Tag: brain tumor

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Quantitative MRI Tractography of White Matter Tracts After Tumor Craniotomy Surgery: Comparative Analysis Between Tubular Retractor and Open Craniotomy Surgery

Operative Neurosurgery 30:525–532, 2026

This study compares quantitative diffusion MRI tractography outcomes after deep-seated brain tumor resections using tubular retraction (TR) versus open craniotomy (OC) with spatula/cottonoid retraction. In a matched cohort of 20 patients, TR achieved comparable extent of resection with improved postoperative fractional and geodesic anisotropy metrics and a greater mean increase in Karnofsky Performance Score.

Methods include pre/postoperative 1.5T DTI, autosegmented tractography of ipsilateral tracts, and statistical comparison of FA, GA, diffusivity metrics, and tract volume. Results suggest TR reduces certain retraction-related white matter distortion without worsening diffusivity markers, supporting TR as a viable technique for deep subcortical lesions with potential functional benefit.

Goal Quantitatively compare cerebral retraction–related white matter tract changes after deep-seated tumor surgery using tubular retraction (TR) vs open craniotomy (OC) with spatula retraction via diffusion MRI tractography metrics.

Design Retrospective matched-pair analysis of 20 patients (10 TR vs 10 OC), matched by tumor size, depth, and age; all surgeries performed by a single surgeon.

Tractography process/metrics Pre- and postoperative DTI tractography (1.5T MRI) autosegmented ipsilateral supratentorial tracts; quantified FA, GA, MD, RD, AD, and tract volume across specified tracts (e.g., corticospinal, arcuate/SLF, ILF, IFOF, fornix, uncinate, optic radiations).

Extent of resection Resection was comparable between groups (TR 90.4% vs OC 94.8%, P = .395).

Functional outcome Change in Karnofsky Performance Score (KPS) favored TR (mean +11 points) vs OC (no change), P = .035.

Key quantitative findings Postoperative FA and GA differed significantly in favor of TR (FA 0.322 TR vs 0.029 OC, P = .011; GA increased in TR 0.441 vs decreased in OC 0.411, P = .012).

Other imaging metrics Postoperative tract volume was higher in TR than OC (14.9 cm³ vs 10.6 cm³, P = .036), while diffusivity metrics (MD, RD, AD) were broadly comparable between cohorts.

Conclusion TR offers a viable approach for deep-seated tumors with similar resection extent while mitigating some components of retraction injury as reflected by quantitative tractography changes and improved KPS.

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Surgery of peritorcular meningiomas: the structural basis for preservation of torcular venous flow

J Neurosurg 143:1449–1457, 2025

This clinical and anatomical study defines the structural composition of the torcular Herophili and its implications for resection of peritorcular meningiomas, presenting histological evidence of a delaminable collagenous plane between venous endothelium and dural fibrous layers. The authors propose a four-type classification of tumor invasion based on endothelial integrity to guide operative strategy and preserve venous flow.

Clinical outcomes from 14 patients treated between 1997 and 2018 are reported, demonstrating feasibility of gross-total resection for type I–II tumors via layer-by-layer dissection with venous wall reinforcement, while types III–IV require preservation of collateral drainage and tailored reconstructive or adjunctive approaches.

• Torcular Anatomy: The torcular wall consists of two main compartments—an inner venous structure lined by endothelium and supported by elastic and smooth muscle fibers, and an outer fibrous dural layer, separated by a collagenous cleavage plane that enables surgical delamination.

• Meningioma Classification: Peritorcular meningiomas are classified into four types based on anatomical invasion: Type I (dural involvement only), Type II (dural involvement with sinus compression/displacement), Type III (endothelial layer disrupted, tumor penetrates lumen), and Type IV (complete sinus occlusion).

• Surgical Technique: For Type I and II tumors, gross-total resection is feasible by dissecting the tumor away from the inner venous wall at the cleavage plane, preserving venous integrity and flow; in Types III and IV, focus shifts to preserving venous collaterals due to disrupted or occluded flow.

• Preoperative Planning: Detailed imaging and identification of venous collaterals are critical for operative planning, especially when sinus flow is compromised or occluded.

• Outcomes: Gross-total resection was achieved in all patients with Type I and II tumors, with lower recurrence rates; subtotal resection and higher recurrence were associated with Types III and IV and higher-grade meningiomas.

• Complications and Mortality: No surgical mortality was reported; complications included wound infections and, rarely, recurrence or death related to aggressive tumor biology rather than surgery itself.

• Role of Radiotherapy: Radiation therapy was reserved for high-grade, residual, or recurrent tumors, particularly when total resection was not possible or in cases of sinus wall involvement.

