Blood based metabolic markers of glioma from pre-diagnosis to surgery.

Gliomas are highly complex and metabolically active brain tumors associated with poor prognosis. Recent reports have found altered levels of blood metabolites during early tumor development, suggesting that tumor development could be detected several years before clinical manifestation. In this study, we performed metabolite analyses of blood samples collected from healthy controls and future glioma patients, up to eight years before glioma diagnosis, and on the day of glioma surgery. We discovered that metabolites related to early glioma development were associated with an increased energy turnover, as highlighted by elevated levels of TCA-related metabolites such as fumarate, malate, lactate and pyruvate in pre-diagnostic cases. We also found that metabolites related to glioma progression at surgery were primarily high levels of amino acids and metabolites of amino acid catabolism, with elevated levels of 11 amino acids and two branched-chain alpha-ketoacids, ketoleucine and ketoisoleucine. High amino acid turnover in glioma tumor tissue is currently utilized for PET imaging, diagnosis and delineation of tumor margins. By examining blood-based metabolic progression patterns towards disease onset, we demonstrate that this high amino acid turnover is also detectable in a simple blood sample. These findings provide additional insight of metabolic alterations during glioma development and progression.

"Apathetic look" is a valuable indicator of intraoperative supplementary motor area syndrome during awake craniotomy.

Resection of a glioma from the dorsomedial frontal lobe, including the supplementary motor area (SMA), can result in postoperative SMA syndrome. SMA syndrome may occur during awake craniotomies. However, it is often difficult to intraoperatively distinguish between motor dysfunction due to pyramidal tract damage from that due to SMA syndrome. Patients with suspected intraoperative SMA syndrome are indifferent to their surroundings, have stiff facial muscles, and maintain a fixed gaze. We defined this condition as "apathetic look." The present study aimed to investigate whether intraoperative "apathetic look" is useful for identifying intraoperative SMA syndrome in patients with glioma close to motor-related areas, including the SMA, during awake craniotomy. This study included 33 consecutive patients with glioma included in the SMA. We excluded patients whose tumors extended to motor-related areas. We also assessed whether intraoperative SMA syndrome occurred in each patient. We evaluated the correlation between the occurrence of intraoperative SMA syndrome and various clinical factors, including intraoperative "apathetic look." Of the 33 patients, 12 had intraoperative SMA syndrome. Intraoperative "apathetic look" showed strong correlation with intraoperative SMA syndrome (p < 0.0001). Additionally, higher extent of resection (EOR) and resection of the corpus callosum showed a significantly higher incidence of intraoperative "apathetic look." All 12 patients with intraoperative SMA syndrome showed intraoperative "apathetic look" and recovered from SMA syndrome with high EOR. In conclusion, intraoperative "apathetic look" shows strong correlation with intraoperative SMA syndrome. Therefore, "apathetic look" may be a valuable indicator of intraoperative SMA syndrome during awake craniotomy.

AB004. Transsylvian approach for radical resection of insular gliomas: emphasizing the importance of the transsylvian approach for elderly patients with Zone II and III insular gliomas.

