Author: cba

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Focused ultrasound thalamotomy for essential tremor in octogenarians

J Neurosurg 145:27–35, 2026

This multicenter retrospective cohort study evaluates unilateral MR-guided high-intensity focused ultrasound (MRgHIFU) thalamotomy targeting the ventral intermediate nucleus (VIM) for medically refractory essential tremor in patients aged 80 years and older. Results from 129 patients show marked reductions in tremor and disability scores, high patient-reported relief, and generally mild, transient adverse events.

Age-stratified analyses found comparable tremor benefit across 80–84 and ≥85 year groups, modest gait changes, and low rates of serious complications, supporting MRgHIFU as a noninvasive therapeutic option for elderly patients ineligible for deep brain stimulation.

Objective Evaluate safety and efficacy of unilateral MRgHIFU thalamotomy targeting the VIM for medication-refractory essential tremor in patients aged ≥ 80 years.

Design Retrospective, multicenter cohort of consecutive patients treated between 2016 and 2023 at five academic centers, with assessments at baseline, immediately posttreatment, and 3 months.

Primary outcome Tremor severity measured by TETRAS; primary endpoint was change from baseline to follow-up.

Efficacy In 129 patients (mean age 84), mean TETRAS improved by 9.2 points at 3 months (p < 0.001), with significant improvement also seen on CRST and mean patient-reported tremor relief of 81%.

Gait effects DGI gait scores improved modestly overall but were not significant in the ≥ 85 years subgroup.

Safety Adverse events were generally mild/transient; nonsurgical adverse events occurred in 1.6% of patients.

Age-stratified results Treatment response and adverse event profiles did not significantly differ between ages 80–84 and ≥ 85 years.

Conclusion Unilateral MRgHIFU VIM thalamotomy provides a low-complication, noninvasive option that significantly improves tremor and disability in adults aged ≥ 80 years, supporting consideration for those ineligible for invasive procedures like DBS.

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Intraoperative Ultrasound in Chiari 1 Decompression: Clarity or Confusion?

Neurosurgery 99:19–29, 2026

This systematic review evaluates intraoperative ultrasound (iUS) use in guiding the extent of posterior fossa decompression (PFD versus PFD+) for Chiari malformation type 1, analyzing nine studies (844 patients) for iUS criteria, conversion rates, and positive predictive values. It finds substantial heterogeneity in acquisition, qualitative versus quantitative criteria, and outcome reporting, limiting iUS’s reliability for intraoperative decision making.

The authors propose a standardized reporting framework emphasizing defined CSF space measurements, dynamic metrics (e.g., CSF flow velocity, tonsillar excursion), triplicate measurements with dual raters, and ≥12-month validated outcomes to enable reproducible research and clearer assessment of iUS utility.

Clinical dilemma Bone-only posterior fossa decompression (PFD) is less invasive, while dural opening/expansion (PFD+) may be more effective but has higher complication risk; intraoperative ultrasound (iUS) is used to help decide whether PFD alone is sufficient, but its role/criteria are not defined.

Evidence base 9 studies (1 prospective, 8 retrospective) totaling 844 patients (pediatric and adult) were included; risk of bias was low in 1 study, moderate in 3, and high in 5.

How iUS was applied iUS was used after bony decompression and before dural opening; none of the studies used iUS after opening the dura.

Decision criteria heterogeneity 8 studies used qualitative criteria (e.g., “enough space,” tonsillar pulsation, piston-like motion, bidirectional flow), and 1 study used a quantitative CSF flow-velocity threshold.

Conversion surgery outcomes “Conversion” (later revision from PFD to PFD+ due to persistent/worsening symptoms) occurred in 35/844 patients (5% overall), with study-level conversion rates from 0% to 16%.

Predictive value variability Positive predictive value (PPV) for iUS-guided PFD success ranged from 0.857 to 1.000 across studies, varying with criteria and study design.

Main conclusion Current evidence does not support iUS as a robust intraoperative test for deciding extent of decompression because of heterogeneous application and lack of standardized assessment criteria; sensitivity/specificity cannot be determined with available data structure.

Proposed path forward A standardized reporting framework is proposed, emphasizing defined acquisition parameters, quantitative/operationalized criteria, validated outcome measures, and ≥12-month follow-up to enable comparability and future pooled analyses.

