Month: October 2026

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Trigeminal neuralgia: anticipating difficult arterial anatomy before decompression

Acta Neurochirurgica. 2026.  DOI: 10.1007/s00701-026-07055-3

Arterial variants can make microvascular decompression more demanding without necessarily precluding favorable outcomes. Kawano and colleagues identify the trigeminocerebellar artery as particularly relevant: its relationship to the trigeminal root may involve penetrating vessels, encircling loops or perforators that restrict mobilization. The practical message is to anticipate these configurations before surgery, rather than assume every offending artery can be displaced in the same way.

Study and key findings

This retrospective single-center study included 170 adults, aged 19-84 years, undergoing first-time microvascular decompression for drug-resistant classical trigeminal neuralgia: 172 operated sides, including two bilateral cases. Preoperative assessment combined high-resolution MR angiography, heavily T2-weighted imaging and three-dimensional reconstruction.

Among 168 patients with unilateral symptoms, the trigeminocerebellar artery was more frequent on the affected than the contralateral side: 10.7% versus 4.8% (P=.033). Early bifurcation of the superior cerebellar artery showed no significant side difference.

Of 19 operated sides with an offending trigeminocerebellar artery, four showed root penetration, four encircling loops and five multiple perforators. All four penetration configurations were identified preoperatively. Recurrence occurred in 28/172 sides overall (16.3%), including 3/19 in this subgroup (15.8%); comparisons did not demonstrate significant recurrence differences between arterial groups.

Interpretation and limitations

The technical distinction is between an artery passing between sensory and motor roots and one penetrating the sensory root itself. Transposition predominated; nerve splitting was used only in the two cases with direct sensory-root penetration. These observations do not justify routine nerve splitting or establish superiority over alternative decompression techniques.

The retrospective design, selected surgical population and small variant subgroups limit inference. Contralateral comparisons demonstrate association, not causality. MRI-based classification cannot always distinguish a trigeminocerebellar artery from a duplicated superior cerebellar artery. Nonsignificant outcome comparisons do not establish equivalent safety, particularly for uncommon neurological complications.

Clinical takeaway

Preoperative imaging should inform how the artery relates to the root and perforators, not merely identify vascular contact. This series supports anatomy-specific planning and cautious mobilization, while leaving the comparative benefits and risks of individual maneuvers unresolved.

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Cranioplasty and shunting: which should come first?

Neurosurgery. 2026;99(4):873-881

No universally optimal sequence emerges when patients require both cranioplasty and permanent CSF diversion after decompressive craniectomy. Holmgren and colleagues found broadly similar unadjusted outcomes, but an adjusted analysis associated shunting first with fewer cranioplasty removals. This potentially important signal must be interpreted alongside substantial differences in why and when each strategy was chosen.

Study and key findings

This retrospective study from four Swedish centers included 99 patients: 37 underwent cranioplasty first, 37 simultaneous surgery and 25 shunting first. Median follow-up after cranioplasty was 58 months.

Cranioplasty removal occurred in 30%, 24% and 8%, respectively; the unadjusted comparison was not statistically significant (P=.121). Shunt revision rates were 24%, 35% and 36%, also without a significant difference. Functional outcomes did not differ significantly.

After adjustment for cranioplasty material and the interval from decompressive craniectomy to reconstruction, shunting first was associated with lower odds of cranioplasty removal than cranioplasty first: OR 0.12, 95% CI 0.01-0.64, P=.031. Only two removals occurred in the shunt-first group, making this estimate sensitive to small event numbers.

Interpretation and limitations

Treatment groups were not clinically interchangeable. External cerebral herniation prompted shunting in none of the cranioplasty-first patients, compared with 70% of simultaneous and 44% of shunt-first patients. Center, implant material and timing also differed. Residual confounding therefore prevents a causal interpretation of the adjusted association.

The absence of significant differences in other outcomes does not demonstrate equivalence. Because every included patient ultimately received both procedures, the study cannot establish whether cranioplasty first reduces the need for permanent shunting. Detailed valve-management data were unavailable, so no specific pressure-setting protocol can be derived.

Clinical takeaway

Sequence should remain individualized to the CSF disorder, cerebral contour and reconstructive requirements. The association favoring shunting first for cranioplasty retention merits further investigation, but does not justify a universal shunt-first policy or establish identical safety for simultaneous surgery.

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An intraoccipital route to the ventricular atrium: promise and anatomical trade-offs

Journal of Neurosurgery. 2026;145(4):1199-1207

The intraoccipital sulcus may provide a useful route to the ventricular atrium, but following a natural sulcus does not eliminate white matter injury. Anastasopoulos and colleagues map a roof-directed corridor whose potential advantages remain anatomical rather than clinically demonstrated. Their findings inform approach selection without establishing superior safety or preservation of visual function.

Study and key findings

The investigators examined 20 adult cadaveric hemispheres from 10 donors, supplemented by MRI assessment of 20 Human Connectome Project subjects and another 25 healthy individuals.

The anterior approximately 1.2-cm sulcal segment aligned with the atrial roof; posterior trajectories instead led toward the occipital horn. The mean MRI distance from the sulcal fundus to the atrium was 1.90 ± 0.48 cm. These descriptive measurements are not patient-specific safety margins.

Although the medial, roof-directed trajectory offers a potentially favorable relationship to lateral-wall optic radiations, the corridor disrupts the vertical occipital fasciculus and crosses the posterior sagittal stratum and tapetum. It is therefore not a white matter-free route.

