Relationships Between Surgical Approach, Tumor Classification Scheme, and Early Neurocognitive Outcome After Awake Craniotomy for Resection of Insular Glioma

Operative Neurosurgery 30:880–889, 2026

This study evaluates early postoperative neurocognitive outcomes after awake craniotomy for insular glioma resection, comparing transcortical and transsylvian approaches and examining tumor classification schemes. It reports frequent, domain-specific declines—most notably in memory and verbal fluency—and analyzes relationships with tumor hemisphere, insular zone, and extension.

The authors found similar overall neurocognitive change across surgical corridors but identified higher verbal fluency decline with transcortical approaches and greater domain-specific risk linked to left-sided tumors, extra-insular extension, and anterior or inferior insular involvement.

Study aim: Assessed how surgical approach (transsylvian vs transcortical) and tumor classification/location relate to early postoperative neurocognitive function (NCF) after awake resection of insular glioma.

Cohort & design: Retrospective series of 53 newly diagnosed insular glioma patients (47% high-grade; 75% left hemisphere) treated with awake craniotomy, with neuropsychological testing pre-op and within 60 days post-op.

Classification schemes: Tumors were categorized by Berger–Sanai zones (collapsed to anterior/posterior/superior/inferior) and Pitskhelauri extension groups (insula only; insula + extension; predominantly extra-insular).

Overall NCF change: Postoperative decline occurred across multiple domains, with the largest effects most often in memory and verbal fluency (executive function).

Frequency of clinically meaningful decline: 85% declined on ≥1 test (Δz ≤ −1.0), 52% on ≥2 tests, and 22% on ≥5 tests; decline was most frequent/severe in memory and also common in executive function, attention, and processing speed.

Surgical approach comparison: Mean NCF change generally did not differ by approach, but the transcortical approach showed a higher rate of verbal fluency decline than transsylvian (61% vs 26%).

Tumor hemisphere & localization effects: Left-hemisphere tumors were linked to poorer outcomes on multiple tests (notably memory, verbal fluency, naming, and token comprehension), while anterior tumors had worse executive function (mental flexibility) than posterior, and inferior lesions had worse recognition memory than superior.

Tumor extent/size associations: Predominantly extra-insular tumors had greater fluency reduction than insula-only; more Berger–Sanai quadrants involved correlated with worse executive function change; larger tumor volume and higher postoperative FLAIR volume related to worse processing speed and comprehension outcomes.

The Role of Intraoperative Imaging Modalities in Surgical Resection of Supratentorial Gliomas: A Review of 300 Cases

Operative Neurosurgery 30:278–288, 2026

This retrospective study of 300 supratentorial glioma surgeries compares outcomes using intraoperative MRI (iMRI), navigated intraoperative ultrasound (iUS) and no intraoperative imaging. It reports higher gross total resection rates and greater contrast-enhancement extent with iMRI and iUS, with iMRI achieving the highest contrast-enhanced extent of resection (CE-EOR) but longer operative times.

Clinical outcomes show fewer postoperative weaknesses and better overall survival when intraoperative imaging is used. Postoperative cognitive and sensory deficits varied by modality; progression-free survival differences were not significant. Study limitations include a retrospective design, the temporal rollout of modalities and differing surgeon experience.

Gross Total Resection (GTR) Rates: GTR was significantly more common with intraoperative MRI (iMRI, 56.9%) and intraoperative ultrasound (iUS, 57.1%) than without intraoperative imaging guidance (34%) in glioma surgery.

Extent of Resection (EOR): The mean EOR of contrast enhancement was highest with iMRI (96.6%), followed by iUS (93.2%), and lowest without intraoperative imaging (92%).

Postoperative Neurological Deficits: Patients without intraoperative imaging had significantly higher rates of postoperative weakness compared to those with iMRI or iUS (odds ratio = 0.520, CI = 0.272-0.994, P = .048).

Overall Survival (OS): Overall survival was significantly worse in patients without intraoperative imaging guidance (odds ratio = 1.534, CI = 1.058-2.225, P = .024) than in those with iMRI or iUS.

Progression-Free Survival (PFS): No significant differences in progression-free survival were found between the subgroups using iMRI, iUS, or no intraoperative imaging.

