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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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One-and-a-half MIS-TLIF: selective fusion with adjacent-level decompression

Journal of Neurosurgery: Spine. 2026;45(3):339-346

Lumbar stenosis affecting adjacent levels does not necessarily imply that every symptomatic segment requires fusion. The operative challenge is to distinguish the level requiring stabilization from a neighboring stenotic segment that can be decompressed without compromising its mechanical integrity. Farooq and colleagues evaluate a hybrid strategy combining single-level minimally invasive transforaminal lumbar interbody fusion with adjacent-level unilateral laminotomy for bilateral decompression. Their experience provides preliminary clinical support for selective fusion in carefully chosen patients, while emphasizing that preservation of the adjacent segment depends on both preoperative stability and a structure-preserving decompression.

Objective

To assess reoperation after the one-and-a-half MIS-TLIF procedure, particularly subsequent extension of fusion to the adjacent decompressed segment, together with clinical and radiographic outcomes.

Methods

This retrospective single-center series evaluated operations performed by one experienced surgeon between January 2016 and February 2023. Of 36 patients considered, 33 met the inclusion criteria. Mean age was 67.9 years. Patients had degenerative lumbar disease with radiculopathy and mechanical back pain unresponsive to conservative treatment. The strategy combined MIS-TLIF using an expandable cage at the unstable segment with unilateral laminotomy for bilateral decompression (ULBD) at an adjacent stenotic level. The authors specify that adjacent-level decompression was restricted to segments without dynamic instability.

Outcomes included complications, reoperations, back and leg pain, disability and radiographic measures. Median clinical follow-up was 26 months. Complete serial imaging was available for 26 patients, with a median radiographic follow-up of 11.7 months. Fusion assessment relied primarily on standing and dynamic radiographs; CT was used when available rather than obtained routinely.

Main results

Three patients required reoperation (3/33, 9.1%). Two underwent extension of fusion to the previously decompressed adjacent level (2/33, 6.1%), while one underwent revision at the initially instrumented level. These are observed proportions over the reported follow-up, not comparative estimates of risk reduction.

Four patients experienced perioperative complications (12.1%): one CSF leak, one hardware failure, one wound dehiscence and one wound infection. No neurological complications were reported. Mean operative duration was 213.7 minutes, and median hospital stay was 48 hours. Blood loss was recorded in the categories below 50 mL or 50-150 mL in 28 of 33 patients.

Fusion was reported in 25 of the 26 patients with complete imaging (96.2%). Cage subsidence was present in six of these patients at the latest radiographic assessment (23.1%). Disc height and segmental lordosis improved; mean segmental lordosis increased from 14.1 degrees preoperatively to 17.4 degrees immediately after surgery and measured 16.4 degrees at final radiographic follow-up.

Pain and disability scores also improved. Median leg-pain VAS decreased from 5.5 before surgery to 0 at final follow-up. The final mean back-pain VAS was 3.1, compared with a preoperative median of 7.0. Final median ODI was 13.5, compared with a preoperative mean of 42.1. Because the paper reports a mixture of means and medians, these figures should not be subtracted and presented as a uniform average treatment effect.

Interpretation

The most useful surgical distinction is between adjacent stenosis and adjacent instability. This approach does not simply abbreviate a multilevel fusion: it assigns different treatments to levels with different mechanical requirements. The index level receives stabilization, while the adjacent level remains unfused only when it is radiographically stable and suitable for ULBD.

Preservation of the adjacent facets and posterior tension band is central to the rationale. A limited decompression designed to retain these structures cannot be considered mechanically interchangeable with a wide adjacent-level laminectomy. The authors distinguish this indication from bisegmental instability or foraminal stenosis requiring substantial facetectomy, situations in which a two-level fusion may address a different problem. The series does not validate a universal imaging threshold for selecting decompression alone.

The expandable cage introduces a separate technical consideration. The discussion emphasizes endplate preservation and controlled expansion, and the observed subsidence rate warrants attention even in the presence of a high reported fusion rate. Neither these data nor the accompanying illustration establish superiority of a particular cage design or an optimal expansion protocol.

The principal contribution is evidence of feasibility and early durability in a selected cohort. Two adjacent-level fusion extensions over a median of approximately two years are encouraging, but they do not demonstrate prevention of adjacent segment disease. The authors themselves caution that institutional single-level and two-level fusion series had different indications and follow-up periods and are contextual references rather than valid control groups.

Limitations

The study is small, retrospective and confined to one highly experienced surgeon, without a comparative control group. Selection limits applicability to patients with instability at more than one level, high-grade spondylolisthesis, epidural fibrosis or advanced osteoporosis. Seven patients lacked complete serial imaging, and fusion was not routinely confirmed with CT. Clinical and radiographic follow-up durations differ substantially, and the longer-term risk of adjacent-level deterioration remains uncertain. Absence of neurological complications in 33 patients cannot establish a negligible risk. Comparative advantages in morbidity, reoperation or motion preservation remain unproven.

Clinical takeaway

Consider selective fusion as a question of segment-specific pathology: stabilize the level that requires it and assess whether an adjacent stable stenotic level can be adequately decompressed while preserving its supporting structures. This series supports discussing one-and-a-half MIS-TLIF as an option in appropriately selected patients, with explicit counseling about possible later fusion extension. It does not support substituting limited decompression for fusion at a second genuinely unstable segment.

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Hydrocephalus after vestibular schwannoma radiosurgery: ventricular enlargement is not synonymous with shunt dependence

Journal of Neurosurgery 2026;145(3):743-754

Follow-up after stereotactic radiosurgery for vestibular schwannoma must assess more than tumor control: ventricular enlargement can introduce a separate clinical problem, even without overt obstruction. Bauman and colleagues combine an adult institutional cohort with a systematic review to examine this complication and distinguish radiological change from symptomatic hydrocephalus requiring cerebrospinal fluid diversion. Their findings identify associations with age, target volume and subsequent tumor growth, while showing that some patients with enlarged ventricles remain asymptomatic. The central clinical message is therefore one of informed surveillance and individualized assessment, rather than automatic shunting based on imaging alone.

Objective

To determine the incidence and associated risk factors of nonobstructive ventricular enlargement and symptomatic communicating hydrocephalus following primary stereotactic radiosurgery (SRS) for vestibular schwannoma.

Methods

The retrospective Mayo Clinic cohort included 634 patients treated with primary Gamma Knife radiosurgery between January 2000 and July 2023. Median age was 64 years, with a range of 18-89 years. Exclusions included previous tumor resection, preexisting shunts or relevant hydrocephalus, post-SRS obstructive hydrocephalus and follow-up shorter than six months. Median imaging follow-up was 61 months.

The investigators separately examined nonobstructive ventricular enlargement and symptomatic hydrocephalus requiring ventriculoperitoneal shunting. Logistic regression assessed associated factors. Tumor change was classified using the latest available imaging relative to treatment imaging, with salvage-treated progression categorized as growth.

A systematic review searched three databases through January 2024. Twenty-nine studies, including the institutional cohort, contributed 7,825 patients to a random-effects meta-analysis. The institutional adult data and the pooled literature estimates should be distinguished rather than treated as a single homogeneous population.

Main results

Ventricular enlargement occurred in 23/634 patients (3.6%); nine remained asymptomatic and 14 (2.2% of the cohort) required shunting, at a median of eight months after SRS. Age ≥65 years, target volume ≥5 cm³ and subsequent tumor growth were associated with shunt-requiring hydrocephalus in adjusted analyses. The literature synthesis estimated ventricular enlargement/hydrocephalus at 5% and shunt-requiring disease at 4%, with substantial heterogeneity. The study did not reliably distinguish which patients with established ventricular enlargement would subsequently need a shunt.