• Clinical Significance: Preservation of the torcular venous wall and flow is paramount for favorable outcomes; anatomical understanding of the torcula enables safer, more effective resections and reduces recurrence in benign cases.

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Avoidance of Major Vascular Injury in Transcranial Brain Tumor Surgery Using Real-Time Doppler Navigation

Operative Neurosurgery 29:633–638, 2025

This clinical technical note and case series evaluates real-time Doppler probe navigation during transcranial craniotomy for brain tumor resection, describing technique, operative workflow, and outcomes from 501 operations where the Doppler was used. The authors report a low rate of major vessel injury (<1%) and discuss how Doppler guidance complements neuronavigation and ultrasound as tumor resection progresses and brain shift reduces image accuracy.

The paper details patient selection, surgical approaches, probe specifications and intraoperative use, illustrates three case examples with video, and analyzes stroke and infarction rates attributable to vasospasm or small-vessel injury. Limitations include retrospective design and variable probe penetrance; the authors recommend routine Doppler adjunctive use for tumors encasing or adherent to major arteries.

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Factors associated with poor prognosis in elderly biopsy‑only glioblastoma patients

Acta Neurochirurgica (2025) 167:273

In elderly glioblastoma patients undergoing biopsy only, poor preoperative performance status, central tumor location, and larger tumor volume were associated with reduced three-month survival and lower treatment completion rates, highlighting the need for careful preoperative assessment and personalized counseling in this vulnerable group.

Study investigated elderly patients (>65 years) with glioblastoma (GBM) who underwent biopsy only, not surgical resection.

• Median overall survival (OS) was 4.6 months; only half completed oncological treatment.

• Poor preoperative performance status (PS), central tumor location, and larger tumor volume were independently associated with reduced three-month survival.

• Poor PS was the only independent predictor for not completing oncological treatment; these patients had very poor survival (median OS 1.6 months).

• Completion of treatment was linked to longer survival (median OS 8.3 months for completers vs. 3.5 months for non-completers).

• Findings suggest limited benefit of biopsy and oncological treatment in elderly GBM patients with poor PS.

• Results can help guide preoperative counseling and decision-making for this vulnerable patient group.

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Awake surgery with direct electrical stimulation mapping and real‑time cognitive monitoring for functionally guided tumor resection

Acta Neurochirurgica (2025) 167:239

Awake surgery with direct electrical stimulation and real-time cognitive monitoring enables maximal safe brain tumor resection by mapping individual functional networks, preserving quality of life and cognitive abilities. This multidisciplinary, patient-centered approach is gold standard for low-grade gliomas and is increasingly applied to other brain tumors.

• Awake surgery with direct electrical stimulation (DES) mapping is the gold standard for low-grade glioma resection and can also be applied to other brain tumors.

• This approach uses real-time cognitive monitoring to guide tumor removal based on the patient’s individual brain connectome, preserving neurocognitive functions and quality of life.

• A multidisciplinary team—including neurosurgeons, anesthesiologists, and neuropsychologists or speech therapists—is essential for patient selection, preparation, and intraoperative mapping.

• The asleep–awake–asleep protocol with continuous cognitive testing and tailored tasks optimizes functional mapping and minimizes permanent deficits.

• Subpial dissection and limited coagulation reduce vascular injury and promote better cognitive outcomes.

• Early postoperative rehabilitation is crucial for neuroplasticity and functional recovery.

• Careful patient selection and preparation are vital; conditions impairing intraoperative testing are relative contraindications.

• This personalized surgical philosophy has led to high cognitive preservation, low permanent deficit rates, and high return-to-work rates.

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Laser interstitial thermal therapy for high-grade glioma: a systematic review, meta-analysis, and meta-regression

Neurosurg Focus 59(2):E10, 2025

Laser interstitial thermal therapy (LITT) is a minimally invasive treatment for high-grade glioma (HGG) showing mean overall survival of 11.7 months and progression-free survival of 5.3 months. LITT offers acceptable safety, especially for deep or unresectable tumors, but further randomized studies are needed to confirm long-term efficacy.

• Laser interstitial thermal therapy (LITT) is a minimally invasive treatment for high-grade glioma (HGG), especially in deep-seated or unresectable tumors.

• A systematic review and meta-analysis of 21 studies including 602 patients found mean overall survival (OS) after LITT was 11.74 months and mean progression-free survival (PFS) was 5.3 months.

• 6-, 12-, and 24-month OS rates were 77.0%, 48.9%, and 16.1%; PFS rates were 37.1%, 12.8%, and 4.3%, respectively.

• Permanent postoperative deficits occurred in 5.7% of patients, with higher rates in newly diagnosed HGG than recurrent cases (4.15% vs 0.02%).

