INTRODUCTION — Meningiomas account for approximately one-third of all primary central nervous system tumors (table 1). Although most meningiomas are benign (World Health Organization [WHO] grade 1), their location in the central nervous system can cause serious morbidity and mortality.
The management of patients with meningioma requires a balance between definitive treatment of the tumor and avoidance of neurologic damage from the treatment. Patient-specific factors (presence or absence of symptoms, age, comorbidity), the location of the meningioma in relation to critical brain structures and regions, and the histopathologic characteristics (WHO grade) of the meningioma are all important factors in determining the optimal treatment.
Depending upon these characteristics, initial management for patients with a suspected benign (WHO grade 1) meningioma may consist of observation with serial imaging, immediate surgery, surgery plus radiation therapy (RT), or RT alone. Multidisciplinary input is often needed to select the appropriate therapy.
The initial management of benign (WHO grade 1) meningiomas will be reviewed here. Related topics regarding the management of meningioma include:
TREATMENT APPROACH — The management of patients with meningioma requires a balance between definitive treatment of the tumor and avoidance of neurologic damage from the treatment. Patient-specific factors (presence or absence of symptoms, age, comorbidities) and the location of the meningioma in relation to critical brain structures and regions are all important factors in determining the optimal treatment.
Depending upon these characteristics, initial management may consist of observation, surgery, surgery plus radiation therapy (RT), or RT alone (algorithm 1). Multidisciplinary input from neurosurgery, radiation oncology, and neuro-oncology is advised, especially for large and/or deep-seated tumors.
Radiographic diagnosis of meningioma — The approach below assumes that the most likely diagnosis, based on the clinical context and neuroimaging features, is meningioma.
While meningioma is by far the most common cause of a discrete, enhancing, dural-based mass lesion, the differential diagnosis also includes other tumors (eg, metastatic cancer, plasmacytoma, lymphoid malignancy, solitary fibrous tumor/hemangiopericytoma), inflammatory lesions such as sarcoidosis, and infections such as tuberculosis (table 2). Atypical neuroimaging features may be a clue that a dural-based mass is something other than a benign WHO grade 1 meningioma (table 3).
Patients who are being considered for observation or empiric RT may benefit from more extensive systemic evaluation to help exclude alternative etiologies, particularly when imaging features are atypical. (See "Epidemiology, pathology, clinical features, and diagnosis of meningioma", section on 'Diagnostic evaluation'.)
Small, asymptomatic tumors — For most patients with small, asymptomatic meningiomas, we suggest observation with serial magnetic resonance imaging (MRI). Treatment is instituted only if the tumor enlarges significantly or becomes symptomatic [1-6].
The definition of small varies and should be considered on a case-by-case basis. We generally consider asymptomatic tumors up to approximately 3 cm in diameter to be small, although this is not a strict cutoff, and location must also be considered.
A "watch and wait" approach is particularly suitable for very small tumors and for older patients and those with significant comorbidity or limited life expectancy. For relatively healthy younger patients, there is a lower threshold for therapeutic intervention because of the expectation that tumor progression will inevitably require active treatment .
●Surveillance schedule – Patients who are selected for observation should be reassessed with MRI in three to six months from the baseline MRI. If the patient remains asymptomatic and there is no evidence of tumor growth, our approach is to repeat neuroimaging on an annual basis for three to five years, then every two to three years for as long as they remain a candidate for intervention. Others have proposed less intensive radiographic surveillance for incidental meningiomas depending on risk factors, with discontinuation of neuroimaging after 10 years for those tumors that have not progressed .
●Natural history – Many patients selected for observation will never require surgery or RT because they never develop symptoms or radiographic progression. The long-term rates of progression-free survival are not well defined prospectively, however. Based on retrospective studies with variable follow-up time, approximately 65 to 75 percent of patients selected for observation will remain free of intervention after four years [4,8]. Predictors of rapid growth (eg, ≥2 cm3 per year) include size ≥4 cm, absence of calcification, presence of peritumoral edema, and hyperintense or isointense T2-weighted signal on MRI [9,10]. Pending validation, a scoring system based on these factors may be useful for risk stratification .
A meta-analysis identified 20 retrospective studies including 2130 patients diagnosed radiographically with an incidental, asymptomatic meningioma, of which 51 percent were managed with active monitoring . Over a mean follow-up of approximately four years, the pooled risk of symptom development was 8 percent, and the pooled proportion who underwent intervention was 25 percent (95% CI 7.5-48). Mean time to intervention was 25 months. Risk factors for development of symptoms were tumor size ≥3 cm and the presence of peritumoral edema. Among 316 resected tumors, 94 percent were confirmed to be grade 1 meningioma.