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Predictive Values of Lumbar Infusion Testing in Idiopathic Normal Pressure Hydrocephalus Diagnosis

Neurosurgery 99:50–59, 2026

This study evaluates lumbar infusion testing (LIT) as an adjunctive diagnostic tool for idiopathic normal-pressure hydrocephalus (iNPH) in a cohort of 165 patients, defining an optimal Rout threshold (≈12 mm Hg·mL−1·min−1) with good sensitivity and specificity. It reports LIT’s role in multidisciplinary decision-making, its safety, and its contribution to selecting patients for ventriculoperitoneal shunting and improving postshunt outcomes.

The authors detail standardized clinical, radiological, and hydrodynamic assessments, show outcome rates after shunting across pretest probability groups, and propose a diagnostic algorithm positioning LIT as a reproducible, low-morbidity adjunct when clinical and imaging data remain inconclusive.

Goal Evaluate lumbar infusion testing (LIT) performance to support shunt decision-making in suspected idiopathic normal-pressure hydrocephalus (iNPH), given no single reliable diagnostic test exists.

Cohort 201 referred; 165 had interpretable LIT results (mean age 79), assessed with combined clinical, radiological, and hydrodynamic workup.

Symptom profile In the 165-patient LIT cohort, gait disturbance was present in 98.8%, cognitive impairment in 86.6%, and urinary disturbances in 58.8%.

Key metric CSF outflow resistance (Rout) differed significantly across diagnostic probability groups, and the optimal cutoff was ~12 mm Hg/mL/min (AUC 0.8441), yielding 78.1% sensitivity and 74.3% specificity for shunt-response prediction.

Clinical utility (borderline cases) In patients initially classified as possible iNPH who were shunted based on LIT findings, 75.6% improved clinically.

Outcomes (high-probability cases) In the probable iNPH group, 87.1% of shunted patients showed improvement.

Safety No complications (e.g., intracranial hypotension syndrome or infection) were observed after LIT in this cohort.

Conclusion LIT is not definitive for iNPH diagnosis but is a safe, reproducible adjunct that helps in diagnostic uncertainty, supports earlier decision-making, and can help avoid unnecessary surgery when combined with clinical and radiological assessment.

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Resectability of White Matter Tracts in Patients With Language-Critical Gliomas

Neurosurgery 99:140–148, 2026

This study evaluates how resections of language-associated white matter tracts (WMTs) predict persistent postoperative language deficits (PLDs) in 68 glioma patients using tractography, intraoperative mapping, and outcome assessments. Results show WMT resection strongly predicts PLDs with high negative predictive value but modest positive predictive value, and temporal/parietal segments carry the greatest risk.

Anatomic clustering localized high-risk resections to the temporoparietal junction and middle temporal lobe, while frontal operculum and orbitofrontal tracts were often resectable without lasting deficits. Anatomically stratifying tracts (parietal/temporal) improved positive predictive value, supporting tractography-informed surgical planning alongside intraoperative mapping.

Goal Identify predictors of permanent postoperative language deficits (PLDs) in language-eloquent glioma surgery by analyzing which language-associated white matter tract (WMT) segments are resected.

Cohort & approach Retrospective analysis of consecutive adults undergoing awake craniotomy with intraoperative language mapping; WMT tractography reconstructed 6 language-related tracts and parcellated by anatomic location; outcomes based on formal language testing pre-op vs 1–3 months post-op (with clinical follow-up to 6 months for persistence).

Overall predictive signal Any WMT resection strongly increased odds of PLDs (odds ratio 16.0, P = .0115) with high NPV 97.4% but low PPV 29.6%.

Anatomic vulnerability Resections associated with PLDs clustered in the temporoparietal junction (TPJ) and middle temporal lobe (MTL), while resections without PLDs were more diffuse and concentrated in frontal/anterior regions.

Resectability by region Frontal tract segments showed near-complete resectability (PPV = 0 across reported frontal segments), whereas parietal/temporal segments had higher PPVs (eg, parietal AF 0.4, temporal AF 1, temporal IFOF 0.5, temporal ILF 0.5).

Stratified model Focusing only on parietal and temporal tract segment resections improved prediction of PLDs (odds ratio 29.4, P < .001) and increased PPV to 50% (NPV 96.7%).

