Tag: Microsurgery

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

J Neurosurg 144:1403–1409, 2026

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

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

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

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

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

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

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

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

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

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

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A 7-Year Experience in Microsurgical Treatment of Unruptured Intracranial Aneurysms in Older Patients

Neurosurgery 98:1325–1338, 2026

This article reports a 7-year single-center retrospective analysis comparing one-year neurological outcomes after microsurgical clipping of unruptured intracranial aneurysms in patients >65 years versus younger adults. It details patient selection, aneurysm characteristics, statistical methods, and primary endpoint assessment using the modified Rankin Scale.

Findings indicate similar favorable 1-year outcomes between older and younger cohorts, with diabetes and de novo aneurysm formation/growth identified as independent predictors of poor outcome in the older group. The discussion contextualizes results against endovascular options, comorbidity considerations, and limitations of retrospective single-center data.

Question addressed Whether to treat unruptured intracranial aneurysms (UIAs) in patients >65 remains controversial because of frailty/comorbidities and procedural risk vs rupture risk under conservative management.

Study design Retrospective review of UIA patients treated with microsurgical clipping (single quaternary center, 2014–2020), including only those with admission mRS ≤2; primary endpoint was 1-year mRS, with poor outcome defined as mRS >2.

Cohort 390 total surgically treated patients; 132 (34%) were >65 with mean age 71±4 years.

Main outcome No significant difference in poor neurological outcome at 1 year between older vs younger patients (11% vs 9.3%, P=.82), indicating comparable functional outcomes after microsurgery in selected older adults.

Aneurysm differences with age Older patients had larger aneurysm dimensions and more calcification (e.g., calcification 15% vs 2.8%) and higher PHASES/ELAPSS scores than younger patients.

Univariate risk factors (older group) Factors associated with poor 1-year outcome included diabetes, higher Charlson Comorbidity Index, calcification, treating multiple aneurysms, de novo formation/growth, and higher aspect ratio.

Independent predictors On multivariable analysis in older patients, only diabetes (OR 19.1, P=.02) and de novo formation or growth (OR 12.7, P=.02) predicted poor neurological outcome.

Clinical implication Chronological age alone is not a stand-alone contraindication to microsurgical treatment; individualized selection and comorbidity/risk stratification (notably diabetes and aneurysm growth patterns) are key.

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Microsurgery Versus Embolization for Spinal Cord Arteriovenous Malformations: A Proposed Grading System

Neurosurgery 98:786–798, 2026

This study proposes a four-parameter grading system to stratify angioarchitectural complexity of spinal cord arteriovenous malformations (SCAVMs) and compares clinical outcomes of microsurgery versus endovascular embolization across five grades in a 714-patient multicenter cohort. The grade sums points for metameric manifestation, lesion diameter ≥2 cm, anterior sulcal artery supply, and lesion depth, predicting incomplete resection with strong ROC (receiver-operating characteristic) performance.

Results show embolization as the preferred primary treatment owing to lower immediate risk, while microsurgery achieves higher complete obliteration for low-grade lesions (scores 0–1) but carries greater treatment-related deterioration and worse long-term prognosis for higher grades (scores 2–4). Recommendations prioritize embolization, reserving microsurgery for select low-grade or high-risk patients when embolization fails.

Study aim Compare outcomes of microsurgery vs endovascular embolization for SCAVMs by introducing a grading system that stratifies angioarchitectural complexity to enable fairer comparisons.

Cohort & design Retrospective multicenter analysis of 714 SCAVM patients treated (2007–2022); 308 received microsurgery (often after failed/partial embolization) and 406 received exclusive embolization.

Grading system (0–4 points) One point each for anterior sulcal artery supply, metameric manifestations, maximum lesion diameter ≥2 cm, and embedded (deep) lesion depth; total score defines grade.

Predictors basis & performance The four grading variables were independent predictors of incomplete resection in microsurgical cases, and the score showed strong ROC discrimination in modeling and validation groups (AUC ≈ 0.83).

Overall treatment tradeoff Microsurgery achieved a higher complete obliteration rate (61.7% vs 24.4%) but had higher treatment-related deterioration (19.8% vs 4.2%) and higher poor prognosis at last follow-up (52.3% vs 36.2%) than exclusive embolization.

Low grades (0–2) obliteration For scores 0–2, microsurgery produced significantly higher complete obliteration than embolization; for scores 3–4, complete obliteration rates were similar between methods.

Long-term deterioration & prognosis by grade Long-term clinical deterioration after embolization was higher for score 1 (significant) and also higher for score 0 (not significant); for scores 2–4, long-term deterioration risk was comparable, while poor prognosis was generally worse with microsurgery except score 0 (similar).