Interpretation and limitations

The practical question is whether the anterior intraoccipital sulcus provides suitable exposure for a particular atrial lesion. Anterior and posterior sulcal segments are not interchangeable, and lesions extending farther anteriorly may require an unfavorable working distance. A plausible editorial implication is to weigh target geometry and intervening fiber anatomy together, rather than select the approach solely from a recognizable surface landmark.

No operative series, postoperative visual outcomes or clinical comparison with alternative approaches was included. Cadaveric tissue and illustrative template-space tractography cannot establish individual functional safety. Manual MRI measurements also lacked demonstrated interobserver reliability.

Clinical takeaway

The anterior intraoccipital sulcus deserves consideration as an anatomical option for atrial access. Its contribution is a clearer understanding of trajectory and white matter costs, not proof of a safer operation. Clinical validation remains necessary before anatomical feasibility can be translated into claims of neurological benefit.

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Mild posterior ligamentum flavum compression: must cervical arthroplasty be excluded?

Spine (Phila Pa 1976). 2026;51(19):1363-1373

Mild posterior ligamentum flavum compression need not automatically exclude cervical disc replacement in otherwise suitable patients. Pezzi and colleagues report improvements in disability and pain after both arthroplasty and anterior cervical fusion. However, their findings predominantly concern mild disease and do not establish equivalent neurological safety or support arthroplasty for severe posterior compression.

Study and key findings

This single-center retrospective study included 228 adults with degenerative cervical myelopathy or myeloradiculopathy undergoing one- or two-level anterior cervical discectomy and fusion (ACDF; 160 patients) or cervical disc replacement (CDR; 68 patients). Median follow-up was 18.9 months.

Among 127 patients with MRI-defined ligamentum flavum involvement, 101 underwent ACDF and 26 underwent CDR. Weighted analysis found no significant difference in Neck Disability Index trajectories between procedures (P=.26). Disability and pain improved after both operations.

Crucially, 24 of the 26 CDR patients with ligamentum flavum involvement had mild buckling; only two had the more severe grade combining buckling and hypertrophy. The evidence for arthroplasty therefore cannot be generalized across compression severities.

Interpretation and limitations

The practical decision is whether mild posterior buckling should independently rule out motion preservation when an anterior procedure is otherwise appropriate. The findings favor assessing severity and overall anatomy rather than applying a blanket exclusion.

Nevertheless, CDR patients were younger, healthier and less severely affected. Statistical weighting did not fully balance the groups, leaving residual confounding despite further adjustment. Nonsignificant differences do not demonstrate equivalence.

Outcomes emphasized patient-reported disability and pain rather than a dedicated neurological myelopathy scale. Similar recovery scores cannot establish identical spinal cord recovery. Postoperative MRI was available in only 86 patients, limiting conclusions about structural changes. The study does not define a ligament-thickness threshold or validate an anterior-versus-posterior decompression algorithm.

Clinical takeaway

Mild ligamentum flavum buckling may be compatible with cervical arthroplasty in carefully selected patients. Severe posterior compression remains insufficiently studied, and favorable patient-reported outcomes should not substitute for assessment of the adequacy of spinal cord decompression.

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Paraspinal muscle advancement after posterior cervical fusion: reconstructing the wound, not merely closing it

Journal of Neurosurgery: Spine. 2026;45(4):660-667

Soft-tissue closure deserves consideration as part of the reconstructive strategy in posterior cervical surgery, particularly when instrumentation leaves a substantial wound cavity. Adida and colleagues examine whether advancing the paraspinal musculature is associated with fewer wound complications than conventional closure after posterior cervical decompression and fusion. Their comparison of 508 patients provides a clinically relevant signal of fewer infections and wound-related reoperations in adjusted analyses, while illustrating the difficulty of separating a closure technique from changes in perioperative care. The practical contribution is a rationale for vascularized coverage and dead-space reduction, rather than definitive evidence that one closure method should replace all others.

Objective

To compare wound complications and wound-related reoperations after conventional closure or bilateral paraspinal muscle flap advancement following posterior cervical decompression and fusion.

Methods

The investigators compared 380 patients treated with conventional closure between 2011 and 2022 with a prospectively maintained series of 128 consecutive patients receiving muscle flap advancement between 2023 and 2025 at a single academic quaternary center. Active local or systemic infection and follow-up shorter than three months were exclusion criteria. Indications included degenerative disease, deformity, trauma and malignancy; approximately one fifth of each cohort underwent revision surgery.

Wound events included infection, dehiscence, hematoma and seroma. Wound-related reoperation was recorded per patient. Analyses included time-to-event comparisons and Firth-penalized logistic regression. Importantly, the methods and Table 2 describe adjustment with individual covariates rather than a single model simultaneously controlling for every potential confounder.

Main results

Infection was recorded in 31 of 380 conventional-closure patients and 4 of 128 muscle-flap patients, approximately 8% and 3%. Wound-related reoperation occurred in 47 and 9 patients, approximately 12% and 7%, respectively. The reported regression estimates associated muscle flap closure with lower odds of infection (OR 0.275, 95% CI 0.085-0.702) and wound-related reoperation (OR 0.445, 95% CI 0.198-0.912).

Dehiscence remained similar, at approximately 12% versus 11%. Seroma was numerically more frequent with muscle advancement, approximately 9% versus 5%, without a statistically significant difference. Hardware removal occurred in five conventional-closure patients and no muscle-flap patients. These small event counts do not establish a reliable hardware-retention advantage.

The time-to-event analyses were less conclusive than the logistic models. Log-rank comparisons for infection-free and reoperation-free survival did not reach statistical significance, and the reported Cox estimates had confidence intervals crossing unity. Thus, the evidence does not support describing the benefit as uniformly demonstrated across analytical approaches.