●Criteria for intervention – Criteria for initiating treatment in a patient who is being monitored serially are not well defined. Meningiomas often enlarge slowly over many years with minimal or no symptoms, and defining the appropriate time to intervene can be difficult. Most experts consider the rate of year-over-year growth more heavily than the absolute size. As an example, a 2 cm tumor that enlarges by 8 mm in one year generally indicates the need for intervention or at least shorter interval monitoring, whereas a 2 cm tumor that has enlarged to 3 cm over 5 to 10 years may be appropriate for ongoing conservative management.
Age, tumor location, risks of intervention, and fitness for surgery also influence timing and selection of treatment, as discussed below. (See 'Large or symptomatic tumors' below and 'Nonresectable tumors' below and 'Special populations' below.)
Large or symptomatic tumors — Symptomatic meningiomas and asymptomatic tumors that are large, expanding, infiltrating, or associated with surrounding edema should be surgically resected if feasible . Surgery establishes a tissue diagnosis, relieves mass effect, and helps to achieve local control. Complete surgical resection is the goal when a meningioma is in an accessible location, since complete resection of the tumor and its dural attachment can be curative. (See 'Surgical management' below.)
In selected patients with symptomatic tumors in sites where complete excision is difficult or in patients at high risk for complications with surgery, RT is increasingly thought of as an effective alternative option to surgery. Although no randomized trials have been completed comparing stereotactic radiosurgery (SRS) or other conformal RT techniques with surgery, the outcomes appear to be similar to surgery for small- to medium-sized meningiomas [11-15]. Size is an important limiting factor when considering the safety of RT, however. (See 'Nonresectable tumors' below.)
For patients who undergo surgical resection, tissue pathology should be reviewed to confirm the diagnosis of meningioma and the grade of the tumor. The appropriate postoperative management varies depending on tumor grade, extent of resection, and other factors. As examples:
●Complete resection, grade 1 meningioma – Patients with completely resected grade 1 meningiomas do not require further therapy but should undergo serial imaging to monitor for recurrence. The risk of recurrence varies based on location and extent of resection. For completely resected convexity meningiomas, for example, the recurrence rate is approximately 3 to 10 percent. (See 'Surveillance after initial treatment' below and 'Outcomes and prognosis' below.)
●Incomplete resection, grade 1 meningioma – Incompletely resected grade 1 tumors have a higher risk of progression than completely resected tumors , and decisions about postoperative RT are individualized based on location of the residual tumor, patient age, and the potential morbidity associated with progression.
Adjuvant RT for incompletely resected benign WHO grade 1 meningiomas improves local control, but many patients will not recur or will progress slowly after surgery and can avoid the potential morbidity of immediate RT. In single-center observational studies with prolonged follow-up, the local progression rate after subtotal resection of benign meningiomas is approximately 40 to 50 percent at five years and approximately 60 percent at 10 years in most studies .
Adjuvant RT is therefore used more selectively after partial resection of grade 1 meningiomas compared with higher-grade tumors. Retrospective data do support the role of RT in patients who have undergone subtotal resection of meningiomas in poorly accessible areas such as the skull base or posterior sagittal sinus [18-21]. (See 'Radiation therapy' below.)
●Grade 2 or 3 meningioma – Higher-grade meningiomas (grade 2 and 3) have a higher risk of recurrence, independent of extent of resection, and RT is often indicated to improve local control. Such patients should be referred to radiation oncology for discussion of adjuvant therapy. (See "Management of atypical and malignant (WHO grade 2 and 3) meningioma", section on 'Surgical resection'.)
Nonresectable tumors — RT has an important role in the management of meningiomas that are unresectable because of their proximity to critical neurologic structures.
RT alone can be effective in treating meningiomas that are not amenable to even a subtotal resection, providing excellent tumor control and avoiding the risks of surgery [6,11-15,22]. The approach is most commonly used for skull base meningiomas and optic nerve sheath meningiomas. (See 'Skull base meningiomas' below and 'Optic nerve sheath meningiomas' below.)
Tumor size is an important factor that cannot be underestimated when considering RT alone. Larger tumors are associated with an increased risk of reactive edema following RT, which can cause seizures and neurologic deficits that vary based upon the location of the tumor. Subtotal resection in advance of RT is often considered in such cases in an attempt to decrease the risk for RT-related complications.
Medically nonsurgical patients with large tumors at risk for herniation should not be irradiated. Symptomatic glucocorticoids and investigational medical therapies may be considered in such cases. (See "Systemic treatment of recurrent meningioma".)