Interpretation – operative relevance

The findings support closer clinical attention to higher-risk patients and assessment of ventricular change alongside tumor response. Radiological enlargement alone did not mandate diversion in this cohort. The 5 cm³ threshold is an exploratory risk discriminator, not a validated contraindication to SRS or an indication for prophylactic shunting. Likewise, the association with maximum radiation dose concerned ventricular enlargement, not demonstrated shunt dependence; it does not establish that changing dose prevents symptomatic hydrocephalus. Decisions about diversion remain clinical rather than threshold-driven.

Limitations

The institutional analysis was retrospective and included only 23 ventricular-enlargement events and 14 shunt procedures. Multivariable estimates consequently have substantial uncertainty. Treatment-selection patterns favored SRS for smaller lesions, limiting generalizability to the full vestibular schwannoma population. Shunt indications were not governed by uniform, prospectively specified criteria.

Tumor growth was assessed at the latest follow-up, so its association with hydrocephalus should not be interpreted as a validated baseline predictor or proof of temporal causation. The proposed protein-mediated impairment of CSF absorption remains a hypothesis; occult partial obstruction is an alternative discussed by the authors.

The literature synthesis combined heterogeneous definitions, treatment populations and follow-up practices. Statistical heterogeneity was high for both pooled incidence estimates. Some eligible series mixed primary and secondary SRS, and the pooled results were not presented as an adult-only subgroup. The pooled shunting proportion among patients with ventricular enlargement should not be applied as an individual probability or substituted for clinical assessment.

Clinical takeaway

After vestibular schwannoma radiosurgery, evaluate ventricular changes in their clinical context, particularly in older patients, larger treated tumors and cases with subsequent growth. This study supports vigilance but provides neither a reliable rule for predicting shunt dependence nor evidence for prophylactic CSF diversion.

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Cervical disc arthroplasty versus fusion: measuring the burden of recovery

Neurosurgery. 2026;99(3):643-653

The outcome of cervical surgery encompasses not only the patient’s condition at one year, but also the disability experienced while recovering. Asada and colleagues examine this distinction by comparing cervical disc replacement with anterior cervical discectomy and fusion using a cumulative, model-based outcome measure. Their findings associate arthroplasty with a lower burden of neck-related disability during the first postoperative year, without a corresponding advantage in cumulative arm pain. This approach adds a useful dimension to preoperative counseling, although its observational design and the limited validation of the new measure require a cautious interpretation.

Objective

To develop and internally evaluate a modified integrated health state (mIHS) measure and compare cumulative postoperative disability after one- or two-level cervical disc replacement (CDR) and anterior cervical discectomy and fusion (ACDF) for degenerative cervical radiculopathy.

Methods

The authors retrospectively analyzed a prospectively collected, multisurgeon institutional registry covering February 2016 to September 2024. Of 1,273 screened patients, 327 were included: 159 underwent ACDF and 168 underwent CDR. Hybrid constructs, procedures involving three or more levels, missing baseline Neck Disability Index (NDI) scores and baseline NDI below 20 were excluded. The cohort flowchart also excluded myelopathy and trauma.

NDI and neck and arm pain scores were collected before surgery and at intervals through 12 months. Postoperative scores were normalized to baseline, and nonlinear mixed-effects models estimated recovery trajectories. The mIHS summarized the area under these modeled trajectories; it is not a conventional NDI point score. Propensity-score overlap weighting balanced measured baseline characteristics. Patients with shorter follow-up remained eligible, with missing postoperative observations handled under a missing-at-random assumption.

Main results

The one-year NDI-based mIHS was lower after CDR than ACDF (2.68 versus 3.71; difference 1.03, 95% CI 0.80-1.25; p < 0.001), corresponding to a 27.7% relative reduction in this modeled measure. Cumulative neck pain also favored CDR; cumulative arm pain did not differ significantly. Two-level CDR had a similar mIHS to one-level CDR, whereas two-level ACDF carried greater cumulative disability than one-level ACDF. These results describe recovery burden, not a 27.7% reduction in the conventional NDI score.

Interpretation – operative relevance

For patients in whom both procedures are appropriate, the findings support discussing the course of recovery alongside the expected endpoint. Preserved segmental motion after CDR offers a plausible explanation, but this study does not establish it as the cause of better recovery. Nor does it justify extending arthroplasty indications, choosing a particular prosthesis or altering decompression technique. The practical contribution is to procedure selection and counseling rather than a new operative maneuver or proof of long-term superiority.

Limitations

Treatment was not randomized. Before weighting, CDR patients were younger and differed in comorbidity, pathology and number of treated levels. Statistical adjustment cannot remove unmeasured confounding, including the reasons a surgeon selected one procedure over another. Postoperative analgesic consumption was not reliably captured.

Excluding low baseline NDI scores limits applicability to patients with milder disability. Model-based estimates depend on assumptions about recovery trajectories and missing data. The mIHS underwent internal validation only, and its minimum clinically important difference remains undefined; statistical separation therefore cannot be equated with an established patient-perceived benefit threshold.

Follow-up was limited to one year. Imaging was incomplete and nonstandardized, making fusion, motion and heterotopic ossification analyses vulnerable to selection bias. The study does not establish comparative long-term revision rates or device-specific safety.

Clinical takeaway

When counseling suitable candidates for cervical arthroplasty or ACDF, discuss how recovery may unfold, not simply the expected one-year result. This study associates CDR with less cumulative neck-related disability, but its novel outcome measure and observational design do not support a universal preference for arthroplasty.

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Venous sinus stenting: coverage length matters, but durable benefit remains unproven

Neurosurgery. 2026;99(3):710-720

Endovascular treatment of idiopathic intracranial hypertension raises a question beyond correcting the narrowest venous segment: how much of the transverse sinus should be supported by the stent? Jaikumar and colleagues explore the relationship between venous coverage, pressure profiles and subsequent symptoms in an adult cohort. Their analysis suggests that the extent of transverse sinus reinforcement deserves attention during planning, while also highlighting the influence of the wider venous circulation. However, its observational design and inclusion of recurrent symptoms within the improvement category prevent a conclusion that longer coverage guarantees lasting benefit.

Objective

To assess whether the length and proportion of transverse sinus covered by a stent, together with venous anatomy and hemodynamics, were associated with symptom improvement after venous sinus stenting.

Methods

The authors retrospectively studied 114 adults treated between January 2017 and December 2024. Median age was 36 years, and 109 patients were women. Exclusions included relevant meningiomas, established jugular compression etiologies, previous venous sinus thrombosis, missing procedural venography and lumbar puncture within seven days before the qualifying manometry.

The transverse sinus segment was measured on venography from the lateral margin of the superior sagittal sinus to the end of the stenotic segment. Subtracting the unstented distance between that medial landmark and the stent yielded the length of transverse sinus reinforcement. This anatomical measurement is not simply the nominal length of the implanted device.

Separate regression models examined headache, visual symptoms, tinnitus and papilledema. The first three outcomes were patient-reported; papilledema was assessed by a neuro-ophthalmologist. Crucially, complete or partial improvement and recurrence after initial improvement were grouped together, against no change or worsening. The models therefore did not isolate sustained symptom control.