Interpretation

The operative decision is whether to incorporate paraspinal muscle advancement at the index operation to improve coverage of the instrumented cervical wound. The authors describe mobilizing the muscle complex and bringing vascularized tissue into the midline cavity. Their initial Lembert closure imbricated muscle into the defect; the subsequently adopted vest-over-pants configuration overlapped the advanced muscle margins. Both used absorbable sutures, and superficial drainage was described above the reconstructed muscle layer.

These details support a reconstructive concept: address the deep wound cavity and soft-tissue coverage rather than relying solely on superficial approximation. However, the study did not compare the two flap configurations, quantify tension reduction or perfusion, or establish which patients derive the greatest benefit. Its results also cannot define an optimal drain regimen or justify a specific antimicrobial adjunct independently of the overall closure strategy.

Limitations

The cohorts were noncontemporaneous, with retrospective ascertainment in the earlier group and prospective maintenance of the later series. Changes in practice, case selection and complication detection may therefore contribute to the observed associations. The muscle-flap cohort was older, and baseline characteristics were not identical. Limited events and adjustment one covariate at a time leave substantial potential for residual confounding.

Co-interventions are particularly important. Topical vancomycin was used in every muscle-flap case but only most conventional cases, while incisional negative-pressure therapy was introduced during the study and used in 63 muscle-flap patients. The contributions of these measures cannot be isolated. Drain number, duration and removal criteria were not analyzed. The two flap techniques were pooled, and a three-month minimum follow-up does not ensure equivalent long-term observation across cohorts.

The contrast between logistic and time-to-event findings further limits certainty. The study supports an association and a plausible operative rationale, not a causal estimate of how many infections or reoperations muscle advancement itself prevents.

Clinical takeaway

Paraspinal muscle advancement is a promising option for reconstructing the posterior cervical wound after decompression and fusion. The strongest practical message is to plan deep soft-tissue coverage and dead-space management deliberately. This series does not establish universal superiority over conventional closure, favor Lembert over vest-over-pants repair, or determine the independent benefit of drains, topical antibiotics or negative-pressure therapy.

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Body mass index in cervical myelopathy surgery: anticipating operative demands without assuming poor recovery

Spine (Phila Pa 1976). 2026;51(19):1354-1362

Body mass index is readily available during preoperative assessment, but its implications for cervical myelopathy surgery are not straightforward. A technically more demanding operation does not necessarily imply less neurological recovery, and similar average outcomes do not establish equal risk for every patient. Okubo and colleagues address this distinction in a prospective Japanese multicenter cohort, relating BMI to operative variables, cervical alignment and two-year clinical outcomes. Their findings associate obesity with longer procedures and greater blood loss, while showing no statistically significant differences in neurological improvement across BMI categories. The principal relevance is to individualized planning and counseling rather than selection of a specific surgical technique.

Objective

To assess the association between BMI and operative demands, perioperative complications, cervical alignment, neurological recovery and patient-reported outcomes after surgery for degenerative cervical myelopathy.

Methods

The study drew on a prospective cohort from ten high-volume spine centers in Japan between 2018 and 2022. Of 1,105 patients identified with degenerative cervical myelopathy, 935 entered the final analysis after exclusions for previous cervical surgery, missing essential information, loss to follow-up or death during observation.

Patients were classified as underweight (BMI below 18.5; n=35), normal weight (18.5-24.9; n=522), overweight (25.0-29.9; n=292), or having obesity (30 or above; n=86). Posterior decompression predominated in every group; anterior and posterior fusion procedures were less frequent. Complications were defined as adverse events within 30 days of surgery.

Assessment included Japanese Orthopaedic Association (JOA) scores, pain ratings, SF-36 physical and mental component scores, neuropathic pain symptoms, and cervical radiographs. Clinical outcomes at two years were compared using general linear models with adjustment for demographic, comorbidity and imaging variables. Models for outcome changes also incorporated operative time, blood loss and postoperative alignment and motion measurements.

Main results

Patients with obesity had mean operative time of 128.3 minutes and blood loss of 91.2 mL, versus 102.1 minutes and 38.1 mL in normal-weight patients; global comparisons across the four groups were significant. OPLL prevalence was 47.7% versus 16.9%. Adjusted JOA improvement was 3.5, 3.2, 2.6 and 3.1 points across ascending BMI categories (P=.129). Reported complication categories did not differ significantly. Obesity remained associated with less cervical lordosis and motion at two years. Between-group differences in pain, SF-36 and neuropathic pain changes were not statistically significant; this does not demonstrate equivalent outcomes.

Interpretation

The decision informed by this study is how BMI contributes to preparation and expectations when clinical and imaging findings already support surgery. Greater operative demands justify attention to associated comorbidities and cervical anatomy, particularly the higher frequency of OPLL, rather than assuming that neurological recovery will be poor. However, the study does not compare approach-selection algorithms or validate a BMI-specific exposure, fixation or closure technique. Persistent differences in alignment and motion also should not be described as surgical failure: they coexisted with neurological improvement. Conversely, favorable average recovery should not be interpreted as eliminating individual perioperative risk.

Limitations

This observational cohort cannot establish the independent causal effect of BMI. Patients with obesity were younger and more frequently had OPLL, diabetes and hypertension. Statistical adjustment reduces some measured confounding but does not resolve unmeasured differences. Moreover, adjusting for operative demands and postoperative radiographic findings may account for intermediate pathways through which BMI could affect outcomes, rather than estimating its total association with recovery.