Treatment strategy Embolization should be the primary approach for SCAVMs; microsurgery is an alternative if embolization fails to fully obliterate lesions in score 0 (recommended) and selected 1-point patients (optional, especially higher clinical risk), but not first-line for scores 2–4.

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Pineal cyst surgery beyond morphology: a critical evaluation of a consecutive surgical series

Acta Neurochirurgica (2026) 168:85

This study evaluates surgical management of symptomatic pineal cysts in a consecutive single-center cohort, comparing microsurgical, endoscopic, and stereotactic techniques. Radiological measures — notably aqueduct diameter and predominant cyst expansion — were analyzed alongside clinical outcomes using the Chicago Chiari Outcome Scale, showing durable benefit when surgery is guided by clinicoradiological criteria.

Findings indicate aqueduct narrowing and anterior expansion better predict positive postoperative outcomes than cyst size alone. Each surgical approach demonstrated specific indications: microsurgery for suspicious lesions, endoscopy for hydrocephalus/anterior compression, and stereotactic drainage for deep or high-risk cases, with overall high rates of sustained improvement.

Clinical problem: Surgical management of pineal cysts is especially controversial in non-hydrocephalic symptomatic patients because clinical–radiological correlations are inconsistent and many studies rely mainly on size/morphology for decisions.

Study design: Retrospective single-center cohort of 46 symptomatic pineal cyst patients (2008–2024), comparing surgical (n=18) vs non-surgical (n=28) groups and analyzing radiological markers (e.g., cyst dimensions, aqueduct diameter, predominant expansion) alongside outcomes measured by CCOS over time.

Key differentiators for surgery: Compared with non-surgical patients, surgical patients had larger cysts, narrower aqueducts (0.9 vs 1.6 mm, p<0.001), and much more frequent predominant anterior expansion (67% vs 7%, p<0.001).

Overall outcomes: After surgery, 94% achieved good/excellent CCOS (≥12) at 12 months, and 93% maintained good/excellent outcomes at long-term follow-up (mean 62 months).

Predictors: Aqueduct diameter was more closely associated with outcome than pineal cyst size; neither cyst volume nor hydrocephalus consistently predicted postoperative outcome.

Technique comparison: Microsurgical resection (n=12) had favorable long-term outcomes (mean CCOS 14.9) but the highest complication rate (3 patients) and the highest recurrence of headache despite total excision.

Endoscopic approach: Endoscopic fenestration + ventriculostomy (n=3) produced the best long-term outcomes (mean CCOS 15.7) with no recurrences reported.

Stereotactic option: Stereotactic drainage + Rickham reservoir (n=3) achieved stable decompression but lower long-term CCOS (mean 13.0) than other approaches.

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Congress of Neurological Surgeons Systematic Review and Evidence-Based Guideline on Surgical Resection for the Treatment of Patients With Vestibular Schwannomas: Update

Neurosurgery 98:272–277, 2026

These updated Congress of Neurological Surgeons guidelines review surgical management of sporadic vestibular schwannomas using literature from 2015–2022, reaffirming many prior recommendations and highlighting persistent evidence gaps. Key recommendations address approach selection (middle fossa, retrosigmoid, translabyrinthine), hearing-preservation surgery options, and counseling patients about outcomes after prior stereotactic radiosurgery.

The document details systematic review methods, inclusion criteria, and evidence grading, noting most data are class III and insufficient to prove superiority of specific surgical approaches for many questions. It emphasizes individualized treatment decisions, need for multicenter registries or trials, and future research priorities to resolve unanswered clinical issues.

Surgical Approach Selection: No surgical approach (middle fossa, retrosigmoid, or translabyrinthine) has proven superiority for facial nerve preservation or gross total resection in sporadic vestibular schwannoma; choice depends on individual patient factors and tumor characteristics.

Hearing Preservation: Hearing preservation surgery via middle fossa or retrosigmoid approach may be considered for patients with good preoperative hearing as an alternative to observation, but evidence for long-term superiority is limited.

Subtotal Resection and Radiosurgery: Subtotal resection followed by stereotactic radiosurgery does not have sufficient evidence to support better facial nerve or hearing outcomes compared to complete resection.

Microsurgery After SRS: Patients undergoing microsurgical resection after prior stereotactic radiosurgery should be counseled about increased risk of subtotal resection and worse facial nerve function.

Trigeminal Neuralgia: Surgical resection may provide better relief of trigeminal neuralgia symptoms compared to stereotactic radiosurgery in patients with sporadic vestibular schwannoma.