Main results

Improvement was recorded in 93/110 patients with headache, 74/93 with visual symptoms, 30/35 with tinnitus and 77/89 with papilledema; these totals included subsequent recurrences.

Longer transverse sinus coverage was associated with lower adjusted odds of no improvement or worsening for headache (OR 0.782; 95% CI 0.617-0.990), visual symptoms (0.581; 0.387-0.873) and tinnitus (0.881; 0.781-0.993), but not significantly for papilledema (p = 0.052). Elevated jugular-pressure physiology was associated with worse visual outcomes, with considerable uncertainty. Percentage coverage and torcular distance did not consistently reproduce the association with absolute covered length.

Interpretation

Planning should consider the residual unstented segment, venographic anatomy and pressure profile rather than focal stenosis alone. This does not establish a rule for extending stents toward the torcula. Increased wall compliance and adjacent collapse remain hypotheses: neither was directly measured, and wall-thickness mapping was separate exploratory work.

Persistent symptoms should not automatically be attributed to insufficient coverage, because downstream venous pressure may also influence response. However, the jugular-pressure surrogate cannot reliably distinguish systemic venous hypertension from local outflow effects and is not a stand-alone diagnostic test.

Limitations

The retrospective, single-center design is vulnerable to treatment-selection and ascertainment bias. Two-dimensional measurements imperfectly represent a three-dimensional sinus. Follow-up was variable and incomplete, and symptom assessment was largely subjective. Most importantly, grouping recurrence with improvement prevents the reported associations from establishing durability.

Several models contained many predictors relative to the small number of adverse outcomes. The very wide confidence intervals and extreme coefficients in some tables raise concerns about instability and overfitting. Related measurements of total sinus length, covered length, uncovered distance and percentage coverage also warrant caution when interpreting individual coefficients. These are methodological concerns arising from the reported models, not proof that the observed association is absent.

The study does not establish an optimal coverage length, a universal landing zone or the comparative safety of routinely implanting longer or additional stents.

Clinical takeaway

Assess transverse sinus coverage in the context of the entire venous anatomy and pressure profile. This study supports further evaluation of coverage length as a planning variable, but does not justify routine maximal reinforcement or a promise of recurrence prevention. Distinguish initial response from sustained benefit when counseling patients and judging outcomes.

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Bilateral deep brain stimulation: does separating lead implantation improve safety?

Neurosurgery. 2026;99(3):691-699

Whether bilateral stimulation leads should be implanted together or in separate operations remains a consequential planning decision. Hilvert and colleagues examine this question through a retrospective comparison that found no measurable safety advantage from staging, despite greater cumulative operative and hospital use. The findings invite reconsideration of routine staging, but do not remove the need for individualized assessment.

Objective

To compare the clinical safety, subsequent treatment burden and resource utilization associated with staged versus simultaneous bilateral DBS lead implantation for movement disorders.

Methods

The authors retrospectively examined adults undergoing bilateral DBS for Parkinson disease, essential tremor or dystonia at one institution between 2006 and 2023. Patients younger than 18 years, those with previous DBS and those treated for other indications were excluded. Propensity matching used age, sex and diagnosis; the final analysis included 252 patients in each group.

Outcomes included intraoperative events, postoperative complications, delirium, 30-day readmission, medication reduction at one year and reoperation within five years. Additional analyses considered electrode accuracy, anesthesia exposure, operating-room use and hospitalization. Residual differences between groups were addressed through multivariable adjustment.

Main results

Thirty-day complications occurred in 24.2% of staged versus 22.2% of simultaneous cases, without a significant difference. Adjusted principal clinical outcomes likewise did not differ significantly. Staging increased cumulative anesthesia time (approximately 411 versus 254 minutes), operating-room time (388 versus 242 minutes) and hospitalization (2.35 versus 1.57 days), including after adjustment. These totals describe the treatment pathway, not individual operations.

Interpretation

The study questions routine staging without excluding benefit for selected high-risk patients. The median interval between staged lead insertions was seven days; results should not be generalized to protocols allowing months of clinical reassessment.

Simultaneous implantation referred to both leads, not the entire DBS system: pulse-generator placement remained separate. Leads were generally inserted awake with electrophysiological testing. Thus, the findings inform this institutional workflow rather than establish identical safety across alternative anesthetic or targeting strategies. Clinical vulnerability and the purpose of any interval should remain explicit in surgical planning.

Limitations

Allocation was retrospective and nonrandomized, reflecting clinical judgment and changes in institutional practice. Despite matching, staged patients remained older and more frequently had Parkinson disease, while simultaneous patients more often had essential tremor; targets also differed. Adjustment cannot eliminate unmeasured confounding or fully compensate for these imbalances.

Postoperative standardized motor scores were unavailable, so medication reduction cannot establish comparable motor efficacy. Rare adverse events and wide confidence intervals limit the ability to rule out meaningful safety differences. Electrode-accuracy data were available only for a subset, and results from one institution may not transfer to other workflows. Nonsignificant comparisons should not be interpreted as proof of equivalence.

Clinical takeaway

Simultaneous bilateral lead implantation merits consideration when clinically and technically appropriate, because staging did not demonstrate a safety advantage and increased cumulative treatment burden in this cohort. Preserve individualized assessment of cognitive status, comorbidity, diagnosis and patient preference. The study informs shared planning; it does not mandate abandoning staged surgery.

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MIS-TLIF Versus Open TLIF in Combined Lumbar Stenosis and Low-Grade Spondylolisthesis: Discharge Timing and Treatment Pricing

Spine 2026;51:1326–1332

Choosing between minimally invasive and open transforaminal lumbar interbody fusion requires balancing adequate decompression and reconstruction against the burden of surgical exposure. In patients with single-level degenerative stenosis and low-grade spondylolisthesis, Krutko and colleagues provide randomized evidence that early functional recovery need not be compromised by a less extensive approach. Their findings favor a selective interpretation: minimally invasive surgery shortened hospitalization and reduced additional analgesic requirements, but did not establish superior clinical outcomes or lower direct costs. Patient selection, incomplete follow-up and the absence of mature fusion results remain central to applying the study.

Objective

To determine whether minimally invasive TLIF was noninferior to open TLIF for improvement in disability at three months, while comparing clinical, perioperative and direct-cost outcomes.

Methods

This single-center, open-label randomized trial enrolled 96 patients between 2022 and 2024, allocating 48 to each technique. Mean age was 55.8 years, and 74% were women. The registered protocol specified ages 40-75 years; the report describes an additional eligibility requirement of lumbar vertebral attenuation above 120 Hounsfield units. Most procedures involved L4-L5. Two surgeons, each with more than 15 years of experience, performed the operations.

The primary endpoint was change in the Oswestry Disability Index (ODI) at three months, with a prespecified noninferiority margin of 12 points. The primary analysis used available observations from the modified intention-to-treat population; a per-protocol analysis excluded major protocol deviations. Secondary measures included pain, satisfaction, complications, hospitalization and direct costs.

Main results

Three-month ODI data were available for 48 minimally invasive and 39 open-surgery patients. The reported difference was 0.4 points (90% CI -5.7 to 6.5), supporting the authors’ noninferiority conclusion; approximately 83% and 82% achieved clinically important improvement.

Hospitalization averaged 8.0 versus 9.5 days (p = 0.005), and additional analgesia was less frequent after minimally invasive surgery (p = 0.026), although direct costs were 10.5% higher. Pain, satisfaction, blood loss, operative duration and complication comparisons were not statistically significant. Six complications occurred overall, with no reoperations during three months.