• Tumor progression after LITT was observed in about 80% of patients, and overall mortality was 67.7%.

• Deep/unresectable tumors and IDH-wildtype mutations were associated with worse outcomes; smaller tumor size and higher baseline KPS predicted better survival.

• LITT showed acceptable safety and feasibility, but randomized prospective studies are needed to confirm long-term efficacy.

• Common complications included hemiparesis, weakness, and temporary neurological deficits.

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Impact of patient positioning on bleeding rate in stereotactic brain biopsies: semi‑sitting versus supine position

Acta Neurochirurgica (2025) 167:159

The study found that using a semi-sitting position (30° head elevation) during stereotactic brain biopsies significantly reduced the rate of hemorrhagic complications compared to the supine position, suggesting patient positioning is a key, modifiable factor for improving safety and outcomes in these neurosurgical procedures.

• Study compared bleeding rates in stereotactic brain biopsies between semi-sitting and supine positions.

• Retrospective analysis of 78 patients: 39 semi-sitting, 39 supine.

• Hemorrhagic complications were significantly lower in the semi-sitting group (7.7%) vs supine (33.3%).

• Semi-sitting position is a potential protective factor against bleeding (OR 0.17, p=0.009).

• Groups were similar in age, sex, tumor type, and biopsy site; more samples were taken in semi-sitting group.

• No symptomatic bleedings occurred in either group.

• Semi-sitting position may reduce intracranial venous pressure, lowering bleeding risk.

• Authors recommend further prospective, multicenter studies to validate findings.

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Evaluation of the extent of resection of intracranial tumors with virtual intraoperative MRI

J Neurosurg 141:695–701, 2024

Intraoperative MRI (iMRI) is the gold-standard technique for intraoperative evaluation of the extent of resection in brain tumor surgery. Unfortunately, it is currently available at only a few neurosurgical centers. A commercially available software, Virtual iMRI Cranial, provides an elastic fusion between preoperative MRI and intraoperative CT (iCT). The aim of this study was to evaluate the accuracy of this software in determining the presence of residual tumor.

METHODS Virtual iMRI was performed in patients who underwent iCT after intracranial tumor resection. The results of the software in terms of presence or absence of tumor residual were then compared with postoperative MRI performed within 48 hours after surgery to evaluate the diagnostic accuracy of virtual iMRI.

RESULTS Sixty-six patients were included in the present study. The virtual iMRI findings were concordant with the postoperative MRI data in 35 cases (53%) in the detection of tumor residual (p = 0.006). No false-negative findings (i.e., presence of residual on postoperative MRI and absence of residual on virtual iMRI) were encountered. Virtual iMRI had a sensitivity of 1 (95% CI 0.86–1), specificity of 0.26 (95% CI 0.14–0.42), positive predictive value of 0.44 (95% CI 0.3–0.58), and negative predictive value of 1 (95% CI 0.72–1). Subgroup analysis revealed that the virtual iMRI findings were concordant with postoperative MRI findings in all cases (n = 9) of lower-grade glioma (LGG) with a sensitivity of 1 (95% CI 0.59–1) and a specificity of 1 (95% CI 0.16–1) (p = 0.003); a statistically significant association was also found for grade 4 gliomas with a sensitivity of 1 (95% CI 0.69–1) and a specificity of 0.33 (95% CI 0.08–0.7) (p = 0.046) (19 patients). No significant association was found when considering meningiomas or metastases.

CONCLUSIONS The commercially available virtual iMRI can predict the presence or absence of tumor residual with high sensitivity. The diagnostic accuracy of this method was higher in LGGs and much lower for meningiomas or metastases; these findings must be evaluated in prospective studies in a larger population.

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Navigated intraoperative ultrasound in neuro-oncology: volumetric accuracy and correlation with high-field MRI

J Neurosurg 141:79–88, 2024

The use of intraoperative techniques to detect residual tumors has recently become increasingly important. Intraoperative MRI has long been considered the gold standard; however, it is not widely used because of high equipment costs and long acquisition times. Consequently, real-time intraoperative ultrasound (ioUS), which is much less expensive than MRI, has gained popularity. The aim of the present study was to evaluate the capacity of ioUS to accurately determine the primary tumor volume and detect residual tumors.

METHODS A prospective study of adult patients who underwent surgery for intra-axial brain tumors between November 2017 and October 2020 was performed. Navigated intraoperative ultrasound (nioUS) of the brain was used to guide tumor resection and to detect the presence of residual disease. Both convex (5–8 MHz) and linear array (6–13 MHz) probes were used. Tumor volume and residual disease were measured with nioUS and compared with MR images. A linear regression model based on a machine learning pipeline and a Bland-Altman analysis were used to assess the accuracy of nioUS versus MRI.