Older adults — Many older adults with asymptomatic or minimally symptomatic suspected meningiomas are observed with serial imaging, reserving definitive treatment for evidence of rapid enlargement or clinical progression. (See 'Small, asymptomatic tumors' above.)
For tumors that require treatment, surgical resection is an option for otherwise fit older adults with tumors in superficial locations. Older adults are at increased risk for surgical morbidity compared with younger adults but stand to gain similar improvements in neurologic function with resection. In a single-center retrospective study that included 768 consecutive patients undergoing surgical resection of a meningioma, older patients (≥65 years; n = 284) had an increased rate of postoperative complications compared with younger adults (47 versus 37 percent), most commonly bleeding (13 percent), cranial nerve deficit (10 percent), and cerebrospinal fluid leak (8 percent) . The risk of bleeding was highest in adults >80 years of age (29 percent). Functional status improved after surgery in all age groups except patients >80 years.
RT alone is an alternative to surgery in older adults, particularly for symptomatic tumors in deep or functionally high-risk locations. In a retrospective study of 121 older adults with radiologic evidence of a benign meningioma (median age 73 years, range 70 to 85), RT was associated with >90 percent local control and cause-specific survival at five years with minimal toxicity and no new neurologic deficits . Sphenoid wing, petroclival, and frontobasal tumors made up approximately two-thirds of the tumors in this series. Most were treated with fractionated or hypofractionated stereotactic radiotherapy (SRT).
Importantly, size of unresected tumors should be carefully considered. Tumors with significant mass effect may cause significant symptoms and reactive edema following SRT that can be fatal in some cases.
Patients with a history of cancer — The approach to initial management in patients with a newly discovered dural-based mass who have a history of cancer depends largely on the details of the cancer history. Clinicians should be aware that dural-based metastases and meningiomas can have a similar radiographic appearance. Important considerations in determining risk of metastatic cancer include the clinical cancer stage, the time elapsed since diagnosis and treatment, the underlying cancer type, its propensity to metastasize to the central nervous system, the presence or absence of extracranial metastatic disease, and the overall prognosis.
Although metastatic disease should be considered as a possible mimic of meningioma during the initial evaluation in all patients with a cancer history, it is often the case that meningioma remains the most likely diagnosis, particularly when neuroimaging features are typical for meningioma and there is no evidence of metastatic disease outside the central nervous system. Our approach to initial management in these patients is the same as for patients without a history of cancer (algorithm 1). (See 'Treatment approach' above.)
When cancer metastasizes to the dura, it is usually a relatively late-stage event in patients with known metastatic disease involving bone and other organs, and neuroimaging features will not be entirely typical for meningioma. Breast, prostate, and lung cancers are the most common cancer types associated with dural metastases . In cases where metastatic disease is considered at least as likely as or more likely than meningioma, empiric RT is often preferred over surgery, unless the tumor is very large or tissue diagnosis is critical for optimal treatment planning (algorithm 1). (See "Epidemiology, pathology, clinical features, and diagnosis of meningioma", section on 'Diagnostic evaluation'.)
Patients with a history of cranial irradiation have an increased risk for secondary tumors, including meningiomas. Radiation-induced meningiomas have a higher risk of atypical or high-grade features, and surgery is generally preferred as a first-line therapy, when possible. (See 'Radiation-induced meningiomas' below.)
Patients with hormone exposure — Patients with a suspected meningioma should be questioned about use of exogenous estrogens and progestins, since high doses may be implicated in meningioma growth. Use of cyproterone, an anti-androgen and progestin that is not approved in the United States but is available in Europe and elsewhere, has been associated with the occurrence of meningioma, primarily at doses of 25 mg/day and above. (See "Epidemiology, pathology, clinical features, and diagnosis of meningioma", section on 'High-dose cyproterone'.)
For patients taking high-dose cyproterone, withdrawing hormone therapy is often sufficient to stabilize tumor growth rate and has been associated with tumor shrinkage in some cases [26-30]. Among 57 asymptomatic meningiomas detected through an MRI screening protocol in France for patients exposed to cyproterone, chlormadinone, or nomegestrol, 70 percent decreased in size after cessation of progestin therapy, 30 percent remained stable, and none progressed over a median follow-up of 18 months .
For patients with exposure to lower doses of estrogens and/or progestins (eg, menopausal hormone therapy, contraception), decisions about ongoing therapy should be individualized. We typically suggest discontinuation of such therapies based on the theoretical risk that such therapy may promote meningioma growth over time. However, withdrawal is not expected to have a meaningful impact on short-term tumor size and does not generally suffice in patients with indications for immediate treatment.