Interpretation

Approach selection should follow decompression requirements, bone quality and surgical expertise. The minimally invasive technique combined unilateral paramedian exposure, over-the-top decompression and contralateral percutaneous screws; open surgery used midline exposure, laminectomy and bilateral facetectomy. Both groups received two cages and bilateral fixation.

The findings support these constructs in selected single-level disease, not reduced exposure when adequate decompression is uncertain. They do not determine whether fusion is preferable to decompression alone. Higher implant expenditure outweighed shorter hospitalization locally, so the economic result should not be generalized across healthcare systems.

Limitations

The single-center, unblinded design and highly experienced operators limit generalizability. Missing three-month observations were confined to the open group, creating an important risk of attrition bias in a noninferiority trial. The study also recorded five major protocol deviations in each arm. Secondary comparisons were not adjusted for multiplicity, and the small number of complications cannot establish equivalent safety.

The bone-density eligibility threshold restricts extrapolation to patients with poor bone quality. Three-month disability improvement does not establish fusion success, implant durability or long-term freedom from revision. Length of stay and costs reflect the national and institutional healthcare setting.

Clinical takeaway

For selected single-level degenerative stenosis with low-grade spondylolisthesis, MIS-TLIF is supported as an alternative to open TLIF for early functional recovery. Match the approach to decompression requirements, bone quality and operator experience; do not infer superior long-term fusion, fewer complications or lower costs from this trial.

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Surgical management of jugular foramen meningiomas: a function-prioritized perioperative workflow

Neurosurg Focus 61(3):E6, 2026

Surgery for a jugular foramen meningioma requires balancing access to several anatomical compartments against the vulnerability of the lower cranial nerves and venous outflow. An apparently satisfactory resection may still carry a substantial functional cost if swallowing or voice deteriorates. Matsushima and colleagues describe a perioperative strategy linking compartment-based exposure, selective embolization, vagus nerve monitoring and structured swallowing assessment. Their series illustrates how deliberate residual tumor can form part of a function-preserving operation, while emphasizing that avoidance of severe disability does not mean absence of postoperative symptoms.

Objective

To describe a function-prioritized surgical workflow for jugular foramen meningiomas and evaluate recovery of oral intake, swallowing and voice outcomes, extent of resection and subsequent treatment for tumor progression.

Methods

This retrospective single-center study included 26 consecutive primary resections performed between 2014 and 2025. Mean age was 45.1 years, with a range of 16–77 years; the cohort therefore was not exclusively adult. Previous surgery for the same lesion was excluded, although one patient previously treated with stereotactic radiosurgery was retained.

Twenty tumors involved the intradural and intrajugular compartments (IJ), and six also extended extracranially (IJE). Imaging assessed tumor extension, vascularity and sigmoid–jugular venous patency. Embolization was performed selectively in 16 patients, and continuous vagus nerve monitoring was implemented in 16. Outcomes included extubation timing, time to oral intake and swallowing and voice status at one year, together with resection extent and salvage treatment during follow-up.

Main results

The principal approaches were suprajugular in 13 patients, retrosigmoid in nine and transjugular transsigmoid in four. All four transjugular cases had extracranial extension and ipsilateral sigmoid–jugular occlusion, illustrating the anatomical selection underlying approach choice.

Gross-total resection was achieved in seven patients, near-total resection in ten, subtotal resection in eight and partial resection in one. Eighteen operations were classified as Simpson grade IV. Residual disease associated with subtotal or partial resection predominantly occupied the intrajugular or extracranial compartments rather than representing persistent intradural tumor bulk. All six IJE tumors underwent subtotal or partial resection.

All patients were extubated immediately after surgery. Twenty resumed oral intake within seven days, five between days eight and fourteen, and one after fourteen days. At one year, swallowing remained worse than baseline in 14 patients (54%) and voice in 12 (46%). Almost all worsening was mild; one patient had moderate impairment of both functions. No patient required tracheostomy, gastrostomy, long-term tube-feeding dependence or phonosurgical intervention. One surgical site infection required bone flap removal, and one CSF leak was managed with lumbar drainage.

All six patients with IJE tumors reported persistent worsening of swallowing and voice, compared with 40% and 30%, respectively, in the IJ group. Median time to oral intake was eight versus two days. These differences should be interpreted in the context of larger tumors, more baseline dysfunction and different operative exposures in the IJE subgroup.

Among monitored patients, lower preservation of vagus response amplitude was associated with worse swallowing at one year in an exploratory analysis. The most symptomatic patient experienced an abrupt decline to zero. During a median follow-up of 55.6 months, three patients underwent salvage radiosurgery for progression. No patient received routine planned adjuvant radiosurgery after limited resection.

Interpretation – operative relevance

The operative corridor was chosen to expose the involved compartments while accounting for venous function. A retrosigmoid approach served predominantly intradural lesions. When additional intrajugular access was necessary, an intradural suprajugular extension allowed drilling of the jugular foramen roof while preserving the sigmoid–jugular venous system. This distinction is useful when intraforaminal exposure is required but functioning venous drainage should be maintained.

For selected extensive IJE tumors with an occluded ipsilateral venous system, the transjugular transsigmoid approach combined posterior mastoidectomy with high cervical exposure. The reported technique included ligation and division of the exposed sigmoid–jugular system to obtain access to the intrajugular and extracranial disease. This describes a strategy used in four anatomically selected cases; it is not evidence that venous sacrifice is generally safe or that an imaging finding of occlusion alone establishes expendability.

Continuous vagus monitoring complemented intermittent nerve mapping. The authors used repetitive direct stimulation at 1 Hz and compared the final evoked amplitude with baseline. Their practical response to declining or unstable signals was to reassess traction, coagulation and dissection planes, accepting residual tumor when further dissection threatened function. The study does not validate a universal amplitude threshold for stopping resection or prove that monitoring independently improves outcomes.

The location of residual tumor is as important as the overall resection category. Deliberately retaining adherent intrajugular, extracranial or paracarotid disease may preserve function after substantial intradural clearance. Reporting both compartmental residual and resection extent is therefore more informative than interpreting Simpson grade IV as a uniform measure of operative inadequacy.

Functional preservation also extended beyond tumor removal. Intraoperative findings and monitoring changes were communicated to anesthesia, while laryngoscopic and swallowing assessment guided oral intake and diet progression. Immediate extubation in this series should be understood within that individualized multidisciplinary workflow, not as a mandatory postoperative target.

Limitations

This is a small retrospective series without a comparator. Approach, embolization and monitoring were selected according to anatomy and clinical judgment, so their individual effects cannot be separated. The extracranial-extension subgroup comprised only six patients and had shorter follow-up, limiting conclusions about durable tumor control. Swallowing and voice were assessed with clinical severity categories rather than comprehensive patient-reported instruments. The age range includes an adolescent, and aggregate outcomes cannot be treated as exclusively adult results. The association between monitoring amplitude and swallowing is exploratory rather than a validated predictive rule.

Clinical takeaway

Use compartmental extension and functional venous anatomy to plan exposure, and let the lower cranial nerve interface define the safe boundary of resection. Monitoring can inform reassessment during dissection, while deliberate residual disease requires a documented surveillance and salvage strategy. The central achievement in this series was avoidance of severe dependency, not elimination of swallowing and voice morbidity—a distinction that belongs in both surgical planning and patient counseling.