RESULTS Eighty patients (35 females and 45 males) were included. The mean age was 58 years (range 25–80 years). A total of 88 lesions were evaluated; there were 64 (73%) gliomas, 19 (21.6%) metastases, and 5 (5.7%) other tumors, mostly located in the frontal (41%) and temporal (27%) lobes. Most of the tumors (75%) were perfectly visible on ioUS (grade 3, Mair grading system), except for those located in the insular lobe (grade 2). The regression model showed a nearly perfect correlation (R 2 = 0.97, p < 0.001) between preoperative tumor volumes from both MRI and nioUS. Ultrasonographic visibility significantly influenced this correlation, which was stronger for highly visible (grade 3) tumors (p = 0.01). For residual tumors, the correlation between postoperative MRI and nioUS was weaker (R 2 = 0.78, p < 0.001) but statistically significant. The Bland-Altman analysis showed minimal bias between the two techniques for pre- and postoperative scenarios, with statistically significant results for the preoperative concordance.

CONCLUSIONS The authors’ findings show that most brain tumors are well delineated by nioUS and almost perfectly correlated with MRI-based measurements both pre- and postoperatively. These data support the hypothesis that nioUS is a reliable intraoperative technique that can be used for real-time monitoring of brain tumor resections and to perform volumetric analysis of residual disease.

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Minimally invasive keyhole approach for supramaximal frontal glioma resections

J Neurosurg 140:949–957, 2024

The authors aimed to review the frontal lobe’s surgical anatomy, describe their keyhole frontal lobectomy technique, and analyze the surgical results.

METHODS Patients with newly diagnosed frontal gliomas treated using a keyhole approach with supramaximal resection (SMR) from 2016 to 2022 were retrospectively reviewed. Surgeries were performed on patients asleep and awake. A human donor head was dissected to demonstrate the surgical anatomy. Kaplan-Meier curves were used for survival analysis.

RESULTS Of the 790 craniotomies performed during the study period, those in 47 patients met our inclusion criteria. The minimally invasive approach involved four steps: 1) debulking the frontal pole; 2) subpial dissection identifying the sphenoid ridge, olfactory nerve, and optic nerve; 3) medial dissection to expose the falx cerebri and interhemispheric structures; and 4) posterior dissection guided by motor mapping, avoiding crossing the inferior plane defined by the corpus callosum. A fifth step could be added for nondominant lesions by resecting the inferior frontal gyrus. Perioperative complications were recorded in 5 cases (10.6%). The average hospital length of stay was 3.3 days. High-grade gliomas had a median progression-free survival of 14.8 months and overall survival of 23.9 months.

CONCLUSIONS Keyhole approaches enabled successful SMR of frontal gliomas without added risks. Robust anatomical knowledge and meticulous surgical technique are paramount for obtaining successful resections.

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Intraoperative in vivo confocal laser endomicroscopy imaging at glioma margins: can we detect tumor infiltration?

J Neurosurg 140:357–366, 2024

Confocal laser endomicroscopy (CLE) is a US Food and Drug Administration–cleared intraoperative real-time fluorescence-based cellular resolution imaging technology that has been shown to image brain tumor histoarchitecture rapidly in vivo during neuro-oncological surgical procedures. An important goal for successful intraoperative implementation is in vivo use at the margins of infiltrating gliomas. However, CLE use at glioma margins has not been well studied.

METHODS Matching in vivo CLE images and tissue biopsies acquired at glioma margin regions of interest (ROIs) were collected from 2 institutions. All images were reviewed by 4 neuropathologists experienced in CLE. A scoring system based on the pathological features was implemented to score CLE and H&E images from each ROI on a scale from 0 to 5. Based on the H&E scores, all ROIs were divided into a low tumor probability (LTP) group (scores 0–2) and a high tumor probability (HTP) group (scores 3–5). The concordance between CLE and H&E scores regarding tumor probability was determined. The intraclass correlation coefficient (ICC) and diagnostic performance were calculated.

RESULTS Fifty-six glioma margin ROIs were included for analysis. Interrater reliability of the scoring system was excellent when used for H&E images (ICC [95% CI] 0.91 [0.86–0.94]) and moderate when used for CLE images (ICC [95% CI] 0.69 [0.40–0.83]). The ICCs (95% CIs) of the LTP group (0.68 [0.40–0.83]) and HTP group (0.68 [0.39–0.83]) did not differ significantly. The concordance between CLE and H&E scores was 61.6%. The sensitivity and specificity values of the scoring system were 79% and 37%. The positive predictive value (PPV) and negative predictive value were 65% and 53%, respectively. Concordance, sensitivity, and PPV were greater in the HTP group than in the LTP group. Specificity was higher in the newly diagnosed group than in the recurrent group.

