Radiosurgery for Brain Meningiomas: A Location-by-Location Guide to the Evidence

Table of Contents

• Key Points
• Background: What Are Meningiomas and Why Does Location Matter?
• How This Review Was Conducted
• How Meningiomas Are Classified by Location
• Symptoms by Tumor Location
• Treatment Guidelines and Current Practice Patterns
• Parafalcine and Parasagittal Meningiomas
• Convexity Meningiomas
• Cavernous Sinus Meningiomas
• Clinical Implications: What This Means for Patients
• Limitations of the Evidence
• Recommendations and Future Directions
• Frequently Asked Questions
• Source Information

Key Points

• Stereotactic radiosurgery delivers a single high-dose radiation session; hypofractionated stereotactic radiotherapy delivers 2 to 5 sessions; conventional radiotherapy spreads small doses over 5 to 6 weeks.
• Across all subregions reviewed, radiosurgery produced high tumor control rates with acceptably low rates of adverse radiation events.
• In a matched analysis of asymptomatic convexity meningiomas, tumor control was 99% with upfront radiosurgery versus 69.4% with conservative management.
• In one analysis of 65 parasagittal and parafalcine meningioma patients, tumor control at 3 and 5 years was 85% and 70% overall, rising to 93% when previously treated tumors were excluded.
• Keeping radiation to the optic nerve lower than 8–10 Gy may reduce the risk of adverse radiation effects; cranial nerves in the cavernous sinus appear to tolerate relatively higher doses.

Background: What Are Meningiomas and Why Does Location Matter?

Meningiomas are tumors that grow from the protective coverings of the brain. These coverings are called the meninges, and the specific cells that give rise to meningiomas are called arachnoidal cap cells. The tumors grow within the arachnoid mater and pia mater, which are two of the brain's outer protective layers. The name "meningioma" was formally established by the pioneering neurosurgeon Harvey Cushing in 1922.

Meningiomas are the most common primary tumors of the central nervous system (CNS, meaning the brain and spinal cord). They account for 15% of symptomatic intracranial neoplasms (brain tumors that cause symptoms) and 33% of asymptomatic intracranial neoplasms found during autopsy. These tumors disproportionately affect women. About 65% of meningiomas are found in women aged 40 to 50 years.

A definitive diagnosis requires a biopsy or surgical removal of the tumor. However, the typical appearance on imaging often provides enough information for diagnosis. Magnetic resonance imaging (MRI) classically shows a dural-based, well-circumscribed, homogeneously enhancing lesion. In plain language, this means the tumor attaches to the dura (the outermost brain covering), has clear borders, and lights up uniformly when contrast dye is given.

Radiographic classification distinguishes two main shapes. En plaque meningiomas cause extensive thickening of the dura. Globose meningiomas form rounded, extra-axial masses. The World Health Organization (WHO) recognizes 15 histological subtypes of meningiomas. The vast majority are WHO Grade I, which means benign (non-cancerous).

Despite being benign, encapsulated, and having few genetic abnormalities, meningiomas can cause serious and potentially life-threatening problems because of where they are located. WHO Grade II and Grade III meningiomas have higher recurrence rates and require more aggressive treatment. Certain molecular factors indicate malignant behavior. These include mutations in the telomerase reverse transcriptase (TERT) promoter and homozygous deletions in the cell cycle regulator genes CDKN2A and/or CDKN2B.

Meningiomas are typically slow-growing and non-infiltrative. They cause symptoms gradually, and those symptoms depend on the tumor's location. While there is no single symptom that defines a meningioma, these tumors may cause common intracranial tumor symptoms. These include headache from increased intracranial pressure, focal neurological deficits (specific losses of function such as weakness or numbness), and seizures. Brain edema (swelling), mass effect (pressure on nearby structures), or direct compression of critical structures drives the symptoms.

Despite their high prevalence, clinical management varies significantly. Decisions depend on many factors, including tumor location, size, patient age, how the tumor presents, and its pathology.

Treatment options for intracranial meningiomas include surgical resection alone, surgery followed by adjuvant radiation therapy (RT), or primary RT. When safely achievable, the treatment of choice is complete surgical resection (Simpson Grade I–III), which includes removing the dura of origin and any infiltrated bone.