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Comparative outcomes of syringopleural, syringosubarachnoid, and syringoperitoneal shunts for syringomyelia: a single-center retrospective cohort study

J Neurosurg 145:831–842, 2026

When symptomatic syringomyelia persists despite treatment of its underlying cause, choosing a drainage route requires more than selecting the shortest catheter trajectory. The condition of the subarachnoid space, the level of the cavity and the suitability of an extracranial receiving compartment all influence the operation and its subsequent failure modes. Khalafallah and colleagues compare three shunting strategies in a small adult cohort, illustrating the tension between early decompression and durable neurological benefit. Their findings support individualized planning and careful surveillance, rather than a universal hierarchy of shunt types.

Objective

To compare revision burden, time to failure and neurological outcomes after syringopleural, syringosubarachnoid and syringoperitoneal shunting for syringomyelia.

Methods

The authors retrospectively reviewed a prospectively maintained single-surgeon database covering 1997–2025. Thirty-one adults aged at least 18 years underwent 48 procedures: 20 syringopleural, 21 syringosubarachnoid and seven syringoperitoneal operations. Mean patient age was 47.2 years. Underlying conditions included trauma, tethering, meningitis and Chiari I malformation, as well as cases without an identified cause.

Shunt selection was determined by anatomy, presumed drainage physiology, previous operations and comorbidity, rather than random allocation. Four patients received different shunt types during their treatment and contributed to more than one group. Neurological status was classified as improved, unchanged or worse immediately after surgery, at three months and at the last available follow-up. Revision meant returning to the operating room for a shunt-related complication.

Main results

Ten of 31 patients required at least one revision; revision procedures accounted for 17 of the 48 operations. The reported revision proportions were 11/20 for syringopleural, 4/21 for syringosubarachnoid and 2/7 for syringoperitoneal procedures (55.0%, 19.0% and 28.6%; reported p = 0.003). These figures describe a dataset containing repeated operations and overlapping patient groups: they should not be interpreted as independent patient-level probabilities of failure after an initial shunt.

Catheter migration accounted for four of the 11 syringopleural revisions. Other revision indications included recurrent syrinx, obstruction, traumatic injury, subdural hygroma and infection. Neither time to revision nor the patient- or shunt-based revision-free survival comparisons showed a statistically significant difference between groups.

Immediate neurological improvement occurred after 11/20 syringopleural, 7/21 syringosubarachnoid and 1/7 syringoperitoneal procedures. Although numerically highest in the pleural group, the difference was not statistically significant (p = 0.117). At three months, improvement was recorded in 7/16, 6/13 and 2/6 evaluable cases, respectively, again without a significant difference.

Long-term observations were less reassuring but substantially incomplete. At the last assessment, improvement was recorded in one of ten evaluable pleural cases, two of ten subarachnoid cases and none of four peritoneal cases. Approximately half the clinical observations were missing in each group, and imaging completeness was even lower. These results raise concerns about durability but cannot establish the true frequency of late deterioration in the entire cohort.

Interpretation – operative relevance

The first decision is whether a shunt is appropriate at all. The authors place correction of the underlying pathology—such as craniocervical obstruction or tethering—before direct syrinx diversion when such treatment is feasible. Their comparison therefore informs drainage selection in selected refractory cases, not the replacement of cause-directed surgery by routine shunting.

For destination selection, their practice generally favored pleural drainage for cervical or upper thoracic cavities and peritoneal drainage for lower thoracic cavities. These preferences reflected anatomical access and presumed drainage characteristics, not proven superiority at particular spinal levels. Previous chest or abdominal surgery, pulmonary disease, peritonitis and earlier shunt failure also influenced the choice.

The subarachnoid option depended particularly on the receiving space. The authors increasingly restricted it to preserved subarachnoid anatomy or focal, single-level adhesions, avoiding reliance on a severely scarred or functionally obstructed compartment. Their practical message is to assess where fluid can drain effectively, rather than choosing a local shunt solely because it avoids a distal extracranial catheter.

The operative description includes laminectomy, intraoperative ultrasound localization, midline durotomy and myelotomy, and placement of a nonvalved silicone catheter. Pleural and peritoneal systems required subcutaneous tunneling to the selected destination; dural closure around the catheter was made watertight using sutures with sealant and/or graft material. These are the techniques used in the series, not independently tested determinants of outcome.

The observed pleural migrations make catheter stability an important planning concern. However, this study does not compare fixation techniques or establish a superior anchoring method. During revision, the authors considered changing the distal compartment when fibrosis, scarring or impaired absorption was suspected. Finally, early reduction in syrinx size should be interpreted alongside neurological examination: radiographic decompression did not consistently translate into sustained functional recovery.

Limitations

The retrospective, single-surgeon design, small and unequal groups, heterogeneous etiologies and anatomy-driven allocation prevent causal comparisons. Practice evolved over nearly three decades, introducing additional temporal confounding. Repeated procedures and crossover between shunt types complicate the interpretation of group statistics. Neurological outcomes were qualitative, follow-up duration varied and substantial missing clinical and imaging data create a serious risk of attrition bias. In particular, patients returning because of deterioration may be overrepresented among late observations. Seven peritoneal procedures are insufficient to establish that this destination is intrinsically inferior.

Clinical takeaway

When syrinx diversion is justified, match the destination to the spinal level, subarachnoid patency and suitability of the pleural or peritoneal compartment. Plan for mechanical failure and possible revision, and assess success through sustained neurological function rather than early cavity collapse alone. This series offers useful operative considerations, but does not identify a universally preferable shunt.

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Surgical and Endocrine Outcomes of Medial Cavernous Sinus Wall Resection in Functioning Pituitary Tumors

Operative Neurosurgery. 2026;31(3):555-569

Persistent hormonal secretion after pituitary surgery may reflect disease extending beyond the apparent sellar tumor, including focal invasion of the medial cavernous sinus wall and its ligamentous attachments. Carpenter and colleagues examine this anatomical problem through a selected series of wall resections, combining endocrine outcomes with descriptions of intraoperative invasion patterns. The paper’s practical contribution is to clarify where tumor may remain concealed and how exposure can be adapted, while emphasizing the additional vascular and cranial nerve risks of extending the operation.

Objective

To assess endocrine outcomes after selective medial cavernous sinus wall resection and compare intraoperative inspection with preoperative Knosp grading for detection of wall invasion.

Methods

The authors retrospectively reviewed 223 endoscopic endonasal pituitary operations performed between January 2021 and December 2023. Twenty-five patients with functioning tumors underwent medial wall resection on the basis of intraoperative assessment, all by one surgeon. Eighteen were primary operations and seven reoperations.

The selected group included 12 somatotroph, nine corticotroph, two lactotroph and two plurihormonal tumors. Resected wall tissue was submitted separately for histopathological examination. Biochemical outcomes were assessed using subtype-specific criteria, and postoperative MRI was obtained at six to eight weeks. Mean follow-up was 26.2 months, with a range of 13-41 months.

Main results

Histological invasion was demonstrated in 20 cases. An important denominator distinction is that one specimen was lost: Table 2 therefore reports 20 positive and four negative results among 24 evaluable cases, or approximately 83%. The 80% quoted in the abstract expresses the 20 confirmed cases against the entire 25-patient surgical cohort.

The reported postoperative hormonal remission rate was 80% overall, approximately 89% after primary surgery and 57% after reoperation. These rates should not be equated with permanent cure: one patient with Cushing disease relapsed one year after an initial remission. Patients with persistent secretion required additional medical treatment or radiosurgery.