Surgery Duration: Mean surgery duration was longest with iMRI (260 minutes), intermediate with iUS (194 minutes), and shortest without intraoperative imaging (175 minutes).

Postoperative Functional Status: Karnofsky Performance Status (KPS) at 1 year was lowest in patients without intraoperative imaging guidance, indicating worse functional outcomes.

Study Limitations: The retrospective design, differing periods of iMRI and iUS use, learning curves, and unequal subgroup sizes limit the ability to fully compare all factors and may affect recurrence rate assessments.

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.

Cerebellopontine Angle Meningiomas: A Multi-Institutional Cohort Study

Neurosurgery 97:105–111, 2025

This multi-institutional study of 95 cerebellopontine angle meningioma cases found that gross total resection, especially with internal auditory canal drilling for intracanalicular invasion, improves symptom control and reduces recurrence. Most patients experienced stable or improved hearing, with postoperative complications and recurrence rates detailed.

• Cerebellopontine angle (CPA) meningiomas are challenging due to their proximity to neurovascular structures and present commonly with hearing loss, ataxia, and headaches.

• Gross total resection (GTR) was achieved in 62.1% of 95 patients; smaller tumor size and drilling the internal auditory canal (IAC) for tumors with intracanalicular invasion were associated with higher GTR rates.

• Most patients had stable or improved hearing postoperatively; only a minority experienced worsening.

• Postoperative complications included cranial nerve dysfunction, CSF leak, and hydrocephalus, but there were no perioperative deaths.

• Tumor progression or recurrence occurred in 25.3% of patients, with higher rates in WHO grade 2 tumors; Simpson grade I/II resection and older age reduced recurrence risk.

• Extent of resection (EOR) is not reliably predicted by tumor size alone; other anatomical factors are important.

• Adjuvant radiation was mainly used for higher-grade tumors with subtotal resection, but most progression cases were managed with observation or salvage therapy.

• Surgical resection is effective for symptom control and reducing recurrence, especially with GTR and appropriate IAC management.

Management strategies for cervical schwannomas: a comprehensive review

J Neurosurg Spine 42:650–658, 2025

The review discusses cervical schwannomas, focusing on their pathophysiology, clinical presentation, and management strategies, including surgical resection and stereotactic body radiation therapy (SBRT). It emphasizes the importance of a multidisciplinary approach for optimal patient outcomes and highlights the need for ongoing research.

Cervical schwannomas are benign tumors originating from Schwann cells, often occurring in the intradural, extramedullary space of the cervical spine.

MRI is the primary imaging modality for diagnosing schwannomas, characterized by avid Gd uptake and specific radiographic features.

Surgical resection is the main treatment approach, with gross-total resection preferred to minimize recurrence. Various surgical techniques are available depending on tumor location.

Stereotactic body radiation therapy (SBRT) is a viable alternative for patients who are not surgical candidates, offering good local control and symptomatic relief.

Histological analysis distinguishes schwannomas through specific features such as Antoni A and B areas and Verocay bodies. Immunohistochemical stains like S100 and SOX10 aid in diagnosis.

Multidisciplinary management is crucial, integrating surgical and nonsurgical options to optimize patient outcomes and quality of life.

Observation may be suitable for asymptomatic patients with slow-growing lesions, with regular monitoring to assess progression.

Malignant transformation into peripheral nerve sheath tumors is rare but possible, particularly in patients with NF1.

Digital 3D exoscope is an effective tool for the surgery of falx and parasagittal meningiomas

Acta Neurochirurgica (2025) 167:5

Digital 3D exoscopes are promising tools for microneurosurgery. The results of exoscope-assisted resection of intracranial meningiomas have only been addressed in few case reports. We retrospectively compared the results of exoscope and microscope-assisted surgery of falx and parasagittal meningiomas.

Methods We included all consecutive adult patients (n = 36) with falx or parasagittal meningioma who were operated with curative intention during an 8-year period by one senior neurosurgeon. The operations were performed either with a surgical microscope (n = 16; Zeiss Kinevo or Pentero 900) or a digital 3D exoscope (n = 20, Aesculap Aeos). We reviewed the pre- and postoperative radiological images, clinical examinations and surgical reports to assess clinical outcomes and complications. We also analyzed surgical videos.