BACKGROUND: Insular gliomas present significant challenges due to their deep-seated location and proximity to critical structures, including sylvian veins, middle cerebral arteries (MCAs), lenticulostriate arteries, long insular arteries, and functional cortices and white matter tracts. The Berger-Sanai classification categorizes them into four zones (I-IV), providing a framework for understanding insular gliomas. The key factors for successful insular glioma removal are achieving the greatest insular exposure and surgical freedom. There are two main types of approach methods, such as transsylvian approach with meticulous wider dissection of the sylvian fissure and transcorticosubcortical approach with intraoperative functional brain mapping under awake surgery to remove the functionally silent cortices and white matter tracts. Because splitting the distal sylvian fissure is more challenging, a transcortical approach through the parietorolandic operculum in awake patients has been reported to be more effective access to the posterior insular gliomas (Zone II and III) in the dominant hemisphere. The object of this study emphasize the importance of the transsylvian approach for radical resection of insular gliomas. METHODS: We retrospectively analyzed our experiences with radically resected insulo-opercular gliomas. Basically, we pursue the transsylvian approach for resecting insular gliomas without removal of any normal brain. RESULTS: Motor pathways running beneath the parietorolandic operculum can be damaged by ischemia caused by sacrificing the medullary arteries (MAs) arising from the pial arteries of the M3 and M4 portions of the MCA. Motor deficit after resection of this area was significantly found in the elderly patients. This phenomenon might be described by the age-associated decreasing the vascular reserve capacity. Autopsy brains showed that the sclerotic rate of the MAs increased with age and hypertension. Even with the intraoperative functional brain mapping, we cannot avoid the ischemic complication caused by sacrificing the MAs during stepwise removal of the functionally silent cortices and white matter tracts. CONCLUSIONS: We make a suggestion not to remove the parietorolandic operculum in elderly patients with insular gliomas located at Zone II and III. Distal transsylvian approach should be applied.

AB025. Efficacy of 5-ALA brightness analysis for malignant brain tumor surgery.

BACKGROUND: For fluorescence-guided neurosurgery, 5-aminolevulinic acid (5-ALA) is widely used for intraoperative tumor visualization. We quantified the brightness of 5-ALA by Image J and report the pathological results of glioma, and non-tumor lesions. METHODS: From 2019 to 2023, we investigated 27 high-grade glioma patients who underwent surgery with 5-ALA. Twenty-three cases of glioblastoma (GBM) and four cases of anaplastic astrocytoma (AA) were examined. The pathological diagnosis was based on the classification of World Health Organization (WHO) 2016. The 5-ALA was administered before surgery, and the 5-ALA brightness was quantified. Other than high-grade glioma, four low-grade gliomas (LGGs), two radiation necrosis, and one inflammation patients were evaluated by Image J. RESULTS: In GBM, the mean brightness was 134.5±65.4, except for one negative case. AA showed the mean brightness with 180.5±51.6. All LGGs showed negative in the brightness. In two radiation necrosis cases, the mean brightness was 139.5±37.4. In one inflammatory case, the brightness was 239, but after the lesion removed, the adjacent brain parenchyma showed bright, and the border was not clear. In one GBM case, the ventricle was opened, and the brightness difference between the tumor and the ventricular wall was observed. CONCLUSIONS: 5-ALA brightness analysis by Image J would be helpful to distinguish between malignant glioma and LGG, and other non-tumor lesions to support rapid pathological diagnosis. Also, it would be useful to distinguish between the tumor and the ventricle wall. As for radiation necrosis and inflammation, border of the lesion is unclear.

AB073. Electrocorticography high-gamma dynamics during intraoperative hand movement mapping.

BACKGROUND: Intraoperative functional mapping for glioma resection often necessitates awake craniotomies, requiring active patient participation. This procedure presents challenges for both the surgical team and the patient. Thus, minimizing mapping time becomes crucial. Passive mapping utilizing electrocorticography (ECoG) presents a promising approach to reduce intraoperative mapping efforts via direct electrical stimulation. This study aims to identify an efficient mapping protocol for hand movement by optimizing mapping duration and localization accuracy. METHODS: Three glioma patients (two males, one female) underwent awake craniotomy for tumor resection at Asahikawa Medical University Hospital and Kindai University in Osaka. Patients were maintained at a bispectral index (BIS) level above 90 to ensure wakefulness during mapping. Data were collected using a DC-coupled g.HIamp biosignal amplifier, digitized with 24-bit resolution at a minimum sampling rate of 1,200 Hz. Each session comprised ten runs, each lasting 250 seconds, consisting of a 12-second rest phase (baseline) followed by a 12-second grasping period containing ten grasping movements. High-gamma activity (HGA, 60-170 Hz) was recorded from ECoG locations on the pre- and postcentral gyrus. Locations exhibiting significant grasping-related HGA, with stronger responses during early trials within a run, were classified as "attenuated". RESULTS: Among 37 electrodes on the sensorimotor cortex, 16 exhibited significant HGA during grasping. Three locations demonstrated significant attenuation after three runs, with one location showing attenuation after the first three trials within a run. CONCLUSIONS: The observed attenuation effect of short-term repeated movements during intraoperative monitoring is relatively modest initially. However, as the number of repeated grasping blocks increases, the number of attenuated locations also rises. Consequently, minimizing overall mapping time, rather than reducing the number of tasks per block, is paramount. For statistical analysis, a minimum of 20 grasping trials (two runs of ten movements) or 48 seconds of motor mapping is recommended. Alternatively, a mapping protocol involving a third run or 30 grasping trials (72 seconds) may enhance data robustness. These preliminary findings, though based on a limited patient cohort, warrant confirmation and further investigation, particularly in epilepsy patients.