The authors reported 95% sensitivity and 75% specificity for direct endoscopic assessment of invasion. Histological involvement also occurred in selected patients with low Knosp grades, showing that limited radiographic extension does not exclude microscopic wall disease. These observations concern a highly selected resection cohort, not a screening population of all pituitary tumors.

Complications included one cerebrospinal fluid leak requiring repair, two transient abducens palsies that resolved within 10 days, one deep-vein thrombosis and three cases of postoperative hyponatremia requiring readmission. No internal carotid artery injury was reported.

Interpretation – operative relevance

The anatomical contribution is the recognition of four invasion patterns. Seven cases had focal wall involvement without adjacent ligament invasion. Six had a small wall perforation associated with inferior parasellar ligament involvement. Eight showed caroticoclinoid ligament involvement with extension into the dorsal clinoidal space. Four had diffuse wall thickening and more extensive ligamentous involvement, a pattern encountered particularly in recurrent disease.

These patterns explain why a largely intact-looking wall may conceal tumor beyond a small defect, and why the caroticoclinoid ligament and dorsal clinoidal space deserve attention when interpreting lateral tumor extension. They are descriptive operative findings, not a validated classification that independently determines how much tissue should be removed.

The authors describe wider lateral sellar exposure on the selected side to identify the carotid artery and medial opticocarotid recess. Doppler localization of the artery preceded opening of the anterior cavernous wall in every case. Medial wall mobilization then proceeded from anterior to posterior, with identification and management of its parasellar ligamentous and inferior hypophyseal arterial attachments. The relevant technical principle is controlled exposure of anatomical attachments rather than traction on a poorly defined wall.

Wall appearance and tactile findings informed selection: focal infiltration, irregularity, fibrosis and loss of the normal glossy appearance raised suspicion. Nevertheless, intraoperative inspection complements MRI; it does not justify disregarding radiological anatomy or routinely removing the wall in every functioning tumor.

The series also illustrates the importance of recognizing the limits of safe extension. Carotid injury and ocular motor dysfunction remain relevant risks despite their absence or transient nature in this small cohort. The reported technique requires specific cavernous sinus anatomical expertise, and persistent or inaccessible disease may still require complementary endocrine or radiation treatment.

Limitations

There was no comparable group in which a similarly suspicious wall was deliberately preserved. The study therefore cannot isolate the benefit of wall removal from tumor resection, patient selection or surgical expertise. Histological verification was limited to selected resected tissue, constraining the generalizability of the diagnostic accuracy estimates.

The small, heterogeneous endocrine subgroups and variable follow-up limit estimates of durable remission. The reported Knosp AUC of 0.300 is difficult to reconcile with the stated 65% sensitivity and 75% specificity at the selected threshold without further clarification of the analysis; it should not be used to conclude that MRI grading is generally unreliable. The clinically persuasive observation is narrower: focal wall invasion can be present despite a low Knosp grade.

Clinical takeaway

Treat the medial cavernous wall as a potential site of persistent disease, but make the decision to resect it selective and anatomically explicit. This paper helps identify concealed extension through wall defects and ligamentous attachments; it supports careful assessment and appropriate exposure, not routine wall excision or an assumption that early biochemical remission guarantees lasting cure.

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Imaging-based surgical stratification of parasagittal meningiomas involving the superior sagittal sinus: a case analysis of 62 patients

Neurosurg Focus 61(3):E7, 2026

The surgical challenge of a parasagittal meningioma extends beyond determining whether the superior sagittal sinus is invaded. Safe exposure and resection also depend on residual venous flow, collateral drainage, bridging-vein anatomy and extension across the falx or adjacent convexity dura. Li and colleagues propose an imaging-based framework that brings these relationships into preoperative planning. Their study is most useful as an anatomical guide to the operative strategy, rather than as evidence that a particular sinus-directed maneuver improves outcomes.

Objective

To evaluate the Superior Sagittal Sinus Involvement Grading system (SSIG) in relation to established invasion grading, operative complexity and resection strategy.

Methods

This retrospective, single-center series included 62 consecutive resections performed by one surgeon. Fifty-five tumors were primary and seven recurrent. SSIG was assigned by consensus among three senior neurosurgeons using contrast-enhanced coronal MRI. CT or MR venography was available in 49 patients to assess sinus patency and collateral drainage.

The framework distinguishes convexity-adjacent disease with an intact sinus wall (grade 1), falcine involvement with deeper wall invasion (grade 2), predominantly intraluminal tumor (grade 3), continuous convexity-sinus-falx involvement with residual flow (grade 4a), more extensive invasion with severe stenosis or functional near occlusion (grade 4b), and complete sinus occlusion (grade 5).

For comparisons, grades 1, 2 and 4a formed a low-involvement group of 44 patients; grades 3, 4b and 5 formed a high-involvement group of 18. This grouping reflects anticipated sinus management rather than a simple numerical progression.

Main results

SSIG correlated with Sindou grade (Spearman r = 0.790) and venography-based involvement in the 49 evaluable patients (r = 0.742). Operative time and blood loss differed across the six SSIG categories. However, in the binary low-versus-high comparison, blood loss remained significantly different whereas operative time did not.

Simpson grade I resection was recorded in 38 of 44 low-involvement cases and six of 18 high-involvement cases. Simpson grades II-III were correspondingly more frequent with high involvement: 66.7% versus 13.6%. In this study, that category represented gross tumor removal with preservation of the invaded sinus wall or segment, rather than necessarily indicating a visible residual mass.

Neurological adverse events occurred in 10 patients (16.1%), including seven with new or worsened limb numbness or weakness. The authors also reported systemic morbidity, including lower-extremity venous thrombosis in 22 patients and one pulmonary embolism. Surgery-related complication rates did not differ significantly between the two involvement groups, but the small sample does not establish equivalent safety. No radiographic recurrence or progression was observed during a mean follow-up of 13.3 months.

Interpretation – operative relevance

The first practical contribution concerns exposure. In the authors’ practice, grade 1-2 lesions generally required an ipsilateral parasagittal craniotomy reaching the midline. When intraluminal work or contralateral exposure was anticipated, the bone flap crossed the midline to permit visualization and control of the relevant sinus segment. Thus, falcine and convexity extension help determine the operative corridor in addition to the depth of sinus invasion.

The second concerns venous dissection. The described principles include internal tumor decompression, dissection along the arachnoid interface, sharp separation of adherent veins and particular protection of bridging-vein entry zones. Early treatment of the dural or falcine attachment is integrated with preservation of the functioning venous pathways.

The distinction between grades 4a and 4b is especially useful. Both may involve the convexity, sinus and falx, but residual effective flow favors conservative handling of the sinus wall. Severe narrowing or near occlusion requires a more detailed assessment of compensatory drainage before contemplating sinus-directed resection. An imaging label alone cannot demonstrate that a venous segment is expendable.

For completely occluded grade 5 lesions, the authors describe selected resections without sinus reconstruction after assessment of collateral compensation and protection of the venous drainage at the segment boundaries. This is their reported strategy, not a general recommendation to sacrifice an occluded sinus. The series does not compare reconstruction with nonreconstruction or validate a universal threshold for safe ligation.

Limitations

The study is retrospective and restricted to one surgeon. Subgroups were uneven, with only one grade 3 lesion, and venography was unavailable in 13 patients. Although grading was assigned by consensus, interobserver reproducibility was not formally established. Exploratory comparisons were not adjusted for multiple testing, and the small number of events limits complication analysis. Short follow-up without progression cannot establish long-term tumor control or the superiority of a resection strategy.