Balance and Observation: There is insufficient evidence to support surgery or radiosurgery for improving preoperative balance problems, and no clear evidence that surgery should be primary treatment for small tumors eligible for observation.

Evidence Quality: All reviewed evidence is class III (retrospective series, flawed controls), with significant potential for bias and limitations in drawing strong conclusions.

Future Directions: Improved data from multicenter registries or randomized trials are needed to clarify optimal management, as current recommendations reflect standard practice but lack high-level evidence for many questions.

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Role of surgical treatment of intracranial aneurysms in the era of endovascular therapy: a review

Neurosurg Focus 59(6):E2, 2025

This review evaluates the contemporary role of microsurgical clipping versus endovascular treatment (EVT) for intracranial aneurysms, comparing long-term durability, complication profiles, and anatomical or patient factors that guide modality selection. It synthesizes trial data (ISAT, BRAT), meta-analyses, and location-specific outcomes to highlight differences in occlusion, retreatment, and morbidity.

The article also outlines practical considerations—hybrid strategies, cerebral bypass, training needs, economics, and global disparities—arguing for individualized, multidisciplinary decision-making and preserving microsurgical expertise despite growing EVT adoption.

Treatment Goals: Exclusion of intracranial aneurysms from circulation while preserving parent vessels and neural function remains the primary objective; both endovascular treatment (EVT) and microsurgical clipping are core modalities.

Long-term Outcomes: Microsurgical clipping offers greater durability and lower rates of recurrence, rebleeding, and retreatment compared to EVT, which has higher retreatment rates despite lower short-term morbidity.

Procedure Selection: EVT is generally preferred for older patients and posterior circulation aneurysms, while microsurgery is favored in younger patients, those with hematomas, mass effect, and aneurysms of the middle cerebral and pericallosal arteries.

Aneurysm Location: Surgical clipping achieves higher occlusion and lower recurrence, especially for anterior circulation, middle cerebral artery, and complex aneurysms; EVT is more suitable for posterior circulation and anatomically challenging cases.

Complications and Adjuncts: Microsurgery allows for evacuation of hematomas and cisternal blood (reducing vasospasm and hydrocephalus), while EVT avoids craniotomy risks but may induce mechanical vasospasm and requires antiplatelet therapy.

Hybrid and Advanced Techniques: Hybrid approaches (combining EVT and surgery) and cerebral bypass remain essential for complex, giant, or recurrent aneurysms not amenable to standard treatments.

Cost and Access: Microsurgical treatment incurs lower overall healthcare costs than EVT; global disparities exist, with surgical clipping dominating in low-resource settings due to limited endovascular infrastructure.

Decision-Making: Optimal management requires individualized, multidisciplinary evaluation considering patient factors, aneurysm characteristics, and resource availability; no single factor should solely dictate treatment choice

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Tentorial Dural Arteriovenous Fistulas: A Retrospective Cohort Study

Operative Neurosurgery 29:678–685, 2025

This single-center retrospective cohort study analyzes 275 patients with tentorial dural arteriovenous fistulas (TDAVFs) treated between 2001 and 2022, detailing demographic, angiographic, and treatment data across six Lawton-classified subtypes. Results highlight a predominance of middle-aged male patients, high immediate occlusion rates with endovascular techniques, and subtype-specific differences in venous drainage patterns and complication rates.

The manuscript compares treatment modalities and outcomes, noting superior petrosal sinus TDAVFs more often require microsurgery, while Galenic and torcular subtypes showed lower immediate cure rates and higher complications or new fistula formation. Follow-up angiographic and clinical data emphasize favorable functional recovery for most patients despite treatment-related risks.

• Patient Demographics: Tentorial dural arteriovenous fistulas (TDAVFs) predominantly affect middle-aged men, with 85.8% of cases occurring in males and a mean age of 51.1 years.

• Subtype Distribution: The most common TDAVF subtype is superior petrosal sinus (34.9%), followed by tentorial sinus (31.6%), Galenic (15.6%), torcular (7.3%), incisural (5.5%), and straight sinus (5.1%).

• Aggressiveness and Presentation: TDAVFs are less common than other DAVFs but are the most aggressive, frequently presenting with hemorrhage or progressive neurological deficits; more than half of patients present with intracranial hemorrhage or nonhemorrhagic neurological deficits (NHNDs).

• Treatment Approach: Most TDAVFs (83.0%) can be effectively treated with endovascular embolization, but superior petrosal sinus TDAVFs more often require microsurgical intervention (31.6% in this group).