Results Gross-total resection (Simpson grade I-II) was achieved in approximately 90% of the patients in both groups (89% in exoscope and 92% in microscope group). The duration of the operation was slightly longer (117 vs. 88 min) in the exoscope group. Surgical outcomes were comparable, despite there being larger tumors (median diameter 53 vs. 38 mm) with higher grades (WHO Grade 2–3: 45% vs. 19%) in the exoscope group. Transient postoperative complications were more frequent in the exoscope group (40 vs. 25%) mainly related to the larger tumor size.

Conclusion The digital 3D exoscope is an effective tool for performing surgery on falx and parasagittal meningiomas. The extent of removal, clinical results and complications seem to be comparable to surgical microscope even in large tumors. Larger prospective studies are required to confirm this result.

Preservation of cranial nerve function in large and giant trigeminal schwannoma resection

Acta Neurochirurgica (2024) 166:198

Trigeminal schwannomas (TSs) are intracranial tumors that can cause significant brainstem compression. TS resection can be challenging because of the risk of new neurologic and cranial nerve deficits, especially with large (≥ 3 cm) or giant (≥ 4 cm) TSs. As prior surgical series include TSs of all sizes, we herein present our clinical experience treating large and giant TSs via microsurgical resection.

Methods This was a retrospective, single-surgeon case series of adult patients with large or giant TSs treated with microsurgery in 2012–2023.

Results Seven patients underwent microsurgical resection for TSs (1 large, 6 giant; 4 males; mean age 39 ± 14 years). Tumors were classified as type M (middle fossa in the interdural space; 1 case, 14%), type ME (middle fossa with extracranial extension; 3 cases, 43%), type MP (middle and posterior fossae; 2 cases, 29%), or type MPE (middle/posterior fossae and extracranial space; 1 case, 14%). Six patients were treated with a frontotemporal approach (combined with transmastoid craniotomy in the same sitting in one patient and a delayed transmaxillary approach in another), and one patient was treated using an orbitofrontotemporal approach. Gross total resection was achieved in 5 cases (2 near-total resections). Five patients had preoperative facial numbness, and 6 had immediate postoperative facial numbness, including two with worsened or new symptoms. Two patients (28%) demonstrated new non-trigeminal cranial nerve deficits over mean follow-up of 22 months. Overall, 80% of patients with preoperative facial numbness and 83% with facial numbness at any point experienced improvement or resolution during their postoperative course. All patients with preoperative or new postoperative non-trigeminal tumor-related cranial nerve deficits (4/4) experienced improvement or resolution on follow-up. One patient experienced tumor recurrence that has been managed conservatively.

Conclusions Microsurgical resection of large or giant TSs can be performed with low morbidity and excellent long-term cranial nerve function.

Preoperative Versus Postoperative Radiosurgery of Brain Metastases: A Meta-Analysis

World Neurosurg. (2024) 182:35-41

OBJECTIVE: While postoperative resection cavity radiosurgery (post-SRS) is an accepted treatment paradigm for brain metastasis (BM) patients who undergo surgical resection, there is emerging interest in preoperative radiosurgery (preSRS) followed by surgical resection as an alternative treatment paradigm. Here, we performed a meta-analysis of the available literature on this matter.

METHODS: Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, a search of all studies evaluating pre-SRS and postSRS was completed. Local recurrence (LR), overall survival (OS), radiation necrosis (RN), and leptomeningeal disease (LMD) were evaluated from the available data. Moderator analysis and pooled effect sizes were performed using a proportional meta-analysis with R using the metafor package. Statistics are presented as mean [95% confidence interval].

RESULTS: We identified 6 pre-SRS and 33 post-SRS studies with comparable tumor volume (4.5-17.6 cm3 ). There were significant differences in the pooled estimates of LR and LMD, favoring pre-SRS over post-SRS. Pooled aggregate for LR was 11.0% [4.9-13.7] and 17.5% [15.1-19.9] for pre- and post-SRS studies (P [ 0.014). Similarly, pooled estimates of LMD favored pre-SRS, 4.4% [2.6-6.2], relative to post-SRS, 12.3% [8.9-15.7] (P [ 0.019). In contrast, no significant differences were found in terms of RN and OS. Pooled estimates for RN were 6.4% [3.1-9.6] and 8.9% [6.3-11.6] for pre- and post-SRS studies (P [ 0.393), respectively. Pooled estimates for OS were 60.2% [55.8-64.6] and 60.5% [56.9-64.0] for pre- and post-SRS studies (P [ 0.974).

