effect of neuromodulation in patients refractory to pharmacological therapy. Research question: To explore spinal cord stimulation's mechanisms of action, indications, and management. Material and methods: The paper initially explores the mechanism of action of this procedure based on the generation of an electric field between electrodes placed on the posterior dural surface of the spinal cord probably interfering with the transmission of pain stimuli to the brain. Subsequently, the most consolidated criteria for selecting patients for surgery, which constitute a major issue of debate, were defined. Thereafter, the fundamental patterns of stimulation were summarized by exploring the advantages and side effects. Lastly, the most common side effects and the related management were discussed. Results: Proper selection of the patient is of paramount importance to achieve the best results from this specific neuromodulation treatment. Regarding the different types of stimulation patterns, no definite evidence-based guidelines exist on the most appropriate approach in relation to the specific type of neuropathic pain. Both burst stimulation and high-frequency stimulation are innovative techniques that reduce the risk of paresthesias compared with conventional stimulation. Discussion and conclusion: Novel protocols of stimulation (burst stimulation and high frequency stimulation) may improve the trade-off between therapeutic benefits and potential side effects. Likewise, decreasing the rates of hardware-related complications will be also useful to increase the application of neuromodulation in clinical settings.

A High Respiratory Drive Is Associated with Weaning Failure in Patients with COVID-19-Associated Acute Respiratory Distress Syndrome: The Role of the Electrical Activity of the Diaphragm.

BACKGROUND: Mechanical ventilation is the main supportive treatment of severe cases of COVID-19-associated ARDS (C-ARDS). Weaning failure is common and associated with worse outcomes. We investigated the role of respiratory drive, assessed by monitoring the electrical activity of the diaphragm (EAdi), as a predictor of weaning failure. METHODS: Consecutive, mechanically ventilated patients admitted to the ICU for C-ARDS with difficult weaning were enrolled. Blood gas, ventilator, and respiratory mechanic parameters, as well as EAdi, were recorded at the time of placement of EAdi catheter, and then after 1, 2, 3, 7, and 10 days, and compared between patients with weaning success and weaning failure. RESULTS: Twenty patients were enrolled: age 66 (60-69); 85% males; PaO2/FiO2 at admission 148 (126-177) mmHg. Thirteen subjects (65%) were classified as having a successful weaning. A younger age (OR(95%CI): 0.02 (0.01-0.11) per year), a higher PaO2/FiO2 ratio (OR(95%CI): 1.10 (1.01-1.21) per mmHg), and a lower EAdi (OR(95%CI): 0.16 (0.08-0.34) per µV) were associated with weaning success. CONCLUSION: In critically ill patients with moderate-severe C-ARDS and difficult weaning from mechanical ventilation, a successful weaning was associated with a lower age, a higher oxygenation, and a lower respiratory drive, as assessed at the bedside via EAdi monitoring.

The Application of Sodium Fluorescein in Resection of Medulloblastoma Under YELLOW 560 Filter: Feasibility and Preliminary Results of a Monocentric Cohort and Systematic Review.

BACKGROUND: Maximizing surgical resection of medulloblastoma (MB) affects overall survival; nevertheless, surgical resection remains a because of the infiltrative behavior of this tumor. Several dyes have been tested for improving tumor visualization; however, few reports with different protocols of fluorophores use are available and the results are inconsistent. Hence, we report our experience with sodium fluorescein in MB surgery, aiming to assess the role of this technique on the extent of resection. Furthermore, we performed a literature review of this topic. METHODS: Fluorescence characteristics, extent of resection, and clinical outcome were analyzed in 9 consecutively operated patients with MB. A comprehensive literature search and review for English-language articles concerning fluorescein application in MB was conducted. RESULTS: In our cohort, no side effect related to fluorescein occurred; all tumors presented with an intense or moderate yellow-green enhancement, and fluorescein was judged fundamental in distinguishing tumors from viable tissue in 7 of 9 cases. Gross total resection or near-total resection (i.e., a residual tumor volume <1.5 cm3) was achieved in 8 patients. The review explored the different techniques and surgical interpretations as well as surgical radicality; we did not find a homogenous protocol for fluorescein injection in the published articles. Fluorescence appeared moderate or intense in almost all cases, with a high percentage of usefulness and consensual achievement of a high rate of gross total resection. CONCLUSIONS: Based on these results, we can infer that fluorescein-guided surgical resection is a safe and valuable method for patients with MB.