The analysis included patients selected for surgery and excluded those who died or were lost during follow-up. Consequently, its complication comparisons cannot be generalized to all patients initially considered for surgery or used to establish mortality safety. Care at high-volume Japanese centers and the predominance of posterior decompression further limit extrapolation to other settings or procedure mixes.

Only 35 patients were underweight and 86 had obesity, without a separate analysis of severe obesity classes. Rare complications and modest clinical differences could therefore have been missed. The authors’ post hoc analysis indicated limited power for JOA and mental-component changes; nonsignificant findings are not evidence of equivalence. BMI also does not characterize muscle mass, nutritional status or visceral adiposity. Two years is insufficient to settle long-term adjacent-segment disease, reoperation or progressive alignment changes. Finally, inconsistencies in some tabulated variability labels and secondary outcome intervals warrant caution when interpreting precise estimates.

Clinical takeaway

In this selected surgical cohort, a higher BMI was associated with greater operative demands but not a statistically significant reduction in two-year neurological improvement. The findings argue against treating BMI alone as a reliable predictor of poor recovery. They do not establish a universal BMI threshold for proceeding with surgery, prove equal complication risk, or test whether preoperative weight reduction changes outcomes. Clinical severity, anatomy, comorbidities and the planned operation remain central to individualized assessment.

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Domino connectors in adult spinal deformity: greater corrective capacity, but not proven clinical superiority

Journal of Neurosurgery: Spine 2026;45(4):516-526

Combined sagittal and coronal malalignment poses a particular challenge in adult spinal deformity surgery because correction must address both planes without concentrating excessive forces on individual fixation points. Vila and colleagues investigate the side-to-side domino connector as an active correction tool rather than simply a device for linking rods. Their multicenter cohort associates its use with greater correction and better maintained sagittal alignment at two years. However, comparable patient-reported outcomes and a higher rate of rod breakage/pseudarthrosis require a balanced interpretation: improved radiographic correction does not, by itself, establish greater clinical benefit or mechanical safety.

Objective

To compare radiographic correction, complications and patient-reported outcomes after adult spinal deformity surgery with or without a side-to-side domino connector used for correction of combined sagittal and coronal malalignment.

Methods

This retrospective analysis used a prospectively collected database from six European centers. It included 224 patients undergoing instrumented fusion to the pelvis with at least two years of follow-up: 81 with a domino connector and 143 without. Eligibility required a C7-to-central sacral vertical line distance greater than 20 mm together with sagittal malalignment defined by at least one of the study’s pelvic tilt, sagittal vertical axis, thoracic kyphosis or global tilt criteria.

Connector use was selected by the surgeon, often for more severe, rigid deformities. The connector group started with worse biplanar malalignment and underwent pedicle subtraction osteotomy more frequently. Propensity matching produced 69 pairs based on baseline global tilt, coronal displacement, osteotomy use and rod number. A separate analysis compared patients without pedicle subtraction osteotomy. Outcomes included standing radiographs, mechanical and neurological complications, unplanned reoperations, Oswestry Disability Index and Scoliosis Research Society-22 scores.

Main results

In the matched cohort, two-year global tilt was 24.6° with connectors versus 33.1° without, and L1-S1 lordosis was 54.8° versus 49.0°. Final coronal displacement did not differ significantly. In the full cohort, mechanical complications occurred in 41.9% of both groups, but the combined rod-breakage/pseudarthrosis category was higher with connectors: 22.2% versus 9.1% (P=.006). Unplanned reoperation rates were 27.2% versus 34.3%, without a significant difference. Two-year ODI and SRS-22 scores were comparable. Greater lumbar lordosis also persisted in the subgroup without pedicle subtraction osteotomy, although that comparison retained baseline imbalances.

Interpretation

The technical distinction is the intended force direction, referenced to trunk shift rather than simply curve concavity. For distraction-based correction, the authors place the connector on the side of coronal malalignment; for compression during asymmetric osteotomy closure, they place it opposite the shift. Their illustrated sequence establishes lumbopelvic fixation and initial correction through a contoured contralateral rod before connector-assisted adjustment. Intraoperative imaging checks coronal alignment against a pelvic reference. This is a useful framework for planning correction, but force distribution is a proposed mechanical rationale, not proof that the connector independently prevents fixation failure.

Limitations

This was not a randomized comparison, and matching cannot eliminate unmeasured confounding. Deformity rigidity, surgeon preferences, center-specific practice and the heterogeneity of control constructs may affect both correction and complications. Matching addressed selected variables rather than every baseline difference; thoracic kyphosis remained different between matched groups. The subgroup without pedicle subtraction osteotomy likewise does not isolate the device’s intrinsic effect from other corrective maneuvers.

The clearest persistent radiographic advantage was sagittal. Greater correction from a more displaced starting position should not be confused with significantly better final coronal balance. Similarly, comparable ODI and SRS-22 scores do not establish equivalence, but they do mean that superior patient-reported benefit was not demonstrated at two years.

An identical aggregate mechanical complication rate does not neutralize the higher rod-breakage/pseudarthrosis rate. Greater deformity severity and osteotomy use may contribute, but this study cannot establish their causal contribution or exclude a device-related contribution. The absence of reported intraoperative implant complications is also insufficient to establish general safety. The study received industry funding, and several authors disclosed relevant financial relationships. Longer follow-up and prospective comparative evaluation are needed to clarify durability and clinical benefit.

Clinical takeaway

A domino connector can be considered a correction adjunct when managing complex biplanar adult deformity, with its placement determined by the planned compression or distraction mechanism. This study supports its corrective potential, not routine use in every construct, replacement of an indicated osteotomy, or an expectation of better functional outcomes. Planning should retain equal attention to alignment, the lumbopelvic foundation and subsequent mechanical failure risk.