Resection volume The volume of tract resected did not differ by functional outcome (U = 84.0, P = .70), suggesting location/segment matters more than amount.

Clinical implication WMT resections in orbitofrontal, anterior temporal, and frontal operculum regions were often tolerated, while parietal/temporal WMT injuries substantially increased PLD risk.

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Speech mapping in awake high-grade glioma resection: subcortical tract proximity as a predictor of language outcomes

J Neurosurg 145:179–189, 2026

This clinical study evaluates intraoperative predictors of postoperative language decline in awake resections of language-eloquent high-grade gliomas using diffusion tractography, 5-ALA, and subcortical stimulation with standardized language testing. It reports rates of transient and permanent deficits, correlates specific white matter tracts (IFOF, ILF, AF/SLF) with domain-specific impairments, and presents stimulation thresholds predictive of decline.

The paper emphasizes that preoperative deficits and positive stimulation of multiple tracts increase risk of lasting language impairment, while most single-tract-related declines tend to recover by three months; proposed SCS amplitude cutoffs are offered as practical guidance to balance maximal resection and language preservation.

Objective Identify intraoperative predictors of postoperative language decline and predictors of temporal language recovery after awake resection of language-eloquent high-grade glioma (HGG).

Methods Single-center cohort (Jan 2017–Nov 2024) undergoing awake craniotomy with diffusion tractography, 5-ALA, subcortical stimulation (SCS), and intraoperative language testing; language outcomes assessed at 48 hours, 2 weeks, and 3 months.

Outcomes New or worsened postoperative language deficit occurred in 53.1% (69/130) and was permanent (>3 months) in 9.2% (12/130).

Key intraoperative predictor (domain-specific) Clinical deterioration during awake testing predicted short-term decline in semantic processing (IFOF) (RR 3.47), reading (ILF) (RR 21.4), and auditory naming/repetition (AF/SLF) (RR 6.98).

Permanent-deficit risk factors Higher risk of persistent language decline was associated with preoperative speech deficit (RR 2.65), intraoperative ILF-related reading deterioration (RR 8.92), and positive SCS of multiple language tracts.

Tract sensitivity & recovery Posterior ILF–related reading function showed the greatest sensitivity to decline and the lowest propensity for recovery; all observed reading deficits were linked to tumors near the posterior ILF.

SCS threshold cutoffs ROC/Youden-derived SCS amplitudes predictive of postoperative deficits were reported per tract: IFOF 5.5 mA (48h/2w), 4.5 mA (3m); ILF (reading) 7.0 mA (48h/2w), 4.5 mA (3m); AF/SLF 5.5 mA (48h/2w), 2.5 mA (3m).

Multiple-tract involvement At 3 months, deficits occurred in 7.4% (5/68) with single-tract positive SCS versus 75.0% (9/12) with two tracts; both patients with all three tracts stimulated had persistent deficits beyond 3 months.

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Multiple-level (≥ 3) cervical artificial disc replacement: illustrative case and systematic review of the literature

Neurosurg Focus 61(1):E8, 2026

This systematic review and illustrative case evaluate outcomes of multilevel (≥3 levels) cervical artificial disc replacement (C-ADR), synthesizing data from five studies and one clinical example to assess pain relief, functional recovery, range-of-motion preservation, complications, and reoperation rates. The review reports consistent, durable improvements in VAS and NDI scores, preserved segmental and global cervical motion, low revision rates, and primarily transient complications across 3- and 4-level cohorts.

The article compares multilevel C-ADR with anterior cervical discectomy and fusion (ACDF), emphasizing motion-preserving biomechanical advantages that may reduce adjacent segment degeneration. Limitations include sparse, mostly retrospective data, heterogeneous reporting, and limited long-term follow-up, prompting a call for larger prospective trials and extended surveillance for implant longevity and ASD risk.

Objective Characterize outcomes and complications after multilevel (≥ 3 levels) cervical artificial disc replacement (C-ADR), including an illustrative 3-level case for technical discussion.

Methods Systematic review conducted per PRISMA guidelines, querying PubMed and MEDLINE (August 2025) for primary peer-reviewed studies reporting ≥ 3-level C-ADR outcomes, including range of motion (ROM) preservation and complications.

Clinical outcomes Across 5 studies of 3- and 4-level C-ADR, patients had substantial, durable improvements in pain, disability, and quality of life (e.g., neck/arm VAS decreases > 50%) with benefits reported up to 7 years.

