Meningioma — Types, Symptoms, Diagnosis, Treatment, and Prognosis

Most readers benefit from reviewing this Quick Summary together with the sections on Symptoms, Diagnosis, Surgical Treatment, Radiation Therapy, and Treatment Decision-Making. Later sections provide more detailed explanations intended for patients seeking a deeper understanding before important treatment decisions are made.

What Is a Meningioma

A meningioma is a usually slow-growing tumor that arises from the meninges and is typically attached to the dura mater—the layer covering the brain. It receives its blood supply from the meningeal arteries and grows gradually, compressing the brain and surrounding structures without infiltrating the brain tissue.

Most meningiomas arise from specialized cells located within the arachnoid layer, often referred to as arachnoid cap cells. When genetic changes occur in these cells, they may begin to multiply abnormally and gradually form a tumor. Unlike tumors that originate inside the brain tissue, meningiomas grow outside the brain, usually attached to the dura mater. As the tumor enlarges, it usually compresses the surrounding brain tissue instead of growing directly into it. Because of this growth pattern, most meningiomas remain well-defined masses that can usually be surgically separated from the brain.

Epidemiological studies show that meningiomas represent approximately 35–41% of all primary intracranial tumors in adults, making them the most common primary brain tumor. Small incidental meningiomas may be present in approximately 0.5–1% of the general population, based on autopsy and imaging studies. Most of them never cause symptoms or require treatment.

Meningiomas are also rare in children, representing less than 2% of all pediatric brain tumors. When they occur in younger patients, they are more frequently associated with genetic syndromes such as neurofibromatosis type 2 (NF2).

To learn more about other types of brain tumors, visit our Brain Tumors page.

Image: A meningioma growing from the coverings of the brain (meninges, dura mater) and compressing surrounding parts of the brain, without infiltrating them.

Biological Classification of Meningiomas

The biological behavior of meningiomas is determined through histopathological analysis using the World Health Organization (WHO) classification.

Three main categories are recognized:
• WHO grade I — benign meningioma. This is the most common form, representing roughly 80–85% of meningiomas. These tumors typically grow slowly and often remain stable for long periods. When completely removed surgically, the chance of recurrence is relatively low.
• WHO grade II — atypical meningioma. Atypical meningiomas account for approximately 10–15% of of cases in surgical series of meningiomas. These tumors show increased cellular activity and a higher likelihood of recurrence after surgery. After complete tumor removal, some patients may be managed with MRI follow-up rather than immediate radiation therapy.
• WHO grade III — malignant (anaplastic) meningioma. These tumors are rare, representing roughly 1–3% of cases in surgical series of meningiomas. They grow more aggressively, recur more frequently, and usually require combined treatment with surgery and radiation therapy.

Although histological grade is important, clinical outcome also depends strongly on tumor location and the possibility of complete surgical removal.

Genetic and Biological Causes

Most meningiomas arise from sporadic genetic mutations that occur during life rather than inherited genetic disorders. At the molecular level, tumor development usually results from two main biological mechanisms:

• inactivation of tumor suppressor genes, which normally prevent uncontrolled cell growth
• activation of oncogenic signaling pathways, which stimulate cell proliferation

The most frequently involved gene is NF2, located on chromosome 22. Loss of function of this gene disrupts normal cell growth control and allows tumor formation. Other molecular alterations identified in meningiomas include mutations involving genes such as TRAF7, AKT1, SMO, and KLF4, while additional less common alterations may involve genes such as PIK3CA or TERT.

These molecular differences partly explain why tumors in different anatomical regions may behave differently.

The only clearly established environmental risk factor is exposure to ionizing radiation, particularly during childhood.

Meningiomas occur approximately two to three times more frequently in women than in men, suggesting that hormonal influences may play a role in tumor development and growth.

Although most meningiomas arise sporadically, a small proportion occur in the context of inherited genetic syndromes. The best known example is neurofibromatosis type 2 (NF2), a hereditary condition caused by mutations of the NF2 gene on chromosome 22. Patients with NF2 frequently develop multiple meningiomas, a condition referred to as meningiomatosis, in which several tumors arise in different intracranial and spinal locations. Multiple meningiomas may also appear sporadically without a hereditary syndrome, but they are particularly characteristic of NF2. In addition, meningiomas may occur in association with other rare genetic disorders such as schwannomatosis or Cowden syndrome, although these situations are much less common. Overall, hereditary syndromes account for only a small minority of meningioma cases.