However, the inherent risks of surgery may prevent complete removal. This is particularly true for tumors that infiltrate vital intracranial structures or for patients who are frail. Subtotal resection (partial removal) and higher-grade tumors (WHO II and III) have higher rates of recurrence. Multiple resections increase morbidity (complications) due to scarring and increased infiltration.

Since the 1980s, when radiotherapy planning via MRI or computerized tomography (CT) began, the 5-year progression-free survival rate for benign meningiomas increased from 77% to 98%. When complete surgical resection is not feasible, subtotal resection with adjuvant radiation can achieve results comparable to total resection.

Radiotherapy can be delivered to intracranial meningiomas in different ways:

• Stereotactic radiosurgery (SRS) uses a single irradiation fraction (one treatment session).
• Hypofractionated stereotactic radiotherapy (HSRT) delivers 2 to 5 ablative doses of focused radiation.
• Conventional radiotherapy entails daily delivery of small individual radiation doses over 5 to 6 weeks.

Historically, both SRS and fractionated stereotactic radiotherapy (FSRT) were reserved for recurrent or malignant lesions, or for patients who were poor candidates for surgery. Increased frequency of brain imaging, together with an aging population, has permitted the diagnosis of asymptomatic meningiomas. RT has become a first-line therapy for select meningioma cases, particularly small meningiomas in challenging or high-risk anatomical locations. Combination treatments with surgery and SRS/FSRT are also increasingly used. However, controversies remain regarding the timing, type, and dosing of various RT techniques.

Population-based analysis reveals an increased incidence of meningiomas in recent years alongside decreasing tumor size at diagnosis. A meta-analysis on meningioma growth showed that although half of incidental meningiomas exhibit no growth, the remaining half exhibited either linear or exponential growth.

Strategic surgical decision-making hinges on precisely determining where the meningioma originates and on anatomical considerations. Adjacent anatomical structures dictate how easy it is to access the tumor surgically, the ability to achieve complete resection, and the risk of morbid tumor progression.

Over recent years, significant research has focused on RT for meningioma control. Prior investigations detailed outcomes in broader regions such as the skull base and parasellar regions. Recent reports have accumulated that detail outcomes, nuances, and updated SRS treatment regimens for specific anatomical subregions. Instead of a study investigating skull-base meningiomas broadly, more specific analyses now investigate subregions such as petroclival, olfactory groove, and foramen magnum.

This narrative review discusses anatomical challenges inherent in specific locations and synthesizes the latest evidence on radiosurgical intervention. The authors also delve into the intricacies of radiosurgical methodology, dosimetric considerations (how radiation doses are planned and measured), and future directions of radiotherapy.

How This Review Was Conducted

The authors used a narrative review framework. They searched recent literature from 2000 to 2024 using the MEDLINE database. The search keywords were "meningioma," "radiosurgery," and each anatomic location individually. The authors also included relevant articles fitting this time period (2000–2024) that were noted in ascendency searching (following references from other papers).

Articles were included if they described radiosurgery for meningiomas, especially if they described anatomical location. Articles were excluded if they were not translated into English, were not available in full text, or discussed meningioma in broad anatomic descriptions.

How Meningiomas Are Classified by Location

Meningiomas are named based on their anatomical location. The most common sites reported are falcine, parasagittal, convexity, and sphenoid wing meningiomas. Their presentation entirely depends on the adjacent neuronal and vascular structures impacted by mass effect.

Prior reviews have reported the most common presenting symptoms across all meningiomas:

• Headache: 33.3–36.7%
• Focal cranial nerve deficit: 28.8–31.3%
• Seizure: 16.9–24.6%
• Cognitive change: 14.4%
• Weakness: 11.1%
• Vertigo/dizziness: 9.8%
• Ataxia/gait change: 6.3%
• Pain/sensory change: 5.6%
• Proptosis (bulging eye): 2.1%
• Syncope (fainting): 1.0%

A significant minority of patients, 9.4%, are asymptomatic. Although broad symptoms like headache are shared across locations, specific location-based presenting symptoms differ. With modern imaging advances, meningiomas are being discovered earlier and smaller than ever before. Early-stage diagnoses often lack the locational symptoms seen with larger presenting tumors.