AB083. Epilepsy and low-grade glioma-seizure control after surgical resection: a retrospective cohort study.

BACKGROUND: Seizures are a common manifestation in patients with low grade glioma (60-75%), and 60-90% patients attain seizure freedom after resection. Seizure control varies with histopathology, extent of resection and type of seizures. There is inconsistency in literature regarding utility of anti-epileptic drugs (AEDs) after tumor resection. We aimed to determine factors associated with seizure control in patients after low-grade glioma (LGG) resection. METHODS: It was a retrospective cohort study. Medical record of all patients who underwent LGG resection at our center from 2019 to 2021 were reviewed; 77 patients fulfilled the selection criteria. Patients were also contacted via phone calls to collect information about their seizure control as per Engel Classification. Data was analyzed using SPSSv21. RESULTS: The mean age was 34.9±11.3 years, and there was male predominance (62; 80.5%). Generalized seizures were the most common type (54; 70%), and Levetiracetam was the most commonly prescribed AED (60; 77.9%). The median duration of pre-operative AED use was 4 [interquartile range (IQR): 1-24] months. Frontal lobe was the most common location of tumor (36; 46.8%). Most of the patients had their surgery under general anesthesia (51; 61.4%), while 29 (37.7%) underwent awake craniotomy. Nearly half of the patients had a gross total resection (31; 40.3%), and another 15 (19.5%) had near-total resection. Sixteen patients (20.8%) had their AEDs stopped within first 6 months post-operatively (at variable intervals), and all of them had Engel Class IA to ID control at time of follow-up (P=0.008). The 12 patients with grade I glioma also had optimum seizure control (P=0.03). CONCLUSIONS: Patients with grade I glioma have better seizure control after surgery. Tumor biopsy is associated with worse seizure outcome, though not statistically significant. Larger studies are needed to determine the ideal time and patient group for discontinuing AED after surgery.

Awake Surgery for Right Frontal Lobe Glioma: Preserving Emotional Recognition and Facilitating Early Return to Work.

BACKGROUND/AIM: Many glioma patients struggle to return to work after surgery because of higher brain dysfunction. Although the right frontal lobe has historically been considered functionally silent, reports of performing awake surgery to evaluate higher brain functions in patients with tumors in this area have increased. We present two cases of patients who underwent awake surgery for malignant glioma in the right frontal lobe to preserve emotional recognition and facilitate an early return to work. CASE REPORT: Case 1 was a 48-year-old right-handed woman employed as a nursery school teacher and case 2 was a 21-year-old right-handed man employed in sales. Both had contrast-enhancing right frontal lobe tumors exhibiting high signal intensity on fluid attenuated inversion recovery imaging and underwent awake surgery. During the operation, cortical mapping was performed using the Reading the Mind in the Eyes, calculation, and motor tasks. Resection of sites involved in motor and emotional recognition functions was avoided. In case 1, all regions of high signal intensity were completely resected; in case 2, all regions exhibiting enhancement were resected. Both patients were discharged home without neurological deficits and returned to work within 21 days after surgery. CONCLUSION: It may be important to focus not only on overall survival and progression-free survival in glioma patients, but also on factors associated with life satisfaction, such as time to return to work after surgery and time until work becomes difficult. Awake surgery aimed at preserving higher brain functions is useful and may also improve life satisfaction.