CONCLUSIONS CLE may detect tumor infiltration at glioma margins. However, it is not currently dependable, especially in scenarios where low probability of tumor infiltration is expected. The proposed scoring system has excellent intrinsic interrater reliability, but its interrater reliability is only moderate when used with CLE images. These results suggest that this technology requires further exploration as a method for consistent actionable intraoperative guidance with high dependability across the range of tumor margin scenarios. Specific-binding and/or tumor-specific fluorophores, a CLE image atlas, and a consensus guideline for image interpretation may help with the translational utility of CLE.

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Confocal laser endomicroscopy in glial tumors—a histomorphological analysis

Neurosurgical Review (2024) 47:65

The extent of resection and neurological outcome are important prognostic markers for overall survival in glioma patients. Confocal laser endomicroscopy is a tool to examine tissue without the need for fixation or staining. This study aims to analyze gliomas in confocal laser endomicroscopy and identify reliable diagnostic criteria for glial matter and glial tumors.

Material and methods One-hundred-and-five glioma specimens were analyzed using a 670-nm confocal laser endomicroscope and then processed into hematoxylin-eosin-stained frozen sections. All confocal images and frozen sections were evaluated for the following criteria: presence of tumor, cellularity, nuclear pleomorphism, changes of the extracellular glial matrix, microvascular proliferation, necrosis, and mitotic activity. Recurring characteristics were identified. Accuracy, sensitivity, specificity, and positive and negative predictive values were assessed for each feature.

Results All 125 specimens could be processed and successfully analyzed via confocal laser endomicroscopy. We found diagnostic criteria to identify white and grey matter and analyze cellularity, nuclear pleomorphism, changes in the glial matrix, vascularization, and necrosis in glial tumors. An accuracy of > 90.0 % was reached for grey matter, cellularity, and necrosis, > 80.0 % for white matter and nuclear pleomorphism, and > 70.0 % for microvascular proliferation and changes of the glial matrix. Mitotic activity could not be identified. Astroglial tumors showed significantly less nuclear pleomorphism in confocal laser endomicroscopy than oligodendroglial tumors (p < 0.001). Visualization of necrosis aids in the differentiation of low grade gliomas and high grade gliomas (p < 0.002).

Conclusion Autofluorescence-based confocal laser endomicroscopy proved not only useful in differentiation between tumor and brain tissue but also revealed useful clues to further characterize tissue without processing in a lab. Possible applications include the improvement of extent of resection and the safe harvest of representative tissue for histopathological and molecular genetic diagnostics.

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Confocal laser endomicroscopy in glial tumors—a histomorphological analysis

Neurosurgical Review (2024) 47:65

The extent of resection and neurological outcome are important prognostic markers for overall survival in glioma patients. Confocal laser endomicroscopy is a tool to examine tissue without the need for fixation or staining. This study aims to analyze gliomas in confocal laser endomicroscopy and identify reliable diagnostic criteria for glial matter and glial tumors.

Material and methods One-hundred-and-five glioma specimens were analyzed using a 670-nm confocal laser endomicroscope and then processed into hematoxylin-eosin-stained frozen sections. All confocal images and frozen sections were evaluated for the following criteria: presence of tumor, cellularity, nuclear pleomorphism, changes of the extracellular glial matrix, microvascular proliferation, necrosis, and mitotic activity. Recurring characteristics were identified. Accuracy, sensitivity, specificity, and positive and negative predictive values were assessed for each feature.

Results All 125 specimens could be processed and successfully analyzed via confocal laser endomicroscopy. We found diagnostic criteria to identify white and grey matter and analyze cellularity, nuclear pleomorphism, changes in the glial matrix, vascularization, and necrosis in glial tumors. An accuracy of > 90.0 % was reached for grey matter, cellularity, and necrosis, > 80.0 % for white matter and nuclear pleomorphism, and > 70.0 % for microvascular proliferation and changes of the glial matrix. Mitotic activity could not be identified. Astroglial tumors showed significantly less nuclear pleomorphism in confocal laser endomicroscopy than oligodendroglial tumors (p < 0.001). Visualization of necrosis aids in the differentiation of low grade gliomas and high grade gliomas (p < 0.002).

Conclusion Autofluorescence-based confocal laser endomicroscopy proved not only useful in differentiation between tumor and brain tissue but also revealed useful clues to further characterize tissue without processing in a lab. Possible applications include the improvement of extent of resection and the safe harvest of representative tissue for histopathological and molecular genetic diagnostics.

