Neuropathology

Incidental meningioma active surveillance

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Incidental meningioma active surveillance

Active surveillance is a non-interventional management strategy where the tumor is closely monitored with regular imaging and clinical assessments instead of immediate treatment.

Indications for Active Surveillance

Asymptomatic patients

Tumor discovered incidentally

Small size (< 2–3 cm)

No mass effect or brain edema

No radiological signs of aggressiveness (e.g., brain invasion, rapid growth)

The patient has significant comorbidities or advanced age

The tumor is located in an eloquent or high-risk area for surgery

Surveillance Protocol (Typical Schedule)

Baseline MRI with contrast to characterize the tumor

Follow-up MRI at 6 months

If stable → annual imaging for 5 years

If still stable → consider imaging every 2–3 years

Lifelong monitoring is most cases, especially in younger patients

Clinical Follow-up

Regular neurological exams

Monitor for new symptoms: headache, seizures, focal deficits, cognitive changes

Reassess management if:

Tumor grows (commonly defined as >2 mm/year)

New or worsening symptoms appear

Advantages of Active Surveillance Avoids risks of surgery or radiation

Preserves the quality of life in asymptomatic individuals

Many meningiomas remain stable for years or a lifetime

When to Reconsider Treatment Radiological progression (volume increase, edema, mass effect)

Symptom development

Patient preference changes

Tumor in surgically accessible location with low expected morbidity

Cohort studies

A population-based study explores the prevalence and symptomatology of incidentally found meningiomas in a specific aging population—the 70-year-olds participating in the Gothenburg H70 Birth Cohort Study. The authors analyzed MRIs from 792 individuals and found a 1.8% prevalence of incidental meningiomas, with a notable gender skew (12 of the 14 cases were female) 1)

One of the key strengths of this work is its community-based sampling, which reduces the referral bias often present in hospital-based series. It also adds valuable information to the growing body of literature supporting a more conservative treatment approach in asymptomatic or minimally symptomatic individuals, especially in the elderly.

The study challenges the reflexive assumption that nonspecific symptoms like headache or dizziness are attributable to small, incidentally found meningiomas. This is crucial, as overattribution can lead to unnecessary neurosurgical interventions, with accompanying risks and psychological burden.

On the flip side, the small absolute number of identified meningiomas (n=14) limits the statistical power to detect nuanced associations between clinical variables and tumor presence. Furthermore, the authors did not perform longitudinal follow-up to assess tumor growth or symptom progression, which could be relevant in determining the true clinical impact of these incidental findings.

In summary, this study provides solid evidence that supports watchful waiting in many cases of incidental meningioma, particularly in elderly women. It underscores the need for clinical restraint and careful consideration before attributing symptoms or deciding on intervention.

Retrospective Comparative Cohort Study with Propensity Score Matching

Hallak et al. employ a retrospective study design with propensity score matching to balance confounding factors between patients undergoing stereotactic radiosurgery (SRS) and those under active surveillance 2)

Key findings include:

  • Superior radiological control in the SRS group (97.37%) compared to observation (71.93%), with a statistically significant advantage (p < 0.01).
  • Neurological safety appears slightly compromised in SRS (1.39% new deficits), while no new deficits occurred under surveillance.
  • The need for surgical resection was low in both arms, slightly higher in the observation group (3.5% vs 0.9%), though not statistically significant (p = 0.063).
  • A trend toward lower mortality in the SRS group (9.65% vs 18.42%) was noted, yet without reaching statistical significance (p = 0.06). Notably, no deaths in the observation group were directly attributed to meningioma progression.

From a clinical decision making perspective, the study underscores the value of personalized management. While SRS offers more robust tumor control, the marginal increase in risk of neurological complication, coupled with a non-significant impact on survival or surgical rescue, suggests watchful waiting remains a valid approach—especially in patients with limited life expectancy or comorbidities.

Future prospective trials with functional outcomes, quality-of-life metrics, and cost-effectiveness analyses are needed to refine treatment algorithms. Nevertheless, this article adds weight to current trends toward de-escalation in certain low-risk neurosurgical cases.

