Author: cba

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The Mastoid Foramen and Mastoid Emissary Vein Canal as Surgical Landmarks for Mastoid Pneumatization During Retrosigmoid Approach

Operative Neurosurgery 31:74–84, 2026

This study investigates the anatomical, radiological, and intraoperative relationships between the mastoid foramen (MF), mastoid emissary vein canal (MEVC), and mastoid air cell (MAC) pneumatization to improve planning and safety of the retrosigmoid approach (RSA). It reports measurements from cadaveric specimens, high-resolution CT of 100 patients, and surgical outcomes from 54 RSA procedures, linking MF/MEVC positions with pneumatization grades.

Key findings show the MF and MEVC are reliably posterior to MACs in most cases, with higher pneumatization grades correlated with shorter MF‑MAC and mMEVC‑MAC distances. Preoperative radiological assessment of these landmarks guided burr hole placement and border‑sealing techniques, reducing intraoperative MAC openings and postoperative complications.

Goal Assess whether the mastoid foramen (MF) and mastoid emissary vein canal (MEVC) can predict mastoid pneumatization and guide safer retrosigmoid approach (RSA) craniectomy planning.

Methods Combined anatomic dissection/drilling (2 dry temporal bones; 2 formalin-fixed heads), radiology (100 high‑resolution CTs; Han grade 1–4), and surgical review (54 RSA cases with complication tracking).

Classification & measures MF labeled “posterior” vs “anterior” to the most posterior mastoid air cell (MAC); MEVC labeled type 1 (posterior to MACs) vs type 2 (within MACs); quantified MF‑MAC distance and minimal MEVC‑MAC (mMEVC‑MAC) distance.

Key anatomy pattern MF was posterior to MACs in 99.4% of CT sides; MEVC was posterior to MACs in 88.0% (i.e., type 2 “within MACs” in the remainder).

Pneumatization relationships Higher Han pneumatization grades were associated with shorter MF‑MAC and mMEVC‑MAC distances (both P < .001), and these two distances were strongly correlated (r = 0.741, P < .001).

Age association Mastoid pneumatization grade decreased with age (inverse correlation, P < .001).

Surgical risk signal Intraoperative MAC opening occurred in 5.6% (3/54), and all had Han grade 4 pneumatization with type 2 MEVC (“within” MACs).

Clinical outcome No major intraoperative complications were reported; only one CSF wound leak (1.9%) occurred postoperatively and resolved with lumbar drainage.

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Safety and Efficacy of Real-Time Intraoperative Ultrasound-Guided Posterolateral Thoracic Diskectomy

Operative Neurosurgery 31:20–27, 2026

This article reports a single-center retrospective case series evaluating real-time intraoperative ultrasound (IOUS)-guided posterolateral thoracic diskectomy for symptomatic thoracic disk herniation (TDH). The study of 32 patients (41 levels) demonstrates significant reductions in pain and Nurick scores, low blood loss, moderate operative times, no postoperative complications, and high fusion rates at follow-up.

The manuscript details patient selection, surgical technique using IOUS for direct ventral cord visualization during posterolateral diskectomy, perioperative outcomes, and limitations. Authors conclude IOUS-guided posterolateral diskectomy is a safe, effective, and broadly adoptable method that improves decompression while minimizing morbidity compared with traditional anterior or lateral approaches.

Clinical problem: Thoracic disk herniation surgery is technically challenging because the thoracic canal is narrow and the spinal cord blocks direct access/visualization of ventral pathology.

Technique: Real-time intraoperative ultrasound (IOUS) is used during a posterolateral thoracic diskectomy to directly visualize the spinal cord and TDH, guide instrument positioning, and confirm decompression intraoperatively.

Study design: Retrospective single-surgeon series of symptomatic TDH patients treated with IOUS-guided posterolateral diskectomy from May 2020 to Feb 2025 at a major academic center.

Cohort details: 32 patients (41 levels); 50% had calcified disks (n=16), predominantly central lesions (n=13), including 2 “giant” TDHs (>40% canal).

Key operative steps: Laminectomy and partial bony removal (including <¼ pedicle), creation of a cavity by removing small cranial/caudal endplate portions, then using an ultrasound-visualized curette to push the disk fragment ventrally into the cavity for safe removal, with repeat IOUS confirmation of anterior cord decompression.

Clinical outcomes: Significant improvement in pain and neurological/ambulatory function (VAS 5.9±2.0 to 1.8±1.2; Nurick 2.8±0.7 to 1.0±0.8; P<.001 for both).

Perioperative metrics: Mean operative time 132.8±32.9 minutes, mean blood loss 118.1±77.6 mL, and average length of stay 4.7±2.6 days.

Safety/fusion: No postoperative complications were observed; among those with ≥1-year follow-up (30/32), all achieved Lenke-Bridwell Grade A or B fusion without pseudarthrosis or revision surgery.

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Multi-Institutional Assessment of Circulating Cell-Free DNA in Cerebrospinal Fluid Facilitates Central Nervous System Lymphoma Diagnosis and Treatment Initiation

Neurosurgery 99:40–49, 2026

This multi-institutional clinical study evaluates a CLIA-certified rapid PCR assay detecting the MYD88 L265P variant in cell-free DNA from cerebrospinal fluid to diagnose central nervous system (CNS) lymphoma. The assay demonstrated 100% specificity, 40% sensitivity, and facilitated earlier treatment initiation, sometimes obviating the need for risky CNS tissue biopsy.