Small spheno-ethmoidal meningoencephalocele versus ethmoidal mucocele in spontaneous intracranial hypotension.

Background: Meningoencephalocele is defined as an abnormal sac of brain tissue and meninges extending beyond natural skull margins, often leading to cerebrospinal fluid (CSF) leakage. When this condition arises in the spheno-ethmoidal region, the diagnosis becomes more challenging as it can be mistaken for other nasal pathologies, such as mucocele. Research question: We show in this case report a non-congenital sphenoethmoidal meningoencephalocele causing rhinoliquoral fistula and spontaneous intracranial hypotension. Results: this 65-year-old woman presented with sporadic rhinoliquorrhoea associated with orthostatic headache, nausea and dizziness. Brain MRI revealed a small lesion of an ethmoidal sinus, which was successfully treated with endoscopic endonasal surgery. Histology confirmed the presence of meningoencephalic tissue positive for S100 protein on immunohistochemistry. Conclusions: When dealing with lesions of the paranasal sinuses in contact with the anterior skull base, rhinoliquorrhoea presence suggests meningoencephalocele. In dubious cases, a proper workup, including a thorough clinical history and neurological examination, specific imaging, and a direct search of CSF-like markers, is essential to support the differential diagnosis. In such cases, a transnasal endoscopic surgical approach is recommended to obtain a final histological diagnosis and to perform eventual dural plastic surgery.

What have we learned in fluorescein-guided resection of brain metastases? An update after 79 consecutive cases.

BACKGROUND: Cerebral metastasis (CM) is the most common malignancy affecting the brain. Individualized treatment of CM still represents a challenge for neuro-oncological teams: in patient eligible for surgery, complete tumor removal is the most relevant predictor of overall survival (OS) and neurological outcome. The development of surgical microscopes harboring specific filter able to elicit the fluorescent response from sodium fluorescein (SF) has facilitated fluorescein-guided microsurgery and the identification of pathological tumor tissue, especially at the tumor margins. In this study, we analyzed the effect of SF on the visualization and resection of a large monoinstitutional cohort of CM. METHODS: Surgical database of FLUOCERTUM study (Besta Institute, Milan, Italy) was retrospectively reviewed to find CM surgically removed with a fluorescein-guided technique from March 2016 to December 2022. SF was intravenously injected (5 mg/kg) immediately after induction of general anesthesia. Tumors were removed using a microsurgical technique with the YELLOW560 filter (Carl Zeiss Meditec, Oberkochen, Germany). In the most recent cases, biopsies at the tumor margins were performed to evaluate the ability of fluorescein to discriminate between fluorescent and nonfluorescent tissue at the lesion borders. RESULTS: Seventy-nine patients were included; most of them showed a bright, diffuse fluorescent staining that markedly enhanced tumor visibility; 11 melanomas presented a specific faint enhancement of the black pigmented central nodule with high fluorescence at tumor boundaries. Only in a minimal percentage of cases (N.=4-5.1%), fluorescein enhancement was tenuous, thus not providing a significant help during tumor resection. Altogether, in more than 90% of cases, SF was considered useful in the identification of tumoral tissue and in achieving a high rate of CM resection; thus, gross total resection was achieved in 96.2% (N.=76) of patients and in no case the detection of tumor remnants was an unexpected event. The resulted sensitivity and specificity of fluorescein in identifying tumor tissue at the tumor margin was 88.9% with a predictive positive value of 88.9%. No adverse event was registered during the postoperative course. CONCLUSIONS: The use of SF is a valuable method for safe fluorescence-guided tumor resection. Our data showed a positive effect of fluorescein-guided surgery on intraoperative visualization during resection of CM, suggesting a role in improving the extent of resection of these lesions.