Clinical takeaway

Plan the exposure and resection boundary around functional venous anatomy, not sinus invasion alone. SSIG offers a useful structure for reviewing convexity and falcine extension, residual flow and collateral pathways; its principal value is to organize surgical judgment while keeping preservation of effective venous drainage central to the operation.

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Achieving Alignment and Implant-Specific Goals in Anterior Lumbar Interbody Fusion, and Predictors of Postoperative Intradiscal Lordosis

Operative Neurosurgery 31:431–444, 2026

Planning anterior lumbar interbody fusion requires distinguishing the lordosis built into an implant from the additional correction achieved at the treated segment. Hamouda and colleagues examine how baseline alignment, cage characteristics, operative level and posterior fixation contribute to this relationship. By comparing intraoperative and postoperative imaging, their study also addresses whether the correction obtained during surgery is maintained on standing. The findings support individualized alignment planning, while cautioning against interpreting implant geometry or the choice of construct as an isolated determinant of surgical success.

Objective

To identify predictors of postoperative intradiscal lordosis and its change from baseline after one- or two-level ALIF, and to evaluate the relationship between intraoperative supine alignment and early postoperative standing measurements.

Methods

This retrospective, single-center study included 204 adults treated between 2019 and 2023 at 258 levels: 80 at L4–5 and 178 at L5–S1. Ninety patients underwent stand-alone ALIF and 114 received supplementary posterior instrumentation. Patients with prior lumbar interbody fusion, surgery for trauma, tumor or infection, combined interbody approaches, or pelvic fixation were excluded.

The authors reviewed standing preoperative radiographs, intraoperative images and postoperative standing radiographs, obtained a median of two days after surgery. Measurements included intradiscal lordosis, disc height, spinopelvic alignment, implant dimensions and cage position. Separate regression models evaluated the final intradiscal angle and the change from baseline. Median overall follow-up was 12.4 months, although the principal alignment comparisons concerned the early postoperative period.

Main results

Tables 2 and 3 report a median intradiscal lordosis of 6.7° before surgery and 17.8° postoperatively, with a median individual change of 10.4°. The median gain was 8.1° after stand-alone ALIF and 11.5° with posterior instrumentation. The between-construct difference was significant at L5–S1, but not at L4–5.

Greater cage lordosis, greater baseline intradiscal lordosis, L5–S1 implantation and posterior instrumentation independently predicted a larger postoperative angle. Each additional degree of implant lordosis was associated with 0.62° greater postoperative intradiscal lordosis (95% CI 0.44–0.79). This coefficient describes the adjusted association with the final angle, not the correction gained from baseline.

The separate change model showed that greater preoperative lordosis was associated with less additional correction. Thus, achieving a larger final angle and gaining more lordosis are distinct outcomes.

Intraoperative imaging showed no significant additional increase in intradiscal lordosis after posterior instrumentation compared with the preceding post-ALIF measurement. The authors considered differences in initial correction and maintenance of alignment on standing as possible explanations for the better results in the circumferential group, rather than attributing them solely to posterior corrective maneuvers.

Interpretation — operative relevance

The most useful planning distinction is between the intended final segmental angle and the additional correction required to reach it. A cage’s stated lordosis should not be presented as the expected angular gain. A segment with relatively preserved baseline lordosis may reach a larger final angle while requiring less correction than a more collapsed disc space.

The operative description emphasizes trial selection that provides contact with both vertebral endplates without excessive distraction. This is relevant to the balance between restoring alignment and avoiding an unnecessarily aggressive increase in disc height. The study does not establish a numerical distraction limit or demonstrate that selecting the tallest or most lordotic available implant improves clinical outcomes.

Posterior fixation was associated with greater correction, particularly at L5–S1, but the intraoperative comparisons do not show that the posterior stage itself reliably adds lordosis. The decision to supplement the anterior construct therefore requires the broader stabilization and decompression assessment; the reported group difference is not, by itself, an indication for instrumentation. In the described practice, an open posterior approach was generally used when decompression was also needed, whereas percutaneous fixation was favored when stabilization alone was required.

Finally, intraoperative alignment should be interpreted in relation to postoperative standing measurements. The study supports attention to this transition, but does not provide a validated patient-specific formula for predicting standing correction from a supine image.

Limitations

The retrospective design and nonrandom selection of constructs prevent causal conclusions. Baseline alignment differed between groups, and implant selection and endplate preparation depended on surgeon judgment. The heterogeneous indications also limit the ability to isolate the influence of individual anatomical features or technical maneuvers. Patient-reported outcomes were not available, so greater radiographic correction cannot be equated with better pain relief, function or long-term clinical benefit.

There are internal numerical discrepancies between the abstract, narrative and tables. The overall descriptive values above follow the concordant entries in Tables 2 and 3; conflicting subgroup estimates have not been used to define a quantitative treatment target.

Clinical takeaway

Define the required correction before selecting the implant, distinguish angular gain from final lordosis, and consider the treated level and fixation strategy together. This study supports anatomically informed ALIF planning and assessment of achieved alignment, rather than maximizing cage dimensions or assuming that posterior instrumentation will automatically produce further correction.

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Drainage Volume, Drainage Time, and Irrigation Volume in Chronic Subdural Hematoma

Neurosurgery 99:537–544, 2026

Postoperative drainage is an important component of chronic subdural hematoma surgery, yet the interpretation of drainage volume and duration remains clinically relevant to the prevention of recurrence. This analysis of the FINISH trial examines their association with reoperation, alongside the volume of intraoperative irrigation. Its findings invite a critical appraisal of the assumption that greater drainage necessarily reflects more effective evacuation, while emphasizing the distinction between observational associations and evidence sufficient to establish a standardized drainage protocol.

Objective

To examine whether drainage and irrigation measurements relate to recurrence requiring reoperation.

Methods

This post hoc analysis used 546 patients from the multicenter FINISH irrigation trial. Logistic regression assessed drainage volume, duration and irrigation volume against outcomes.

Main results

Reoperation occurred in 84 patients (15.4%). Median drainage was 70 mL over 48 hours. Each additional 100 mL was associated with higher reoperation odds (OR 1.15, 95% CI 1.02–1.31). Reoperation rates were 18.2% with drainage under 48 hours and 12.1% at 48 hours or longer. Irrigation volume was not associated with reoperation.

Interpretation — operative relevance

The practical decision is how to interpret the postoperative drain within the evacuation strategy. The study does not justify deliberately increasing or restricting output. A high output may identify a different clinical situation rather than cause recurrence.

Similarly, these comparisons do not establish that extending every drain beyond 48 hours improves outcome. The duration comparison was not randomized, even though the parent trial was. More irrigation should not be equated automatically with a better operation.

Limitations

Drainage exposures were observational. Clinical decisions and unmeasured factors may explain part of the associations. The abstract does not provide a validated output-based removal algorithm or enough procedural detail to compare drain position, suction or irrigation technique.

Clinical takeaway

Document output and elapsed drainage time together, and interpret them alongside clinical recovery. This paper is useful for reviewing a unit’s drain protocol; it does not supply a new mandatory removal threshold or irrigation dose.

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Spinal meningiomas: histopathological grading using a benchmark radiomics model with notes on disease control

Neurosurg Focus 61(3):E8, 2026

Could preoperative imaging help anticipate the biological behavior of spinal meningiomas?
This study applies radiomics—quantitative analysis of imaging features—to distinguish tumor pathology groups.
The model showed promising discrimination using open-source tools and internal validation.
Its potential role is to inform counselling, but clinical adoption requires independent testing.