• Immediate Occlusion and Complications: Immediate complete occlusion was achieved in 92.8% of treated cases, with Galenic TDAVFs showing a lower occlusion rate and both Galenic and superior petrosal sinus TDAVFs exhibiting higher complication rates (12.5% overall).

• Outcomes: Favorable clinical outcomes (mRS <3) were achieved in 82.6% of patients, with torcular and tentorial sinus TDAVFs associated with better outcomes compared to other subtypes.

• Recurrence and New Fistulas: Recurrence after complete occlusion was rare (0.9%), but torcular TDAVFs had a higher tendency to develop new fistulas post-treatment (2.6% of cases).

• Key Technical Considerations: Endovascular treatment is preferred when feasible, but surgical approaches are indicated for lesions with unfavorable arterial access or higher risk of complications, particularly in superior petrosal sinus TDAVFs.

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Implementation of high-definition fiber tractography for preoperative evaluation and surgical planning of brainstem cavernous malformation

J Neurosurg 142:968–976, 2025

The study discusses the use of high-definition fiber tractography (HDFT) in the surgical planning and resection of brainstem cavernous malformations, highlighting its role in reducing postoperative deficits and improving patient outcomes by accurately delineating white matter tracts and optimizing surgical approaches.

• High-definition fiber tractography (HDFT) is implemented for preoperative planning in brainstem cavernous malformations (BSCM) to improve surgical outcomes.

• Study Objective: Evaluate the role and long-term outcomes of HDFT in the surgical management of BSCMs.

• Methods: Retrospective evaluation of 11 patients who underwent HDFT and microsurgical resection.

• Results: Gross-total resection achieved in 72.7% of patients; no new permanent neurological deficits reported.

• HDFT Benefits: Provides critical anatomical information, decreases morbidity, and aids in defining eloquent perilesional boundaries.

• Challenges: Unpredictable displacement of white matter tracts by cavernomas necessitates tailored surgical approaches.

• Limitations: Small sample size, single-center study, and restricted MRI compatibility.

• Conclusion: HDFT is a pivotal tool for safer, more effective resection of BSCMs, warranting further prospective studies.

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Optimal Timing of Microsurgical Treatment for Ruptured Arteriovenous Malformations: A Systematic Review and Meta-Analysis

Neurosurgery 96:18–28, 2025

The timing of microsurgical treatment (MST) for ruptured brain arteriovenous malformations (bAVM) is a contentious issue in the literature. This study aimed to investigate the impact of MST timing on outcomes in patients with ruptured bAVMs, considering MST with and without preoperative endovascular treatment (EVT).

METHOD: Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 guidelines, a comprehensive search was conducted across multiple databases, yielding 15 studies meeting the inclusion criteria. The timing was defined as the duration from the rupture of bAVM to the MST. The patients were divided into 4 different groups based on MST timing: <48 hours, <1 week, <2 weeks, and <1 month. The primary outcome was favorable outcome defined as a modified Rankin Scale score of 0 to 2 or a Glasgow Outcome Scale score of 4 to 5 in the last clinical follow-up. Secondary outcomes included periprocedural mortality and complete excision.

RESULTS: MST time >48 hours were associated with a significantly higher favorable outcome rate (odds ratio: 9.71, 95% Cl: 3.09-30.57, P < .01) and a lower mortality rate (OR: 0.15, 95% Cl: 0.02-0.88, P = .04) compared with MST timing ≤48 hours. After exclusion of patients who underwent MST with preoperative EVT, MST time >48 hours had a significantly higher rate of favorable outcome (OR: 9.39, 95% CI: 2.53-34.89, P < .01).

CONCLUSION: This meta-analysis suggests that delayed surgical intervention beyond 48 hours may be associated with improved favorable outcomes in patients who underwent MST with and without preoperative EVT for ruptured bAVMs.

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Microsurgical anatomy and approaches to thalamic gliomas. Part 2: Maximal safe resection of thalamic gliomas improves outcomes.

J Neurosurg 141:1472–1483, 2024

As presented in Part 1 of this series, thalamic gliomas (TGs) are deep-seated, difficult-to-access tumors surrounded by vital neurovascular structures. Given their high operative morbidity, TGs have historically been considered inoperable lesions. Although maximal safe resection (MSR) has become the treatment standard for lobar and even deep-seated mediobasal temporal and insular gliomas, the eloquent location of TGs has precluded this management strategy, with biopsy and adjuvant treatment being the mainstay. The authors hypothesized that MSR can be achieved with low morbidity and mortality for TGs, thus resulting in improved outcomes.