Surgical Complexity and Complications: The Need for a Common Language.

BACKGROUND: Quality measurement and outcome assessment have recently caught an attention of the neurosurgical community, but lack of standardized definitions and methodology significantly complicates these tasks. OBJECTIVE: To identify a uniform definition of neurosurgical complications, to classify them according to etiology, and to evaluate them comprehensively in cases of intracranial tumor removal in order to establish a new, easy, and practical grading system capable of predicting the risk of postoperative clinical worsening of the patient condition. METHODS: A retrospective analysis was conducted on all elective surgeries directed at removal of intracranial tumor in the authors' institution during 2-year study period. All sociodemographic, clinical, and surgical factors were extracted from prospectively compiled comprehensive patient registry. Data on all complications, defined as any deviation from the ideal postoperative course occurring within 30 days of the procedure, were collected with consideration of the required treatment and etiology. A logistic regression model was created for identification of independent factors associated with worsening of the Karnofsky Performance Scale (KPS) score at discharge after surgery in comparison with preoperative period. For each identified statistically significant independent predictor of the postoperative worsening, corresponding score was defined, and grading system, subsequently named Milan Complexity Scale (MCS), was formed. RESULTS: Overall, 746 cases of surgeries for removal of intracranial tumor were analyzed. Postoperative complications of any kind were observed in 311 patients (41.7%). In 223 cases (29.9%), worsening of the KPS score at the time of discharge in comparison with preoperative period was noted. It was independently associated with 5 predictive factors-major brain vessel manipulation, surgery in the posterior fossa, cranial nerve manipulation, surgery in the eloquent area, tumor size >4 cm-which comprised MCS with a range of the total score from 0 to 8 (higher score indicates more complex clinical situations). Patients who demonstrated KPS worsening after surgery had significantly higher total MCS scores in comparison with individuals whose clinical status at discharge was improved or unchanged (3.24 ± 1.55 versus 1.47 ± 1.58; P < 0.001). CONCLUSION: It is reasonable to define neurosurgical complication as any deviation from the ideal postoperative course occurring within 30 days of the procedure. Suggested MCS allows for standardized assessment of surgical complexity before intervention and for estimating the risk of clinical worsening after removal of intracranial tumor. Collection of data on surgical complexity, occurrence of complications, and postoperative outcomes, using standardized prospectively maintained comprehensive patient registries seems very important for quality measurement and should be attained in all neurosurgical centers.

Fluorescein-guided resection of a left frontal pre-rolandic cerebral metastasis: how I do it.

BACKGROUND: Cerebral metastases (CM) are the most common intracranial tumors; several studies have underlined the fundamental role of neurosurgical lesion removal. METHOD: We describe the surgical resection of a left frontal single metastasis. We attempted to achieve a radical resection under the intraoperative guidance of fluorescein, with the aid of intraoperative neurological monitoring. This technique can be applied to each contrast enhancing, intra-axial, infiltrative lesion. CONCLUSION: Fluorescein-guided surgery is a valuable tool in CM surgery to increase the rate of resection; further prospective evaluation of the role of fluorescein in this field is in planning, aiming to study the prognostic impact.

Sporadic spinal psammomatous malignant melanotic nerve sheath tumor: A case report and literature review.