Impact of Microsurgery and Postoperative Radiotherapy on Neurological Function in Intramedullary Spinal Cord Gliomas.

OBJECTIVE: To assess the clinical efficacy of combined microsurgery and postoperative radiotherapy for the treatment of intramedullary spinal gliomas and its impact on neurological function. STUDY DESIGN: An observational study. Place and Duration of the Study: Department of Neurosurgery, Baoding No.1 Central Hospital, Hebei, China, between January 2020 and 2023. METHODOLOGY: Sixty patients diagnosed with spinal cord intramedullary gliomas were divided equally into an experimental and control group. The control group received microsurgical treatment, and the experimental group received microsurgical treatment combined with postoperative radiotherapy. The treatment effectiveness, neurological function, and follow-up results of the two groups were compared. RESULTS: After treatment, the clinical efficacy of the experimental group treatment was significantly better than that of the control group (p <0.05). The National Institutes of Health Stroke Scale (NIHSS) scores were significantly lower, and the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire-30 (EORTC QLQ-C30) scores were significantly higher in the experimental group than in the control group (p <0.05). The 1-3-year survival rate and median survival time of the experimental group were significantly higher than those of the control group (p <0.05). The incidence of complications was 3.33% in the experimental group and 6.67% in the control group, but the difference was not statistically significant (p >0.05). The postoperative recurrence rate was significantly lower in the experimental (0%) than in the control group (13.33%, p <0.05). CONCLUSION: Combined microsurgery and postoperative radiotherapy was found to be more effective than microsurgery alone. It was also more conducive to the recovery of neurological function and improved the patient's quality of life. KEY WORDS: Intramedullary spinal cord glioma, Microsurgery, Neurological function, Radiotherapy.

MR-guided focused ultrasound in pediatric neurosurgery: current insights, technical challenges, and lessons learned from 45 treatments at Children's National Hospital.

OBJECTIVE: MR-guided focused ultrasound (MRgFUS) is an evolving technology with numerous present and potential applications in pediatric neurosurgery. The aim of this study was to describe the use of MRgFUS, technical challenges, complications, and lessons learned at a single children's hospital. METHODS: A retrospective analysis was performed of a prospectively collected database of all pediatric patients undergoing investigational use of MRgFUS for treatment of various neurosurgical pathologies at Children's National Hospital. Treatment details, clinical workflow, and standard operating procedures are described. Patient demographics, procedure duration, and complications were obtained through a chart review of anesthesia and operative reports. RESULTS: In total, 45 MRgFUS procedures were performed on 14 patients for treatment of diffuse intrinsic pontine glioma (n = 12), low-grade glioma (n = 1), or secondary dystonia (n = 1) between January 2022 and April 2024. The mean age at treatment was 9 (range 5-22) years, and 64% of the patients were male. With increased experience, the total anesthesia time, sonication time, and change in core body temperature during treatment all significantly decreased. Complications affected 4.4% of patients, including 1 case of scalp edema and 1 patient with a postprocedure epidural hematoma. Device malfunction requiring abortion of the procedure occurred in 1 case (2.2%). Technical challenges related to transducer malfunction and sonication errors occurred in 6.7% and 11.1% of cases, respectively, all overcome by subsequent user modifications. CONCLUSIONS: The authors describe the largest series on MRgFUS technical aspects in pediatric neurosurgery at a single institution, comprising 45 total treatments. This study emphasizes potential technical challenges and provides valuable insights into the nuances of its application in pediatric patients.

A nomogram with Ki-67 in the prediction of postoperative recurrence and death for glioma.