METHODS A retrospective single-center study was performed on all TG patients from 2006 to 2020. Clinical, imaging, and pathology reports were obtained. Univariate and multivariate analyses were performed to determine prognostic variables. Case examples illustrate various approaches and the rationale for staging resections of more complex TGs.

RESULTS A total of 42 patients (26 males, 16 females), among them 12 pediatric (29%) cases, were included. Their mean age was 36.0 ± 21.4 (median 30, range 3–73) years. The median maximal tumor diameter was 45 (range 19–70) mm. Eighteen patients (43%) had a prior stereotactic needle tumor biopsy, with the ultimate diagnosis changed for 7 patients (39%) following microsurgical resection. The most common surgical approaches were transtemporal (29%), anterior interhemispheric transcallosal (29%), and superior parietal lobule (25%). Overall, the combined subtotal and grosstotal resection rate was 95% (n = 40). Low-grade gliomas (LGGs; grades I and II) comprised one-third of the group, whereas half of the patients had glioblastoma multiforme. There were no operative mortalities. Although temporary postoperative motor deficits were observed in 12 patients (28.6%), all improved during the early postoperative period except 1 (2.4%), who had mild residual hemiparesis. Two patients required CSF diversion for hydrocephalus. The 2-year overall survival rate was 90% for LGG patients and 15% for high-grade glioma (HGG) patients. Multivariate analysis revealed that histological grade, age, and extent of resection were independent prognostic factors associated with survival.

CONCLUSIONS Management of TGs is challenging, with resection avoided by many, if not most, neurosurgeons, especially for HGGs. The results reported here demonstrate improved outcomes with resection, particularly in younger LGG patients. The authors therefore advocate for MSR for a select cohort of TG patients using carefully planned surgical approaches, contemporary intraoperative adjuncts, and meticulous microsurgical techniques.

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Arteriovenous malformations in the cerebellopontine angle: assessment of the “backdoor resection” technique and microsurgical results in 38 patients

J Neurosurg 141:1198–1211, 2024

Posterior fossa arteriovenous malformations (AVMs) represent 7% to 15% of all intracranial AVMs and are associated with an increased risk of hemorrhage, morbidity, and mortality compared with supratentorial AVMs, thus prompting urgent and definitive treatment. Cerebellopontine angle (CPA) AVMs are a unique group of posterior fossa AVMs incorporating characteristics of brainstem and cerebellar lesions, which are particularly amenable to microsurgical resection. This study reports the clinical, radiological, operative, and outcome features of patients with CPA AVMs in a large cohort.

METHODS The authors conducted a single-surgeon, 2-institution retrospective cohort study of all consecutive patients with CPA AVMs treated with microsurgical resection during a 25-year period.

RESULTS CPA AVMs represented 22% (38 of 176) of all infratentorial AVMs resected by the senior author. Overall, 38 patients (22 [58%] male and 16 [42%] female) met the study inclusion criteria and were analyzed. Most patients presented with hemorrhage (n = 29, 76%). The median age at surgery was 56 (range 6–82) years. Subtypes included 22 (58%) petrosal cerebellar AVMs, 11 (29%) lateral pontine AVMs, and 5 (13%) AVMs involving both the brainstem and cerebellum. Most AVM niduses were small (< 3 cm; n = 35, 92%) and compact (n = 31, 82%). Fourteen (37%) patients harbored flow-related aneurysms. Twenty (53%) patients underwent preoperative embolization. Complete angiographic obliteration was achieved with microsurgery in 35 (92%) patients. Five (13%) patients with poor neurological conditions at presentation died before hospital discharge. Of the 7 (18%) patients with new postoperative neurological deficits, 5 had transient deficits. The median (interquartile range) follow-up was 1.7 (0.5–3.2) years; 32 (84%) patients were alive at last follow-up, and 30 (79%) had achieved a favorable neurological outcome (modified Rankin Scale [mRS] score 0–2). The only independent predictor of unfavorable postoperative outcome (mRS score 3–6) was the preoperative mRS score (p = 0.002).

CONCLUSIONS CPA AVMs are unique posterior fossa lesions, including petrosal cerebellar and lateral pontine AVMs. The “backdoor resection” technique provides a safe and efficient strategy with high obliteration rates and a low risk of treatment-related morbidity. Microsurgical resection should be considered the frontline treatment for most CPA AVMs, except for those with a significant diffuse brainstem component.

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Microsurgical management of recurrent intracranial aneurysm after endovascular treatment: a series of 60 consecutive patients

J Neurosurg 141:1235–1243, 2024

The aim of this study was to evaluate the morbidity associated with microsurgical treatment in patients with a recurrent aneurysm to improve their surgical management.