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Awake Versus Asleep Craniotomy for Patients With Eloquent Glioma: A Systematic Review and Meta-Analysis

Neurosurgery 94:38–52, 2024

Awake vs asleep craniotomy for patients with eloquent glioma is debatable. This systematic review and meta-analysis sought to compare awake vs asleep craniotomy for the resection of gliomas in the eloquent regions. METHODS: MEDLINE and PubMed were searched from inception to December 13, 2022. Primary outcomes were the extent of resection (EOR), overall survival (month), progression-free survival (month), and rates of neurological deficit, Karnofsky performance score, and seizure freedom at the 3-month follow-up. Secondary outcomes were duration of operation (minute) and length of hospital stay (LOS) (day).

RESULTS: Fifteen studies yielded 2032 patients, from which 800 (39.4%) and 1232 (60.6%) underwent awake and asleep craniotomy, respectively. The meta-analysis concluded that the awake group had greater EOR (mean difference [MD]= MD= 8.52 [4.28, 12.76], P < .00001), overall survival (MD = 2.86 months [1.35, 4.37], P = .0002), progression-free survival (MD = 5.69 months [0.75, 10.64], P = .02), 3-month postoperative Karnofsky performance score (MD = 13.59 [11.08, 16.09], P < .00001), and 3-month postoperative seizure freedom (odds ratio = 8.72 [3.39, 22.39], P < .00001). Furthermore, the awake group had lower 3-month postoperative neurological deficit (odds ratio = 0.47 [0.28, 0.78], P = .004) and shorter LOS (MD = -2.99 days [-5.09, -0.88], P = .005). In addition, the duration of operation was similar between the groups (MD = 37.88 minutes [-34.09, 109.86], P = .30).

CONCLUSION: Awake craniotomy for gliomas in the eloquent regions benefits EOR, survival, postoperative neurofunctional outcomes, and LOS. When feasible, the authors recommend awake craniotomy for surgical resection of gliomas in the eloquent regions.

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Minimally Invasive Surgery of Deep-Seated Brain Lesions Using Tubular Retractors and Navigated Transcranial Magnetic Stimulation-Based Diffusion Tensor Imaging Tractography Guidance: The Minefield Paradigm

Operative Neurosurgery 24:656–664, 2023

Surgical treatment of deep-seated brain lesions is a major challenge for neurosurgeons. Recently, tubular retractors have been used to help neurosurgeons in achieving the targeting and resection of deep lesions.

OBJECTIVE: To describe a novel surgical approach based on the combination of tubular retractors and preoperative mapping by navigated transcranial magnetic stimulation (nTMS) and nTMS-based diffusion tensor imaging (DTI) tractography for the safe resection of deep-seated lesions.

METHODS: Ten consecutive patients affected by deep-seated brain lesions close to eloquent motor/language/visual pathways underwent preoperative nTMS mapping of motor/language cortical areas and nTMS-based DTI tractography of adjacent eloquent white matter tracts, including optic radiations. The nTMS-based information was used to plan the optimal surgical trajectory and to guide the insertion of tubular retractors within the brain parenchyma without causing injury to the eloquent cortical and subcortical structures. After surgery, all patients underwent a new nTMS-based DTI tractography of fascicles close to the tumor to verify their structural integrity.

RESULTS: Gross total resection was achieved in 8 cases, subtotal resection in 1 case, and a biopsy in 1 case. No new postoperative deficits were observed, except in 1 case where a visual field defect due to injury to the optic radiations occurred. Postoperative nTMS-based DTI tractography showed the integrity of the subcortical fascicles crossed by tubular retractors trajectory in 9 cases.

CONCLUSION: The novel strategy combining tubular retractors with functional nTMS-based preoperative mapping enables a safe microsurgical resection of deep-seated lesions through the preservation of eloquent cortical areas and subcortical fascicles, thus reducing the risk of new permanent deficits.

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Predictive factors for post operative seizures following meningioma resection in patients without preoperative seizures: a multicenter retrospective analysis

Acta Neurochirurgica (2023) 165:1333–1343

Meningiomas are the most common primary brain tumor and represent 35% of all intracranial neoplasms. However, in the early post-operative period approximate 3–5% of patients experience an acute symptomatic seizure. Establishing risk factors for postoperative seizures will identify those patients without preoperative seizures at greatest risk of postoperative seizures and may guide antiseizure medications (ASMs) management.

Methods Adult seizure naïve patients who underwent primary resection of a World Health Organization (WHO) Grade 1–3 meningioma at the three Mayo Clinic Campuses between 2012–2022 were retrospectively reviewed. Multivariate regression analyses were used to identify radiological, surgical, and management features with the development of new-onset seizures in patients undergoing meningioma resection.