Motion preservation Multilevel C-ADR preserved segmental and global cervical ROM, contrasting with near-complete loss of motion reported after multilevel fusion comparators.

Adjacent segment disease No cases of symptomatic adjacent segment degeneration requiring reoperation were reported in the reviewed multilevel C-ADR studies.

Complications/reoperation Complication rates were low and mostly transient; reoperation was required in only 0%–2% of cases across included studies.

Illustrative case A 50-year-old man with progressive cervical myeloradiculopathy underwent 3-level C-ADR (C4–5, C5–6, C6–7) with uncomplicated recovery, immediate symptom relief, and return to unrestricted activity by 6 weeks with preserved motion at 6 months.

Conclusions/limitations 3- and 4-level C-ADR appears safe and effective for appropriately selected patients with durable pain relief and low revision rates, but evidence remains limited (only five stratified studies; largely retrospective) and devices are not FDA-approved for ≥ 3 levels.

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Corticosteroid Use Before Stereotactic Brain Biopsy for Suspected Lymphoma

Neurosurgery 99:30–39, 2026

This retrospective cohort study evaluates whether preoperative corticosteroid therapy (CST) affects the diagnostic yield of stereotactic brain biopsy (SBB) in 104 patients with pathologically confirmed primary central nervous system lymphoma (PCNSL). The analysis stratifies patients by steroid timing, duration, and cumulative dexamethasone-equivalent dose, reporting diagnostic rates, radiographic features, and complications.

Results show a 92.3% overall diagnostic yield that remained high regardless of CST exposure, dose, or timing, with comparable postoperative complication rates. The authors conclude short-course CST for symptom control appears safe before SBB, while emphasizing multidisciplinary coordination and need for prospective standardized protocols.

Clinical question Whether preoperative corticosteroid therapy (CST) (timing, dose, duration) reduces stereotactic brain biopsy (SBB) diagnostic yield in suspected primary CNS lymphoma (PCNSL), and whether it affects postoperative complications

Cohort & design Retrospective review of 725 SBBs (2014–2025) identifying 104 pathologically confirmed PCNSL cases; CST-naive vs CST-exposed with stratification by last-dose timing, cumulative dexamethasone-equivalent dose, and duration

Overall yield Initial SBB diagnostic yield for PCNSL was 92.3% (96/104), with 8 nondiagnostic initial biopsies

CST vs no CST yield Diagnostic yield was 95.3% with CST (41/43) vs 90.2% without CST (55/61), not significant (P = .46)

Timing of last CST dose Yield remained high across intervals: ≤48 h 96.4%, 48–72 h 91.7%, >72 h 100% (P = .66)

Cumulative dose & duration Yield did not differ by cumulative dexamethasone dose (≤20 mg 95.5%, 21–40 mg 100%, >40 mg 100%, P = 1.0) or by duration (≤5 days 94.6% vs >5 days 100%, P = 1.0)

Complications Postoperative complications occurred in 4.8% of PCNSL cases, with no significant difference between CST-exposed and CST-naive patients (P = .84)

Nondiagnostic biopsies & next steps Only 2/8 initially nondiagnostic cases had prebiopsy CST; all 8 were ultimately confirmed PCNSL via repeat SBB, CSF cytology, or postmortem, supporting repeat/alternative diagnostic approaches when initial biopsy is nondiagnostic

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The suprabulbar approach for jugular fossa schwannomas: case series and technical nuances

J Neurosurg 145:120–131, 2026

This clinical article details a cadaveric and retrospective clinical study of the suprabulbar approach for resection of jugular fossa schwannomas, describing anatomical measurements, stepwise surgical technique, perioperative protocols, and outcomes in 22 patients treated between 1994 and 2024. The authors report a 77% gross-total resection rate, low morbidity, no mortality, and favorable cranial nerve preservation with mean follow-up of 31.4 months.

The paper emphasizes anatomical rationale from bilateral cadaver dissections to define the presigmoid infralabyrinthine window, operative nuances (mastoidectomy, presigmoid dura management, endoscopic assistance), and the approach’s versatility to combine intradural access with neck dissection for large dumbbell tumors while minimizing cranial nerve and venous complications.