The report details prospective implementation across 19 hospitals, methods for CSF processing and qPCR, diagnostic performance metrics, clinical trajectories of MYD88-positive patients, and implications for using CSF liquid biopsy to accelerate safe, targeted CNS lymphoma therapy.

Clinical need CNS lymphoma diagnosis has historically relied on CNS tissue biopsy, which can delay treatment and carries neurological morbidity risk.

Assay approach A CLIA-certified rapid PCR test was implemented to detect the MYD88 L265P variant in cell-free DNA (cfDNA) from CSF as a minimally invasive diagnostic method.

Deployment scale Prospective testing was conducted over 16 months across 19 hospitals: 201 samples from 184 patients; 19 samples (18 patients) were MYD88 L265P positive, with 2 test failures from inadequate DNA.

Performance characteristics In patients with available records, the assay showed specificity 100%, sensitivity 40%, PPV 100%, NPV 83% (positive LR ∞; negative LR 0.6).

Clinical utility Positive MYD88 results enabled CNS lymphoma–directed treatment initiation, including cases treated without CNS tissue confirmation, with 100% concordance between CSF and CNS tissue biopsy among contemporaneous paired cases (N=8).

Time impact MYD88-positive results often returned before biopsy (median 5.5 vs 10.5 days from admission), and time to treatment was shorter when LP/CSF testing avoided CNS biopsy (7 vs 9 days, P=.048).

Predictors/limitations Detection was more likely with leptomeningeal disease (multivariable P=.017) and DLBCL histology (multivariable P=.027); sensitivity remained modest, implying negative tests still require further workup such as biopsy.

Practice caveat (annotation) Because of modest sensitivity and concerns about spectrum bias/loss to follow-up, MYD88 CSF testing can supplement or obviate biopsy in selected cases, but generally does not replace the need for tissue-based molecular profiling.

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Fully Endoscopic Microvascular Decompression for Hemifacial Spasm Using 2-Dimensional/3-Dimensional Endoscopy

Operative Neurosurgery 30:870–879, 2026

This clinical case series reports outcomes of 204 patients who underwent fully endoscopic microvascular decompression (MVD) for hemifacial spasm (HFS), comparing 2D and preliminary 3D endoscopic techniques and analyzing learning-curve effects. Detailed methods, operative technique, intraoperative monitoring (LSR), and complication rates are presented alongside imaging and intraoperative findings.

Results show a 97.1% overall effectiveness with low long-term complication rates and improving outcomes over time; the 3D endoscope afforded improved stereoscopic perception though with higher cost and minor drawbacks, and the authors recommend further study of 3D endoscopy in MVD.

Study scope Retrospective analysis of 204 hemifacial spasm patients treated with fully endoscopic microvascular decompression using 2D (191) or 3D (13) endoscopy (July 2017–Oct 2024); mean follow-up 20.4 months.

Surgical approach Procedures used a retrosigmoid infrafloccular route with LSR monitoring; polytetrafluoroethylene (Teflon) pledgets placed between facial nerve REZ and offending vessels, with further exploration if LSR persisted.

Effectiveness At last follow-up, 198/204 (97.1%) had cessation or significant reduction of spasms (excellent 86.8%, good 10.3%).

Complications Immediate postoperative complications included facial weakness (7), hearing loss (11), tinnitus (1), infection (1), dysphagia (1), and CSF leak (1); 10 patients had persistent complications at last follow-up (6 hearing loss, 3 facial weakness, 1 tinnitus).

Learning curve Outcomes improved over time: effectiveness 95.6% → 97.1% → 98.5% (early/middle/late), while complication rates decreased 5.9% → 5.9% → 2.9%.

Offending vessels Most common offending vessel was AICA (43.1%), with multiple vessels in 33.3% of cases (including combinations with VA and PICA).

3D endoscopy pros/cons 3D endoscope provided subjectively better stereoscopic vision/depth perception aiding surgery, but had drawbacks including slight vertigo and high cost.

Overall conclusion Fully endoscopic MVD offers wide visualization of the neurovascular conflict region and helps minimize brain injury from retraction; favorable outcomes and low complications once technical proficiency is achieved, with more research needed on 3D’s role.

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Isocitrate Dehydrogenase Wild-type Glioblastoma Resection Under Fluorescein Sodium and White Light Guidance Based on Response Assessment in Neuro-Oncology Resect Criteria

Operative Neurosurgery 30:861–869, 2026

This study evaluates sodium fluorescein–guided resection versus white‑light surgery in isocitrate dehydrogenase wild‑type glioblastoma, using RANO resection classes and quantitative MRI volumes to compare residual contrast‑enhanced tumor burden. The retrospective analysis of 162 patients shows significantly lower postoperative CE residual volume and higher complete CE resection rates with fluorescein guidance.

The paper also correlates molecular markers with resection outcomes, finding MGMT promoter methylation associated with higher complete CE resection rates and suggesting fluorescein guidance may particularly improve CE resection across molecular subgroups, while survival differences require longer follow‑up and larger cohorts.

Objective Increase extent of resection of the contrast-enhanced (CE) portion of IDH–wild-type glioblastoma, using the RANO absolute residual-volume resection classes to quantify what sodium fluorescein guidance achieves vs white light (WL) surgery.

Design/measurement Retrospective comparative study of 162 patients (fluorescein 82 vs WL 80), with pre/post-op MRI volumetrics outlined in Brainlab and categorized by RANO EOR classes.