Symptoms by Tumor Location

The following table lists the most common presenting symptoms from intracranial meningiomas arising at various specific anatomic allocations. Non-specific symptoms such as headache were excluded.

• Parasagittal/Falcine — Anterior: Personality change, confusion, altered consciousness, reduced attention span, short-term memory deficits, emotional instability, and apathy.
• Parasagittal/Falcine — Middle: Motor symptoms (commonly spastic weakness of the contralateral foot and leg), sensory symptoms, partial seizures.
• Parasagittal/Falcine — Posterior: Visual alterations or headache.
• Confluence of Falx and Tentorium: Headache, disequilibrium, visual dysfunction, impaired cognition or behavioral change, and upgaze paresis (difficulty looking upward).
• Convexity: Seizures and sensory changes.
• Parasellar: Visual impairment (additional symptoms are widely variable depending on subregional location).
• Suprasellar: Asymmetric visual impairment.
• Petroclival: Cranial nerve V deficits, cranial nerve VI palsy, vertigo, dizziness, balance and walking disturbances, and weakness of the extremities.
• Clinoidal: Visual disturbances.
• Perioptic: Visual loss.
• Cavernous Sinus: Oculomotor nerve palsy.
• Intraventricular: Visual field deficits, ataxia, paresis, seizure, and hydrocephalus.
• Foramen Magnum: Dizziness/ataxia, cranial nerve deficits, numbness, weakness, and hydrocephalus.
• Olfactory Groove: Mental status disturbances and headaches, partial or complete anosmia (loss of smell).
• Cerebellopontine Angle: Tinnitus, hearing loss, dizziness, trigeminal dysfunction, neurocognitive impairment.

As further research emerges on specific anatomic allocations, results can be interpreted on a more specific basis than prior broad encompassing regions. For example, prior results have been posted on radiosurgery for "skull base" meningiomas. But this broad category encompasses subregions like the clivus, petrous bone, cavernous sinus, tentorium, sphenoid bone, sella turcica, olfactory groove, and optic nerve sheath. This paper reviews evidence for radiosurgery within these specific anatomical subregions, highlights regional challenges, and provides a depth of available outcome-based evidence on tumor control.

Treatment Guidelines and Current Practice Patterns

Meningioma management lacks a clear-cut algorithm. An appropriate management strategy is determined on a case-by-case basis. Despite being a common intracranial tumor, countries and surgical centers vary in management approaches.

Trends derived from the Surveillance, Epidemiology, and End Results (SEER) database of the National Cancer Institute in 2017 showed the following:

• 42.4% of patients with meningiomas underwent surgical treatment with or without radiotherapy.
• 52.1% were managed with active surveillance.
• Of those managed surgically, 8.7% received RT at some point, with 95% receiving it after surgery.
• Only 5.6% of patients underwent radiation therapy alone.

While some meningiomas may not increase in size, many do if watched long enough, especially in young patient populations. It is statistically unlikely that a 20-year-old will have 50 growth-free years. Therefore, treatment decision-making must consider age.

Prior publications on the natural history of meningioma growth have shown exponential or linear growth in 63% and 53% of cases, and overall growth in up to 83.5% of tumors. Considering growth potential is particularly relevant for small asymptomatic meningiomas adjacent to vasculature or cranial nerves.

Recently, increased investigation has examined RT as primary monotherapy instead of conservative observation. An important study by Sheehan et al. compared SRS alone versus active surveillance in asymptomatic incidental meningiomas. Their analysis found SRS affords superior radiologic tumor control versus active surveillance without an increasing risk of neurological deficits.

Updated 2021 European Association of Neuro-Oncology (EANO) guidelines list observation as the first option for asymptomatic meningiomas. These guidelines also include RT as complementary therapy or even an alternative approach to surgery in certain situations.

Parafalcine and Parasagittal Meningiomas

The falx cerebri is a sickle-shaped structure running within the longitudinal fissure between the two cerebral hemispheres. It is anchored anteriorly to the crista galli and posteriorly to the occipital protuberance. It forms a sail-like divider of the two hemispheres. Meningiomas originating from the falx are termed parafalcine meningiomas. If the meningioma grows into at least one wall of the superior sagittal sinus, it is referred to as a parasagittal meningioma.