Distribution of Meningiomas by Location

Because the meninges cover the entire brain, meningiomas can develop in many different parts of the skull. Their frequency varies significantly depending on location.

The approximate distribution of intracranial meningiomas is as follows:

• Convexity meningiomas — approximately 20–25%. These arise on the outer surface of the brain beneath the skull.
• Parasagittal and falcine meningiomas — about 20–25%. These tumors grow near the superior sagittal sinus, the major venous channel of the brain.
• Sphenoid wing meningiomas — roughly 15–20%. These develop near the skull base behind the eyes.
• Olfactory groove meningiomas — about 8–10%. They arise above the nasal cavity near the olfactory nerves responsible for smell.
• Tuberculum sellae meningiomas — about 5–10%. These occur in the middle of the skull base near the optic nerves and optic chiasm.
• Posterior fossa meningiomas — approximately 7–10%.

Within this group:

• Tentorial meningiomas — about 3–6%. These arise from the tentorium cerebelli, a membrane separating the upper brain from the cerebellum.
• Cerebellopontine angle (CPA) meningiomas — approximately 2–4%. These develop in the angle between the cerebellum and the brainstem, an area that also contains several important cranial nerves related to hearing and balance.

Rare locations include:

• Cavernous sinus meningiomas. These develop in the cavernous sinus, a venous space located behind the eyes at the base of the skull, where several important cranial nerves and the internal carotid artery pass.

• Petroclival meningiomas. These arise at the junction between the petrous part of the temporal bone and the clivus, deep in the central skull base near the brainstem.

• Foramen magnum meningiomas. These occur at the foramen magnum, the large opening at the base of the skull where the brainstem transitions into the spinal cord.

The location of the tumor is extremely important because it determines both the symptoms and the complexity of surgical treatment.

Image: Common locations of meningiomas

Multiple Meningiomas (Meningiomatosis)

Most patients develop a single meningioma, but approximately 5–10% of patients present with multiple tumors. This condition is referred to as multiple meningiomas or meningiomatosis.

Multiple meningiomas may occur sporadically, but they are particularly associated with neurofibromatosis type 2, in which patients may develop numerous tumors along the meninges.

Management of multiple meningiomas is individualized. In many cases only the symptomatic or growing tumors are treated, while the remaining lesions are monitored with periodic imaging.

How Meningiomas Grow and Affect the Brain

Meningiomas usually grow slowly over many years. Because they arise outside the brain tissue, they primarily damage the brain through compression rather than invasion.

As the tumor enlarges, it gradually presses on adjacent brain structures. This pressure interferes with normal neuronal activity and may lead to neurological deficits.

Another important mechanism is peritumoral brain edema, a form of swelling in the surrounding brain tissue caused by leakage of fluid from nearby blood vessels. This swelling increases intracranial pressure and often worsens symptoms.

Together with the tumor itself, this edema can produce a mass effect, meaning that the expanding lesion compresses and displaces normal brain structures. Because the skull is a rigid, closed cavity with very limited space for expansion, increasing pressure may force parts of the brain to shift from their normal position. In severe cases, brain tissue can be pushed through natural openings within the skull, a condition known as brain herniation. Herniation represents a dangerous stage of mass effect in which displaced brain structures may compress vital centers in the brainstem responsible for consciousness, breathing, and circulation.

Large tumors may also compress nearby arteries or veins, disrupting normal blood circulation in the brain. In certain locations, tumors may obstruct the normal circulation of cerebrospinal fluid, leading to hydrocephalus.

Even though most meningiomas do not invade brain tissue, prolonged compression may still cause permanent neurological damage if the tumor becomes very large.

Image: Brain Herniations — An extradural hematoma (the same is also for meningioma + brain swelling) creates a mass effect, pushing parts of the brain into narrow spaces where they normally do not belong. In these tight areas, the pressure can compromise vital parts of the brain, including the brainstem, which controls breathing and consciousness. Among the different types of herniation, transtentorial (uncal) herniation is the most clinically significant pattern because it is the one most often associated with sudden deterioration.

Studies following patients with untreated meningiomas have shown that a substantial proportion of tumors remain stable for long periods. Approximately 30–35% of meningiomas show no measurable growth during long-term imaging follow-up. Among tumors that do grow, the increase in size is usually slow and gradual, often measured in millimeters per year rather than rapid expansion.

Symptoms According to Tumor Location

The symptoms caused by meningiomas depend largely on their anatomical location. Headache is also a common symptom, which can either be a direct result of the meningioma or merely an incidental symptom that led to the MRI scan where the meningioma was discovered.