Key EOR result Residual CE tumor volume was lower with fluorescein guidance than WL (median 0.0 cm³ vs 0.5 cm³, P = .023).

Complete CE resection rate Proportion with 0 cm³ residual CE (RANO I + IIA) was higher with fluorescein (62.2%) than WL (42.5%), P = .012.

RANO distribution shift RANO class distribution differed between groups (P = .015), with more IIA and fewer IIB resections under fluorescein guidance.

Non-CE resection No significant between-group differences were found in preoperative CE/NCE volumes or postoperative NCE residual volumes, consistent with fluorescein primarily highlighting BBB-disrupted (enhancing) tissue.

MGMT association MGMT promoter methylation was associated with higher likelihood of achieving nonresidual CE (complete CE resection), P = .005; fluorescein guidance and MGMT status were significant predictors of nonresidual CE.

Survival Overall survival did not significantly differ between fluorescein-guided and WL groups (log-rank P = .15), while MGMT-methylated patients had significantly better survival than unmethylated (P = .019; HR = 0.52).

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A New Area of Neurosurgery: First Robotic Neurosurgery Clinical Case Series

Operative Neurosurgery 30:929–937, 2026

This clinical report presents the first institutional case series using the da Vinci Xi robotic system applied to neurosurgical procedures, detailing patient selection, operative technique, training, and outcomes for five patients with lesions including clivus chordoma, odontoid metastasis, peroneal neuropathy, and an arachnoid cyst. The series emphasizes procedural feasibility, intraoperative setup, and interdisciplinary collaboration with otolaryngology for transoral and intracranial approaches.

The authors highlight benefits such as enhanced precision, tremor filtration, and minimally invasive access in narrow corridors, while candidly discussing limitations including lack of haptic feedback, high capital costs, training needs, and the current absence of neurosurgery-specific instrument integration; postoperative follow-up showed favorable outcomes without new neurological deficits.

Goal Share early clinical experience adapting the da Vinci Xi surgical robot for neurosurgical procedures, addressing limited current adoption in neurosurgery.

Training Surgeon completed formal robotic training plus simulation, then practiced planned operations on cadavers and calf brains under guidance before clinical use.

Series Five patients underwent robot-assisted neurosurgery (2018–2022) for clivus chordoma (2), odontoid metastatic mass (1), peroneal neuropathy (1), and arachnoid cyst (1).

Technique Cases used a typical 2 robotic arms + 4K camera setup; the surgeon operated from a console with tremor filtration and enhanced instrument dexterity.

Approaches Robotic procedures included transoral tumor resection/odontoidectomy, peroneal nerve decompression, and intracranial arachnoid cyst fenestration (robot used after initial craniotomy steps in the cyst case).

Outcomes No intraoperative or postoperative neurological deficits or complications were observed; all 5 patients had favorable outcomes with 6–24 months follow-up.

Advantages Particular value noted for working in narrow/deep corridors (eg, clivus/odontoid) and for tasks like transoral resection and cyst fenestration, leveraging articulated movement and tremor cancellation.

Limitations/needs Key constraints include lack of tactile feedback, potential device malfunction, nonstandardized training, dedicated staffing needs, and high costs; practical training is emphasized as essential, with further evaluation needed.

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Is the chin-brow vertical angle always a reliable parameter for surgical planning in the correction of thoracolumbar kyphosis secondary to ankylosing spondylitis?

J Neurosurg Spine 44:858–865, 2026

This clinical retrospective study evaluates whether the chin-brow vertical angle (CBVA) reliably predicts the osteotomized vertebra angle (OVA) when planning pedicle subtraction osteotomy for thoracolumbar kyphosis secondary to ankylosing spondylitis. Patients were stratified by cervical range of motion (CROM) and radiographic changes in CBVA, cervical Cobb angles, and global sagittal parameters were analyzed.

Results show a strong correlation between ΔCBVA and OVA in patients with limited CROM (≤20°), but no correlation when CROM exceeded 20°, indicating that CBVA alone is unreliable for OVA design in patients with flexible cervical spines. The study recommends considering cervical mobility when selecting OVA planning methods and suggests supplementing CBVA with measures of cervical compensation in flexible cases.

Objective Examine how well CBVA predicts needed correction (OVA) in ankylosing spondylitis (AS) thoracolumbar kyphosis across different cervical range of motion (CROM) values.

Design/Groups Retrospective cohort of AS patients undergoing single-level thoracic or lumbar pedicle subtraction osteotomy (PSO) (2015–2019) with ≥2-year follow-up; grouped by CROM: ≤10°, 10–20°, and >20°.

Key finding (CROM ≤20°) Strong correlation between ΔCBVA (preop→immediate postop) and OVA in CROM ≤10° and 10–20° groups (r = 0.881 and 0.932; both p < 0.001), supporting CBVA-based planning when cervical motion is limited.

Key finding (CROM >20°) No correlation between ΔCBVA and OVA when CROM > 20° (r = 0.198, p = 0.314), and most patients (89%) had ΔCBVA smaller than OVA, implying undercorrection risk if CBVA alone guides OVA.

Cervical adaptation mechanism With higher cervical mobility, postoperative cervical alignment changes substantially (CNA group cervical kyphosis change 20.25° vs 4.97° in CA), which can blunt CBVA change despite large osteotomy correction.