CONCLUSIONS: This meta-analysis supports further exploration of pre-SRS as a strategy for the treatment of BM.

Safety of brainstem safe entry zones: comparison of microsurgical outcomes associated with superficial, exophytic, and deep brainstem cavernous malformations

J Neurosurg 139:113–123, 2023

Safe entry zones (SEZs) enable safe tissue transgression to lesions beneath the brainstem surface. However, evidence for the safety of SEZs is scarce and is based on anatomical studies, case reports, and small series.

METHODS A cohort of 154 patients who underwent microsurgical brainstem cavernous malformation (BSCM) treatment during a 23-year period and who had preoperative MR images and intraoperative photographs or videos was retrospectively examined. This study assessed the safety of SEZs for access to deep BSCMs, preoperative MRI to predict BSCM surface proximity, and the relationships between BSCM subtype, surgical approach, and SEZs. Lesions were characterized as exophytic, superficial, or deep on the basis of preoperative MRI and intraoperative inspection. Outcomes were scored as good (modified Rankin Scale [mRS] score ≤ 2) or poor (mRS score > 2) and relative outcomes as stable/ improved or worse relative to baseline (± 1 point).

RESULTS Resections included 34 (22%) in the midbrain, 102 (66%) in the pons, and 18 (12%) in the medulla. Of those, 23 (15%) were exophytic, 57 (37%) were superficial, and 74 (48%) were deep. Established SEZs were used for 97% (n = 72) of deep lesions; the preferred SEZ associated with its subtype was used for 91% (n = 67). MR images accurately depicted exophytic BSCMs that did not require SEZ approaches (sensitivity, 96%) but overestimated the proximity of lesions superficial to brainstem surfaces (specificity, 67%), resulting in unanticipated SEZ use. Final neurological outcomes were good in 80% of patients with follow-up data (119/149), and relative outcomes were stable/improved in 93% (139/149). Outcomes for patients with brainstem transgression through an SEZ did not differ from outcomes for patients with superficial or exophytic lesions that did not require SEZ use (final mRS score ≤ 2 in 72% of all patients with deep lesions vs 82% of all patients with superficial or exophytic lesions [p = 0.10]). Among patients with follow-up, the rates of permanent new cranial nerve deficits in patients with deep BSCMs and superficial or exophytic BSCMs were 21% and 20%, respectively (p = 0.81), with no significant change in overall cranial nerve deficit (0 and −1, p = 0.65).

CONCLUSIONS Neurological outcomes for patients with deep BSCMs were equivalent to those for superficial or exophytic BSCMs, validating the safety of SEZs for deep BSCMs. Preoperative T1-weighted MR images overestimated the lesion’s surface proximity, necessitating detailed knowledge of SEZs and readiness to use them in cases of radiologicalmicrosurgical discordance. Most patients achieved favorable outcomes despite the transgression of eloquent brainstem tissue in and around SEZs.

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.

Surgery of Insular Diffuse Gliomas—Part 2: Probabilistic Cortico-Subcortical Atlas of Critical Eloquent Brain Structures and Probabilistic Resection Map During Transcortical Awake Resection

Neurosurgery 89:579–590, 2021

Insular diffuse glioma surgery is challenging, and tools to help surgical planning could improve the benefit-to-risk ratio.

OBJECTIVE: To provide a probabilistic resection map and frequency atlases of critical eloquent regions of insular diffuse gliomas based on our surgical experience.

METHODS: We computed cortico-subcortical “eloquent” anatomic sites identified intraoperatively by direct electrical stimulations during transcortical awake resection of insular diffuse gliomas in adults.