 

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Motor mapping in brain tumor surgery: what monopolar stimulation adds at the subcortical boundary

Journal of Neurosurgery 2026;145(4):1141-1150

Resection near motor pathways requires a balance between oncological objectives and preservation of neurological function. Although both bipolar and monopolar stimulation are established mapping techniques, their practical performance may differ at the subcortical resection boundary. Chow and colleagues examine a single surgeon’s experience across 300 craniotomies, comparing low-frequency bipolar stimulation with high-frequency monopolar stimulation. Monopolar mapping was associated with more frequent identification of subcortical motor pathways and fewer intraoperative seizures, without a demonstrated reduction in permanent deficits. The findings inform mapping strategy while illustrating why better intraoperative detection should not be equated automatically with superior long-term outcomes.

Objective

To compare cortical and subcortical motor pathway identification, intraoperative seizures, extent of resection and postoperative neurological deficits between low-frequency bipolar stimulation (LFBS) and high-frequency monopolar stimulation (HFMS).

Methods

This retrospective single-center series covered operations performed by one surgeon between July 2008 and December 2023. The analysis included 119 asleep LFBS procedures, 91 awake LFBS procedures and 90 asleep HFMS procedures. Awake operations incorporated language mapping when required; no awake HFMS cohort was studied. Asleep mapping changed from LFBS to HFMS in 2017, making the principal asleep comparison historical rather than randomized.

Neurological deficits were assessed against the preoperative baseline and classified as permanent when persisting beyond six months. Tumor volumes were measured on MRI obtained before and within 48 hours after surgery, separating enhancing tumor from T2/FLAIR abnormalities.

LFBS motor responses were assessed through observation, palpation and/or patient report; HFMS used time-locked motor evoked potentials. Subcortical mapping was selective, not routine in every procedure. The authors alternated resection with stimulation near potential corticospinal tract boundaries, rather than using continuous dynamic mapping throughout the series.

Main results

Among asleep procedures, seizures occurred in 39/119 LFBS cases (33%) versus 12/90 HFMS cases (13%). When subcortical mapping was used, pathways were identified in 8/19 versus 46/59 cases, respectively. Persistent motor deficits occurred in 4/119 versus 2/90 procedures; no significant difference emerged across the three cohorts. Mean enhancing-tumor resection was 92.7% with asleep LFBS, 83.6% with awake LFBS and 83.5% with HFMS. Nonenhancing-tumor resection did not differ significantly. Cortical identification rates were 90%-96%. These findings favor HFMS for detection and total seizure burden, not proven superiority in lasting functional preservation.

Interpretation

The operative relevance lies in recognizing motor fibers before further subcortical resection, rather than selecting a probe on cortical identification alone. HFMS provided recorded responses and progressively lower stimulation thresholds as the surgeon approached the corticospinal tract. This may help define a functional stopping boundary, but the proposed link between earlier stopping, lower enhancing-tumor resection and fewer deficits remains a hypothesis. The observed identification proportions are not diagnostic sensitivity estimates: mapping was selectively applied to different patients. Moreover, bipolar awake mapping addressed language as well as movement, so these results do not establish that monopolar motor mapping can replace awake language testing.

Limitations

The historical transition between techniques introduces confounding from surgeon experience and evolving practice. Awake cases differed substantially in laterality, language involvement, tumor location and baseline motor function. Subcortical mapping was used in 66% of HFMS procedures but only 16% of asleep LFBS and 6.6% of awake LFBS procedures, limiting direct comparison. Different methods of detecting motor responses add another source of heterogeneity.

Only eight permanent motor deficits occurred across 300 operations. Absence of a significant difference therefore does not demonstrate equivalence. Fewer total seizures with HFMS should not be interpreted as fewer generalized seizures: that outcome did not differ significantly. The study also does not isolate mapping effects from other operative adjuncts, including intraoperative MRI.

Selection required accessible imaging and clinical documentation for at least six months, potentially excluding patients with incomplete follow-up. Repeated operations were included, and adjustment for within-patient correlation is not clearly described. The reported number of unique patients differs between the abstract and results, although the 300-procedure denominator is consistent. These limitations favor interpreting the study as a practice-based comparison rather than a definitive ranking of mapping strategies.

Clinical takeaway

For asleep tumor surgery near motor pathways, HFMS offers a practical subcortical mapping option supported here by higher pathway-identification rates and fewer total intraoperative seizures. The evidence does not establish a universal safe stimulation threshold, justify more aggressive resection, or prove fewer permanent deficits. Mapping choice and interpretation should remain integrated with the functional objectives of the operation, including separate language assessment when indicated.

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Dynamic MRI in cervical myelopathy: when positional compression changes the surgical plan

Neurosurgery 99:928–937, 2026

Planning decompression for degenerative cervical myelopathy requires identifying not only the severity of spinal cord compression but also its distribution across levels and its response to movement. Neutral-position MRI may not fully represent this positional component. In a randomized single-center study, Ajem and colleagues examined whether additional flexion-extension MRI could refine operative planning and improve early neurological recovery. Dynamic imaging frequently changed the intended operation, and reported functional outcomes favored its use at three months. These findings are clinically relevant, but short follow-up and inconsistencies in outcome reporting temper the strength of the conclusions.

Objective

To determine whether adding dynamic MRI to conventional imaging changes surgical planning and improves three-month functional recovery in adults undergoing surgery for degenerative cervical myelopathy.