Improved predictor Adding cervical alignment change (ΔCobb C0–7) to CBVA change yields closer agreement with OVA (ΔCobb C0–7 + ΔCBVA correlated with OVA in both CA and CNA groups; CA r = 0.87 p < 0.001; CNA r = 0.38 p = 0.044).

Clinical recommendation CBVA is not consistently reliable for OVA design; it is not recommended as a guiding parameter when CROM > 20°.

Outcomes Both cervical-ankylosis–range (CROM ≤20°) and nonankylosis–range (CROM >20°) subgroups achieved satisfactory orthopedic improvement after surgery despite differences in cervical compensation.

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Prospective untreated outcomes in patients with cerebral cavernous malformation

J Neurosurg 144:1344–1352, 2026

This prospective cohort study quantifies long-term functional outcomes in 332 untreated patients with cerebral cavernous malformation (CCM), using modified Rankin Scale (mRS) scores to evaluate disability over a mean 6.6-year follow-up. It reports incidence of symptomatic hemorrhage (SH), temporal patterns of recovery after a first SH, and external validation of published predictive nomograms.

Key findings identify brainstem location, a history of self-reported psychiatric disorder, and two or more SHs as independent predictors of long-term disability; most patients improved within one year after a first hemorrhage, and ten-year disability risk for nonbrainstem CCM was under 8%.

Objective Elucidate long-term morbidity and disability risk in adults with untreated cerebral cavernous malformation (CCM).

Methods Prospectively followed registry cohort; functional outcome tracked using mRS, with disability defined as mRS ≥ 3; time-to-disability analyzed via Kaplan–Meier and risk factors via Cox models; previously published morbidity nomograms were externally validated.

Cohort 332 patients (58.4% female; mean age 44.5); 19.8% familial CCM; 28.0% brainstem location; 38.3% presented with symptomatic hemorrhage (SH).

Recovery after first SH Among patients with SH who had no further SH and no surgery (n=48), disability (mRS ≥ 3) was 27.1% at diagnosis, improving to 6.2% at 1 year and 4.7% at 5 years, with most improvement in year 1.

Hemorrhage burden Over mean 6.6 years, 31.0% had ≥1 prospective SH and 14.5% had multiple prospective SHs; disability rose sharply with each SH (mRS ≥ 3: 2.3% with 0 SH up to 100% after 5 SHs in untreated follow-up).

Location risk Brainstem CCM carried substantially higher disability risk (18.8% at 5 years; 35.4% at 10 years) versus nonbrainstem locations (4.1% at 5 years; 7.5% at 10 years).

Predictors Multivariate predictors of disability included brainstem location, self-reported psychiatric disorder, and ≥2 SHs.

Nomogram validation Prior nomograms showed high specificity but limited sensitivity; AUC 0.687 for predicting mRS ≥ 2 and 0.783 for predicting mRS ≥ 3.

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Adjacent segment disease treated with stand-alone lateral lumbar interbody fusion: an analysis of domino adjacent segment revisions

J Neurosurg Spine 44:884–893, 2026

This clinical study compares stand-alone lateral lumbar interbody fusion (LLIF) with circumferential LLIF plus posterior instrumentation for treating adjacent segment disease (ASD) after prior posterior lumbosacral fusion. Primary outcome focused on “domino” proximal ASD revisions, with secondary measures including cage subsidence, radiographic alignment, and perioperative metrics.

Results from 236 patients show stand-alone LLIF had significantly lower 5-year domino ASD revision rates, shorter operative times and hospital stays, and comparable alignment despite higher rates of moderate-to-severe cage subsidence. Multivariable and competing-risk analyses supported stand-alone LLIF’s protective association against subsequent adjacent-segment reoperations.

Objective Assess whether stand-alone LLIF is a durable ASD revision strategy with lower risk of subsequent “domino” adjacent-segment revision compared with circumferential LLIF (LLIF + posterior fusion extension).

Design/Methods Single-center retrospective cohort (Jan 2008–Aug 2023) of patients with prior posterior lumbosacral fusion undergoing ASD revision via stand-alone vs circumferential LLIF; primary outcome was domino ASD revision; survival analysis and multivariable Cox regression used, adjusting for alignment, stenosis severity, and fused levels.

Cohort 236 patients included (131 stand-alone; 105 circumferential); baseline demographics/treated levels similar; preop MRI showed more severe central stenosis in the circumferential group (more Schizas grade D).

Primary outcome Stand-alone LLIF had a lower 5-year incidence of domino ASD revision (13.7% vs 28.6%, p = 0.005).

Adjusted association After multivariable adjustment, stand-alone LLIF remained independently associated with fewer domino ASD revisions (HR 0.43, 95% CI 0.23–0.79; p = 0.007).

Radiographic outcomes Overall radiographic alignment was comparable between groups, but stand-alone LLIF had higher cage subsidence (Marchi grade ≥ II: 22.9% vs 9.5%, p = 0.019), and subsidence was not associated with increased revision risk.

Perioperative outcomes Stand-alone LLIF had significantly shorter operative time and hospital stay than circumferential LLIF (with lower blood loss also reported).

Conclusion Stand-alone LLIF is supported as a treatment option for ASD after prior posterior fusion, with less domino ASD revision and similar radiographic alignment, at the cost of higher subsidence rates.

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Ethical aspects of waiting lists in neurosurgery

Acta Neurochirurgica (2026) 168:135

This narrative review examines the ethical implications of prolonged waiting lists for elective neurosurgery worldwide, using a four-principles bioethics framework (beneficence, nonmaleficence, autonomy, justice). It synthesizes literature, global examples, and case illustrations to show how extended delays can worsen outcomes, increase psychosocial burden, and mask hidden rationing.