Problem Jugular fossa schwannomas are rare lower cranial nerve tumors whose complex anatomy makes surgery difficult and morbidity-prone, especially for swallowing/voice deficits.

Approach The suprabulbar approach uses a presigmoid infralabyrinthine/retrofacial window created via mastoidectomy to access the jugular fossa while preserving the labyrinth and facial nerve, and enabling jugular bulb decompression.

Anatomic basis Cadaveric measurements characterized the surgical corridor (means: sigmoid sinus width 13.5 ± 3.9 mm; jugular bulb width 10.9 ± 1.4 mm; sigmoid-to-retrofacial space 12.8 ± 3 mm; labyrinth-to–jugular bulb dome 10.6 ± 2.6 mm; jugular foramen diameter 8.1 ± 1.2 mm).

Clinical series 22 patients (1994–2024) underwent resection; tumors were predominantly dumbbell-shaped type D (91%), mean max diameter 2.9 ± 1.1 cm, with frequent presenting dysphagia (64%) and hearing loss (41%).

Technique extensions Intradural tumor can be followed via presigmoid dural opening, distal tumor can be removed endoscopically, and caudal extracranial extension can be addressed with single-stage upper neck dissection when needed.

Resection outcomes Gross-total resection was achieved in 77% (17/22); subtotal resection occurred in 5 cases (including one due to intraoperative arrhythmias).

Safety profile No deaths or permanent neurological deficits; transient postoperative cranial nerve deficits occurred in 14% and resolved during follow-up; one perioperative complication was a suspected CSF leak treated with spinal drainage.

Follow-up/recurrence Mean follow-up was 31.4 months; 64% improved in preoperative neurological deficits; confirmed recurrence occurred in 14% (3/22), all successfully reoperated.

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Use of pelvic incidence to predict proximal junctional failure in long-segment spinal fusion

J Neurosurg Spine 45:44–54, 2026

This clinical study evaluates how pelvic incidence (PI) affects spinopelvic correction and proximal junctional failure (PJF) after long-segment thoracolumbar fusion with pelvic fixation in 204 adult spinal deformity patients. Patients were stratified by PI (<55° vs >55°) and analyzed for radiographic outcomes, complications, and PROMs using frequentist and Bayesian models.

Key findings show lower PI independently predicts higher PJF risk (21% vs 9%), with lower thoracic UIV and revision surgery as additional predictors; lower PI patients more often met age-adjusted alignment goals but experienced greater overcorrection relative to individualized morphology.

Objective Evaluate how pelvic incidence (PI) affects spinopelvic correction and complication rates (especially proximal junctional pathology) after long-segment fusion for adult spinal deformity.

Cohort Retrospective analysis of 204 patients undergoing open posterior long-segment thoracolumbar fusion with pelvic fixation (≥ 6 levels) with ≥ 1-year follow-up; grouped by PI cutoff 55° into lower PI (n=108) vs higher PI (n=96).

Primary finding (PJF rates) Lower PI patients had higher proximal junctional failure (PJF) at 1 year than higher PI patients (21% vs 9%, p=0.019).

UIV subgroup With an upper thoracic UIV (T2–5), PJF was 15% in lower PI vs 0% in higher PI (p=0.014).

Independent predictors Multivariate analysis: lower PI (OR 4.3, p=0.006), lower thoracic UIV (T10–12) (OR 6.5, p=0.005), and revision surgery (OR 23.8, p=0.001) independently predicted PJF.

Model confirmation Bayesian mixed-effects modeling also identified lower PI (OR 6.25, posterior probability 0.996) and lower thoracic UIV (OR 7.03, posterior probability 0.997) as significant predictors of PJF.

PJK vs PJF Proximal junctional kyphosis (PJK) rates were similar between PI groups at 1 year (38% vs 41%, p=0.697), despite the PJF difference.

Planning implication Preoperative PI morphology may guide individualized surgical planning to reduce risk of junctional pathology, since lower PI carried higher PJF risk after long-segment fusion.

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The Lumboperitoneal Shunt Study: A Systematic Review and Single-Arm Meta-Analysis of 2696 Patients

Neurosurgery 99:3–18, 2026

Scope Systematic review + single-arm random-effects meta-analysis of 49 studies including 2696 patients who underwent lumboperitoneal shunt (LPS) placement.