Objective

To develop a preoperative radiomics classifier for spinal meningioma pathology and explore factors associated with disease control.

Methods

Investigators retrospectively reviewed institutional surgical records from 2012–2025. Manually segmented contrast-enhanced images underwent PyRadiomics feature extraction. An ensemble classifier used 10 features and nested cross-validation.

The study’s “high-grade” category combined WHO grade 2 tumors with grade 1 tumors showing atypia; this is not equivalent to conventional WHO high-grade classification.

Main results

Among 74 patients, the model achieved an area under the receiver-operating-characteristic curve of 0.879 and a mean F1 score of 0.748.

The clinical analysis included 55 patients, with median radiographic follow-up of 22.2 months and four recurrences. Subtotal resection was associated with poorer progression-free survival than gross-total resection: HR 10.62 (95% CI 1.46–77.05; P=.019). Institutional abstract

Interpretation

The imaging approach merits further investigation, but discrimination within one institution does not establish performance across scanners, imaging protocols or patient populations. An AUC of 0.879 should not be described as “87.9% diagnostic accuracy.”

The recurrence analysis is exploratory. Its wide confidence interval signals considerable uncertainty, and it does not justify pursuing complete resection at the expense of neurological function.

Limitations

The small retrospective cohort and internal validation limit generalizability. The unconventional pathology grouping complicates comparison with other grading studies. Four recurrence events provide limited support for prognostic modelling.

Publisher and PubMed retrieval failed; verification relied on the authors’ institutional abstract. Full methodological details and supplementary material could not be assessed.

Clinical takeaway

Radiomics is a promising research adjunct for preoperative assessment of spinal meningiomas. This model should not yet determine resection extent, radiation treatment or surveillance schedules without external validation and confirmation of clinical utility.

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Long-Term Outcomes of Gamma Knife Surgery for Vestibular Schwannomas: Tumor Stability Supports Reduced Surveillance After 10 Years

J Neurosurg 145:721–731, 2026

How long should imaging continue after apparently successful radiosurgery for a vestibular schwannoma? This large single-center series follows 878 patients after single-session Gamma Knife treatment, with a median clinical follow-up exceeding 12 years. Patients stable and free of salvage treatment during the first 5 years had very little subsequent true progression. Hearing preservation improved in the more recent treatment era, while delayed cystic and cranial-nerve complications remained uncommon but possible. The findings support less intensive imaging after a decade of stability, not the complete abandonment of individualized clinical follow-up.

Objective

To evaluate the long-term durability, functional outcomes and late adverse events of Gamma Knife surgery for sporadic vestibular schwannoma and determine whether routine imaging intensity can be reduced after prolonged stability.

Methods

This retrospective single-center study included 878 patients treated with single-session Gamma Knife surgery between May 1991 and January 2020. Tumors were classified from intracanalicular disease through severe brainstem compression using a modified Koos-based system. A prespecified subgroup contained 793 patients with at least 5 years of follow-up and no salvage treatment during the first 5 years.

Main results

The median clinical follow-up was 154.5 months. Overall, 7.5% required salvage treatment. Early salvage was more frequent for tumors with severe brainstem compression and fourth-ventricle deviation: 24.7% at 5 years versus 3.6% for less advanced types.

Among patients stable during the first 5 years, cumulative salvage incidence at 15 years was 2.1%, and true progression was identified in only two patients (0.3%). In patients with Gardner–Robertson class I hearing, 10-year serviceable-hearing preservation improved from 48% in the 1991–2004 era to 63% in 2005–2023. Delayed cyst-related complications occurred in 3.1%, trigeminal neuralgia in 1.6%, persistent facial palsy in 0.1% and malignant transformation in 0.2%.

Interpretation

Early anatomical severity predicts the initial need for rescue, but prolonged stability is strongly reassuring. The very low late-progression rate makes indefinite frequent MRI difficult to justify in every stable patient. Nevertheless, the presence of rare delayed effects means that surveillance should transition to a risk-adapted strategy with clear instructions for symptom-triggered reassessment.

Limitations

This was a retrospective experience from one high-volume center over almost three decades. Dose planning, imaging quality, hearing assessment and selection for radiosurgery evolved substantially. The proposal to reduce surveillance is inferred from observed event rates rather than tested prospectively, and the results apply principally to sporadic small- and medium-sized tumors suitable for single-session treatment.

Clinical takeaway

After Gamma Knife surgery, maintain closer imaging during the first years, especially for large tumors with brainstem compression. If control remains stable through 5 years and no concerning symptoms develop, progressively lengthen intervals; after 10 years, consider individualized low-intensity surveillance while preserving access for new hearing, facial, trigeminal, vestibular or hydrocephalic symptoms.

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Surgical Versus Nonoperative Treatment for Adult Spinal Deformity: A Multicenter Propensity Score–Matched Study of Two-Year Patient-Reported Outcomes

Spine 2026;51:1197–1208

Choosing between reconstruction and nonoperative care for adult spinal deformity demands a realistic estimate of benefit rather than radiographic enthusiasm alone. This multicenter analysis uses propensity matching to compare patients with similar measured baseline characteristics. At 2 years, surgery produced substantially greater improvement in disability and scoliosis-specific quality of life. Clinically meaningful benefit was achieved by a much larger proportion of surgical patients, although the cohort was relatively young and only mildly to moderately impaired at baseline. The results strengthen comparative-effectiveness evidence but do not replace individualized discussion of complications and residual confounding.

Objective

To compare 2-year patient-reported outcomes after surgical and nonoperative management of adult spinal deformity while reducing measured treatment-selection bias through propensity-score matching.

Methods

The retrospective comparison used prospectively collected data from an adult spinal-deformity registry at six centers. Of 580 eligible patients, 338 underwent surgery and 242 received nonoperative care. Propensity scores incorporated demographic variables, radiographic alignment measures and baseline Oswestry Disability Index (ODI) and Scoliosis Research Society–22 (SRS-22) scores. One-to-one matching produced 160 balanced pairs.

Main results

At 2 years, mean ODI improvement was −19.4 ± 14.2 points after surgery and −4.2 ± 12.3 with nonoperative care (p<0.001). A clinically meaningful ODI improvement of at least 15 points was achieved by 72% of surgical patients versus 29% of nonoperative patients.

The mean 2-year SRS-22 total score was 3.95 ± 0.67 after surgery and 3.46 ± 0.75 after nonoperative care (p<0.0001). The minimum clinically important difference for the SRS-22 total score was reached by 81.3% and 36.9%, respectively.

Interpretation

Among matched patients, reconstruction was associated with a large and clinically visible improvement beyond that observed with nonoperative management. Propensity matching makes the groups more comparable but cannot recreate randomization. The magnitude of benefit should therefore be presented alongside the patient’s operative risk, deformity phenotype, frailty, goals and probability of complications or revision.

Limitations

Treatment was not randomized, and unmeasured factors such as surgeon judgment, symptoms, patient preference and socioeconomic context may still influence both selection and outcome. The matched cohort had a mean age of about 45 years and mild-to-moderate baseline impairment, limiting extrapolation to older or frailer patients. Two-year follow-up does not capture late mechanical failure, revision burden or durability.

Clinical takeaway

For an appropriately selected adult with symptomatic deformity, surgery offers a substantially greater chance of meaningful 2-year improvement than continued nonoperative care. Use those probabilities in shared decision-making, but pair them with center-specific complication and revision estimates rather than presenting benefit in isolation.

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