RESULTS: From 61 insular diffuse gliomas (39 left, 22 right; all left hemispheric dominance for language), we provided a frequency atlas of eloquence of the opercula (left/right; pars orbitalis: 0%/5.0%; pars triangularis: l5.6%/4.5%; pars opercularis: 37.8%/27.3%; precentral gyrus: 97.3%/95.4%; postcentral and supramarginal gyri: 75.0%/57.1%; temporal pole and superior temporal gyrus: 13.3%/0%), which tailored the transcortical approach (frontal operculum to reach the antero-superior insula, temporal operculum to reach the inferior insula, parietal operculum to reach the posterior insula). We provided a frequency atlas of eloquence identifying the subcortical functional boundaries (36.1% pyramidal pathways, 50.8% inferior fronto-occipital fasciculus, 13.1% arcuate and superior longitudinal fasciculi complex, 3.3% somatosensory pathways, 8.2% caudate and lentiform nuclei). Vascular boundaries and increasing errors during testing limited the resection in 8.2% and 11.5% of cases, respectively. We provided a probabilistic 3-dimensional atlas of resectability.

CONCLUSION: Functional mapping under awake conditions has to be performed intraoperatively in each patient to guide surgical approach and resection of insular diffuse gliomas in right and left hemispheres. Frequency atlases of opercula eloquence and of subcortical eloquent anatomic boundaries, and probabilistic 3-dimensional atlas of resectability could guide neurosurgeons.

Surgery of Insular Diffuse Gliomas—Part 1: Transcortical Awake Resection Is Safe and Independently Improves Overall Survival

Neurosurgery 89:565–578, 2021

Insular diffuse glioma resection is at risk of vascular injury and of postoperative new neurocognitive deficits.

OBJECTIVE: To assess safety and efficacy of surgical management of insular diffuse gliomas.

METHODS: Observational, retrospective, single-institution cohort analysis (2005-2019) of 149 adult patients surgically treated for an insular diffuse glioma: transcortical awake resection with intraoperative functional mapping (awake resection subgroup, n = 61), transcortical asleep resection without functional mapping (asleep resection subgroup, n = 50), and stereotactic biopsy (biopsy subgroup, n = 38). All cases were histopathologically assessed according to the 2016World Health Organization classification and cIMPACTNOW update 3.

RESULTS: Following awake resection, 3/61 patients had permanent motor deficit, seizure control rates improved (89% vs 69% preoperatively, P = .034), and neurocognitive performance improved from 5% to 24% in tested domains, despite adjuvant oncological treatments. Resection rates were higher in the awake resection subgroup (median 94%) than in the asleep resection subgroup (median 46%; P < .001). There was more gross total resection (25% vs 12%) and less partial resection (34% vs 80%) in the awake resection subgroup than in the asleep resection subgroup (P< .001). Karnofsky Performance Status score <70 (adjusted hazard ratio [aHR] 2.74, P = .031), awake resection (aHR 0.21, P = .031), isocitrate dehydrogenase (IDH)-mutant grade 2 astrocytoma (aHR 5.17, P = .003), IDHmutant grade 3 astrocytoma (aHR 6.11, P < .001), IDH-mutant grade 4 astrocytoma (aHR 13.36, P = .008), and IDH-wild-type glioblastoma (aHR 21.84, P < .001) were independent predictors of overall survival.

CONCLUSION:Awake surgery preserving the brain connectivity is safe, allows larger resections for insular diffuse gliomas than asleep resection, and positively impacts overall survival.

Surgery versus radiosurgery for facial nerve schwannoma

J Neurosurg 135:542–553, 2021

Intracranial facial nerve schwannomas (FNS) requiring treatment are frequently recommended for surgery or stereotactic radiosurgery (SRS). The objective of this study was to compare facial nerve function outcomes between these two interventions for FNS via a systematic review and meta-analysis.

METHODS A search of the Ovid EMBASE, PubMed, SCOPUS, and Cochrane databases from inception to July 2019 was conducted following PRISMA guidelines. Articles were screened against prespecified criteria. Facial nerve out- comes were classified as improved, stabilized, or worsened by last follow-up. Incidence was pooled by random-effects meta-analysis of proportions.