Results Of 113 seizure naïve patients undergoing meningioma resection 11 (9.7%) experienced a new-onset post-operative seizure. Tumor volume ≥ 25 cm 3 (Odds Ratio (OR) 5.223, 95% Confidence Interval (CI) 1.546 – 17.650, p = 0.008) and cerebral convexity meningiomas (OR 4.742, 95% CI 1.255 – 14.336, p = 0.016) were most associated with new onset postoperative seizures in multivariate analysis. ASMs and corticosteroid therapies did not display a significant difference among those with and without a new onset postoperative seizure.

Conclusion In the current study, a larger tumor volume (≥ 25 cm3 ) and/or convexity meningiomas predicted the development of new onset post-operative seizures. Those who present with these factors should be counseled for their increased risk of new onset post-operative seizures and may benefit from prophylactic ASMs therapy.

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Initial experience with magnetic resonance–guided focused ultrasound stereotactic surgery for central brain lesions in young adults

J Neurosurg 137:760–767, 2022

Magnetic resonance–guided focused ultrasound (MRgFUS) is an incisionless procedure capable of thermoablation through the focus of multiple acoustic beams. Although MRgFUS is currently approved for the treatment of tremor in adults, its safety and feasibility profile for intracranial lesions in the pediatric and young adult population remains unknown.

METHODS The long-term outcomes of a prospective single-center, single-arm trial of MRgFUS at Nicklaus Children’s Hospital in Miami, Florida, are presented. Patients 15–22 years of age with centrally located lesions were recruited, clinically consistent with WHO grade I tumors that require surgical intervention. This cohort consisted of 4 patients with hypothalamic hamartoma (HH), and 1 patient with tuberous sclerosis complex harboring a subependymal giant cell astrocytoma (SEGA).

RESULTS In each case, high-intensity FUS was used to target the intracranial lesion. Real-time MRI was used to monitor the thermoablations. Primary outcomes of interest were tolerability, feasibility, and safety of FUS. The radiographic ablation volume on intra- and postoperative MRI was also assessed. All 5 patients tolerated the procedure without any complications. Successful thermoablation was achieved in 4 of the 5 cases; the calcified SEGA was undertreated due to intratumor calcification, which prevented attainment of the target ablation temperature. The HHs underwent target tissue thermoablations that led to MR signal changes at the treatment site. For the patients harboring HHs, FUS thermoablations occurred without procedure-related complications and led to improvement in seizure control or hypothalamic hyperphagia. All 5 patients were discharged home on postoperative day 1 or 2, without any readmissions. There were no cases of hemorrhage, electrolyte derangement, endocrinopathy, or new neurological deficit in this cohort.

CONCLUSIONS This experience demonstrates that FUS thermoablation of centrally located brain lesions in adolescents and young adults can be performed safely and that it provides therapeutic benefit for associated symptoms. Clinical trial registration no.: NCT03028246

 

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Supraorbital and mini-pterional keyhole craniotomies for brain tumors

J Neurosurg 136:1314–1324, 2022

The authors’ objective was to compare the indications, outcomes, and anatomical limits of supraorbital (SO) and mini-pterional (MP) craniotomies in patients with intra- and extraaxial brain tumors, and to assess approach selection, utility of endoscopy, and surgical field overlap.

METHODS A retrospective analysis was conducted of all brain tumor patients who underwent an SO or MP approach. The analyzed characteristics included pathology, endoscopy use, extent of resection, length of stay (LOS), and complications. On the basis of preoperative MRI data, tumor heatmaps were constructed to compare surgical access provided by both routes, including coronal projection heatmaps for parasellar tumors.

RESULTS From 2007 to 2020, 158 patients underwent 173 (84.8%) SO craniotomies and 30 patients underwent 31 (15.2%) MP craniotomies; 71 (34.8%) procedures were reoperations. Of these 204 operations, 110 (63.6%) SO and 21 (67.7%) MP approaches were for extraaxial tumors (meningiomas in 65% and 76.2%, respectively). Gliomas and metastases together represented 84.1% and 70% of intraaxial tumors accessed with SO and MP approaches, respectively. Overall, 56.1% of tumors accessed with the SO approach and 41.9% of those accessed with the MP approach were in the parasellar region. Axial projection heatmaps showed that SO access extended along the entire ipsilateral and medial contralateral anterior cranial fossa, parasellar region, ipsilateral sylvian fissure, medial middle cranial fossa, and anterior midbrain, whereas MP access was limited to the ipsilateral middle cranial fossa, sylvian fissure, lateral parasellar region, and posterior aspect of anterior cranial fossa. Coronal projection heatmaps showed that parasellar access extended further superiorly with the SO approach compared with that of the MP approach. Endoscopy was utilized in 98 (56.6%) SO craniotomies and 7 (22.6%) MP craniotomies, with further tumor resection in 48 (49%) and 5 (71.4%) cases, respectively. Endoscope-assisted tumor removal was clustered in areas that were generally at farther distances from the craniotomy or in angled locations such as the cribriform plate region where microscopic visualization is limited. Gross-total or neartotal resection was achieved in 120/173 (69%) SO approaches and 21/31 (68%) MP approaches. Major complications occurred in 11 (6.4%) SO approaches and 1 (3.2%) MP approach (p = 0.49). The median LOS decreased to 2 days in the last 2 years of the study.