Search/eligibility Databases: PubMed, Embase, Web of Science (through Sept 2023); included observational studies reporting LPS complications; excluded case reports (≤4 patients), non-English, overlapping cohorts, prior non-LPS shunts; study was not prospectively registered.

Main etiologies Largest indication groups were communicating hydrocephalus (693), normal pressure hydrocephalus (631), and idiopathic intracranial hypertension (275) (1599 combined).

Revision risk Overall pooled risk of requiring shunt revision: 25% (95% CI 18%–32%; I²=93%) at median mean follow-up 19.2 months; by etiology: CH 21%, IIH 46%, NPH 10%.

Complication risks Infection: 1% (95% CI 1%–2%; I²=25%); shunt-related mortality: 0.1% (3 deaths).

Overdrainage/tonsillar herniation Overdrainage occurred in 119 patients with high heterogeneity (I²=75%); tonsillar herniation in 19 patients with significant heterogeneity (I²=50%), both reported as minimal pooled risk.

Revision causes Most common reasons for revision were obstruction (30%) and migration/slippage/fracture (20%).

Overall conclusion LPS shows acceptable revision and complication rates and appears comparable to ventriculoperitoneal shunts (VPS), but substantial heterogeneity limits confidence; supports broader integration of LPS in Western practice and calls for randomized trials.

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Hemodynamic parameters as biomarkers for predicting microvascular decompression efficacy in classic trigeminal neuralgia

J Neurosurg 145:36–44, 2026

This clinical study evaluates hemodynamic parameters derived from computational fluid dynamics (CFD) to predict microvascular decompression (MVD) efficacy in patients with classic trigeminal neuralgia (CTN). Using preoperative MR angiography and CFD, the authors compared PSF, PSPD, maximum WSS, and OSI between effective and ineffective MVD cohorts and developed logistic models to forecast surgical outcomes.

Results show lower peak systolic flow (PSF) and higher PSPD, maximum WSS, and OSI in effective cases; PSF and maximum WSS emerged as independent predictors. The best predictive model achieved AUC 0.920 with 90% sensitivity and specificity, supporting integration of hemodynamic metrics into preoperative decision-making for personalized CTN treatment.

Objective Evaluate whether CFD-derived hemodynamic parameters can predict microvascular decompression (MVD) efficacy in classic trigeminal neuralgia (CTN).

Design/participants 56 unilateral CTN patients (May 2022–Dec 2023) split into 28 effective vs 28 ineffective MVD outcomes; effectiveness defined as VAS pain score dropping to 0 on postoperative day 1, while ineffectiveness meant pain persisted (>0) through 3 months.

Workflow Use preoperative time-of-flight MR angiography to identify the neurovascular compression (NVC) zone, reconstruct the offending vessel segment, and run CFD to quantify PSF, PSPD, WSS, and OSI.

Key group differences Effective MVD associated with lower PSF (0.202 vs 0.306 ml/sec) and higher PSPD, maximum WSS, and OSI in the NVC zone (all statistically significant).

Independent predictors PSF and maximum WSS remained significant predictors of MVD efficacy in multivariable logistic regression.

Prediction performance A backward-selection logistic model achieved AUC 0.920 with 90% sensitivity and 90% specificity for predicting MVD efficacy.

Clinical interpretation Hemodynamic patterns consistent with higher vascular resistance/adverse shear environment at effective NVC sites, supporting use of CFD metrics to distinguish effective vs ineffective NVC.

Implication Integrating hemodynamic parameters (especially PSF and maximum WSS) could guide personalized treatment selection and improve preoperative prediction of MVD benefit.

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Repeat gamma knife radiosurgery for recurrent trigeminal neuralgia

Acta Neurochirurgica (2026) 168:143

This systematic review and meta-analysis evaluates outcomes after repeat Gamma Knife radiosurgery (GKRS) for recurrent trigeminal neuralgia, pooling data from 21 studies comprising 2,020 retreatments. It quantifies efficacy (BNI I–III favourable pain control ~77% after retreatment, 62% at long-term follow-up) and recurrence (~29%), and reports complication rates, notably facial hypoesthesia (~39%).

The paper follows PRISMA and Cochrane guidance, performs single-arm GLMM meta-analyses, sensitivity checks, and meta-regressions that found no consistent predictors of outcome. Limitations include retrospective series, moderate–severe bias, substantial heterogeneity, and variable dosimetry and reporting; prospective standardized studies are recommended.