RESULTS Thirty-three articles with a pooled cohort of 519 patients with FNS satisfied all criteria. Twenty-five articles described operative outcomes in 407 (78%) patients; 10 articles reported SRS outcomes in 112 (22%). In the surgical cohort, facial nerve function improved in 23% (95% CI 15%–32%), stabilized in 41% (95% CI 32%–50%), and worsened in 30% (95% CI 21%–40%). In the SRS cohort, facial nerve function was improved in 20% (95% CI 9%–34%), stable in 66% (95% CI 54%–78%), and worsened in 9% (95% CI 3%–16%). Compared with SRS, microsurgery was associated with a significantly lower incidence of stable facial nerve function (p < 0.01) and a significantly higher incidence of wors- ened facial nerve function (p < 0.01). Tumor progression and complication rates were comparable. Outcome certainty assessments were very low to moderate for all parameters.

CONCLUSIONS Unfavorable facial nerve function outcomes are associated with surgical treatment of intracranial FNS, whereas stable facial nerve function outcomes are associated with SRS. Therefore, SRS should be recommended to patients with FNS who require treatment, and surgery should be reserved for patients with another indication, such as decompression of the brainstem. Further study is required to definitively optimize and validate management strategies for these rare skull base tumors.

Spetzler-Martin Grade III Arteriovenous Malformations: A Comparison of Modified and Supplemented Spetzler-Martin Grading Systems

Neurosurgery 88:1103–1110, 2021

The modified Spetzler-Martin (SM) grading system proposes that grade III arteriovenous malformation (AVM) subtypes are associated with variable microsurgical risks, with small AVMs (III−) having lower risk and medium/eloquent AVMs (III+) having higher risk. Adding patient age and AVM bleeding status and compactness to the SM grade produces a score – the supplemented SM (Supp-SM) grade – to more accurately assess preoperative risk.

OBJECTIVE: To compare the predictive power of the modified SMand Supp-SM grades for risk assessment in patients with grade III AVMs.

METHODS: Patients with SM grade III AVMs treated between 2011 and 2018were retrospectively reviewed. Good outcomes were defined as modified Rankin Scale (mRS) scores ≤ 2 or unchanged/improved mRS scores (pre- vs postsurgery).

RESULTS: Of 102 patients with SM grade III AVMs, 59% had grade III− and 24% had grade III+ AVMs. Supp SM grade 6 and grade 7 AVMs accounted for 44% and 24%, respectively. Overall, 33% of patients worsened but outcomes did not significantly differ by SM III subtype. Neurological outcomes were associated with Supp-SM grade, with proportions of patients with worsening increasing from 0% with Supp-SM grade 4 AVMs to 54% with Supp-SM grade 7 AVMs. Analyses of factors associated with neurological worsening identified age > 60 yr and Supp-SM grade 7 as significant.

CONCLUSION: Supp-SM grades were more predictive of microsurgical outcomes than modified SM grades for grade III AVMs, with a hard cutoff for acceptable surgical risk at Supp-SM grade 6. Supp-SM grading is a better decision-making tool than subtyping with the modified SM scale.

 

Anatomical multifocal high-grade glioma resection

Acta Neurochirurgica (2021) 163:953–957

If an awake surgery is somehow not available for gliomas at the language area, understanding the anatomy and well designed surgical strategy are important.

Method We present a case with left hemispheric multifocal high-grade gliomas located deeply at the left temporal pole, the Wernicke’s area, and mesial temporal region. Because the patient could not endure the awake surgery and obtain practicable functional magnetic resonance imaging (MRI) for eloquent cortex evaluation, we removed the lesions following the anatomical resection strategy guided by diffusion tensor imaging (DTI).

Conclusion This case demonstrates the value of DTI and the importance of anatomical resection strategies in glioma surgeries.

Is supratotal resection achievable in low-grade gliomas? Feasibility, putative factors, safety, and functional outcome

J Neurosurg 132:1692–1705, 2020

Surgery for low-grade gliomas (LGGs) aims to achieve maximal tumor removal and maintenance of patients’ functional integrity. Because extent of resection is one of the factors affecting the natural history of LGGs, surgery could be extended further than total resection toward a supratotal resection, beyond tumor borders detectable on FLAIR imaging. Supratotal resection is highly debated, mainly due to a lack of evidence of its feasibility and safety. The authors explored the intraoperative feasibility of supratotal resection and its short- and long-term impact on functional integrity in a large cohort of patients. The role of some putative factors in the achievement of supratotal resection was also studied.