CONCLUSIONS This clinical experience suggests the SO and MP craniotomies are versatile, safe, and complementary approaches for tumors located in the anterior and middle cranial fossae and perisylvian and parasellar regions. The SO route, used in 85% of cases, achieved greater overall reach than the MP route. Both approaches may benefit from expanded visualization with endoscopy.

 

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Outcome of glioblastoma resection in patients 80 years of age and older

Acta Neurochirurgica (2022) 164:373–383

Objective To evaluate the role and possible complications of tumor resection in the management of glioblastoma (GBM) in a series of patients 80 years of age and older with review of literature.

Methods The authors retrospectively analyzed cases involving patients 80 years or older who underwent biopsy or initial resection of GBM at their hospital between 2007 and 2018. A total of 117 patients (mean age 82 years) met the inclusion criteria; 57 had resection (group A) and 60 had biopsy (group B). Functional outcomes and survival at follow-up were analyzed.

Results Group A differed significantly from group B at baseline in having betterWHO performance status, better ASA scores, more right-sided tumors, and no basal ganglia or “butterfly” gliomas. Nevertheless, 56% of group A patients had an ASA score of 3. Median survival was 9.5 months (95% CI 8–17 months) in group A, 4 months (95% CI 3.5–6 months) in group B, and 17.5 months (95% CI 12–24 months) in the 56% of group A patients treated with resection and Stupp protocol. Rates of postoperative neurologic and medical complications were almost identical in the 2 groups, but the rate of surgical site complications was substantially greater in group A (12% vs 5%). There was no significant difference in mean preoperative and postoperative KPS scores (group A).

Conclusions In selected patients 80 years or older, radical removal of GBM was associated with acceptable survival and a low perioperative complication rate which is comparable to that of a biopsy. Although the median survival of the whole group was lower than reported for younger patients, a subgroup amenable to radical surgery and Stupp protocol achieved a median survival of 17.5 months.

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Tumor location and reduction in functional MRI estimates of language laterality

J Neurosurg 135:1674–1684, 2021

Brain tumors located close to the language cortex may distort functional MRI (fMRI)–based estimates of language dominance. The nature of this distortion, and whether this is an artifact of numerous confounders, remains unknown. The authors hypothesized tumor bias based on laterality estimates independent of confounders and that the effects are the greatest for tumors proximal to Broca’s area.

METHODS To answer this question, the authors reviewed more than 1113 patients who underwent preoperative fMRI to match samples on 11 known confounders (tumor location, size, type, and grade; seizure history; prior neurosurgery; aphasia presence and severity; and patient age, sex, and handedness). The samples included 30 patients with left hemisphere tumors (15 anterior and 15 posterior) and 30 with right hemisphere tumors (15 anterior and 15 posterior), thus totaling 60 patients (25 women; 18 left-handed and 4 ambidextrous; mean age 47 [SD 14.1] years). Importantly, the authors matched not only patients with left and right hemisphere tumors but also those with anterior and posterior tumors. Standard fMRI laterality indices (LIs) were calculated using whole-brain and region of interest (ROI) approaches (Broca’s and Wernicke’s areas).

RESULTS Tumors close to Broca’s area in the left hemisphere decreased LIs independently of known confounders. At the whole-brain level, this appeared to reflect a decrease in LI values in patients with left anterior tumors compared with patients with right anterior tumors. ROI analysis replicated these findings. Broca’s area LIs were significantly lower (p = 0.02) in patients with left anterior tumors (mean LI 0.28) when compared with patients with right anterior tumors (mean LI 0.70). Changes in Wernicke’s area–based LIs did not differ as a function of the tumor hemisphere. Therefore, in patients with left anterior tumors, it is essential to assess language laterality using left posterior ROIs. In all remaining tumor groups (left posterior tumors and right hemisphere tumors), language laterality derived from the anterior language ROI was the most robust measure of language dominance.

CONCLUSIONS Patients with tumors close to Broca’s area showed more bilateral fMRI language maps independent of known confounders. The authors caution against the assumption that this reduced language laterality suggests no or little risk to language function following tumor resection in the left inferior frontal gyrus. Their results address how to interpret fMRI data for neurosurgical purposes, along with theoretical questions of contralesional functional compensation and disinhibition.

 

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