• Convexity meningiomas often produce seizures because they irritate the surface of the brain. Patients may also develop progressive weakness or numbness affecting the arm and/or leg on the opposite side of the body.
• Parasagittal meningiomas (tumors located along the midline of the skull) frequently affect the brain regions responsible for opposite leg movement. Patients may gradually develop weakness or stiffness of the legs and difficulty walking.
• Sphenoid wing meningiomas may affect structures responsible for vision and eye movement. Patients may notice progressive visual loss, double vision, or sometimes bulging of one eye.
• Olfactory groove meningiomas often cause gradual loss of smell and may later (when meningioma significantly enlarges) produce personality changes due to pressure on the frontal lobes with brain edema.
• Tuberculum sellae meningiomas commonly produce progressive visual disturbances because they compress the optic nerves and optic chiasm (the junction where the optic nerves from both eyes cross).
• Tentorial meningiomas may produce dizziness, imbalance, or coordination problems due to their compression on the cerebellum.
• Cerebellopontine angle (CPA) meningiomas frequently cause hearing loss, tinnitus, or balance disturbances because they lie near the cranial nerves responsible for hearing and equilibrium.

Less common tumors may produce more specific symptoms:

• Cavernous sinus meningiomas may cause double vision and facial numbness due to involvement of cranial nerves controlling eye movement.
• Foramen magnum meningiomas may cause neck pain, progressive weakness, and walking difficulty due to compression of the upper spinal cord.

Diagnosis of Meningioma

The most important diagnostic test is MRI of the brain with contrast.

During this examination, the patient lies inside the MRI scanner while magnetic fields generate highly detailed images of the brain. A contrast agent injected through a vein highlights tumor tissue.

MRI allows physicians to determine:

• tumor size
• precise location
• relationship to cranial nerves and blood vessels
• presence of surrounding brain edema

Meningiomas typically appear as well-defined tumors located outside the brain tissue, attached to the dura, often accompanied by a characteristic imaging feature known as the dural tail.

The final diagnosis is confirmed through histopathological analysis after surgery or biopsy.

Image: Brain MRI showing a bright meningioma (image after applying contrast) in the right parietal region, causing a significant mass effect (compression) on the brain due to its size and surrounding brain edema. In the inferior extension of the tumor, there is a bright dural thickening called the ‘dural tail sign’.

However, several other conditions may produce similar MRI findings and must be considered in the differential diagnosis.

These include:

• dural metastases, which may mimic meningiomas when metastatic cancer spreads to the meninges
• hemangiopericytoma (solitary fibrous tumor), a rare dural tumor that can appear very similar radiologically but behaves more aggressively
• schwannomas, particularly in locations such as the cerebellopontine angle, where they may resemble meningiomas on imaging
• lymphoma involving the dura
Because imaging findings may overlap, the final diagnosis is often confirmed by histopathological examination of the tumor after surgical removal or biopsy.

Although MRI is the main imaging method used to diagnose meningiomas, other techniques may occasionally provide additional information. CT scans are particularly useful for evaluating changes in the skull bone, such as hyperostosis (the growth of bone in contact with meningioma) or calcification within the tumor. In selected cases, vascular imaging such as CT angiography or MR angiography may also be performed to assess the relationship of the tumor to major arteries or venous sinuses when surgical planning requires more detailed evaluation. Conventional catheter angiography (DSA) is now rarely required and is mainly performed when preoperative tumor embolization is being considered.

Monitoring Without Treatment: When Meningiomas are Only Observed

Not all meningiomas require immediate treatment.

Approximately 30–50% of newly diagnosed meningiomas are initially managed with active surveillance rather than immediate surgery. Among incidentally discovered tumors, however, observation without surgery is chosen in the majority of patients, often around 60–80%, particularly when the tumor is small and not causing symptoms.

Monitoring is usually recommended when:

• the tumor causes no neurological symptoms, especially if it is small
• imaging shows little or no growth over time
• the tumor is not compressing critical brain structures
• there is little or no surrounding brain edema
• the patient is elderly or has serious medical conditions

On imaging studies, meningiomas that are partially or extensively calcified often represent tumors with long-standing slow growth, and this finding may further support a decision for observation rather than immediate surgery. Follow-up generally involves MRI examinations every 6–12 months initially.

Symptomatic Treatment

Medications are often used to control complications caused by the tumor.