The paper identifies systemic drivers of waiting lists—including resource limits, poor management, and policy choices—and argues for multifaceted solutions: transparent prioritization, improved referral and patient-flow systems, strengthened accountability across government, institutions, and clinicians, and better data collection to guide ethically grounded reforms.

Scope Long waiting times and large waiting lists for elective neurosurgery are a persistent global problem, intensified when outpatient and diagnostic delays are included.

Evidence gap Most available waiting-time evidence comes from high-volume non-neurosurgical procedures (e.g., cataract, hip/knee), with limited neurosurgery-specific research and few comprehensive multicenter/multinational datasets.

Clinical & psychosocial harm Delayed neurosurgical care is associated with uncertainty, dissatisfaction, pain/anxiety, severe depression risk, worse outcomes, higher costs, reduced quality of life, inequalities, and erosion of patient trust.

Bioethics—beneficence & nonmaleficence Extended waiting generally conflicts with doing good and avoiding harm by prolonging suffering and enabling deterioration, though limited exceptions exist where delaying surgery can prevent unnecessary procedures (e.g., some disc herniations with potential spontaneous recovery).

Bioethics—autonomy Long waits can undermine patient autonomy by preventing timely treatment aligned with patient wishes, limiting options as conditions evolve, and weakening informed consent when circumstances change between consent and surgery; lack of transparent queue/wait-time information is a key problem.

Bioethics—justice tension Under constrained access, distributive justice principles can conflict; long waiting lists can function as hidden rationing, with risks of unequal access tied to socioeconomic status, age, ethnicity, communication skills, gender, or geography.

Accountability Ethical responsibility for waiting lists spans government (macro resource commitments), hospital management (meso organization/capacity), and physicians (micro-level indications, prioritization, patient information/advocacy), though not equally.

Conclusion & direction Long waiting lists potentially violate three core biomedical principles (beneficence, nonmaleficence, autonomy) and challenge justice; addressing them requires better documentation plus multifaceted reforms beyond simply adding resources, emphasizing transparent prioritization and fair, ethical governance.

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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.

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Early Initiation of Radiation Therapy Improves Survival in Elderly Patients With Glioblastoma

Neurosurgery 98:1402–1412, 2026

This clinical study evaluates the effect of early postoperative radiation therapy (RT) initiation on survival in patients aged 65 and older with IDH‑wildtype glioblastoma, analyzing outcomes from a prospective registry of 56 patients treated between 2020–2024. Survival analyses, including Kaplan‑Meier curves and Cox regression, compare outcomes for RT started <20 days versus ≥20 days after surgery and examine RT fractionation and temozolomide use.

Results show that initiating RT within 20 days post‑surgery is associated with improved overall survival and progression‑free survival on univariate analysis, while multivariate models indicate confounding by performance status and adjuvant temozolomide; adjuvant TMZ remains a strong positive predictor of survival. The authors conclude early RT may benefit elderly GBM patients and call for prospective randomized trials to confirm timing effects.

Study aim: Evaluate whether earlier start of postoperative radiation therapy (RT) improves survival in elderly (≥65) patients with newly diagnosed IDH-wildtype glioblastoma.

Cohort & design: Retrospective cohort using a prospective registry (2020–2024), 56 patients, comparing RT start <20 days vs ≥20 days after surgery; endpoints were overall survival (OS) and progression-free survival (PFS).

Univariate survival finding: Starting RT <20 days after surgery was associated with improved OS (P=.0460) and PFS (P=.0075) versus ≥20 days.

Adjusted (multivariate) finding: After adjustment (including KPS and adjuvant temozolomide), RT timing was not statistically significant for OS (P=.2962) or PFS (P=.0670), indicating likely confounding.

Temozolomide effect: Adjuvant temozolomide was a significant predictor of better outcomes on multivariate analysis for both OS (P=.0038; HR 0.16) and PFS (P=.0133; HR 0.27).

Fractionation nuance: Among those starting RT early (<20 days), conventionally fractionated RT (60 Gy/30 fx) showed significantly improved PFS (P=.0164), while hypofractionated RT (40 Gy/15 fx) did not reach significance (P=.0509).

Baseline group differences: The <20-day RT group had better performance status (higher KPS, lower ECOG) and higher rates of receiving adjuvant temozolomide, which may influence observed survival differences.

Clinical implication noted: Timely initiation of adjuvant therapy (RT and chemotherapy) may be particularly important in elderly patients, but stronger evidence (e.g., prospective randomized trial) is needed to define optimal timing and account for confounding/logistical delays.

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Ventral Spinal Cord Displacement: A Guide to Differentiating Spinal Cord Herniation From Dorsal Arachnoid Web

Operative Neurosurgery 30:977–984, 2026

This article reviews imaging and operative distinctions between spinal arachnoid webs (SAW) and spinal cord herniation (SCH), using two detailed case illustrations with narrated 2-D operative videos. It highlights diagnostic imaging features, intraoperative findings, and tailored surgical techniques to optimize differentiation and management.

Focusing on technical nuance, the paper contrasts midline-sparing unilateral laminectomy and arachnoid lysis for SAW with bilateral laminectomy, cord mobilization, and ventral alloderm sling reconstruction for SCH, and emphasizes intraoperative ultrasound and neuromonitoring for safe reduction and decompression.