METHODS From 2012 to 2022, among the 3128 patients with ruptured or unruptured intracranial aneurysms managed at the authors’ institution, 954 patients were treated by a microsurgical procedure. Of these 3128 patients, 60 consecutive patients (6.3%) who had a recurrent microsurgically treated aneurysm after previous endovascular treatment were included in this study. Additional microsurgical treatment was considered in case of progressive remnant growth or significant aneurysm recurrence. Intraoperative and postoperative complications were noted. Early (< 7 days) and long-term clinical and radiological monitoring were performed. Good functional outcome was considered as a modified Rankin Scale score < 3.

RESULTS The mean age at initial treatment was 45 years (range 26–65 years). The mean delay between the first treatment and microsurgical treatment of the recurrence was 64 months (range 2 days–296 months). The mean size of the fundus recurrence was 5 mm, and the mean size of the neck recurrence was 4.6 mm. Five patients (8.3%) presented with subarachnoid hemorrhage associated with rupture of the recurrent aneurysm. Three patients died (6%) of aneurysm rupture and/or intensive care complications. The total morbidity rate associated with the microsurgical procedure was 14.5% (8/55) in patients with unruptured recurrent aneurysms. Among these patients, postoperative definitive complications (ischemic lesions) directly related to the microsurgical procedure were present in 3 patients (5.5%). Intraoperative rupture was recorded in these 3 patients. In the 54 surviving patients with unruptured recurrent aneurysms, good functional outcome was noted in 49 (91%). Poor functional outcome was significantly associated with intraoperative rupture.

CONCLUSIONS Microsurgery remains an effective therapeutic option for recurrent intracranial aneurysms. However, in the authors’ experience, postoperative morbidity is higher than in patients with nonrecurrent aneurysms. Therefore, a pretherapeutic multidisciplinary evaluation is mandatory to reduce the potential morbidity associated with the retreatment as much as possible. When endovascular occlusion of the aneurysm requires both stenting and coiling, alternative microsurgical treatment should be carefully evaluated, as microsurgical clipping will become much more challenging in cases of aneurysm recurrence.

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Extended Long-Term Outcome After Conservative Decompressive Microsurgery and Routine Adjuvant Fractionated Stereotactic Radiotherapy for Symptomatic Cavernous Sinus Meningiomas

Neurosurgery 95:834–841, 2024

Cavernous sinus meningiomas (CSM) pose one of the most difficult to treat subgroup of skull base meningiomas. The purpose of this study was to evaluate the efficacy of an interdisciplinary treatment approach for symptomatic CSM which incorporated conservative function preserving microsurgery and routine adjuvant fractionated stereotactic radiotherapy (FSRT).

METHODS: A homogenous group of patients with symptomatic primary CSM with extracavernous extension was treated between 2005 and 2012. All patients were available for a minimum follow-up of 5 years. Clinical follow-up included detailed examination of oculomotor deficits, visual status, and endocrinologic function. Radiologic follow-up was conducted by tumor volumetry.

RESULTS: Overall, 23 patients were included in this study (78.3% women; median age 58 years). Diplopia was the most common presenting symptom, followed by headache and visual disturbances. Surgical morbidity was low (3/23; 13%). FSRT was applied after a median of 2 months after surgery. At a median clinical follow-up of 113 months, 70.45% of the presenting symptoms had improved, 25% remained unchanged, and in 2 cases (4.54%), worsening occurred. Overall tumor regression was evident in 19/21 World Health Organization 1 and in 1/2 of World Health Organization 2 CSM, respectively, at a median radiological follow-up of 103 months.

CONCLUSION: Our findings demonstrate the efficacy of an interdisciplinary treatment approach for symptomatic primary CSM with extracavernous extension with decompression of neurovascular elements followed by FSRT. Precise preoperative planning and intraoperative decision making in combination with routine postoperative radiotherapy can achieve excellent tumor control, improve neurologic function, and minimize long-term morbidity.

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Microsurgical Resection of Brainstem Cavernous Malformations in Older Adults: A Multicenter, 30-Year Experience

Neurosurgery 95:669–675, 2024

Microsurgical resection is the only curative intervention for symptomatic brainstem cavernous malformations (BSCMs), but the management of these lesions in older adults (≥65 years) is not well described. This study sought to address this gap by examining the safety and efficacy of BSCM resection in a cohort of older adults.