• Brain swelling (edema) is commonly treated with corticosteroids, most often dexamethasone, which reduces edema (brain swelling) in the surrounding brain tissue.
• Seizures are treated with antiepileptic medications, such as levetiracetam or other modern antiseizure drugs.

These medications stabilize the patient but do not eliminate the tumor itself.

Meningioma and Epilepsy

Seizures may sometimes be the first symptom of a meningioma, particularly when the tumor is located on the convexity of the brain or near the cerebral cortex.

However, it is important to understand that not every seizure in a patient with a meningioma is necessarily caused by the tumor. Epilepsy is relatively common in the general population, and the coexistence of a small incidental meningioma does not automatically mean that the tumor is responsible for the seizures.

For this reason, physicians must carefully evaluate whether the tumor is actually the source of epileptic activity. This assessment usually includes:

• analysis of tumor location relative to the cerebral cortex
• evaluation of peritumoral brain edema
• correlation between EEG findings and the tumor region
• consideration of other possible causes of epilepsy

When seizures are clearly related to the tumor, surgical removal of the meningioma often significantly reduces seizure frequency, and in some patients seizures may stop completely.

Antiepileptic medications are usually used to control seizures before and for some period after surgery.

Surgical Treatment of Meningiomas

Surgery remains the primary treatment for symptomatic or progressively growing meningiomas. The procedure is performed through a craniotomy, which involves temporarily removing a portion of the skull to access the tumor.

In most cases the operation proceeds through several stages:

• Skin incision and craniotomy
The scalp is opened using a carefully planned incision. Depending on the location of the tumor, the incision may be linear, curved, or horseshoe-shaped. Whenever possible, it is placed within the hairline for cosmetic reasons. In most modern neurosurgical procedures the hair does not need to be completely shaved. A small bone flap is then created to expose the dura mater covering the brain or the tumor.

• Opening of the dura
The dura mater is carefully opened to expose the tumor and the surrounding brain structures.

• Internal tumor debulking
Whenever possible, the surgeon first attempts to control or detach the tumor from its dural attachment, because meningiomas receive much of their arterial blood supply from vessels entering through the dura. Early management of this attachment reduces bleeding during the procedure. The tumor is then reduced from the inside, most often using an ultrasonic aspirator (CUSA). This internal debulking decreases tumor volume and pressure, making subsequent dissection from the surrounding brain, nerves, and blood vessels safer.

• Microsurgical dissection
The tumor is gradually separated from the surrounding brain tissue, cranial nerves, and blood vessels under high magnification (neurosurgical microscope).

• Tumor removal
The tumor is usually removed in several pieces, allowing safe separation from surrounding structures.

• Treatment of the dural attachment
Because meningiomas arise from the dura, the involved portion of the dura is usually removed together with the tumor whenever possible to reduce the risk of recurrence. When complete removal is not safe, the dural base may be coagulated. If a segment of dura must be removed, the defect is typically reconstructed using a dural graft to restore a watertight barrier around the brain. This graft may be created from the patient’s own tissue (such as periosteum elevated from the skull during the operation or muscle fascia) or from biocompatible artificial dural substitutes specifically designed for neurosurgical reconstruction.

• Removal of infiltrated bone (when present)
Some meningiomas cause thickening or infiltration of the adjacent skull bone (hyperostosis). In such cases the abnormal bone may be drilled away, and occasionally a larger bone segment must be removed and at the same surgery or later, reconstructed with cranioplasty.

• Dural reconstruction and closure
After tumor removal the dura is reconstructed using a dural graft if necessary. The bone flap is replaced (or reconstructed if bone was removed), and the scalp is closed.

Image: The image illustrates a craniotomy. Both the skin incision and the skull opening are performed within the hair-bearing area of the scalp. The dura is opened to expose the tumor or the brain as part of the surgical approach to the tumor. After the procedure, the bone flap is secured and the scalp is reconstructed, ensuring no cosmetic defect remains after healing.

Image: Stages of surgical removal of a meningioma. After craniotomy and opening of the dura, image (a) shows the dark brown meningioma. Image (b) illustrates its separation from the brain, blood vessels, and other normal tissues, followed by its piecemeal reduction. Image (c) shows the removal of the remaining peripheral parts of the meningioma. Image (d) shows the condition after the meningioma has been completely removed.

Modern Surgical Technologies

Modern neurosurgery employs several technologies to increase precision and safety.