1)

de Dios E, Näslund O, Choudhry M, Berglund M, Skoglund T, Sarovic D, Rydén L, Kern S, Skoog I, Thurin E. Prevalence and symptoms of incidental meningiomas: a population-based study. Acta Neurochir (Wien). 2025 Apr 3;167(1):98. doi: 10.1007/s00701-025-06506-7. PMID: 40178655.
2)

Hallak H, Mantziaris G, Pikis S, Islim AI, Peker S, Samanci Y, Nabeel AM, Reda WA, Tawadros SR, El-Shehaby AMN, Abdelkarim K, Emad RM, Mathieu D, Lee CC, Liscak R, Alvarez RM, Kondziolka D, Tripathi M, Speckter H, Bowden GN, Benveniste RJ, Lunsford LD, Jenkinson MD, Sheehan J. A retrospective comparison of active surveillance to stereotactic radiosurgery for the management of elderly patients with an incidental meningioma. Acta Neurochir (Wien). 2025 Feb 6;167(1):37. doi: 10.1007/s00701-025-06452-4. PMID: 39912992; PMCID: PMC11802698.

Fourth ventricle tumor surgery complications

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Fourth ventricle tumor surgery complications

Fourth ventricle tumor surgery is delicate and carries specific risks due to the complex anatomy of the region. The fourth ventricle lies in the posterior fossa of the brain, nestled between the brainstem and cerebellum. Because of this, complications can involve vital neurological structures.

🔴 Neurological Complications

Cranial Nerve Deficits

Especially CN VI (abducens), CN VII (facial), and CN VIII (vestibulocochlear).

May cause diplopia, facial weakness, or hearing loss.

Cerebellar Dysfunction

Ataxia, dysmetria, intention tremor.

Can be transient or permanent.

Brainstem Injury

Risk of respiratory or cardiovascular instability.

It can lead to coma or death in extreme cases.

Mutism / Cerebellar Cognitive Affective Syndrome

Especially in pediatric patients after resection of medulloblastomas or ependymomas.

Characterized by mutism, emotional lability, and executive dysfunction.

💧 CSF-related Complications

Hydrocephalus (pre- or post-operative)

Due to obstruction of CSF pathways (aqueduct or outlets of the fourth ventricle).

May require an external ventricular drain (EVD) or VP shunt.

CSF Leak / Pseudomeningocele

From poor dural closure or pressure buildup.

Risk of infection or wound healing issues.

Meningitis / Ventriculitis

Especially if there’s a CSF leak or prolonged drain use.

💉 Vascular Complications

Hemorrhage

Intraoperative bleeding from a tumor or surrounding vessels.

Postoperative hematoma causing brainstem compression.

Ischemia

Injury to perforating arteries (e.g., branches of the posterior inferior cerebellar artery – PICA).

It can cause infarcts in the brainstem or cerebellum.

🛌 Systemic and General Complications

Infection

Seizures (rare for the posterior fossa)

Respiratory compromise (especially in children or after brainstem manipulation)

Wound complications

🧠 Tumor-specific factors

Ependymomas: Adherence to the floor of the 4th ventricle increases brainstem injury risk.

Medulloblastomas: prone to CSF spread, so thorough surgical and oncologic planning is key.

Choroid plexus tumors: highly vascular, bleeding risk.

Cohort studies

In a large multicenter cohort study Persson et al. investigate postoperative word-finding abilities in children undergoing posterior fossa tumor surgery (PFTs), with data from 184 children across Europe. The authors address a critical yet understudied postoperative complication—word-finding difficulty, which goes beyond classic cerebellar mutism syndrome (CMS) and focuses on more subtle higher-order language impairments 1)

The study’s key strength lies in its pre- and postoperative comparisons using a speeded picture-naming test, providing quantitative insights into word retrieval speeds. Interestingly, the results reveal no significant change between pre- and postoperative performance on average. This means that while some children improved, others declined, underscoring the heterogeneous outcomes in PFT surgeries.

A striking finding is that 95% of children performed more than two standard deviations slower than age norms after surgery, despite no aggregate decline. This discrepancy suggests that even without a gross drop in individual scores, the cohort as a whole demonstrates clinically significant delays, potentially overlooked in standard assessments.

The study identifies fourth ventricle tumor as a specific risk factor (B = -4.09, p < 0.05), linking it to possible damage of the dentato-thalamo-cortical pathway. This aligns with previous neuroanatomical models implicating cerebellar-thalamo-cortical circuits in language function, not just motor planning.

From a clinical perspective, these findings call for routine postoperative language screening—even in patients who do not develop mutism—to detect subtle deficits that may affect communication and academic performance. Furthermore, early intervention strategies may be needed, particularly for children with tumours in higher-risk locations.

This study contributes valuable evidence supporting the existence of subtle yet functionally important postoperative language impairments in children with PFTs. It urges the neurooncology and neuropsychology communities to broaden the scope of postoperative assessments to include not only mutism but also word-finding and higher cognitive-linguistic functions.