METHODS Four hundred forty-nine patients with a presumptive radiological diagnosis of LGG consecutively admitted to the neurosurgical oncology service at the University of Milan over a 5-year period were enrolled. In all patients, a policy was adopted to perform surgery according to functional boundaries, aimed at achieving a supratotal resection whenever possible, without any patient or tumor a priori selection. Feasibility, general safety, and tumor or patient putative factors possibly affecting the achievement of a supratotal resection were analyzed. Postsurgical patient functional performance was evaluated in five cognitive domains (memory, language, praxis, executive functions, and fluid intelligence) using a detailed neuropsychological evaluation and quality of life (QOL) examination.

RESULTS Total resection was feasible in 40.8% of patients, and supratotal resection in 32.3%. The achievement of a supratotal versus total resection was independent of age, sex, education, tumor volume, deep extension, location, handedness, appearance of tumor border, vicinity to eloquent sites, surgical mapping time, or surgical tools applied. Supratotal resection was associated with a long clinical history and histological grade II, suggesting that reshaping of brain networks occurred. Although a consistent amount of apparently MRI-normal brain was removed with this approach, the procedure was safe and did not carry additional risk to the patient, as demonstrated by detailed neuropsychological evaluation and QOL examination. This approach also improved seizure control.

CONCLUSIONS Supratotal resection is feasible and safe in routine clinical practice. These results show that a long clinical history may be the main factor associated with its achievement.

5-Aminolevulinic Acid and Contrast-Enhanced Ultrasound: The Combination of the 2 Techniques to Optimize the Extent of Resection in Glioblastoma Surgery

Neurosurgery 86:E529–E540, 2020

The survival benefit in maximizing resection in glioblastomas (GBMs) has been demonstrated by numerous studies. The true limit of infiltration of GBMs has been an overwhelming obstacle, and several technological advances have been introduced to improve the identification of residual tumors.

OBJECTIVE: To evaluate whether the integration of 5-aminolevulinic acid (5-ALA) with microbubble contrast-enhanced ultrasound (CEUS) improves residual tumor identification and has an impact on the extent of resection (EOR), overall survival (OS), and progressionfree survival (PFS).

METHODS: A total of 230 GBM procedures were retrospectively studied. Cases were stratified according to the surgical procedure into 4 groups: 5-ALA- and CEUS-guided surgeries, 5-ALA-guided surgeries, CEUS-guided surgeries, and conventional microsurgical procedures.

RESULTS: Patients undergoing conventional microsurgical procedures showed the worst EORs compared to the assisted techniques (5-ALA and CEUS procedures). Both 5-ALA and CEUS techniques improved the EOR compared to conventional microsurgical procedures. However, their combination gave the best results in terms of the EOR (P = .0003). The median EOR% and the number of supramarginal resections are hence superior in the 5-ALA + CEUS + group compared to the others; this observation had consequences on PFS and OS in our series.

CONCLUSION: In terms of the EOR, the best results can be achieved through a combination of both techniques,where the 5-ALA-guided procedure is followed by a final survey with CEUS. Compared with other intraoperative imaging techniques, CEUS is a real-time, readily repeatable, safe, and inexpensive technique that provides valuable information to the surgeon before, during, and after resection.

Resection of gliomas deemed inoperable by neurosurgeons based on preoperative imaging studies

J Neurosurg 129:567–575, 2018

Maximal safe resection is a primary objective in the management of gliomas. Despite this objective, surgeons and referring physicians may, on the basis of radiological studies alone, assume a glioma to be unresectable. Because imaging studies, including functional MRI, may not localize brain functions (such as language) with high fidelity, this simplistic approach may exclude some patients from what could be a safe resection. Intraoperative direct electrical stimulation (DES) allows for the accurate localization of functional areas, thereby enabling maximal resection of tumors, including those that may appear inoperable based solely on radiological studies. In this paper the authors describe the extent of resection (EOR) and functional outcomes following resections of tumors deemed inoperable by referring physicians and neurosurgeons.