• Neuronavigation systems function as intraoperative GPS, allowing the surgeon to navigate within the skull with millimeter accuracy.
• Ultrasonic aspirators (CUSA) fragment and aspirate tumor tissue while preserving surrounding blood vessels and nerves.
• Intraoperative neurophysiological monitoring allows continuous monitoring of nerve function during surgery, helping avoid surgical damage to important nerves.

These technologies significantly reduce the risk of neurological injury.

In selected cases, surgeons may perform preoperative embolization before surgical removal of a meningioma. This procedure involves inserting a catheter into arteries supplying the tumor and injecting materials that reduce blood flow to the tumor in order to decrease intraoperative bleeding. Embolization is mainly considered for large, highly vascular meningiomas supplied by branches of the external carotid artery. Today it is used in a relatively small proportion of cases because the procedure itself may carry risks such as stroke, cranial nerve injury, or unintended embolization of normal vessels, and advances in modern microsurgical techniques have reduced the need for routine embolization.

Endoscopic Surgery for Skull Base Meningiomas

In addition to classical microsurgical craniotomy, some meningiomas located at the base of the skull can be removed using endoscopic techniques. These procedures access the tumor through natural anatomical corridors, most commonly through the nasal cavity, avoiding large external incisions and extensive brain retraction.

This approach is most often used for selected tumors located in the midline skull base, particularly:

• Tuberculum sellae meningiomas
• Planum sphenoidale meningiomas
• Olfactory groove meningiomas
• certain clival and anterior skull base meningiomas

In these operations the surgeon inserts a rigid endoscope through the nostrils. The endoscope contains a camera and light source that provide a high-magnification panoramic view of the surgical field.

The basic steps of endoscopic meningioma surgery usually include:

• Endonasal access through the nasal cavity
• removal of a portion of the skull base bone to expose the dura
• opening of the dura covering the tumor
• internal debulking of the tumor
• careful separation of the tumor from the optic nerves, blood vessels, and surrounding structures
• removal of the tumor in fragments
• reconstruction of the skull base defect, often using vascularized tissue flaps to prevent cerebrospinal fluid leakage

Because the surgical corridor comes from below rather than from above the brain, this approach may avoid significant brain retraction.

However, only a minority of meningiomas are suitable for endoscopic removal. Current surgical series suggest that approximately 10–15% of skull base meningiomas may be appropriate candidates for endoscopic approaches, depending on tumor size, location, and relationship to surrounding arteries and nerves.

Advantages of Endoscopic Surgery

Endoscopic skull base surgery offers several potential advantages:

• no large scalp incision and no craniotomy
• minimal or no brain retraction
• direct midline access to tumors beneath the brain
• improved visualization of deep skull base structures

These advantages can result in shorter recovery times and less manipulation of normal brain tissue in carefully selected patients.

Limitations and Risks

Despite these benefits, endoscopic surgery is not suitable for many meningiomas.

Important limitations include:

• difficulty removing large tumors extending laterally
• limited control of tumors that encase major arteries
• challenges in removing extensive dural attachment or infiltrated bone
• increased risk of cerebrospinal fluid leakage if skull base reconstruction is not adequate

For these reasons, microsurgical craniotomy remains the most common treatment for the majority of meningiomas, particularly those located on the convexity or along the brain surface.

The choice between microsurgical and endoscopic approaches depends on multiple factors, including tumor location, size, vascular relationships, and the experience of the surgical team.

Image: Many skull base tumors, such as meningiomas, pituitary adenomas, and others, can be removed without a craniotomy using an endoscopic endonasal approach.

Extent of Tumor Removal — Simpson Classification

The completeness of tumor removal is classified using the Simpson grading system.

• Simpson Grade I — complete removal of the tumor and its dural attachment
– recurrence risk approximately 5–10% over long-term follow-up
– probability of needing another intervention ~3–5%

• Simpson Grade II — tumor removed, dural attachment coagulated
– recurrence risk approximately 10–20%
– probability of further treatment ~5–10%

• Simpson Grade III — tumor removed but dura left intact
– recurrence risk approximately 20–30%
– probability of additional treatment ~10–20%

• Simpson Grade IV — subtotal removal
– recurrence risk approximately 40–60%
– additional treatment (surgery or radiotherapy) often required in 30–50%

• Simpson Grade V — biopsy or decompression only
– tumor progression expected in most patients (>80–90%)
– further definitive treatment usually necessary

The Simpson grade strongly influences the likelihood of tumor recurrence.

Radiation Therapy for Meningiomas

Radiation therapy is used when complete surgical removal is not possible, when tumors recur, or when a small residual tumor remains after surgery. It may also be considered for small meningiomas that demonstrate clear growth during imaging follow-up, particularly when surgery carries increased risk.