This study examined to evaluate the predictive value of a nomogram with Ki-67 in overall and disease-free survival in glioma patients, a total of 76 patients diagnosed with glioma by pathology in Tengzhou Central People's Hospital were enrolled. The baseline data and follow ups were retrospectively collected from medical records. The associations between Ki-67 and survival status were examined using log-rank test, univariate and multivariate Cox proportional hazard regression models. Calibrations were performed to validate the established nomograms. Ki-67 negative group showed of a longer OS survival time and a longer PFS survival time with log-rank test (x2 = 16.101, P < 0.001 and x2 = 16.961, P < 0.001). Age older than 50 years (HR = 2.074, 95% CI 1.097-3.923), abnormal treatment (HR = 2.932, 95% CI 1.343-6.403) and Ki-67 positive (HR = 2.722, 95% CI 1.097-6.755) were the independent predictive factors of death. High grade pathology (HR = 2.453, 95% CI 1.010-5.956) and Ki-67 positive (HR = 2.200, 95% CI 1.043-4.639) were the independent predictive factors of recurrence. The C-index for the nomogram of OS and PFS were 0.745 and 0.723, respectively. The calibration results showed that the nomogram could predict the overall and disease-free 1-year survival of glioma patients. In conclusion, the nomograms with Ki-67 as independent risk factor for OS and PFS could provide clinical consultation in the treatment and follow-up of malignant glioma.

Time series analysis combined with transcriptome sequencing to explore characteristic genes and potential molecular mechanisms associated with ultrasound-guided microwave ablation of glioma.

OBJECTIVE: This study aimed to explore marker genes and their potential molecular mechanisms involved in US-guided MWA for glioma in mice. METHOD: The differentially expressed genes (DEGs1 and DEGs2) and lncRNAs (DELs1 and DELs2) were obtained between Non (glioma tissues without MWA) and T0 groups (0h after MWA), as well as between Non and T24 groups (24h after MWA). The down-regulation cluster genes (CONDOWNDEGs) and upregulation cluster genes (CONUPDEGs) were identified by time series analysis. Candidate genes were obtained by overlapping CONDOWNDEGs with downregulation DEGs (DOWNDEGs)1 and DOWNDEGs2, as well as CONUPDEGs with up-regulation DEGs (UPDEGs)1 and UPDEGs2. The expressions of immune checkpoints and inflammatory factors, gene set enrichment analysis (GSEA), and protein subcellular localization were performed. The eXpression2Kinases (X2K), GeneMANIA, transcription factor (TF), and competing endogenous (ce) RNA regulatory networks were conducted. The expression of marker genes was validated by quantitative real-time polymerase chain reaction (qRT-PCR). RESULTS: Five marker genes (IL32, VCAM1, IL34, NFKB1 and CXCL13) were identified, which were connected with immune-related functions. Two immune checkpoints (CD96 and TIGIT) and six inflammatory factors played key roles in US-guided MWA for glioma. ceRNA regulatory networks revealed that miR-625-5p, miR-625-3p, miR-31-5p and miR-671-5p were associated with target genes. qRT-PCR indicated both IL32, VCAM1, and NFKB1 were potential markers under US-guided MWA-related time series analysis. CONCLUSION: The use of US-guided MWA might be a practical method for influencing the function of target genes, regulating time frames to decrease inflammation, and stimulating immune responses in glioma therapy.

Visualization of Brain Tumors with Infrared-Labeled Aptamers for Fluorescence-Guided Surgery.