Surveillance after initial treatment — Brain MRI with contrast is the best modality to monitor for evidence of recurrence or for progression of residual disease. Meningioma size is best evaluated on T1 postcontrast sequences; T2-based measurements can be followed if contrast is contraindicated but are less sensitive and not well validated prospectively . Computed tomography (CT) with contrast is used for patients with a contraindication to MRI. There are no studies that define the optimal schedule for such imaging.
●For asymptomatic or minimally symptomatic patients managed with active surveillance, our approach is to repeat the imaging procedure in three to six months, annually for three to five years, and every two to three years thereafter if there is no evidence of progression. (See 'Small, asymptomatic tumors' above.)
●For patients whose initial management consisted of surgery and/or RT, factors influencing the frequency of repeat imaging include the completeness of resection, the location of the tumor, and its pathology (WHO grade 1 versus grade 2 or 3). In general, imaging should be repeated in the postoperative period, annually for three to five years, and then every two to three years so that any evidence of recurrent or progressive disease can be detected while the disease burden is relatively limited.
Recurrent disease — Most recurrences of meningioma are local or adjacent to a radiation treatment field. Metastases of cranial meningiomas to the spinal cord due to spreading through the cerebrospinal fluid are rare and are more frequently associated with atypical or malignant meningiomas [33,34]. There are only isolated case reports of metastases outside the central nervous system [35,36].
For patients who recur locally after their initial treatment, additional surgery and/or RT (SRS, SRT, or planned intraoperative brachytherapy following a gross total resection) can sometimes provide effective therapy and occasionally permit long-term recurrence-free survival. The principles underlying the use of surgery or RT are similar to those for patients presenting de novo, but appropriate management requires a consideration of the effects of prior surgery and/or RT. (See 'Large or symptomatic tumors' above and 'Nonresectable tumors' above.)
SURGICAL MANAGEMENT — Multiple advances in neurosurgery, including microsurgery, improved preoperative imaging, and intraoperative image-guided approaches, have extended the neurosurgeon's ability to resect lesions that were previously considered only partially resectable or unresectable, while minimizing damage to normal brain. Advances in endoscopic endonasal surgery have made anterior cranial base and clival tumors in particular more resectable as well .
Extent of resection — Complete resection, when feasible, is associated with significantly improved local control and progression-free survival compared with partial resection, independent of meningioma grade and other prognostic factors [38-41]. Complete surgical resection should include the dural attachment of the meningioma.
The Simpson grading system has been used to describe the extent of surgical resection :
●Grade I, complete resection, including the dural attachment and any abnormal bone
●Grade II, complete resection, with coagulation of the dural attachment
●Grade III, complete resection, without resection or coagulation of the dural attachment
●Grade IV, subtotal resection
●Grade V, tumor biopsy only
Studies demonstrating an overall survival advantage from complete resection of benign meningiomas generally antedate the adjuvant use of radiation therapy (RT) with contemporary conformal techniques for patients with residual disease [42-44]. The use of modern adjuvant RT techniques to treat residual disease appears to yield results comparable to more aggressive surgery and can minimize treatment-related neurologic deficits for tumors in deep locations.
In contemporary practice, the goal of surgery is to achieve as extensive a resection as possible while minimizing neurologic deficits. The extent of resection varies depending upon the location of the tumor, whether there is imaging evidence of invasion, and the presurgical status of the patient (eg, neurologic deficits, comorbidity).
●Complete resection is usually attempted for tumors of the convexity, olfactory groove, anterior third of the sagittal sinus, and some tentorial and posterior fossa tumors.
●Partial resection rather than complete resection may be more appropriate for less accessible tumors, such as those involving the posterior sagittal sinus region or clivus.
●Biopsy alone or empiric treatment without a tissue diagnosis may be needed for inaccessible tumors such as those involving the medial sphenoid wing or cavernous sinus. Definitive RT is the treatment of choice in these cases. (See 'Nonresectable tumors' above.)
Because meningiomas are vascular tumors, preoperative embolization may be useful to increase resectability in carefully selected patients with skull base or giant convexity meningiomas in which the presumed feeding arteries are not readily accessible [45-48], but there are no well-conducted prospective studies and there is wide variability in utilization. In retrospective series of up to 200 patients, the reported complication rate of preoperative embolization ranges from 3 to 13 percent, with most complications being minor and transient . Rare major or long-term complications include intratumoral hemorrhage, stroke, and cranial neuropathies. When indicated, this procedure can be performed the day prior to surgery.