Parafalcine and parasagittal meningiomas account for 30% of intracranial meningiomas. Microsurgery is the mainstay of treatment for meningiomas at this location, despite high recurrence rates and the risk of venous injury during surgical excision. Engulfment of the pericallosal arteries deters radical excision, and radiotherapy could be useful in these cases. With high rates of venous invasion, complete resection is generally unfeasible. Optimal management remains controversial because both surgical and non-surgical options frequently fail to provide definitive treatment.

A review by Pinzi et al. in 2019 found limited literature on stereotactic radiotherapy (SRT) and radiosurgery (RS) for parafalcine and parasagittal meningiomas. Only five available studies existed, and only one study had been published since 2015. Their analysis found falcine tumors were suitable for complete resection, while parasagittal meningiomas were difficult due to sagittal sinus adherence.

It has been reported previously that parasagittal and parafalcine meningiomas have suboptimal radiosurgical response versus skull-based lesions. Pinzi et al. concluded from their data review that SRT and RS could be more widely applied for parafalcine and parasagittal meningiomas. These approaches represent viable options for primary and adjuvant therapy for parasagittal and parafalcine meningiomas.

Ding et al. published a retrospective analysis of 65 patients treated with a median prescription dose of 15 Gy for parasagittal and parafalcine meningiomas in one fraction. They found a tumor control rate of 85% at 3 years and 70% at 5 years. When excluding treated tumors (those that had prior resection, embolization, and radiotherapy), they found the control rate at both 3 and 5 years was 93%. This suggests that prior treatment negatively affected radiosurgical efficacy, but additional studies are needed. Parasagittal location, no prior resection, and younger age were independent predictors of tumor progression-free survival.

Meningiomas at the confluence of the falx and tentorium (CFT) represent less than 2% of intracranial meningiomas and are surgically challenging. Abdallah et al. published a paper reporting the largest series focused exclusively on outcomes of Gamma Knife radiosurgery for meningiomas arising from the confluence of the CFT in 2022. Their paper detailed 20 CFT meningioma patients. Ten patients underwent radiosurgery for progression of residual tumor following resection, and 10 underwent radiosurgery as primary management.

The marginal and maximum doses delivered in this series were 13.0 Gy (IQR 12.1–14.8) and 26 Gy (IQR 25.0–29.5), respectively. All radiation was carried out with a single unfractionated session. The 1-, 5-, and 10-year local tumor control rates were 100% (N=20), 100% (N=10), and 83% (N=4), respectively. Tumor volume decreased in 11 patients and was stable in eight patients. Their study concluded that radiosurgery is a safe and effective treatment for CFT meningiomas that can be utilized not only as adjuvant therapy, but also for primary management.

Together, these studies suggest that radiosurgical intervention for parasagittal meningiomas may be more effective than for parafalcine meningiomas. There was good tumor control overall and acceptable rates of adverse events. More studies are warranted on this subgroup of meningiomas to determine optimal treatment.

Convexity Meningiomas

Convexity meningiomas are predominant among extra-axial tumors encountered in neurosurgery. They grow on the outer surface of the cerebrum directly adjacent to the flat bones of the skull. These tumors are relatively simple to approach and resect because both the mass and involved dura mater can be removed. However, they account for only about one-sixth of meningiomas.

Craniotomy and removal of convexity meningiomas along with their dural base is the treatment of choice for symptomatic patients. Despite easier surgical access, the optimal treatment for asymptomatic convexity meningiomas remains unclear. Options include active surveillance or SRS. Observation is the most commonly preferred initial treatment. However, 4.6–26.3% of these asymptomatic patients will develop symptoms and require treatment. The role of SRS for upfront treatment of asymptomatic convexity meningiomas has yet to be well defined.

Pikis et al. in 2022 investigated data from patients with asymptomatic convexity meningiomas at 14 participating centers. They used a focused analysis from the International Multicenter Matched Cohort Analysis of Incidental Meningioma Progression During Active Surveillance (IMPASSE) study. Their study examined two unmatched cohorts of patients with asymptomatic convexity meningiomas: one received upfront SRS (N=99), and one was managed conservatively (N=140). The mean marginal dose of radiation was 13.26 Gy.