Problem: Spinal arachnoid web (SAW) and spinal cord herniation (SCH) can present similarly (myelopathy/radiculopathy) and both often look like focal anterior cord displacement on MRI, yet require very different operative strategies.

Definitions: SAW is abnormally thickened arachnoid tissue in the subarachnoid space that can tether/compress the cord and disrupt CSF flow (edema/syrinx), while SCH is cord displacement through an opening in the dura/arachnoid (often ventral).

Imaging workup: CT myelography is recommended to evaluate/confirm suspected findings because its resolution can outperform MRI for distinguishing these entities.

Key imaging clues: Visible ventral CSF between cord and ventral dura argues against herniation, while absence of ventral CSF supports SCH; cord twisting at the abnormal level is a more specific sign for SCH; the “scalpel sign” is commonly linked to SAW but can occur in both.

Limits of imaging: Arachnoid webs are below MRI/CT resolution, and diagnostic patterns are imperfect (reported SAWs can lack the scalpel sign or mimic SCH on CT myelogram).

SAW surgery: Definitive treatment is lysis/excision of the thickened arachnoid band, often via laminectomy with ultrasound localization; dentate ligament division can help inspect the ventral compartment to exclude ventral pathology.

SCH surgery: Management typically uses wider exposure (often bilateral laminectomy), spinal cord mobilization/rotation (sectioning dentate ligaments ± dorsal rootlets), reduction of the herniation, and placement/suturing of a ventral alloderm sling to span the dural defect, with close neuromonitoring and ultrasound confirmation.

Outcomes in cases: SAW case showed postoperative normalization of cord position and complete syrinx regression after web excision/lysis; SCH case showed complete reduction of herniation on postoperative MRI with substantial functional improvement (including near-resolution of bowel/bladder symptoms).

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The posterior approach for removal of all thoracic disc herniations

J Neurosurg Spine 44:876–883, 2026

his single-surgeon series evaluates a posterior partial transpedicular approach for symptomatic thoracic disc herniation augmented by intraoperative ultrasound (IOUS) and ultrasonic aspiration (UA). Over 108 patients (137 discs) treated from 2012–2024, the technique produced significant neurological improvement with an acceptable complication and reoperation profile.

The report details patient selection, operative steps, radiographic grading, neuromonitoring use, outcomes (Frankel grade improvements), and multivariate predictors, highlighting the method’s versatility for giant and calcified herniations and its accessibility to general spine surgeons.

Clinical problem Thoracic disc herniation is surgically challenging due to ventral location, frequent calcification, and risk of severe neurologic compromise; anterior/lateral approaches can be effective but carry substantial morbidity and technical demands.

Study aim Evaluated safety, efficacy, and versatility of a posterior partial transpedicular discectomy augmented with intraoperative ultrasound (IOUS) and ultrasonic aspiration (UA) for symptomatic TDH.

Cohort & design Retrospective single-surgeon series of 108 consecutive patients (137 TDHs) treated from 2012–2024; outcomes tracked with Frankel grades preop, 3–6 months, and final follow-up; multivariate regression used to identify predictors of improvement.

Key technique Posterior midline exposure with laminectomy, <50% medial facetectomy, and superomedial caudal pedicle removal using UA to create a corridor; IOUS used after laminectomy, during ventral work, and after resection to confirm decompression and detect residual/migrated fragments; IONM used in all cases.

Case mix severity Most patients presented with myelopathy (86.1%); many discs were giant (>40% stenosis, 68.6%) and frequently calcified (complete 38.7%, incomplete 21.2%).

Neurologic outcomes Mean Frankel grade improved from 3.77 preop to 4.54 at last follow-up (p < 0.001); 61.1% improved by ≥1 Frankel grade; follow-up for the primary outcome was 100%.

Safety & complications IOUS and UA enabled safe decompression in all cases; reoperation-requiring complications occurred in 9.3% (most commonly reherniation 4.6%); no postoperative CSF leaks through the wound were reported.

Predictors & conclusion Less neurologic improvement was associated with diabetes and obesity (and heart disease); overall conclusion: posterior partial transpedicular approach with IOUS and UA is safe, effective, and broadly applicable for TDH (including large/calcified lesions) and can be adopted by general spine surgeons.

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A novel interpretable classification of lumbar spinal stenosis using a cascade deep learning approach and T2-weighted MRI

J Neurosurg Spine 44:847–857, 2026

This clinical article presents a fully automated, interpretable three-stage deep learning pipeline for detecting and grading lumbar spinal stenosis (LSS) using axial T2-weighted MRI. The framework integrates region classification, YOLO-based ROI detection, and CNN-based severity grading, validated on internal (640 patients, 17,440 slices) and external (515 patients, 8,000 slices) datasets with high accuracy and explainability via Grad-CAM.

The study details dataset curation, model architectures (ResNet-18, RegNetX-400MF, EfficientNet-B0, YOLOv5/8), training protocols, evaluation metrics, and clinical implementation pathways, highlighting strengths, limitations (single-rater labels, class imbalance, 2D slice analysis), and future directions toward volumetric and multi-expert validation.

Objective Standardize and automate lumbar spinal stenosis (LSS) identification, classification, and grading from axial T2-weighted lumbar MRI to reduce diagnostic variability.

Pipeline Three-stage cascade: (1) classify slices into sacral/lumbar/thoracic regions, (2) detect and crop anatomical ROIs, (3) grade LSS as binary or multiclass severity.