Surgical morbidity — Postoperative neurologic deficits can be a direct complication of surgery. The reported incidence of such neurologic deficits ranges from 2 to 30 percent depending upon the location of the tumor and the extent of the resection. Cortical brain injury may occur if the arachnoid and pia are adherent to the tumor and there is disruption of the pial vasculature with subsequent cortical microinfarction. Cranial nerve deficits are a risk in surgery for skull base meningiomas, and intraoperative cranial nerve monitoring should be used for tumors located near the cranial nerves.
The reported overall surgical mortality has varied widely, reflecting differences in patient selection criteria as well as changes in surgical care. Factors associated with an increased mortality included poor preoperative clinical condition, brain compression from tumor, advanced age, incomplete tumor removal, and intracranial hematoma requiring evacuation .
Older series indicated that the mortality was higher in older adults [50,51]. More recent series, using contemporary neurosurgical techniques, have shown that surgery is feasible in carefully selected older adults [51,52]. As an example, there was no perioperative mortality in a carefully selected series of 74 patients aged ≥80 years, and the incidence of postoperative complications was only 9 percent .
Perioperative medical management — In addition to neurologic deficits that are a direct consequence of surgery, common medical complications include seizures, deep venous thrombosis (DVT), pulmonary embolism, pneumonia, myocardial infarction, and arrhythmias.
Seizures — Seizures are a frequent presenting symptom of meningiomas. Seizures can also occur in the postoperative period.
●Prophylactic anticonvulsants are generally not indicated prior to treatment in patients without a history of seizures. (See "Seizures in patients with primary and metastatic brain tumors", section on 'Indications for antiseizure medication therapy'.)
●Patients undergoing surgery for supratentorial tumors are typically placed on prophylactic anticonvulsants perioperatively. In patients who have not had a seizure, anticonvulsants should be gradually tapered and then discontinued postoperatively . (See "Seizures in patients with primary and metastatic brain tumors", section on 'Postoperative prophylaxis'.)
Cerebral edema — Glucocorticoids are used preoperatively to reduce brain edema in symptomatic patients. During the surgical procedure, options to reduce intracranial pressure if the tumor is large or if significant brain retraction is anticipated include furosemide, dexamethasone, osmotic therapy (eg, mannitol), head elevation, and hyperventilation. (See "Anesthesia for craniotomy in adults", section on 'Brain relaxation'.)
Glucocorticoids are tapered postoperatively. The increments and duration of the taper should be individualized according to the extent of edema, the completeness of resection, and the preoperative glucocorticoid dose and duration. (See "Management of vasogenic edema in patients with primary and metastatic brain tumors".)
Deep venous thrombosis — DVT is especially problematic both because the thromboembolic risk in general is increased in patients undergoing brain surgery and because meningiomas can produce a hypercoagulable state. In a study in which 275 patients undergoing meningioma resection were screened for venous thromboembolism (VTE) with pulmonary perfusion scintigraphy on postoperative day 2 and lower limb ultrasound on day 7, rates of symptomatic and asymptomatic VTE were 4 and 26 percent, respectively . On multivariate analysis, predictors of increased risk included older age (≥65 years) and low postoperative performance status.
Prophylactic anticoagulation may lower the risk of thromboembolic events and should be considered in the postoperative period for all patients with brain tumors. Subcutaneous low molecular weight heparin is recommended postoperatively for patients requiring craniotomy for removal of a meningioma. In addition, pneumatic compression boots should be used until the patient is ambulatory. (See "Treatment and prevention of venous thromboembolism in patients with brain tumors" and "Prevention of venous thromboembolic disease in adult nonorthopedic surgical patients".)
RADIATION THERAPY — Image-guided conformal radiation therapy (RT) techniques used to treat meningioma most commonly include stereotactic radiosurgery (SRS), fractionated stereotactic radiotherapy (SRT), intensity-modulated RT (IMRT), volumetric-modulated arc RT (VMAT), and proton radiotherapy. There are also other advanced RT delivery systems that deliver conformal RT that is essentially equivalent to IMRT or VMAT. Use of these techniques reduces collateral radiation dose to the normal brain compared with older standard RT techniques such as three-dimensional (3D) conformal radiotherapy. This is particularly important for the delivery of radiation to meningiomas that are in close proximity to critical structures such as the pituitary gland and the optic nerves.
●Stereotactic radiosurgery – SRS utilizes multiple convergent beams to deliver a high single dose of radiation to a radiographically discrete treatment volume, thereby minimizing radiation dose to adjacent structures. An external localization system is used to increase accuracy of radiation targeting and delivery.