After propensity matching for age, they compared 98 patients in each cohort. A matched analysis showed that tumor control was 99% in SRS-treated patients and 69.4% in patients managed conservatively. Their results suggested that upfront SRS treatment of asymptomatic convexity meningiomas is associated with increased tumor control without an increased risk of new neurological deficits.

Another group of patients with convexity meningiomas underwent a retrospective review by Ruiz-Garcia et al. in 2021. They analyzed 18 patients with neurofibromatosis type 2 (NF2) with convexity meningiomas. One hundred and twenty convexity meningiomas were treated with single-fraction radiosurgical treatment, with a median marginal dose of 12.0 Gy. Actuarial tumor control rates at 5, 10, and 15 years were 100%, with only one radiation-induced adverse event.

Overall, the studies reviewed suggest that upfront SRS may offer superior control over watching and waiting. Convexity meningiomas lack extensive evidence on SRS. Symptomatic lesions are highly accessible for surgical intervention, but small asymptomatic incidental convexity meningiomas may benefit from SRS over watchful waiting. Additionally, patients with a high tumor lifetime burden, similar to those with NF2, may benefit from limiting invasive intervention to critical cases only. Fewer craniotomies may preserve quality of life in NF2 patients.

Cavernous Sinus Meningiomas

The cavernous sinus is a bilateral structure located lateral to the sella turcica. It extends from the superior orbital fissure anteriorly to the petrous part of the temporal bone posteriorly. Complete surgical resection of cavernous sinus (CS) meningiomas is quite difficult due to the numerous important regional structures. It therefore carries significant patient risk.

The cavernous sinus houses a segment of the internal carotid artery (ICA), the sympathetic plexus, cranial nerves III, IV, and VI, and the first two branches of cranial nerve V. Additionally, a narrow surgical corridor and close relation with the optic chiasm further complicate open resection. Microsurgical operations may cause cranial nerve palsies, ICA injury or occlusion, and/or cerebrospinal fluid leak.

Anatomical localization of vital structures, lack of arachnoid surfaces, and the tendency of CS meningiomas to invade nerve fascicles makes surgical cure extraordinarily difficult to achieve. Achieving complete resection depends on the degree of ICA involvement and vascular wall invasion. The available literature shows a tumor growth control rate of CS meningiomas greater than 90%. But ongoing debate still exists regarding the optimal treatment. No class 1 evidence exists supporting the superiority of SRS alone, fractionated radiotherapy alone, or any combination of either with subtotal resection.

Basak et al. sought to compare the efficacy of surgery and Gamma Knife therapy with Gamma Knife therapy alone for cavernous sinus meningiomas in 2023. This study uniquely compared two treatment methodologies at a single institution. Nine patients had surgery and radiosurgery, and eleven had radiosurgery alone. A mean marginal dose of greater than 13 Gy in a single fraction was used in both groups.

Extraocular nerve palsy (weakness of the eye muscles) is the most common complication with tumor management and is a disturbing detriment to patient quality of life. Their results showed this complication was more likely with surgical excision. Recovery was more likely with Gamma Knife treatment alone.

Cranial nerves within the cavernous sinus seem to tolerate relatively higher doses than the optic apparatus. But optic nerve complications should be considered due to its radiation sensitivity. Keeping radiation to the optic nerve lower than 8–10 Gy may reduce the risk of adverse radiation effects.

After Basak et al. The authors reviewed the available literature and their own cohort. The authors concluded that a distance of greater than 3 mm between the tumor and the optic apparatus is an important consideration for safe radiosurgical treatment.

Clinical Implications: What This Means for Patients

The evidence reviewed here carries several important messages for patients with meningiomas.

First, radiosurgery is not a single treatment but a family of precise radiation techniques. SRS delivers one high-dose session. HSRT delivers 2 to 5 sessions. Conventional radiotherapy spreads small doses over 5 to 6 weeks. The choice among these approaches depends on tumor size, location, and proximity to sensitive structures such as the optic nerve.

Second, tumor location matters enormously. A convexity meningioma on the brain's outer surface behaves very differently from one inside the cavernous sinus, where critical nerves and the carotid artery are packed together. This is why the field has moved from studying "skull base meningiomas" as one group to studying each subregion separately.