METHODS The authors retrospectively examined the cases of 58 adult patients who underwent glioma resection within 6 months of undergoing a brain biopsy of the same lesion at an outside hospital. All patients exhibited unifocal supratentorial disease and preoperative Karnofsky Performance Scale scores ≥ 70. The EOR and 6-month functional outcomes for this population were characterized.

RESULTS Intraoperative DES mapping was performed on 96.6% (56 of 58) of patients. Nearly half of the patients (46.6%, 27 of 58) underwent an awake surgical procedure with DES. Overall, the mean EOR was 87.6% ± 13.6% (range 39.0%–100%). Gross-total resection (resection of more than 99% of the preoperative tumor volume) was achieved in 29.3% (17 of 58) of patients. Subtotal resection (95%–99% resection) and partial resection (PR; < 95% resection) were achieved in 12.1% (7 of 58) and 58.6% (34 of 58) of patients, respectively. Of the cases that involved PR, the mean EOR was 79.4% ± 12.2%. Six months after surgery, no patient was found to have a new postoperative neurological deficit. The majority of patients (89.7%, 52 of 58) were free of neurological deficits both pre- and postoperatively. The remainder of patients exhibited either residual but stable deficits (5.2%, 3 of 58) or complete correction of preoperative deficits (5.2%, 3 of 58).

CONCLUSIONS The use of DES enabled maximal safe resections of gliomas deemed inoperable by referring neurosurgeons. With rare exceptions, tumor resectability cannot be determined solely by radiological studies.

Method for temporal keyhole lobectomies in resection of low- and high-grade gliomas

J Neurosurg 128:1388–1395, 2018

The purpose of this study was to describe a method of resecting temporal gliomas through a keyhole lobectomy and to share the results of using this technique.

METHODS The authors performed a retrospective review of data obtained in all patients in whom the senior author performed resection of temporal gliomas between 2012 and 2015. The authors describe their technique for resecting dominant and nondominant gliomas, using both awake and asleep keyhole craniotomy techniques.

RESULTS Fifty-two patients were included in the study. Twenty-six patients (50%) had not received prior surgery. Seventeen patients (33%) were diagnosed with WHO Grade II/III tumors, and 35 patients (67%) were diagnosed with a glioblastoma. Thirty tumors were left sided (58%). Thirty procedures (58%) were performed while the patient was awake. The median extent of resection was 95%, and at least 90% of the tumor was resected in 35 cases (67%). Five of 49 patients (10%) with clinical follow-up experienced permanent deficits, including 3 patients (6%) with hydrocephalus requiring placement of a ventriculoperitoneal shunt and 2 patients (4%) with weakness. Three patients experienced early postoperative anomia, but no patients had a new speech deficit at clinical follow-up.

CONCLUSIONS The authors provide their experience using a keyhole lobectomy for resecting temporal gliomas. Their data demonstrate the feasibility of using less invasive techniques to safely and aggressively treat these tumors.

 

Frontal Keyhole Craniotomy for Resection of Low- and High-Grade Gliomas

Neurosurgery 82:388–396, 2018

Minimally invasive techniques are increasingly being used to access intraaxial brain lesions.

OBJECTIVE: To describe a method of resecting frontal gliomas through a keyhole craniotomy and share the results with these techniques.

METHODS: We performed a retrospective review of data obtained on all patients undergoing resection of frontal gliomas by the senior author between 2012 and 2015.We describe our technique for resecting dominant and nondominant gliomas utilizing both awake and asleep keyhole craniotomy techniques.

RESULTS: After excluding 1 patient who received a biopsy only, 48 patients were included in the study. Twenty-nine patients (60%) had not received prior surgery. Twenty-six patients (54%) were diagnosed with WHO grade II/III tumors, and 22 patients (46%) were diagnosedwith glioblastoma. Twenty-five cases (52%)were performed awake.At least 90% of the tumor was resected in 35 cases (73%). Three of 43 patients with clinical follow-up experienced permanent deficits.

CONCLUSION: We provide our experience in using keyhole craniotomies for resecting frontal gliomas. Our data demonstrate the feasibility of using minimally invasive techniques to safely and aggressively treat these tumors.