SRS requires the radiation target to be adequately spaced from normal tissues that may be injured by the high dose delivered in a single treatment. Where safety to normal tissues cannot be met, the radiation dose can be divided into much smaller doses and delivered as SRT.
●Stereotactic radiotherapy – SRT uses focused radiation in the same way as SRS but fractionates the radiation over a series of sessions. Fractionation improves normal tissue tolerance of radiation, and SRT may be a reasonable alternative for patients with surgically inaccessible lesions, either as postoperative therapy following subtotal resection, definitive treatment without any surgery, or treatment of recurrent disease [55,56].
SRT is generally used instead of SRS when there is concern for normal tissue injury, either because of larger tumor size or proximity to radiation-sensitive structures, most commonly the optic nerves or chiasm . SRT may be particularly useful for patients with optic nerve sheath meningiomas, in whom surgery can cause postoperative blindness , and for small meningiomas of the skull base . (See 'Skull base meningiomas' below and 'Optic nerve sheath meningiomas' below.)
●Intensity-modulated RT – IMRT is a technique that relies upon software and modification of standard linear accelerator output to vary the radiation intensity across each treatment field. IMRT may be particularly useful for patients with meningiomas when the target is juxtaposed to radiation-sensitive structures or has a particularly complex shape, such as those involving the skull base . IMRT achieves radiation treatments with far less collateral high-dose radiation to normal tissues compared with 3D conformal RT. However, it requires far more time for planning, is inherently more complex, and is more costly. (See "Radiation therapy techniques in cancer treatment", section on 'Intensity-modulated radiation therapy'.)
●Volumetric-modulated arc RT – VMAT is a form of IMRT that combines the arc-based radiation delivery conformality of SRT with the radiation dose intensity modulation of IMRT to create even more conformal radiation plans for complex-shaped tumors while avoiding high-dose radiation to neighboring normal structures. VMAT is most commonly used with skull base meningiomas as the best means of containing high-dose radiation to the target with minimization of collateral high doses to normal tissues.
●Particle therapy – Heavy particles, such as protons and carbon ion beam, are not widely available, although the number of treatment centers is increasing fairly rapidly. There is comparatively more availability and experience with protons than other ion therapies. The rationale of proton therapy in treating patients with meningioma is to avoid acute and long-term potential adverse effects in a patient population with projected long-term survival [61-63].
Protons achieve greater avoidance of normal tissue radiation dose than photon-based techniques. In turn, protons may help to prevent side effects such as radiation-associated secondary tumors and hypopituitarism, if the irradiated target is in proximity to the pituitary. As with photon radiation, technological advancements have made intensity modulation feasible with protons, a technique called intensity-modulated proton therapy (IMPT). Additional experience is required to determine whether or not these approaches offer any benefit compared with other contemporary conformal techniques.
Dose and target
●Primary RT – When RT is used as primary therapy, the dose varies based on the modality and location. For skull base meningiomas treated with SRS, a dose of 12 to 15 Gy is typically used. If single doses above 18 Gy are used for SRS, there is a significant risk of toxicity to cranial nerves within the cavernous sinus. For fractionated RT, including SRT, IMRT, VMAT, and other delivery systems, an acceptable dose range for benign meningiomas is 45 to 54 Gy, although 50 to 54 Gy is more commonly used.
●Adjuvant RT – Accurate delineation of the residual or recurrent tumor following surgery using contemporary imaging studies is critical for optimal results with postoperative RT . When RT is used postoperatively to treat residual disease, a dose of 50 to 54 Gy in daily fractions of 1.8 to 2 Gy is generally used for benign meningiomas, the same as would be used for primary RT . Higher doses of radiation are generally recommended for WHO grade 2 and 3 meningiomas but have not been found to improve local control in WHO grade 1 meningiomas . (See "Management of atypical and malignant (WHO grade 2 and 3) meningioma", section on 'Adjuvant radiation therapy'.)
In settings where there is no significant mass effect on the brain prior to treatment, potential adverse effects of external beam RT on the surrounding normal brain are rarely seen using daily fractions of 1.8 to 2 Gy to a total dose of 54 Gy and are uncommon at doses up to 59.4 Gy. (See "Acute complications of cranial irradiation".)
The only prospective randomized trial in benign meningiomas used a mix of proton/photon therapy and compared radiation doses for benign meningiomas . Patients were randomized between 55.8 Gy(relative biologic effectiveness [RBE]) and 63 Gy(RBE), both doses above current clinical practice and thus limited in utility. Not surprisingly, there was no difference between outcomes of the two arms. With a median follow-up of 17 years, local control at 10 years was 98 percent and at 15 years was 90 percent. Perhaps most important was the toxicity finding of 20 percent incidence of a cerebral vascular accident at a median time of 5.6 years from radiation treatment.