Background: Sporadic Spinal Psammomatous Malignant Melanotic Nerve Sheath Tumor (SSP-MMNST) is a rare subgroup of peripheral nerve sheath tumors arising along the spine. Only a few reports of SSP-MMNST have been described. In this paper, we review the literature on SSP-MMNST focusing on clinical, and diagnostic features, as well as investigating possible pathogenetic mechanisms to better implement therapeutic strategies. We also report an illustrative case of a young female presenting with cervicobrachial pain due to two SSP-MMNSTs arising from C5-6 right spinal roots. Case description: We report a case of a 28-year-old woman presenting with right arm weakness and dysesthesia. Clinical examination and neuroimaging were performed, and, following surgical removal of both lesions, a histological diagnosis of SSP-MMNST was obtained. Results: The literature review identified 21 eligible studies assessing 23 patients with SSP-MMNST, with a mean onset age of 41 years and a slight male gender preference. The lumbar district was the most involved spinal segment. Gross-total resection (GTR) was the treatment of choice in all amenable cases, followed in selected cases with residual tumor by adjuvant radiotherapy or chemotherapy. The metastatic and recurrence rates were 31.58% and 36.8%, respectively. Conclusion: Differently from common schwannomas, MMNST represents a rare disease with known recurrence and metastatization propensity. As reported in our review, SSP-MMNST has a greater recurrence rate when compared to other forms of spinal MMNST, raising questions about the greater aggressiveness of the former. We also found that residual disease is related to a higher risk of systemic disease spreading. This metastatic potential, usually associated with primary lumbar localization, is characterized by a slight male prevalence. Indeed, whenever GTR is unachievable, considering the higher recurrence rate, adjuvant radiation therapy should be taken into consideration.

Towards a common language in neurosurgical outcome evaluation: the NEON (NEurosurgical Outcome Network) proposal.

BACKGROUND: The aim of this study was to achieve a consensus on the minimum set of outcome measures and predictors to be used in the neurosurgical practice and on the timing of outcome assessment. METHODS: A consensus building approach was employed. All neurosurgical departments in Lombardy (Italy) were invited to participate by the Carlo Besta Neurologic Institute IRCCS Foundation. Three workshops were organized during which a multidisciplinary group called Neurosurgical Outcome Network (NEON) was created and the methodology to select outcome measures, predictors, and timing of outcome assessment was established. Eight working groups were created for the different neurosurgical diseases (neuro-oncological, skull base, vascular, traumatic, spinal, peripheral nervous system, malformation, functional) and 8 workshops were organized to identify the outcome measures and predictors specific for each of the neurosurgical diseases based on the experts' clinical practice and the existing literature. RESULTS: A total of 20 neurosurgical departments participated in this study. Specific outcome measures, predictors and the timing of outcome assessment were identified for each of the 8 neurosurgical diseases. Moreover, a list of variables common to all pathologies were identified by the NEON group as further data to be collected. CONCLUSIONS: A consensus on the minimum set of outcome measures and predictors and the timing of outcome assessments for 8 neurosurgical diseases was achieved by a group of neurosurgeons of the Lombardy region, called NEON. These sets could be used in future studies for a more homogeneous data collection and as a starting point to reach further agreement also at national and international level.

Are Thalamic Intrinsic Lesions Operable? No-Man's Land Revisited by the Analysis of a Large Retrospective, Mono-Institutional, Cohort.

Thalamic gliomas represent a heterogeneous subset of deep-seated lesions for which surgical removal is advocated, although clear prognostic factors linked to advantages in performance status or overall survival are still lacking. We reviewed our Institutional Cancer Registry, identifying patients who underwent surgery for thalamic gliomas between 2006 and 2020. Associations between possible prognostic factors such as tumor volume, grade, the extent of resection and performance status (PS), and overall survival (OS) were evaluated using univariate and multivariate survival analyses. We found 56 patients: 31 underwent surgery, and 25 underwent biopsy. Compared to biopsy, surgery resulted positively associated with an increase in the OS (hazard ratio, HR, at multivariate analysis 0.30, 95% confidence interval, CI, 0.12-0.75). Considering the extent of resection (EOR), obtaining GTR/STR appeared to offer an OS advantage in high-grade gliomas (HGG) patients submitted to surgical resection if compared to biopsy, although we did not find statistical significance at multivariate analysis (HR 0.53, 95% CI 0.17-1.59). Patients with a stable 3-month KPS after surgery demonstrated to have a better prognosis in terms of OS if compared to biopsy (multivariate HR 0.17, 95% CI, 0.05-0.59). Age and histological grades were found to be prognostic factors for this condition (p = 0.04 and p = 0.004, respectively, chi-square test). Considering the entire cohort, p53 positivity (univariate HR 2.21, 95% CI 1.01-4.82) and ATRX positivity (univariate HR 2.69, 95% CI 0.92-7.83) resulted associated with a worse prognosis in terms of OS. In this work, we demonstrated that surgery aimed at tumor resection might offer a stronger survival advantage when a stable 3-month KPS after surgery is achieved.