METHODS: Records of patients who underwent BSCM resection over a 30-year period were reviewed retrospectively. Baseline characteristics and outcomes were compared between older (≥65 years) and younger (<65 years) patients.

RESULTS: Of 550 patients with BSCM who met inclusion criteria, 41 (7.5%) were older than 65 years. Midbrain (43.9% vs 26.1%) and medullary lesions (19.5% vs 13.6%) were more common in the older cohort than in the younger cohort (P = .01). Components of the Lawton BSCM grading system (ie, lesion size, crossing axial midpoint, developmental venous anomaly, and timing of hemorrhage) were not significantly different between cohorts (P ≥ .11). Mean (SD) Elixhauser comorbidity score was significantly higher in older patients (1.86 [1.06]) than in younger patients (0.66 [0.95]; P < .001). Older patients were significantly more likely than younger patients to have poor outcomes at final follow-up (28.9% vs 13.8%, P = .01; mean follow-up duration, 28.7 [39.1] months). However, regarding relative neurological outcome (preoperative modified Rankin Scale to final modified Rankin Scale), rate of worsening was not significantly different between older and younger patients (23.7% vs 14.9%, P = .15).

CONCLUSION: BSCMs can be safely resected in older patients, and when each patient’s unique health status and life expectancy are taken into account, these patients can have outcomes similar to younger patients.

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Treatment of conus medullaris arteriovenous malformation: the role of microsurgical treatment

J Neurosurg Spine 41:115–121, 2024

Conus medullaris arteriovenous malformation (AVM) is rare and challenging to treat. To better define the presentation, prognosis, and optimal treatment of these lesions, the authors present their treatment experiences for conus medullaris AVM.

METHODS Eleven patients with AVM of the conus medullaris were identified between March 2013 and December 2021. Among these patients, 7 who underwent microsurgical treatment were included. Patient data, including age, sex, symptoms at presentation, neurological status, radiological findings, nidus depth (mainly pial lesion vs intramedullary lesion), type of treatment, and recurrence at follow-up, were collected. Postoperative angiography was performed in all patients. Spinal cord function was evaluated using the Frankel grade at the time of admission and 1 year after surgery.

RESULTS All 7 patients presenting with myeloradiculopathy were treated surgically. Four patients (57.1%) underwent endovascular embolization, followed by resection. The other 3 patients underwent microsurgery only. Complete occlusion was confirmed with postoperative angiography in all patients. Of the 3 patients who were nonambulatory before surgery (Frankel grade C), 2 were able to walk after surgery (Frankel grade D) and 1 remained nonambulatory (Frankel grade C) at 1-year follow-up.

CONCLUSIONS Based on the authors’ clinical experiences, the results of multimodal treatment for conus medullaris AVM are good, with microsurgical treatment playing an important role. The microsurgical strategy can differ depending on the location of the nidus, and when possible, good results can be expected through microsurgical resection.

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

Acta Neurochirurgica (2024) 166:198

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

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

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

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

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A new classification of parasagittal bridging veins based on their configurations and drainage routes pertinent to interhemispheric approaches: a surgical anatomical study

J Neurosurg 140:271–281, 2024

OBJECTIVE Opening the roof of the interhemispheric microsurgical corridor to access various neurooncological or neurovascular lesions can be demanding because of the multiple bridging veins that drain into the sinus with their highly variable, location-specific anatomy. The objective of this study was to propose a new classification system for these parasagittal bridging veins, which are herein described as being arranged in 3 configurations with 4 drainage routes.

METHODS Twenty adult cadaveric heads (40 hemispheres) were examined. From this examination, the authors describe 3 types of configurations of the parasagittal bridging veins relative to specific anatomical landmarks (coronal suture, postcentral sulcus) and their drainage routes into the superior sagittal sinus, convexity dura, lacunae, and falx. They also quantify the relative incidence and extension of these anatomical variations and provide several preoperative, postoperative, and microneurosurgical clinical case study examples.

RESULTS The authors describe 3 anatomical configurations for venous drainage, which improves on the 2 types that have been previously described. In type 1, a single vein joins; in type 2, 2 or more contiguous veins join; and in type 3, a venous complex joins at the same point. Anterior to the coronal suture, the most common configuration was type 1 dural drainage, occurring in 57% of hemispheres. Between the coronal suture and the postcentral sulcus, most veins (including 73% of superior anastomotic veins of Trolard) drain first into a venous lacuna, which are larger and more numerous in this region. Posterior to the postcentral sulcus, the most common drainage route was through the falx.