OUTCOMES AND PROGNOSIS — The results of treatment vary depending upon the location of the meningioma as well as the therapeutic approach.
Optimal therapy needs to be individualized based upon the anatomic location of the tumor and patient-specific considerations. Results are discussed for three meningioma locations, convexity meningiomas (which usually can be managed with surgery alone), skull base lesions (which often require a multidisciplinary approach), and optic nerve sheath meningiomas (for which radiation therapy [RT] is often used alone), as well as the limited data available for treatment of radiation-induced meningiomas.
Evolving research also indicates that the genetic profile of meningiomas varies by tumor location and may also impact prognosis. (See "Epidemiology, pathology, clinical features, and diagnosis of meningioma", section on 'Molecular pathogenesis'.)
Convexity meningiomas — WHO grade 1 convexity meningiomas are associated with an excellent prognosis after surgical resection alone. Because of their superficial location, the large majority of convexity meningiomas can be completely resected, and adjuvant or salvage RT is rarely indicated. (See 'Extent of resection' above.)
Rates of recurrence after Simpson grade I or II resection range from 3 to 10 percent [41,65-67]. Simpson grade III and IV resections are associated with significantly higher recurrence rates (approximately 10 to 25 percent for Simpson grade III and 33 to 50 percent for Simpson grade IV). Elevated MIB-1 index (≥3 percent) and atypical histologic features are also associated with increased risk of recurrence [39,41,68].
The surgical complication rate is approximately 8 to 10 percent. In one series, new neurologic deficits occurred in 2 percent of patients postoperatively, all of which represented worsening of motor weakness that was present preoperatively in patients with large (>4 cm) tumors .
Skull base meningiomas — The management of patients with skull base meningiomas is difficult because these lesions generally have an indolent history with only mild symptoms . At the same time, radical surgery is associated with substantial morbidity because of the involvement of critical vascular structures, cranial nerves, and/or brainstem.
A combined-modality approach with individualized treatment planning and multidisciplinary input from neurosurgery and radiation oncology is therefore optimal to achieve both tumor control and low morbidity from treatment [6,69,70]. Patients with minimal or no symptoms are often initially managed with observation. Surgical resection is usually indicated for patients with large tumors, especially those with edema and symptomatic mass effect.
Conformal fractionated RT or stereotactic radiosurgery (SRS) is used for treatment of residual tumor following surgery (for larger tumors) or used definitively for smaller tumors, especially those at high risk for surgical complications [11-15]. Although no randomized trials have been completed comparing SRS with surgery or other radiotherapy techniques, the outcomes appear to be similar to surgery for small- to medium-sized meningiomas. When SRS is used, attention must be given to radiation dose and the risk to vision or to other nerves that may be incidentally irradiated.
The outcomes and prognosis of skull base meningiomas managed in a multidisciplinary manner are generally good. In a series of 101 patients with presumed benign skull base meningioma who were treated with either fractionated RT alone (66 cases) or subtotal resection plus postoperative RT (35 patients), the local control rates were 95 percent at five years and 92 percent at 10 and 15 years . Median follow-up was only five years, however.
For appropriately selected tumors, outcomes after SRS alone or in combination with surgery are also good, although late progression events do occur [11,72-74]. A 2021 systematic review identified seven studies with long-term follow-up (median at least five years) in a total of 645 patients with cavernous sinus meningiomas treated with SRS alone or after prior resection (40 percent of patients) . With a median follow-up of 74 months, rates of progression-free survival at 5, 10, and 15 years after SRS were 93, 85, and 81 percent, respectively. Clinical improvement in cranial nerve deficits was reported in 36 percent of patients at last follow-up. Worsening or new-onset cranial nerve deficits were reported in 12 percent with long-term follow-up.
Optic nerve sheath meningiomas — RT, using either conventional or stereotactic techniques, is an effective primary treatment modality for optic nerve sheath meningiomas [58,76-80]. Surgery carries a high risk for visual deterioration and is generally avoided where possible.
Based on small, mostly single-center retrospective studies, 35 to 50 percent of patients experience visual improvement with RT (conventional or stereotactic) [58,76,78-80]. Patients with good vision at presentation (eg, 20/50 or better) have better overall visual outcomes and long-term stability compared with those who present with a significant decrease in vision [79,81].