Third, for small asymptomatic tumors, upfront radiosurgery is increasingly being investigated as an alternative to watchful waiting. The IMPASSE analysis found tumor control of 99% with upfront SRS versus 69.4% with conservative management in matched patients with asymptomatic convexity meningiomas. The Sheehan analysis similarly found SRS afforded superior radiologic tumor control versus active surveillance without an increasing risk of neurological deficits.

Fourth, prior treatment can reduce the effectiveness of later radiosurgery. In the Ding et al. analysis, tumor control at 3 and 5 years was 85% and 70% overall, but rose to 93% at both time points when previously treated tumors were excluded.

Fifth, radiation dose to sensitive structures must be carefully limited. Keeping radiation to the optic nerve below 8–10 Gy may reduce the risk of adverse radiation effects. Cranial nerves within the cavernous sinus appear to tolerate relatively higher doses than the optic apparatus.

Limitations of the Evidence

The authors acknowledge several limitations in the available evidence.

Meningioma management lacks a clear-cut algorithm, and countries and surgical centers vary widely in their management approaches. This variability makes it difficult to compare results across studies.

For parafalcine and parasagittal meningiomas, the Pinzi et al. review found limited literature, with only five available studies and only one published since 2015. Optimal management for these tumors remains controversial because both surgical and non-surgical options frequently fail to provide definitive treatment.

For cavernous sinus meningiomas, no class 1 evidence exists supporting the superiority of SRS alone, fractionated radiotherapy alone, or any combination of either with subtotal resection. This means the highest level of clinical evidence is lacking for this location.

For convexity meningiomas, the role of SRS for upfront treatment of asymptomatic tumors has yet to be well defined, and these tumors lack extensive evidence on SRS overall.

The Ding et al. finding that prior treatment negatively affected radiosurgical efficacy requires additional studies to confirm. The authors note that more studies are warranted on the parasagittal and parafalcine subgroup to determine optimal treatment.

This review is a narrative review rather than a systematic review or meta-analysis. The authors searched MEDLINE for articles published between 2000 and 2024 and included articles based on their judgment. This approach may not capture every relevant study.

Recommendations and Future Directions

Meningioma management remains individualized. Decisions are based on patient comorbidities (other medical conditions), tumor location and characteristics, symptomatic burden, and patient age.

In addition to stereotactic radiosurgery's established role for surgically inaccessible, recurrent, and high-grade meningiomas, its use as upfront management for small asymptomatic meningiomas is increasingly investigated. For all subregions reported in this review, radiosurgical intervention resulted in high tumor control rates and acceptably low adverse radiation events.

Key takeaways for patients and clinicians include the following:

1. Ask about tumor location in specific terms, not just "skull base" or "brain tumor." Specific subregion data now exist for many locations.
2. Discuss whether active surveillance or upfront radiosurgery is appropriate for an asymptomatic tumor. The evidence increasingly favors upfront SRS for small asymptomatic convexity meningiomas.
3. Consider age and life expectancy in treatment decisions. A 20-year-old is statistically unlikely to have 50 growth-free years, so treatment decision-making must consider age.
4. If radiosurgery is planned near the optic nerve, ask how the radiation dose to the optic apparatus will be limited. Keeping radiation to the optic nerve lower than 8–10 Gy may reduce the risk of adverse radiation effects.
5. If prior surgery or radiation has already been performed, understand that this may reduce the effectiveness of later radiosurgery.

The authors call for more studies on specific meningioma subgroups to determine optimal treatment. As research on specific anatomic allocations continues to emerge, results can be interpreted on a more specific basis than prior broad encompassing regions.

Frequently Asked Questions

What is stereotactic radiosurgery and how is it different from regular radiotherapy?

Stereotactic radiosurgery (SRS) is a precise, non-invasive radiation technique that delivers a single high-dose treatment session. Hypofractionated stereotactic radiotherapy delivers 2 to 5 sessions, while conventional radiotherapy spreads small doses over 5 to 6 weeks. The choice among these approaches depends on tumor size, location, and proximity to sensitive structures such as the optic nerve.

Does tumor location really change my treatment options?