Methods

The trial was conducted at a single institution between February 2023 and December 2024. Seventy-four patients were randomized in equal groups after an initial surgical plan had been documented using static MRI. The control group proceeded according to that plan; the dynamic group underwent additional imaging that could change the approach, decompression levels or procedure. Eligibility excluded minors, previous spine surgery, spinal trauma or congenital anomalies, and concomitant lumbar stenosis. Most participants had severe myelopathy.

Dynamic imaging used sagittal T2-weighted sequences in flexion and extension on a 3-T scanner. Positioning was individualized and limited by tolerance without provoking neurological symptoms. The operating surgeon and a senior radiologist reviewed the findings, with additional adjudication when necessary. Five experienced surgeons performed the procedures, retaining discretion over the final operation.

The primary outcome was recovery rate derived from modified Japanese Orthopaedic Association (mJOA) scores at three months. Secondary assessments included mJOA scores, Nurick grades, changes in surgical planning and complications. Randomization concerned the imaging strategy, not the surgical approach.

Main results

Dynamic MRI changed the plan in 22/37 patients (59.5%): 12 anterior-to-posterior conversions, one posterior-to-anterior conversion, six increases in decompression levels and three changes from discectomy to corpectomy. Table 4 reports recovery of at least 50% in 34/37 dynamic-imaging patients versus 22/37 controls. Mean recovery rates were 55.42% and 46.76%, respectively; postoperative mJOA scores were 15.47 and 13.77. The reported between-group Nurick difference was not significant. One patient in each imaging group died after posterior surgery. These results require interpretation alongside the reporting limitations below.

Interpretation

The practical contribution is the opportunity to reconsider a documented operation when positional imaging reveals a different distribution of compression. The predominance of anterior-to-posterior conversions shows that dynamic information affected corridor selection as well as decompression extent. However, imaging-driven changes do not establish that every additional compressed level requires surgery. Clinical concordance and individualized review remain essential, and this study does not provide a validated rule for extending decompression. Nor does it isolate which particular change produced better recovery. Its findings support further evaluation of dynamic imaging as a planning adjunct, rather than automatic escalation of surgery.

Limitations

This small, single-center trial provides only three-month follow-up and does not establish durable neurological benefit, improved quality of life or reduced reoperation. Although described as single-blinded, the report does not clearly identify the blinded party or explain allocation concealment. Surgeons necessarily knew the additional imaging findings, and procedure selection was not standardized. Motion artifacts and discomfort may also limit the examination.

Numerical inconsistencies deserve particular attention. The reported P value of .044 for mean recovery rate is not readily reconciled with the sample sizes, means and standard deviations under the independent-samples t-test described in the methods. Recovery-category counts are also difficult to reconcile fully with the reported means and variability. The direction of the findings is therefore more credible as a preliminary signal than the precise magnitude or statistical certainty of benefit.

The anterior-versus-posterior comparison was not randomized: posterior patients had worse baseline mJOA scores and more levels decompressed. It cannot establish that one approach is inherently safer or more effective. Complication percentages in Table 5 do not correspond to the stated approach-group denominators, further limiting quantitative safety comparisons. The two deaths warrant acknowledgment but cannot support an approach-specific risk estimate in this sample.

Clinical takeaway

Dynamic MRI may help refine the choice of approach and decompression extent when positional findings materially change the assessment of cervical cord compression. This trial offers a useful planning signal, not definitive evidence for routine imaging in every patient or decompression of every dynamically narrowed level. Confirmation in larger trials with transparent outcome reporting and longer follow-up is needed.

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Vestibular schwannoma surgery: choosing the corridor around hearing, volume and anatomy

J Neurosurg 145:1128–1140, 2026

Choosing an operative corridor for vestibular schwannoma requires balancing tumor removal with hearing, facial function and the demands of safe neurovascular dissection. Erginoglu and colleagues compare single-stage retrosigmoid and translabyrinthine resections in a consistent surgical practice, examining tumor volume alongside anatomical grade. Their findings associate the translabyrinthine route with more complete removal and less postoperative edema in larger tumors, while the retrosigmoid route retains the possibility of hearing preservation. Rather than establishing a universally superior approach, the study illustrates how audiometry, internal auditory canal involvement and the tumor-brainstem relationship should inform individualized planning.

Objective

To compare resection, cranial nerve function, radiological changes and recovery after retrosigmoid (RS) and translabyrinthine (TL) surgery, and assess how preoperative tumor volume influences outcomes beyond Koos grade.

Methods

This retrospective study included 283 patients undergoing single-stage resection at one tertiary center between 2006 and 2023: 207 through TL and 76 through RS. All procedures involved one neurosurgeon and a consistent neurotology team. Previous surgery or radiotherapy, neurofibromatosis types 1 or 2, and staged, combined or alternative approaches were excluded. Follow-up was at least 12 months.

Serviceable hearing, defined by audiometric class A or B, generally favored RS; nonserviceable hearing generally favored TL. However, anatomical or audiological considerations led to deviations in approximately 30% of cases. The groups therefore differed substantially before surgery: serviceable hearing was present in 30.9% of TL and 72.4% of RS patients.

Tumor volume was estimated from three MRI diameters using a modified ellipsoid formula. Outcomes included extent of resection, House-Brackmann facial function, hearing, MRI abnormalities and modified Rankin Scale scores. Multivariable models and two separate propensity-matched analyses, each with 52 patients per approach, addressed measured baseline differences.

Main results

For Koos III-IV tumors, Table 2 reports gross-total resection in 106/125 TL cases (84.8%) versus 39/56 RS cases (69.6%). Edema occurred in 0.8% versus 30.4%, respectively. Across all grades, favorable one-year facial function among patients starting with House-Brackmann I-II was 93.9% after TL and 94.7% after RS, without significant separation. Hearing preservation occurred only after RS. Median hospitalization was five days after TL versus four after RS in both Koos strata, although rehabilitation discharge was more frequent after RS in larger tumors. Greater volume reduced the likelihood of complete resection.