1)

Persson K, Grønbæk J, Tiberg I, Fyrberg Å, Castor C, Andreozzi B, Frič R, Hauser P, Kiudeliene R, Mallucci C, Mathiasen R, Nyman P, Pizer B, Sehested A, Boeg Thomsen D; CMS study group. Postoperative word-finding difficulties in children with posterior fossa tumours: a crosslinguistic European cohort study. Childs Nerv Syst. 2025 Mar 12;41(1):128. doi: 10.1007/s00381-025-06787-4. PMID: 40075014; PMCID: PMC11903548.

Meningioma grade

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Meningioma grade

World Health Organization grade 1 meningioma.

World Health Organization grade 2 meningioma.

World Health Organization grade 3 meningioma.

The current system of grading has been shown to be unsatisfactory due to its poor reproducibility as well as the considerable variability within grades. With the increasing availability of genomic and epigenomic profiling, several markers have been suggested to correlate with the location, histological subtype, and clinical behavior of meningiomas. These developments have enabled the development of targeted therapy, as well as individualized use of currently available adjuvant methods. These include copy number alterations (CNAs), specific genetic abnormalities (germline and sporadic), and genome-wide methylation profiles 1).

Cohort Studies

Chromosome 1p Loss and 1q Gain for Grading of Meningioma

Type of study: Cohort Study Citation: JAMA Oncol. 2025 Apr 3. doi: 10.1001/jamaoncol.2025.0329. Online ahead of print.

Authors: Alexander P. Landry et al. PMID: 40178835

Critical Review

This multicenter cohort study spanning institutions in Canada, the US, and Germany offers a compelling contribution to the evolving field of molecular neuropathology and meningioma grading. It critically addresses the limitations of the 2021 WHO CNS classification, which incorporated rare markers like homozygous deletion of CDKN2A an B and TERT promoter mutations, by proposing more broadly applicable cytogenetic criteria based on copy number alterations 2).

Key findings include:

  • Loss of chromosome 1p in WHO grade 1 meningiomas correlates with significantly reduced progression-free survival (PFS), approximating outcomes of WHO grade 2 tumors.
  • Combined 1p loss and 1q gain predicted outcomes similar to WHO grade 3, regardless of histopathological grade.
  • These alterations show strong prognostic power, suggesting their inclusion could refine and personalize the current WHO CNS grading system.

The study’s strength lies in its large sample size (n = 1964), long follow-up, and integration of genomic and clinical data. Its statistical approach—mainly Cox regression analysis—was well-suited to evaluate prognostic factors across grades. The authors convincingly demonstrate that current grading overlooks key genomic drivers of progression and recurrence.

Clinical implications:

Incorporating 1p loss as a criterion for WHO grade 2 and 1q gain for WHO grade 3 would allow for a more accurate risk stratification and better patient management. This aligns with the current momentum in neuro-oncology to move beyond histology and adopt integrated molecular grading—already in place for entities like glioma.

Limitations:

  • Although multicenter, some variability in pathology protocols and treatment across sites could have introduced bias.
  • Radiation exposure was not uniformly reported, which could affect PFS independently of genetic markers.
  • The study does not explore the cost or feasibility of widespread cytogenetic screening, which is critical for real-world application.

Conclusion:

This paper is a significant step toward a more nuanced and genomically-informed meningioma classification system. The proposed inclusion of chromosome 1p loss and 1q gain into future WHO grading guidelines deserves serious consideration by the neuro-oncologic community and classification committees.

Back to meningioma section

1)

Goyal-Honavar A, Jayachandran R, Chacko G. Meningiomas – transition from traditional histological grading to molecular profiling in WHO CNS5: A Review. Indian J Pathol Microbiol. 2022 May;65(Supplement):S83-S93. doi: 10.4103/ijpm.ijpm_1085_21. PMID: 35562138.
2)

Landry AP, Wang JZ, Patil V, Liu J, Gui C, Ellenbogen Y, Ajisebutu A, Yefet L, Wei Q, Singh O, Sosa J, Mansouri S, Cohen-Gadol AA, Tabatabai G, Tatagiba M, Behling F, Barnholtz-Sloan JS, Sloan AE, Chotai S, Chambless LB, Mansouri A, Makarenko S, Yip S, Ehret F, Capper D, Tsang DS, Moliterno J, Gunel M, Wesseling P, Sahm F, Aldape K, Gao A, Zadeh G, Nassiri F. Chromosome 1p Loss and 1q Gain for Grading of Meningioma. JAMA Oncol. 2025 Apr 3. doi: 10.1001/jamaoncol.2025.0329. Epub ahead of print. PMID: 40178835.