Clinical context Trigeminal neuralgia causes intense, episodic, shock-like facial pain; Gamma Knife radiosurgery (GKRS) is used for medically refractory cases, and recurrence after initial GKRS can prompt consideration of repeat GKRS.

Study design Systematic review and meta-analysis conducted under PRISMA guidance; included English-language studies of patients needing repeat GKRS after inadequate response to medications and/or a single GKRS, with ≥12 months follow-up.

Evidence base 21 studies were included, comprising 2,486 initially treated patients and 2,020 undergoing repeat GKRS; most were female, median ages ranged 54.5–79.6 years, and ~85% were idiopathic trigeminal neuralgia.

Treatment patterns Most repeat procedures targeted the trigeminal root entry zone (REZ), typically using 70–80 Gy marginal doses; intervals between procedures varied widely (5–138 months; median ≈36 months).

Effectiveness Pain relief after repeat GKRS commonly occurred in ~70–90% of patients with typical improvement in BNI pain scores (often IV–V to I–IIIb); pooled favourable pain control (BNI I–III) after the latest treatment was 76.68%.

Durability & recurrence Median follow-up ranged 14–74 months; recurrence after repeat GKRS was reported around 10–35% (pooled recurrence 29.07%), and favourable pain control at last follow-up decreased to 61.94%.

Safety profile Facial sensory disturbances were frequent (reported 20–45%; pooled facial hypoesthesia 39.04%); bothersome dysesthesias and anesthesia dolorosa were uncommon (<3%).

Predictors/heterogeneity Meta-regression found no significant association between pain relief and age, pain duration, interval since prior GKRS, or dose, with substantial inter-study heterogeneity persisting.

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Image‑based robot‑assisted deep brain stimulation under general anesthesia

Acta Neurochirurgica (2026) 168:149

This technical report details a fully image-based, robot-assisted workflow for deep brain stimulation (DBS) performed under general anesthesia using the Neuromate® platform, integrating high-resolution MRI–CT fusion, fiducial-based robotic registration, and intraoperative O-arm 3D imaging for verification. The method emphasizes millimetric anatomical targeting across STN, GPi, VIM, ANT, and VTA, with specific considerations for trajectory safety and directional lead orientation.

The document also describes operative logistics: Leksell frame fixation coupled to the robot, burr-hole and guide-cannula techniques, bilateral lead implantation, same-session generator placement, and perioperative management to minimize CSF loss, pneumocephalus, and hemorrhagic risk. Limitations, learning-curve aspects, costs, and key checklist items for procedural reproducibility are summarized.

Purpose: Robot-assisted DBS is used to enhance stereotactic accuracy and workflow reproducibility, offering a fully image-based alternative to physiological mapping and enabling procedures under general anesthesia.

Targets: Common anatomical targets include STN, GPi, VIM, ANT, and VTA, selected based on therapeutic goal; target choice also determines instrumentation.

Planning: Preoperative planning relies on high-resolution MRI for direct anatomical targeting plus thin-slice CT for stereotactic registration and image fusion; DTI/atlases are optional adjuncts.

Fixation & setup: The head is rigidly fixed with a Leksell frame for stability (not stereotactic referencing), coupled to the Neuromate® robot; positioning includes slight trunk elevation to reduce pneumocephalus risk.

Registration & safety: Robotic accuracy is verified using a frontal fiducial marker, Neurolocate laser-based recognition, and O-arm intraoperative 3D imaging fused to the plan; a virtual safety sphere constrains robotic movements and a test trajectory confirms calibration.

Implant workflow: A robot-guided burr hole is created and a fixation device (e.g., Stimloc®/SureTek®) placed; a guide cannula is advanced to target depth, held ~30–45 s to reduce recoil, then withdrawn before inserting the electrode along the carved trajectory.

Complication mitigation: Minimize CSF loss to reduce pneumocephalus/brain shift; plan trajectories to avoid sulci, ventricular transgression, and vascular structures; ensure deliberate directional lead rotational alignment using the manufacturer marker.

Verification & completion: Intraoperative O-arm 3D imaging verifies lead depth/alignment and detects complications; bilateral cases repeat contralaterally after first-side confirmation; generator implantation is performed in the same session with impedance testing to confirm system integrity.

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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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