Yes. A convexity meningioma on the brain's outer surface behaves very differently from one inside the cavernous sinus, where critical nerves and the carotid artery are packed together. This is why research has moved from studying skull base meningiomas as one group to studying each subregion separately, and why management remains individualized based on location and other factors.

For a small asymptomatic meningioma, is upfront radiosurgery better than watchful waiting?

In a matched analysis of patients with asymptomatic convexity meningiomas, tumor control was 99% with upfront stereotactic radiosurgery versus 69.4% with conservative management. A separate analysis by Sheehan and colleagues found radiosurgery gave superior radiologic tumor control versus active surveillance without an increasing risk of neurological deficits. However, the role of upfront radiosurgery for asymptomatic tumors is still being investigated.

If I already had surgery or radiation, does that affect later radiosurgery?

In one retrospective analysis of 65 patients with parasagittal and parafalcine meningiomas, tumor control at 3 and 5 years was 85% and 70% overall, but rose to 93% at both time points when previously treated tumors were excluded. This suggests prior treatment may reduce radiosurgical effectiveness, but the authors note additional studies are needed to confirm this finding.

What are the risks of radiosurgery near the optic nerve?

The optic apparatus is radiation-sensitive. Keeping radiation to the optic nerve lower than 8–10 Gy may reduce the risk of adverse radiation effects. Cranial nerves within the cavernous sinus appear to tolerate relatively higher doses than the optic apparatus. A distance of greater than 3 mm between the tumor and the optic apparatus is an important consideration for safe radiosurgical treatment.

What does a tumor control rate of 99% or 69% actually mean for me?

Tumor control rates describe the percentage of patients whose tumor did not progress over a defined period in a specific study. For example, in a matched analysis of asymptomatic convexity meningiomas, control was 99% with upfront radiosurgery and 69.4% with conservative management. These numbers come from particular patient groups and may not apply to every situation.

What should I ask my doctor about my meningioma treatment?

Ask about your tumor location in specific terms, not just skull base or brain tumor, because subregion data now exist for many locations. Discuss whether active surveillance or upfront radiosurgery is appropriate for an asymptomatic tumor. Consider age and life expectancy in decisions. If radiosurgery is planned near the optic nerve, ask how the radiation dose to the optic apparatus will be limited.

Should I get a second opinion before having radiosurgery for a meningioma, or is the treatment plan usually clear?

Meningioma management lacks a clear-cut algorithm and is decided case by case, with approaches varying between countries and centers. Location matters enormously: a convexity tumor behaves differently from one in the cavernous sinus, and specific subregion evidence now exists. For cavernous sinus meningiomas, no class 1 evidence supports SRS alone, fractionated radiotherapy alone, or either combined with subtotal resection. Prior surgery or radiation may also reduce later radiosurgical effectiveness. An independent review can help clarify whether surveillance or upfront radiosurgery fits your tumor. Diagnostic Detectives Network provides independent expert second opinions.

Source Information

Original article title: Radiosurgery for Intracranial Meningiomas: A Review of Anatomical Challenges and an Update on the Evidence.

Authors: Goldman MJ, Teh BS, Lo SS, Butler EB, Baskin DS.

Author affiliations: Department of Neurological Surgery, Houston Methodist Neurological Institute, Houston Methodist Hospital, Houston, TX, USA; Department of Radiation Oncology, Houston Methodist Hospital, Houston, TX, USA; Departments of Radiation Oncology and Neurological Surgery, University of Washington, Seattle, WA, USA; Kenneth R. Peak Brain and Pituitary Tumor Treatment Center, Houston Methodist Hospital, Houston, TX, USA; Department of Neurological Surgery, Weill Cornell Medical College, New York, NY, USA; Department of Medicine, Texas A&M Medical School, Houston, TX, USA

Publication: Cancers 2025, Volume 17, Article 45. Published 27 December 2024. DOI: https://doi.org/10.3390/cancers17010045

Article type: Review. Academic Editor: Brigitta G. Baumert.

Note: This patient-friendly article is based on peer-reviewed research. It is intended for educational purposes and does not replace consultation with a qualified healthcare provider. Treatment decisions for meningiomas should be made on a case-by-case basis with a multidisciplinary care team.