Typical radiation doses for meningiomas are:

• 50–54 Gy in fractionated radiotherapy
• 12–16 Gy delivered in a single session in stereotactic radiosurgery (e.g., Gamma Knife)

Radiation therapy can effectively stop tumor growth in many patients. Modern radiation techniques provide long-term tumor control in approximately 85–95% of benign meningiomas, especially when small tumors are treated with stereotactic radiosurgery.

In modern clinical practice, approximately 10–15% of newly diagnosed meningiomas are treated primarily with radiation therapy rather than surgery. This approach is usually chosen for small tumors located in surgically difficult areas, or in situations where the patient prefers a non-surgical treatment option after discussion of the risks and benefits.

Radiosurgery is generally most suitable for tumors smaller than about 2.5–3 cm that are not causing significant compression of the brain.

However, radiation treatment is not appropriate for all meningiomas. Even relatively small tumors may be unsuitable for radiosurgery if they lie very close to structures that tolerate only limited radiation exposure.

Tumors in the following locations are often poor candidates for radiosurgery:

• tuberculum sellae and planum sphenoidale meningiomas, which lie close to the optic nerves and optic chiasm
• optic nerve sheath meningiomas
• tumors directly contacting the brainstem, such as some clival or petroclival meningiomas
• certain cavernous sinus meningiomas extending toward the optic pathways

In tumors located close to critical structures such as the optic nerves, optic chiasm, or the pituitary stalk, single-session radiosurgery may carry a higher risk of radiation injury to these structures. In such situations, fractionated radiation is often used to reduce this risk, because the total radiation dose is divided into several smaller treatments that allow surrounding tissues to recover between sessions.

Fractionated radiation may be delivered either as stereotactic treatment in 3–5 sessions (typically about 5–7 Gy per fraction, total 21–30 Gy) or as conventionally fractionated radiotherapy over several weeks (usually about 1.8–2 Gy per fraction to a total dose of approximately 50–54 Gy).

In selected patients with small tumors located near the optic pathways, radiation therapy may sometimes be used instead of surgery, particularly when the risk of surgical complications is considered high. However, in other cases surgical removal may still be the preferred option, especially when the tumor produces significant compression of the optic nerves or when decompression is required.

The final treatment decision is usually made by a multidisciplinary team, typically including a neurosurgeon, radiation oncologist, and neuroradiologist, after careful evaluation of tumor size, location, patient age, symptoms, and overall medical condition.

Planned Subtotal Resection Followed by Radiation

During surgery, the primary goal is usually complete tumor removal, including its dural attachment. However, in some cases a portion of the tumor may be firmly adherent to critical blood vessels or cranial nerves. Attempting to remove this portion could cause severe neurological injury.

In these situations the surgeon may intentionally leave a small residual tumor to protect important structures. This strategy, known as planned subtotal resection, is followed by stereotactic radiosurgery to control the remaining tumor. Modern series suggest that this combined strategy is used in approximately 10–15% of meningioma operations, particularly for tumors located near the cavernous sinus, skull base arteries, or cranial nerves.

This approach allows surgeons to balance maximal tumor control with preservation of neurological function.

Recurrence of Meningiomas

Recurrence of Meningiomas
The likelihood of recurrence depends on tumor grade and completeness of removal.

• After complete removal of benign meningiomas, recurrence occurs in approximately 5–10% of cases over 10–15 years.
• After subtotal removal, recurrence rates may reach 20–40%.
• Atypical meningiomas recur in approximately 30–40% of cases.
• Malignant meningiomas may recur in 50–80% of patients.

Because recurrence may occur many years after treatment, long-term MRI follow-up is essential.

When a meningioma recurs, treatment decisions depend on several factors:

• tumor growth rate
• tumor size
• location
• previous treatments
• patient symptoms
• histological grade

When MRI findings are uncertain, specialized PET imaging using radiotracers that bind to somatostatin receptors in the tumor may sometimes help identify recurrent meningioma, because many meningiomas show strong uptake on these scans.

Not all recurrences require immediate treatment. Some can be safely monitored, while others require additional therapy.

Observation of Small Recurrences

Small recurrent meningiomas that show minimal or no growth may initially be managed with MRI surveillance.

Observation is most commonly chosen when:

• the tumor is small
• the patient has no neurological symptoms
• imaging shows slow or stable growth
• the recurrence is located in a high-risk surgical area

Follow-up usually involves MRI every 6–12 months to monitor tumor growth.