The role of sodium fluorescein in pediatric supratentorial intra-axial tumor resection: new insights from a monocentric series of 33 consecutive patients.

INTRODUCTION: Surgical resection represents the mainstay of treatment, in pediatric central nervous system (CNS) tumors, and aggressive resection correlates with prognosis for several histotypes. Sodium fluorescein (SF), a green, water-soluble dye, is used as neurosurgical fluorescent tracer thanks to its property to accumulate in cerebral regions of blood-brain barrier disruption, acting as a valid tool to improve the extent of resection in tumors enhancing at preoperative MRI. Brain neoplasms represent a heterogeneous group of tumors in the pediatric age, constituting the most common solid cancers; they typically show a varying degree of contrast enhancement on MRI. MATERIALS AND METHODS: In March 2016, the authors started a prospective, observational trial to evaluate intraoperative fluorescence's characteristics of CNS tumors, the percentage of extent of resection, thanks to fluorescein aid, and side effects related to fluorescein administration. This report is based on a retrospective analysis of a group of 33 consecutive pediatric patients harboring a supratentorial lesion. RESULTS: In 17 of 33 (51.5%) procedures, fluorescence was reported as intense; in 14 of 33 (42.4%), moderate; and in 2 of 33 (6.1%), slight. Intraoperative fluorescence corresponds to preoperative-MRI-documented contrast enhancement. In 28 of 33 (84.8%) surgical procedures, SF was considered useful; in 2 of 33 (6.1%), partial useful; and in 3 of 33 (9.1%), not essential because the tumor was already recognizable. No adverse effect to SF administration was registered. CONCLUSION: Fluorescein-guided surgery with a dedicated filter on the microscope is a safe and effective technique to improve visualization and resection of different pediatric brain tumors.

A new study protocol for in-vivo assessment of tumor diagnosis and microscopic tumor infiltration at the resection cavity in central nervous system tumors by a new miniature confocal endomicroscope (CONVIVO system).

BACKGROUND: Confocal laser technology has been recently suggested as a promising method to obtain near real-time intraoperative histological data. We recently demonstrated the accuracy of a newly designed confocal endomiscroscope (CONVIVO) in offering an intraoperative diagnosis during high-grade gliomas (HGGs) removal in an ex vivo study. With this work we aim to perform a standardized, prospective and blinded-to-histological section study for evaluating the potentiality of CONVIVO in offering in-vivo data regarding histological diagnosis and presence of tumor at margins during resection of central nervous system (CNS) tumors. METHODS: This prospective, observational, standardized, blinded-to-histological section, clinical trial was approved by the institutional review board in Carlo Besta Neurologic Institute IRCCS Foundation in Milan and is expected to last 24 months. 75 patients will be included, with at least 53 of them being HGGs based on the statistical sample size calculation. Main objectives will be the assessing of the concordance of tumor diagnoses between CONVIVO images and frozen section at the center of all tumor subtypes and the evaluation of the accuracy of CONVIVO in the identification of tumor tissue at the margins, compared to standard histology. For this purpose, "virtual biopsies" and physical biopsies will be performed directly on patient tumor tissue and surrounding brain parenchima during tumor resection, comparing the results of CONVIVO analysis and frozen and histological sections. RESULTS: Despite promising preliminary data on ex vivo usefulness of CLE machines are emerging in literature, still few studies are available when looking at in vivo potentiality of CONVIVO. At this regard, this study will be the first work where a standardized, prospective, and blinded-to-histological section CONVIVO analysis will be performed in an in-vivo setting in neuro-oncological surgery. CONCLUSIONS: We hypothesize that this new technique may have a role in offering data regarding presence of tumor tissue, eventually giving an intraoperative diagnosis in neuro-oncological surgery, rendering more fluid the decision-making process in the operating room. Furthermore, the result of this study will provide a solid base for further expanding the clinical applications of confocal machines in neurosurgery.