Datasets Internal training set: 640 patients with 17,440 retained axial T2 slices; external validation set: 8000 preprocessed, neurosurgeon-graded axial slices from an open-access dataset (515 patients).

Grading scheme Labels follow Schizas central canal stenosis grades A–D; a binary version groups A+B as nonstenotic and C+D as clinically significant stenosis.

Models Lightweight CNN backbones (ResNet-18, RegNetX-400MF, EfficientNet-B0) used for stages 1 and 3; YOLOv5/YOLOv8 used for ROI detection.

Validation approach Patient-level splits with 10-fold cross-validation to reduce overfitting and data leakage; an independent internal test set (62 patients, 1679 slices) reserved for final evaluation.

Performance Achieved 97.87% accuracy for binary LSS grading and 95.52% accuracy for multiclass grading, outperforming prior models in this setting.

Interpretability & clinical aim Grad-CAM heat maps highlight regions influencing predictions to support trust and potential workflow integration as an interpretable decision-support tool.

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Exploring the Diagnostic Test Accuracy of MicroRNAs as Potential Biomarkers for Glioblastoma

Neurosurgery 98:1221–1230, 2026

This systematic review and meta-analysis evaluates microRNA (miRNA)–based liquid biopsies for diagnosing glioblastoma (GBM), synthesizing data from 15 studies and 28 biomarker evaluations across 868 samples. Key diagnostic metrics—pooled sensitivity 0.84 and specificity 0.89—indicate strong potential, with miR-21 showing the highest accuracy among single-miRNA assays.

The report details search strategy, inclusion criteria, statistical methods, subgroup analyses (miRNA type, biofluid source, control type), and study quality assessment. Limitations include methodological heterogeneity, high risk of bias in patient selection, inconsistent reporting (CSF source, IDH status), and small cohort sizes, underscoring need for standardized clinical validation.

Aim Evaluate the diagnostic accuracy of microRNA (miRNA) liquid biopsies (blood/serum/plasma/CSF) for diagnosing glioblastoma (GBM) via systematic review and meta-analysis.

Methods PRISMA-guided searches of Ovid Medline and Embase (updated through Oct 16, 2024); included studies had histologic GBM confirmation and extractable 2×2 diagnostic data; pooled estimates generated using a random-effects bivariate model.

Evidence base 15 included articles (published 2011–2022) provided 28 miRNA evaluations, totaling 868 samples from 551 GBM patients and 811 samples from 578 controls.

Overall accuracy Pooled sensitivity 0.84 and specificity 0.89, with heterogeneity of 66% (sensitivity) and 39% (specificity); pooled AUC 0.89.

Likelihood ratios Pooled PLR 7.26, NLR 0.19, and DOR 40.17, indicating strong overall discriminatory performance.

Key biomarker miR-21 showed the highest pooled performance among assessed groupings (sensitivity 0.90, specificity 0.95).

Subgroups Single miRNAs had higher specificity than multi-miRNA panels, while diagnostic capability did not differ clearly by biofluid source (CSF vs blood) in this dataset.

Limitations All included studies had high risk of bias in patient selection, and many had bias in index test interpretation/flow-timing; limited CSF comparisons and inconsistent qPCR thresholds/normalization contributed to heterogeneity and constrain clinical translation without standardization and validation.

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Morphometric assessment of the posterior cranial fossa and its contents in patients with chiari malformation type I and type 0

Acta Neurochirurgica (2026) 168:117

This study presents a retrospective, landmark-based morphometric analysis of the clivus, tentorium, and posterior cranial fossa on midsagittal MRI in 326 subjects, comparing Chiari malformation Type I (CM-I), Chiari Type 0 (CM-0), and matched controls. Key measured parameters include clivus length and angle, tentorial angle, foramen magnum diameter, and area-based ratios relating cerebellum, posterior fossa, and intracranial cavity.

Findings indicate that CM-I patients exhibit clival shortening, reduced posterior cranial fossa area, altered tentorial orientation, and increased cerebellar occupancy relative to posterior fossa and brain, whereas CM-0 patients show morphometry comparable to controls. The authors conclude CM-I has distinct morphoanatomical remodeling, while CM-0 may represent a functional clinical entity without consistent structural substrate.

Definitions: CM-I is defined by ≥5 mm cerebellar tonsillar descent below the foramen magnum on MRI, while CM-0 is defined by <3 mm descent despite Chiari-like symptoms.

Design: Retrospective mid-sagittal MRI morphometry of 326 adults (CM-I n=111, CM-0 n=27, controls n=188) using multiple cranial base, posterior fossa, cerebellar, and intracranial measurements plus area-based ratios.

Key CM-I anatomy: Compared with CM-0 and controls, CM-I showed shorter clivus length, smaller posterior cranial fossa area, and larger cerebellar area; foramen magnum diameter and total brain area were similar across groups.

Crowding ratios: CM-I had higher cerebellum/posterior fossa and cerebellum/brain area ratios, indicating increased relative cerebellar occupancy despite preserved global cranial proportions.

CM-0 vs controls: CM-0 morphometric measurements were largely comparable to healthy controls, with no consistent structural differences in the main posterior fossa metrics highlighted.

Interpretation: CM-I aligns with a pattern of cranial base remodeling and posterior fossa insufficiency, whereas CM-0 may be better viewed as a functionally defined condition rather than one with a consistent structural substrate.