CONCLUSIONS The authors propose a systematic classification for the parasagittal venous network. Using anatomical landmarks, they define 3 venous configurations and 4 drainage routes. Analysis of these configurations with respect to surgical routes indicates 2 highly risky interhemispheric surgical fissure routes. The risks are attributable to the presence of large lacunae that receive multiple veins (type 2) or venous complex (type 3) configurations that negatively impact a surgeon’s working space and degree of movement and thus are predisposed to inadvertent avulsions, bleeding, and venous thrombosis.

 

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The sub‑occipital transtentorial approach for pineal region tumors

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Acta Neurochirurgica (2023) 165:3461–3465

Two major approaches exist for the surgical removal of pineal region tumors: the supracebellar infratentorial and the sub-occipital transtentorial.

Methods We present the Lyon’s technique of the sub-occipital transtentorial approach for pineal region tumors and our tricks to avoid complications. The principle is to expose the pineal region under the occipital lobe and not through the interhemispheric fissure.

Conclusions The sub-occipital transtentorial approach is a direct, extra cerebral, safe, and effective way to access tumors of the pineal region.

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Audiovestibular symptoms and facial nerve function comparing microsurgery versus SRS for vestibular schwannomas

Acta Neurochirurgica (2022) 164:3221–3233

Surgery and radiosurgery represent the most common treatment options forcvestibular schwannoma. A systematic review and meta-analysis were conducted to compare the outcomes of surgery versus stereotactic radiosurgery (SRS).

Methods The Cochrane library, PubMed, Embase, and clinicaltrials.gov were searched through 01/2021 to find all studies on surgical and stereotactic procedures performed to treat vestibular schwannoma. Using a random-effects model, pooled odds ratios (OR) and their 95% confidence intervals (CI) comparing post- to pre-intervention were derived for pre-post studies, and pooled incidence of adverse events post-intervention were calculated for case series and stratified by intervention type.

Results Twenty-one studies (18 pre-post design; three case series) with 987 patients were included in the final analysis. Comparing post- to pre-intervention, both surgery (OR: 3.52, 95%CI 2.13, 5.81) and SRS (OR: 3.30, 95%CI 1.39, 7.80) resulted in greater odds of hearing loss, lower odds of dizziness (surgery OR: 0.10; 95%CI 0.02, 0.47 vs. SRS OR: 0.22; 95%CI 0.05, 0.99), and tinnitus (surgery OR: 0.23; 95%CI 0.00, 37.9; two studies vs. SRS OR: 0.11; 95%CI 0.01, 1.07; one study). Pooled incidence of facial symmetry loss was larger post-surgery (14.3%, 95%CI 6.8%, 22.7%) than post-SRS (7%, 95%CI 1%, 36%). Tumor control was larger in the surgery (94%, 95%CI 83%, 98%) than the SRS group (80%, 95%CI 31%, 97%) for small-to-medium size tumors.

Conclusion Both surgery and SRS resulted in similar odds of hearing loss and similar improvements in dizziness and tinnitus among patients with vestibular schwannoma; however, facial symmetry loss appeared higher post-surgery.

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Overview of the microanatomy of the human brainstem in relation to the safe entry zones

J Neurosurg 137:1524–1534, 2022

The primary objective of this anatomical study was to apply innovative imaging techniques to increase understanding of the microanatomical structures of the brainstem related to safe entry zones. The authors hypothesized that such a high-detail overview would enhance neurosurgeons’ abilities to approach and define anatomical safe entry zones for use with microsurgical resection techniques for intrinsic brainstem lesions.

METHODS The brainstems of 13 cadavers were studied with polarized light imaging (PLI) and 11.7-T MRI. The brainstem was divided into 3 compartments—mesencephalon, pons, and medulla—for evaluation with MRI. Tissue was further sectioned to 100 μm with a microtome. MATLAB was used for further data processing. Segmentation of the internal structures of the brainstem was performed with the BigBrain database.

RESULTS Thirteen entry zones were reported and assessed for their safety, including the anterior mesencephalic zone, lateral mesencephalic sulcus, interpeduncular zone, intercollicular region, supratrigeminal zone, peritrigeminal zone, lateral pontine zone, median sulcus, infracollicular zone, supracollicular zone, olivary zone, lateral medullary zone, and anterolateral sulcus. The microanatomy, safety, and approaches are discussed.

CONCLUSIONS PLI and 11.7-T MRI data show that a neurosurgeon possibly does not need to consider the microanatomical structures that would not be visible on conventional MRI and tractography when entering the mentioned safe entry zones. However, the detailed anatomical images may help neurosurgeons increase their understanding of the internal architecture of the human brainstem, which in turn could lead to safer neurosurgical intervention.

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