Fluorescein sodium in the surgical treatment of pleomorphic xanthoastrocytomas: Results from a retrospective study.

Objective: Pleomorphic xanthoastrocytoma (PXA) is a rare brain tumor, most commonly affecting children and young adults. Surgical resection represents the mainstay of treatment, and extent of resection is associated with improved survival. In this study, we analyzed the role of sodium fluorescein (SF) in improving intraoperative visualization easing resection. Methods: Surgical database of FLUOCERTUM study (Besta Institute, Milan, Italy) was retrospectively reviewed to find pleomorphic xanthoastrocytomas and anaplastic xanthoastrocytomas, according to WHO-2016/2021 classification, surgically removed by a fluorescein-guided technique from March 2016 to February 2022. SF was intravenously injected (5mg/kg) immediately after induction of general anesthesia. Tumors were removed using a microsurgical technique with the YELLOW 560 filter (Carl Zeiss Meditec, Oberkochen, Germany). Results: Twelve patients (7 males and 5 females; 3 pediatric patients, mean age 10 years, range 5 to 13 years and 9 adult patients, mean age 50.6 years, range 35 to 63 years) underwent fluorescein-guided surgery. No side effects related to SF occurred. In all tumors, contrast enhancement on preoperative MRI correlated with intense, heterogeneous yellow fluorescence with bright fluorescent cystic fluid. Fluorescein was considered helpful in distinguishing tumors from viable tissue in all cases. Gross total resection was achieved in 8 cases (66.7%); in 4 cases, otherwise, the resection was subtotal with fluorescent residual spots to avoid neurological worsening (33.3%). Conclusions: The use of SF is a valuable method for safe fluorescence-guided tumor resection. Our data documented a positive effect of fluorescein-guided surgery on intraoperative visualization, suggesting a probable role in improving the extent of resection during yellow surgery of PXA.

Sporadic and von Hippel-Lindau Related Hemangioblastomas of Brain and Spinal Cord: Multimodal Imaging for Intraoperative Strategy.

Hemangioblastomas (HBs) are rare, benign tumors often related to von Hippel-Lindau disease. They represent the most frequent primary cerebellar tumors in adults. Neurosurgical procedures aim to obtain a gross-total resection of tumor nodules, avoiding intra-postoperative hemorrhage. The introduction of new intraoperative imaging techniques has considerably changed surgical strategies in neuro-oncology. We present an overview of clinical and radiological data of a mono-institutional retrospective cohort, focusing on the role of intraoperative multimodal imaging in surgical strategy. From 2015 to 2021, we identified 64 (81%) cranial (42 cerebellar, 8 supratentorial, and 14 of the brainstem) HBs and 15 (19%) spinal (4 cervical and 11 dorsal) HBs in 79 patients. Intraoperatively, indocyanine green videoangiography with FLOW800 was used in 62 cases (52 cranial and 10 spinal), intraoperative ultrasound and contrast-enhanced ultrasounds in 22 cases (18 cranial and 4 spinal HBs), and fluorescein in 10 cases (in 6 cranial and 2 spinal cases used as SF-VA). Gross total resection was achieved in 100% of the cases (53 mural nodule removal and 26 complete resections of the solid tumor). No side effects were reported following the combination of these tools. Multimodal intraoperative techniques provide valuable and reliable information to identify the tumor and its vasculature, guiding a more precise and safer resection and reducing the risk of recurrence.