Repeat Surgery

Surgical reoperation is considered when:

• the recurrent tumor causes neurological symptoms
• imaging shows significant tumor growth
• the tumor is accessible for safe removal
• mass effect on the brain becomes clinically important

Repeat surgery aims to remove the recurrent tumor and its dural attachment whenever possible.

However, reoperation may be more technically demanding because:

• scar tissue from the previous surgery may be present
• important blood vessels or nerves may already be displaced
• bone reconstruction may have altered anatomy

For these reasons, surgical decisions must carefully balance potential benefit and risk.

Radiation Therapy for Recurrence

Radiation therapy is frequently used for recurrent meningiomas, particularly when complete surgical removal is not feasible.

Radiation may be recommended when:

• residual tumor remains after surgery
• recurrence occurs after previous surgery
• the tumor lies in a surgically difficult skull base location
• the tumor shows atypical or malignant histology

Two main radiation approaches are used:

• fractionated radiotherapy, typically delivering 50–54 Gy
• stereotactic radiosurgery, usually delivering 12–16 Gy in a single focused treatment

Radiation therapy can effectively control tumor growth in a large proportion of patients.

Treatment Strategy by Tumor Grade

Management also depends strongly on the WHO tumor grade.

• WHO grade I meningiomas. After complete surgical removal, most patients require only periodic MRI follow-up. If the tumor recurs during follow-up, management may include continued observation, repeat surgery, or stereotactic radiosurgery, depending on the rate of growth and clinical symptoms.
• WHO grade II (atypical) meningiomas. These tumors recur more frequently. Postoperative radiotherapy is often recommended, particularly after incomplete tumor removal, although some patients may be managed with close MRI follow-up after complete resection.
• WHO grade III (malignant) meningiomas. These aggressive tumors typically require postoperative radiotherapy regardless of the completeness of surgical removal, together with close imaging follow-up.

Long-Term Monitoring

Because meningiomas may recur many years after treatment, long-term follow-up is essential.

Typical surveillance includes:

• annual MRI for several years after treatment
• longer imaging intervals if the tumor remains stable

Early detection of recurrence allows treatment before significant neurological damage develops.

Experimental and Targeted Therapies

Several medications have been studied for recurrent or progressive meningiomas when surgery and radiotherapy are no longer sufficient. These include bevacizumab, which targets tumor blood vessel growth, as well as drugs acting on molecular pathways such as AKT or SMO inhibitors. Somatostatin-receptor–based treatments such as octreotide and combinations including everolimus have also been investigated. However, current evidence remains limited, and surgery and radiation therapy remain the main treatments for most meningiomas. In recent years, researchers have been studying targeted drugs for selected meningiomas with specific molecular alterations such as NF2, AKT1, or SMO mutations. Some medications, including inhibitors of growth signaling pathways or anti-angiogenic drugs, are being evaluated in clinical trials. However, at present there is no established drug therapy that reliably controls most meningiomas, and surgery and radiotherapy remain the main treatments.

When Expert Opinions May Differ

In many patients diagnosed with meningioma, different specialists may recommend different treatment strategies. This situation is common in neurosurgery and does not necessarily indicate that one opinion is correct while another is wrong.

Treatment decisions for meningiomas depend on multiple clinical factors, including:

• tumor size
• tumor location
• growth rate observed on MRI
• presence of surrounding brain edema or mass effect
• patient age and overall health
• presence or absence of neurological symptoms
• relationship of the tumor to important arteries, veins, or cranial nerves
• tumor grade if histological diagnosis is already known

Because these factors interact in complex ways, reasonable specialists may arrive at different conclusions regarding the safest management strategy.

Observation vs. Early Surgery

One of the most common differences in opinion occurs when a meningioma is discovered incidentally on MRI and the patient has no symptoms. Some specialists recommend active surveillance, particularly when the tumor is small and shows no signs of growth. Others may recommend early surgery, especially if the tumor is located in an area where future growth could threaten important neurological structures. Both approaches may be appropriate depending on the individual clinical situation.

Differences in Surgical Strategy

Even when surgery is recommended, surgeons may disagree about the optimal surgical approach. In some cases a surgeon may aim for complete removal including the dural attachment, while another may prefer a more conservative removal if the tumor lies close to important blood vessels or cranial nerves. Similarly, some skull base meningiomas may be treated using microsurgical craniotomy, while others may be considered candidates for endoscopic skull base surgery.