Gliomas remain challenging brain tumors to treat due to their infiltrative nature. Accurately identifying tumor boundaries during surgery is crucial for successful resection. This study introduces an innovative intraoperative visualization method utilizing surgical fluorescence microscopy to precisely locate tumor cell dissemination. Here, the focus is on the development of a novel contrasting agent (IR-Glint) for intraoperative visualization of human glial tumors comprising infrared-labeled Glint aptamers. The specificity of IR-Glint is assessed using flow cytometry and microscopy on primary cell cultures. In vivo effectiveness is studied on mouse and rabbit models, employing orthotopic xenotransplantation of human brain gliomas with various imaging techniques, including PET/CT, in vivo fluorescence visualization, confocal laser scanning, and surgical microscopy. The experiments validate the potential of IR-Glint for the intraoperative visualization of gliomas using infrared imaging. IR-Glint penetrates the blood-brain barrier and can be used for both intravenous and surface applications, allowing clear visualization of the tumor. The surface application directly to the brain reduces the dosage required and mitigates potential toxic effects on the patient. The research shows the potential of infrared dye-labeled aptamers for accurately visualizing glial tumors during brain surgery. This novel aptamer-assisted fluorescence-guided surgery (AptaFGS) may pave the way for future advancements in the field of neurosurgery.

What Happens to Serum Levels of Visinin-Like Protein-1, Caveolin-1 and Neuron-Specific Enolase after Supratentorial Glioma Resection: A Pilot Study.

AIM: To observe changes in the serum levels of visinin-like protein-1 (VILIP-1), caveolin-1 (Cav-1) and neuron-specific enolase (NSE) after glioma resection. MATERIAL AND METHODS: Consecutive 14 glioma patients with different histologic grade and 14 age and gender-matched healthy subjects were included in this pilot study. From the patients serum samples were taken in preoperative and on day 2 and 10 of postoperative periods. Healthy subjects provided serum sample once. The serum changes of three proteins were evaluated by ELISA. The results were compared between preoperative and postoperative periods and between patients and controls. RESULTS: Preoperative serum levels of VILIP-1 (p=0.008) and Cav-1 (p=0.012) were significantly higher in the patients. Mean serum levels of VILIP-1 (p=0.002) and Cav-1 (p=0.013) again were significantly higher than those of the controls. NSE did not show significant changes compared to controls in none of the periods. There was a steady decline regarding all three molecules from preoperative to postoperative day 10. However, statistical comparisons did not reveal any significant difference with respect the decline in any molecule. Significant positive correlation was detected between preoperative serum levels of VILIP-1 and Cav-1 (p=0.00001) in the patients and the controls (p=0.0000). CONCLUSION: This pilot study suggested that Cav-1 and particularly VILIP-1 may be used as a valuable serum biomarker for follow-up and for early detection of recurrence in high-grade gliomas. Future studies including larger cohort of patients with homogeneous group of glioma is required.

The role of postoperative blood pressure management in early postoperative hemorrhage in awake craniotomy glioma patients.

Postoperative hemorrhage can severely affect the patients' neurological outcome after awake craniotomy. Higher postoperative blood pressure can increase the risk of postoperative hemorrhage. The aim of this study was to investigate the role of postoperative blood pressure and other common radiological and epidemiological features with the incidence of postoperative hemorrhage. In this retrospective analysis, we included patients who underwent awake surgery at our institution. We assessed the blood pressure both intra- and postoperatively as well as the heart rate for the first 12 h. We compared a cohort with postoperative hemorrhage, who required further treatment (surgical revision or intravenous antihypertensive therapy), with a cohort with no postoperative hemorrhage. We included 48 patients with a median age of 39 years. 9 patients (19%) required further treatment due to postoperative hemorrhage, which was surgery in 2 cases and intensive blood pressure measurements in 7 cases. However, with early treatment, no significant difference in Performance scores at follow-up could be found. Patients with postoperative hemorrhage showed significantly higher postoperative systolic blood pressure during the hours 3-12 (p < 0.05) as well as intraoperatively throughout the procedure (p < 0.05). In ROC and Youden Test, a strong impact of systolic blood pressure over 140mmHg during the early postoperative course could be shown. Postoperative hemorrhage is a rare but possible complication in awake surgery glioma patients. To avoid postoperative hemorrhage, treating physicians should aim strictly on systolic blood pressure of under 140mmHg for the postoperative course.

The Prognostic Value of Preoperative Inflammatory Markers for Pathological Grading of Glioma Patients.