Interpretation

The operative decision should integrate hearing potential with the required exposure. TL offers direct internal auditory canal access and early facial nerve identification, while sacrificing hearing; RS provides broad cerebellopontine angle exposure with a possibility of hearing preservation. The authors describe CSF release and avoidance of fixed retractors during RS, yet intermittent cerebellar manipulation remained necessary. Less manipulation is a plausible explanation for the TL edema findings, not a proven causal mechanism. Dense adherence to the facial nerve or brainstem should still limit resection rather than be overcome to achieve a radiographic endpoint.

Limitations

This was not a randomized comparison. Hearing status and anatomy actively determined the approach, and adjustment cannot eliminate confounding by indication. Single-surgeon consistency improves procedural uniformity but limits generalizability. The 18-year period also encompassed changing practice: RS use declined over time. These results do not compare surgery with observation or radiosurgery, nor do they apply directly to previously treated or staged cases.

Sparse events made several adjusted models unstable. The very large estimated association between TL and favorable discharge function had a wide confidence interval and should not be interpreted as a reliable measure of treatment effect. Multiple comparisons were performed without correction. Gliosis, unlike edema, did not remain significantly different in the matched radiological analysis. Radiological abnormalities also did not consistently correspond to persistent disability.

Reporting inconsistencies warrant caution. The abstract labels the 84.8% and 69.6% figures as combined gross-total/near-total resection, whereas Table 2 assigns them to gross-total resection alone. The reported hearing-preservation percentages use the entire RS Koos subgroups as denominators, rather than clearly restricting them to patients with serviceable preoperative hearing; they should not be presented as individualized preservation probabilities. Patient-reported quality of life and systematic headache outcomes were not collected, and the low recurrence counts do not establish long-term oncological equivalence.

Clinical takeaway

Use tumor volume alongside Koos grade, detailed audiometry and canal-brainstem anatomy to select the corridor. TL may offer useful exposure when hearing preservation is not a realistic priority; RS remains relevant when it is. This series supports tailored planning and function-limited resection, not routine TL selection for every large tumor or an expectation of shorter hospitalization.

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L4-L5 fusion in the lateral position: choosing between anterior and transpsoas access

Spine 2026;51(19):1381-1389

Access to L4-L5 during single-position lumbar fusion is shaped by the relationship between the disc, iliac crest, psoas, lumbar plexus and major vessels. Huynh and colleagues compare anterior lumbar interbody fusion performed in lateral decubitus with transpsoas lateral interbody fusion, examining whether the anterior route offers a useful alternative without repositioning the patient. Their multicenter findings associate lateral-position ALIF with fewer postoperative complications and greater segmental lordosis, while highlighting the importance of anatomical selection. The study expands the discussion of available corridors, but its observational design does not establish one approach as uniformly safer or more effective.

Objective

To compare complications, reoperations, procedural efficiency and sagittal alignment after L4-L5 lateral-decubitus ALIF (L-ALIF) and transpsoas LLIF during one- or two-level lateral single-position surgery.

Methods

The authors retrospectively reviewed prospectively and consecutively enrolled patients from seven surgeons across Australia, Brazil and the United States. The reported cohort comprised 511 patients: 72 undergoing L4-L5 L-ALIF and 439 undergoing L4-L5 LLIF. Mean ages were approximately 66 and 65 years, respectively. Indications included degenerative spondylolisthesis, foraminal stenosis and postlaminectomy instability or syndrome. Previous lumbar fusion, additional TLIF/PLIF, repositioning and staged surgery were excluded.

Approach selection depended on surgeon preference and anatomy. Three surgeons contributed L-ALIF cases, whereas all seven contributed LLIF cases. Additional fusion could involve L3-L4 using LLIF or L5-S1 using L-ALIF. Both groups received posterior pedicle instrumentation without changing the lateral position.

Follow-up was at least 90 days, with radiographic assessment at 90 days. Propensity matching for age, sex, BMI, diabetes, smoking and number of fused levels generated groups of 72 patients each. Complications were classified using the Clavien-Dindo system; neurological symptoms persisting beyond six weeks were classified as major complications.

Main results

In the matched groups, postoperative complications occurred in 4.2% after L-ALIF versus 19.4% after LLIF (p = 0.004); major complications were 2.8% versus 11.1% (p = 0.049). Ninety-day reoperations did not differ significantly (2.8% versus 8.3%; p = 0.146). Operating time, blood loss and length of stay were also similar after matching. L4-L5 segmental lordosis increased by 6.6° versus 1.8° (p = 0.003). Postoperative L4-S1 lordosis was greater with L-ALIF, but its change from baseline did not differ significantly. These are matched-cohort results, distinct from the larger unmatched comparison.

Interpretation

L-ALIF provides an alternative when the transpsoas corridor is constrained, but replaces plexus-related exposure concerns with vascular mobilization considerations. The study used an access surgeon for anterior exposure and EMG-guided mapping for LLIF; unsafe transpsoas docking prompted abandonment of that approach. These safeguards are part of the reported treatment setting, not optional details that the comparison can separate from outcomes. Importantly, the three vascular injuries in the overall LLIF-labeled group occurred during accompanying L5-S1 ALIF exposure, not the L4-L5 transpsoas approach. They cannot be attributed to LLIF itself.