Approximately 10 to 15 percent of patients develop long-term complications, including dry eyes, cataracts, and radiation retinopathy or optic neuropathy. Risk of retinopathy and optic neuropathy is higher with increasing RT dose, age, and vascular risk factors (eg, smoking, diabetes, hypertension) .
Radiation-induced meningiomas — There are only limited data available for the treatment of radiation-induced meningiomas. The available evidence suggests that these should be managed in the same fashion as other meningiomas [82,83].
Although surgery is the preferred modality, RT techniques may be an option for patients whose tumors arise in critical locations or who are poor candidates for surgery. In this setting, the use of RT must consider the prior radiation dose to the brain in planning treatment. In a series of 19 patients with 24 meningiomas diagnosed at a median of 30 years after their original treatment, SRS resulted in a disease-control rate of 75 percent at a median follow-up of 44 months .
Because radiation-induced meningiomas are more commonly atypical and highly proliferative, we generally use a higher dose of RT in tumors without pathologic confirmation.
Quality of life — Numerous factors can affect the outcome and recovery following treatment for a meningioma [84,85]. Contributing factors include the following:
●Neurologic damage from the tumor itself, which is dependent upon the anatomic location of the tumor, as well as whether the tumor is locally invasive. (See "Epidemiology, pathology, clinical features, and diagnosis of meningioma", section on 'Clinical presentation'.)
●Surgical complications. (See 'Surgical morbidity' above.)
●Risks of RT, which can produce a range of symptoms related to reactive edema in the short term and less commonly direct injury to irradiated tissues, such as delayed effects of hypopituitarism , stroke, or neurocognitive impairment. Neurocognitive impairment can be delayed after cranial radiation and is related to volume of brain and radiation dose delivered. (See "Acute complications of cranial irradiation" and "Delayed complications of cranial irradiation".)
●Side effects of medications used to control symptoms, especially antiseizure medications and steroids . (See "Overview of the management of epilepsy in adults", section on 'Side effects of therapy' and "Management of vasogenic edema in patients with primary and metastatic brain tumors", section on 'Complications and prophylaxis'.)
SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Primary brain tumors".)
INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5th to 6th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10th to 12th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.
Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)
●Beyond the Basics topic (see "Patient education: Meningioma (Beyond the Basics)")
SUMMARY AND RECOMMENDATIONS
●Baseline assessment – Management of meningioma requires a balance between definitive treatment of the tumor and avoidance of neurologic damage from the treatment. Patient age, comorbidities, tumor-related symptoms, tumor size, and the location of the tumor in relation to critical brain structures and regions are all important factors in determining the optimal treatment (algorithm 1). (See 'Treatment approach' above.)
●Small, asymptomatic tumors – For patients with small, asymptomatic presumed meningiomas without edema or imaging evidence of invasion, we suggest careful observation without immediate surgery or radiation therapy (RT) (Grade 2C). (See 'Small, asymptomatic tumors' above.)
•We typically repeat MRI in three to six months to establish short-term stability, then at less frequent intervals over time for as long as the patient remains a candidate for intervention and there is no evidence of progression (algorithm 1).
•For younger patients in good overall medical condition, early definitive intervention is an appropriate alternative to active surveillance.
●Large or symptomatic tumors – For most patients with presumed meningiomas that are symptomatic, large, infiltrating, or associated with substantial edema and in accessible locations, we recommend maximal safe resection rather than RT or observation (Grade 1B). (See 'Large or symptomatic tumors' above.)
•In addition to establishing initial tumor control, surgery provides relief of mass effect and confirms the histologic diagnosis and tumor grade.
•Empiric RT may be considered on a case-by-case basis and may be a reasonable alternative to surgery for patients with relatively small but enlarging tumors who wish to avoid surgery, older adults, and patients with significant comorbidities. (See 'Older adults' above.)
●Nonresectable tumors – Most nonresectable meningiomas requiring intervention can be effectively treated with RT (algorithm 1). The radiation dose and technique should be individualized according to tumor size, location, and proximity to critical structures. (See 'Nonresectable tumors' above and 'Conformal techniques' above.)
●Surveillance after treatment – For patients whose initial management consisted of surgery and/or RT, factors influencing the frequency of repeat imaging include the completeness of resection, the location of the tumor, and its pathology.
In general, imaging should be repeated in the postoperative period, annually for three to five years, and then every two to three years as long as the patient remains a candidate for intervention. (See 'Surveillance after initial treatment' above.)
ACKNOWLEDGMENT — The UpToDate editorial staff acknowledges Peter Black, MD, PhD, who contributed to an earlier version of this topic review.
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