Surgery vs. Radiation Therapy

Another area where opinions may differ involves the use of radiation therapy. Some specialists recommend surgical removal first, followed by radiation only if residual tumor remains. Others may recommend primary stereotactic radiosurgery, particularly for small tumors located in surgically complex areas such as the cavernous sinus or near the optic apparatus. Decisions between surgery and radiation therapy may also depend on tumor size, location, growth rate, proximity to critical neurological structures such as the optic nerves or brainstem, and the expected surgical risk for the individual patient.

When Tumor Location Near Critical Structures Changes the Treatment Plan

In some cases, the most important factor influencing differences in recommendations is the tumor’s relationship to critical anatomical structures.

When a meningioma is located near major venous sinuses, the optic nerves, brainstem, or cranial nerves, treatment decisions become significantly more complex. The key issue is not only whether the tumor can be removed, but whether complete removal is safe without causing permanent neurological damage.

In these situations, some specialists may recommend more conservative surgery or partial removal followed by radiation, while others may favor more aggressive resection or primary radiosurgery, depending on how they assess the balance between tumor control and neurological risk.

Why a Second Opinion Can Be Helpful

Because treatment decisions depend on many individual variables, a second neurosurgical opinion can help clarify:

• the urgency of treatment
• whether observation is safe
• whether surgery or radiation is preferable
• what degree of tumor removal is realistically achievable
• the expected neurological risks of treatment

Careful review of MRI images and clinical history often allows specialists to explain why different recommendations may exist and which option is most appropriate for a specific patient.

How Meningioma Prognosis Depends on Location, Grade, and Extent of Removal

The prognosis of meningioma depends primarily on three major factors: the biological grade of the tumor, its anatomical location, and the extent to which it can be safely removed.

In general, WHO Grade I meningiomas have the most favorable prognosis. They usually grow slowly, and when they are completely removed together with their dural attachment, long-term tumor control is often excellent. By contrast, atypical and malignant meningiomas have a higher risk of recurrence, even after apparently complete surgery, and therefore usually require closer follow-up and often additional radiation therapy.

Tumor location is equally important. Meningiomas located on the convexity of the brain are often associated with a better surgical prognosis, because they can usually be approached more directly and separated more safely from critical neurovascular structures. In contrast, skull base meningiomas may lie in close contact with the optic nerves, the brainstem, major arteries, venous sinuses, or multiple cranial nerves, making surgery technically more demanding. In such cases, the surgeon must often choose between more radical removal and preservation of neurological function. When residual tumor remains near critical structures such as the optic nerves, optic chiasm, or the pituitary stalk, postoperative radiotherapy may sometimes be limited by the risk of radiation injury to the visual pathways. In these situations, careful MRI surveillance is often preferred, and treatment is considered only if clear tumor growth is documented.

For this reason, the extent of tumor removal strongly influences long-term outcome. The smaller the amount of residual tumor left behind, the lower the probability of recurrence. However, in modern neurosurgery, the best result does not always mean the most aggressive resection. In some patients, intentionally leaving a very small tumor remnant densely adherent to critical vessels or nerves may provide a better overall outcome than attempting complete removal at the cost of permanent neurological damage.

In practical terms, prognosis is best in patients with benign meningiomas located in surgically favorable regions and removed completely. It is generally less favorable in higher-grade tumors, skull base locations, and in cases where only subtotal removal is possible because of the risk to vital structures.

Can a Meningioma Become Life-Threatening?

Yes, a meningioma can become life-threatening, although this is not the usual course in most patients.

Most meningiomas are slow-growing tumors, and many remain stable for years without causing major neurological problems. However, if the tumor becomes large enough, it may produce severe pressure on the brain, significant surrounding edema, obstruction of cerebrospinal fluid pathways, or progressive compression of the brainstem, optic system, or major blood vessels. In such situations, the danger does not arise only from the biological nature of the tumor itself, but from its mass effect on vital brain structures.

A meningioma may therefore become life-threatening when it causes marked intracranial pressure elevation, brain herniation, hydrocephalus, severe brainstem compression, or repeated seizures with progressive neurological deterioration. This risk is higher in large tumors, tumors located in confined skull base regions, and in more aggressive histological forms such as atypical or malignant meningioma.

For this reason, even though meningiomas are often described as benign tumors, they should never be considered harmless solely on the basis of histological grade. Their real clinical significance depends on tumor size, location, rate of growth, and the effect they produce on surrounding brain structures.

Frequently Asked Questions About Meningioma