The Role of Bypass Surgery for the Management of Complex Intracranial Aneurysms in the Anterior Circulation in the Flow-Diverter Era: A Single-Center Series.

Despite the increasing popularity of flow diverters (FDs) as an endovascular option for intracranial aneurysms, the treatment of complex aneurysms still represents a challenge. Combined strategies using a flow-preservation bypass could be considered in selected cases. In this study, we retrospectively reviewed our series of patients with complex intracranial aneurysms submitted to bypass. From January 2015 to May 2022, 23 patients were selected. We identified 11 cases (47.8%) of MCA, 6 cases (26.1%) of ACA and 6 cases (26.1%) of ICA aneurysms. The mean maximal diameter was 22.73 ± 12.16 mm, 8 were considered as giant, 9 were fusiform, 8 presented intraluminal thrombosis, 10 presented wall calcification, and 18 involved major branches or perforating arteries. Twenty-five bypass procedures were performed in 23 patients (two EC-IC bypasses with radial artery graft, seventeen single- or double-barrel STA-MCA bypasses and six IC-IC bypasses in anterior cerebral arteries). The long-term bypass patency rate was 94.5%, and the total aneurysm exclusion was 95.6%, with a mean follow-up of 28 months. Median KPS values at last follow-up was 90, and a favorable outcome (KPS ≥ 70 and mRS ≤ 2) was obtained in 87% of the cases. The use of bypass techniques represents, in selected cases, a valid therapeutic option in the management of complex anterior circulation aneurysms when a simpler direct approach, including the use of FD, is considered not feasible.

Fluorescein-guided surgery for the resection of pilocytic astrocytomas: A multicentric retrospective study.

Objective: Pilocytic astrocytomas (PAs) are relatively benign tumors, usually enhancing on post-contrast MRI and often characterized by a mural nodule within a cystic component. Surgical resection represents the mainstay of treatment, and extent of resection (EOR) is associated with improved survival. In this study, we analyzed the effect of sodium fluorescein (SF) on the visualization and resection of these circumscribed astrocytic gliomas. Methods: Surgical databases at two neurosurgical departments (Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy and Department of Neurosurgery, University Medical Center Regensburg, Regensburg, Germany) were retrospectively reviewed to identify the cohort of patients with pilocytic astrocytoma who had undergone fluorescein-guided tumor resection at any of the centers between March 2016 and February 2022. SF was intravenously injected (5 mg/kg) immediately after the induction of general anesthesia. Tumors were removed using a microsurgical technique with the YELLOW 560 filter (Carl Zeiss Meditec, Oberkochen, Germany). Results: Forty-four patients (25 males and 19 females; 26 pediatric patients, mean age of 9.77 years, range 2 to 17 years; and 18 adult patients, mean age of 34.39 years, range 18 to 58 years) underwent fluorescein-guided surgery. No side effects related to SF occurred. In all tumors, contrast enhancement on preoperative MRI was correlated with intense, heterogeneous yellow fluorescence with bright fluorescent cystic fluid. Fluorescein was considered helpful in distinguishing tumors from viable tissue in all cases except three patients due to faint fluorescein enhancement. Biopsy was intended in two operations, and partial resection was intended in three operations. Gross total resection was achieved in 24 cases out of 39 patients scheduled for tumor removal (61.54%), in five cases a minimal residual volume was highlighted by postoperative MRI despite the intraoperative subjective evaluation of complete tumor removal (12.82%); in the other 10 cases, the resection was subtotal with fluorescent residual spots to avoid neurological worsening (25.64%). Conclusions: The use of SF is a valuable method for safe fluorescence-guided tumor resection. Our data showed a positive effect of fluorescein-guided surgery on intraoperative visualization during resection of Pas, suggesting a possible role in improving the extent of resection of these lesions.