Reliability/statistics: Analyses used nonparametric tests (Kruskal–Wallis with Bonferroni-corrected Mann–Whitney post hoc), and interobserver measurement reliability was good–excellent (ICC 0.82–0.94).

Limitations: Morphometry was 2D mid-sagittal (not full 3D volumetry) and CSF flow dynamics (e.g., phase-contrast MRI) were not uniformly available, limiting functional assessment—especially relevant to CM-0.

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The role of salvage stereotactic radiosurgery for tumor progression following incomplete microsurgical resection of vestibular schwannoma

J Neurosurg 144:1403–1409, 2026

This clinical study evaluates salvage stereotactic radiosurgery (SRS) for vestibular schwannoma (VS) that progresses after incomplete microsurgical resection, reporting long-term tumor control, freedom from additional treatment (FFAT), and complication rates in a 64-patient cohort. Key outcomes include 10- and 15-year tumor control of 87.5% and 84.4%, and FFAT of 95.3% and 92.2%, respectively.

The methods describe retrospective selection, radiosurgical dosimetry (median margin 12.5 Gy), imaging and follow-up protocols, and statistical analyses using Kaplan–Meier and Cox models; no factors significantly predicted control or FFAT, and common complications included trigeminal neuropathy and hearing worsening.

Objective Assess safety/efficacy of salvage stereotactic radiosurgery (SRS) for vestibular schwannoma (VS) that progresses after incomplete microsurgical resection, including factors affecting tumor control and freedom from additional treatment (FFAT).

Cohort Retrospective series of 64 adults treated with salvage SRS for post-resection tumor progression; median age 51.5 years and 46.9% male.

Treatment parameters Median marginal dose 12.5 Gy (median isodose 50%); median tumor volume 1.6 cm³; median time from surgery to salvage SRS 38.8 months.

Long-term control Tumor control rates after salvage SRS were 87.5% at 10 years and 84.4% at 15 years.

Durability (FFAT) FFAT rates were 95.3% at 10 years and 92.2% at 15 years, indicating most patients avoided further intervention long term.

Predictors No evaluated factors (e.g., Koos grade, age/sex, cranial nerve neuropathies, marginal dose, extent of resection, tumor volume) were significantly associated with tumor control or FFAT in Cox modeling.

Complications Most common post-SRS issue was worsening/new trigeminal neuropathy (15.6% total); hearing worsened in 14.1% (Gardner-Robertson class), and facial nerve function worsened in 4.7% (House-Brackmann).

Conclusion Salvage SRS is a safe and effective long-term strategy for VS tumor progression after incomplete resection, supporting continued monitoring and consideration of SRS once progression is documented.

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History and evolution of the far‑lateral approach in neurosurgery

Acta Neurochirurgica (2026) 168:122

This review chronicles the development and technical refinement of the far‑lateral approach (FLA) for accessing the foramen magnum, lower clivus, and craniovertebral junction, tracing its origins from lateral suboccipital exposures to contemporary transcondylar, supracondylar, paracondylar, and extreme lateral transodontoid variants. It summarizes modifications in skin incisions, bony resection strategies, VA management, positioning, and closure techniques that improved exposure while minimizing brain retraction and craniovertebral morbidity.

The article evaluates clinical outcomes, biomechanical data, and technological integrations—endoscopic assistance, neuronavigation, and neuromonitoring—emphasizing a tailored, pathology-driven philosophy: remove only the bone necessary, mobilize the vertebral artery judiciously, and consider occipitocervical fusion when stability thresholds are exceeded to balance maximal resection with minimal long‑term instability and CSF complications.

Purpose: Provides a more anterior, tangential corridor to the foramen magnum/lower clivus/CVJ for ventrolateral or anterior brainstem pathology, reducing the need for brainstem/cerebellar retraction compared with older midline posterior and transoral routes.

Origins: Evolved from posterolateral aneurysm surgery—early unilateral suboccipital routes in the 1970s, with the first detailed “lateral suboccipital” (far-lateral) description by Heros in 1986 to reach distal vertebral and basilar trunk aneurysms by extending bone removal to the lateral foramen magnum rim.

Key bone-work concept: The major exposure-expanding step is selective occipital condyle drilling (transcondylar variant), typically about one-third to one-half to improve the angle of attack while aiming to preserve craniocervical stability; complete condyle removal is rare and generally prompts fusion.

Modular variants: The approach is used as adjustable “modules,” most notably transcondylar, supracondylar (jugular tubercle drilling), and paracondylar extensions, chosen based on lesion location and direction of extension.

Soft-tissue refinements: Incisions shifted from simple linear cuts to more tailored curvilinear/hockey-stick/C-shaped designs with larger musculocutaneous flaps to improve exposure, enable layered closure, and reduce wound/CSF-leak complications.

Positioning evolution: Use moved away from sitting (air embolism risk) toward lateral/modified park-bench positioning to leverage gravity-assisted relaxation and minimize fixed retraction.

Neurovascular strategy: Standardization of extradural vertebral artery (V3/V4) exposure and mobilization (when needed) improved proximal control and widened the corridor, turning the artery from an obstacle into a structure that can be safely managed to expand working space.

Modern extensions & technology: Continued refinement includes endoscope-assisted visualization, neuronavigation, and neuromonitoring; an extreme extension (ELTO) adds aggressive bony removal (including odontoid/C1 elements) for midline-crossing lesions but carries high instability risk, so occipitocervical fusion is typically performed.

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