Introduction: The independent diagnostic value of inflammatory markers neutrophil to lymphocyte ratio (NLR) and platelet to lymphocyte ratio (PLR) and the diagnostic efficacy of NLR, derived neutrophil to lymphocyte ratio (dNLR), PLR, and lymphocyte-to-monocyte ratio (LMR) in glioma cases remain unclear. We investigated the correlation of preoperative peripheral blood inflammatory markers with pathological grade, Ki-67 Proliferation Index, and IDH-1 gene phenotype in patients with glioma, focusing on tumor grade and prognosis. Methods: We retrospectively analyzed the clinical, pathological, and laboratory data of 334 patients with glioma with varying grades and 345 with World Health Organization (WHO I) meningioma who underwent initial surgery at the Affiliated Hospital of Jining Medical University from December 2019 to December 2021. The diagnostic value of peripheral blood inflammatory markers for glioma was investigated. Results: The proportion of men smoking and drinking was significantly higher in the glioma group than in the meningioma group (P < .05); in contrast, the age and body mass index (Kg/m2) were significantly lower in the glioma group (P = .01). Significant differences were noted in the pathological grade (WHO II, III, and IV), Ki-67 Proliferation Index, and peripheral blood inflammatory markers such as lymphocyte median, NLR, dNLR, and PLR between the groups (P < .05). No significant correlation existed between peripheral blood inflammatory factors and IDH-1 gene mutation status or tumor location in patients with glioma (P > .05). LMR, NLR, dNLR, and PLR, varied significantly among different glioma types (P < .05). White blood cell (WBC) count, neutrophil, NLR, and dNLR correlated positively with glioma risk. Further, WBC, neutrophil, NLR, dNLR, and LMR had a high diagnostic efficiency. Conclusion: Peripheral blood inflammatory markers, serving as noninvasive biomarkers, offer high sensitivity and specificity for diagnosing glioma, differentiating it from meningioma, diagnosing GBM, and distinguishing GBM from low-grade glioma. These markers may be implemented as routine screening tools.

Evaluating the impact of tubular retractors in glioma surgery: A systematic review and meta-analysis.

BACKGROUND: Achieving safe, maximal tumor resection in gliomas can be challenging due to the tumor's intricate relationship with surrounding structures. Tubular retractors offer a minimally invasive approach, preserving functional pathways and reducing complications. To assess their efficacy and safety, we conducted a systematic review and meta-analysis. METHODS: A search across databases identified 26 studies meeting inclusion criteria, encompassing 106 patients with various glioma types and tumor locations. RESULTS: Among 26 eligible studies, 15 provided sufficient data on 106 patients (median age: 50.5 years). Glioblastoma multiforme constituted 52.4 % of tumors, followed by IDH-mutant astrocytomas at 31.0 %. Tumor locations varied, with intraventricular and thalamic involvement in 16.3 % (16/98) of cases, followed by temporal (12.2 %), frontal and occipital (each 8.16 %), basal ganglia (8.16 %), parietal (7.14 %), optic pathway (2.04 %), and caudate nucleus (1.02 %) involvement. VyCor and Brainpath retractors were most used (22.6 % and 21.7 %, respectively). Tubular retractors were often combined with the exoscope (35.9 %). Gross total resection (GTR) was achieved in 69.4 % of cases, near-total resection (NTR) in 5.1 %, and subtotal resection/partial resection (STR/PR) in 25.5 %. Mean extent of resection (EOR) significantly differed between GTR and STR/NTR/PR groups (p<0.001). Postoperative complications included visual deficits (6.38 %), hemiparesis or weakness (2.13 %), multiple complications (1.06 %), and other unspecified complications (3.19 %). CONCLUSION: Tubular retractors are a valuable intraoperative adjunct and component of the surgical armamentarium for glioma surgery allowing bimanual operative techniques to manage hemostasis directly with excellent surgical outcomes and an acceptable complication profile.