Limitations

Treatment was not randomized, and the anatomical reasons for choosing each corridor were not adequately captured. Propensity matching balances measured variables but cannot remove this confounding by indication or the influence of surgeon experience. Only three surgeons supplied L-ALIF cases, compared with seven for LLIF.

Two-level operations combine different approaches, limiting attribution of complications to the L4-L5 corridor. Short follow-up and the absence of patient-reported functional outcomes prevent conclusions about durable symptom relief, fusion success or long-term revision risk. Absence of vascular injury in the 72 L4-L5 L-ALIF patients does not establish absence of risk. Multiple statistical comparisons also increase the possibility of false-positive findings, particularly for borderline results.

The publication contains minor reporting discrepancies, including 438 versus 439 LLIF patients in different locations and a segmental lordosis change of 6.8° in the abstract versus 6.6° in Table 5. The figures summarized here follow the main results and matched tables. Several authors disclosed industry relationships relevant to spinal instrumentation.

Clinical takeaway

For lateral single-position L4-L5 fusion, assess both the anterior vascular corridor and the transpsoas neural corridor before choosing the approach. L-ALIF is a reasonable option in experienced hands and may improve segmental lordosis while avoiding psoas-related symptoms. This study supports individualized planning, not a blanket claim that anterior access is safer or that greater radiographic correction guarantees better clinical recovery.

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Severe lumbar stenosis: selecting patients for indirect decompression

 

Neurosurgery. 2026;99(4):841-852

Severe lumbar canal narrowing does not necessarily identify a uniform surgical problem: reducible soft-tissue compression differs fundamentally from fixed osseous stenosis. Li and colleagues examine this distinction in a randomized comparison of oblique lateral interbody fusion and conventional transforaminal lumbar interbody fusion. Their findings support considering indirect decompression in carefully selected patients with instability, with perioperative advantages and earlier functional improvement after OLIF. However, the similar disability scores at two years, restrictive eligibility criteria and limitations in reporting argue against interpreting the study as evidence that indirect decompression can routinely replace direct neural decompression.

Objective

To compare clinical recovery, radiographic decompression, fusion and complications after OLIF and open TLIF for single-level severe lumbar stenosis with segmental instability.

Methods

The five-center trial assessed 260 patients and randomized 224 adults, 112 to each procedure, between November 2018 and December 2021. Allocation used computer-generated blocks and sequentially numbered sealed envelopes. Five experienced spine surgeons performed the operations. After five losses to follow-up, analyses included 109 OLIF and 110 TLIF patients with at least two years of follow-up.

Eligibility required symptomatic L2-L5 stenosis classified as Schizas C or D, radiographic instability, failure of at least three months of conservative treatment and a reducible, predominantly soft-tissue mechanism. Symptoms relieved by recumbency were an important selection feature. Fixed bony stenosis, ossified ligamentum flavum, ankylosis, sequestrated disc material, high-grade spondylolisthesis and unfavorable access anatomy were excluded, alongside several other conditions.

OLIF used a retroperitoneal corridor anterior to the psoas, interbody distraction and supplemental fixation. The comparator was conventional open TLIF with direct decompression, not minimally invasive TLIF. Outcomes included ODI, back and leg pain, serial canal measurements, alignment, CT-assessed fusion and complications.

Main results

OLIF had shorter operating time (102.8 versus 138.5 minutes) and lower estimated blood loss (24.8 versus 200.6 mL). ODI favored OLIF at three and six months, but not at two years (11.24 versus 11.95; p = 0.102). Two-year back pain scores favored OLIF; leg pain did not differ significantly. OLIF restored more disc height and segmental lordosis, whereas TLIF achieved greater canal area. Two-year fusion rates were 98.2% versus 95.5%, without significant separation. Recorded complications occurred in 6/109 OLIF and 8/110 TLIF patients; the difference was not significant.

Interpretation

The practical message is to assess whether compression is reducible, rather than choosing decompression solely from the Schizas grade. The OLIF protocol emphasized thorough disc clearance, preservation of the bony endplates, appropriate cage sizing and verification of implant position; endoscopic inspection was described as an adjunct. These components were not independently tested. Progressive canal enlargement after OLIF supports a remodeling mechanism, but does not establish that waiting for remodeling is appropriate for fixed compression or neurological deterioration. The findings support selective use, not a universal preference for OLIF.

Limitations

The trial studied a highly selected population treated by experienced surgeons at five Chinese centers. Its results do not establish effectiveness in multilevel disease, fixed osseous compression, deformity or high-grade spondylolisthesis. The open TLIF comparator also limits extrapolation to contemporary minimally invasive alternatives. Two years is insufficient to establish protection against adjacent-segment disease or long-term construct failure.

Although the authors describe the procedures as equivalent, the reported analysis does not specify an equivalence margin or a formal equivalence framework. A nonsignificant difference therefore should not be treated as proof of equivalence, particularly for uncommon complications. The report provides limited detail on sample-size justification, handling of repeated measurements and multiplicity; the presented analyses exclude the five patients lost to follow-up.

There is also an inconsistency in the description of OLIF fixation: the title and illustrations identify lateral vertebral fixation, whereas parts of the methods refer to pedicle screws and rods. This limits reproducibility of the exact construct. The early between-group ODI differences of approximately five points should not be confused with the larger within-patient improvement thresholds cited by the authors.

Clinical takeaway

Consider OLIF as an option for carefully selected, reducible single-level stenosis with instability when access anatomy and surgical expertise are suitable. This trial supports earlier recovery compared with open TLIF, but does not justify extending indirect decompression to fixed stenosis or claiming superior long-term function. Patient selection remains more important than canal grade alone.

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