• Meningiomas are benign tumors that arise from the arachnoidal "cap" cells of the meninges. The meninges are the delicate membranes that are on the surface of the brain. The meninges lie beneath the heavier, sturdier "dura mater" or simply "dura" that lies just beneath the skull. The meningiomas are usually slow-growing tumors that do not invade the surrounding normal brain and do not spread to other parts of the body (There are very rare exceptions.) There is much more variation in the locations within the brain, the impact of the locations within the brain in causing symptoms and the impact of surgery vs. radiation (or radiosurgery) than there is variation in the types of meningioma. Location is the key and drives the reasoning for observation vs. treatment and the type(s) of treatment.



• Treatment is reasonable when there is evidence of growth of small meningiomas or if the size is initially significant and is associated with progressive symptoms over time. The treatments for the meningiomas include surgery, radiation therapy and radiosurgery as discussed below.

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Incidence of Meningiomas

• Demographics Meningiomas account for 13 to 19% of all primary intracranial tumors. The incidence of meningioma in the general population varies from 2.3 cases per 100,000 when detected while the patient is alive to 5.5 per 100,000 if postmortem data are included. The majority of meningiomas (91%) are benign, but this does not preclude recurrence: there is a recurrence rate of between 11.5% and 29% within 7 to 20 years of surgical resection Ref. Any of the benign histological subtypes demonstrating atypical features are more likely to recur, as are papillary and malignant meningiomas. The incidence of atypical and malignant (including papillary) meningiomas has been reported to be 0.9 to 10.6%, with an average of 2.8%. There is a 50% recurrence rate of atypical meningiomas at 10 years, and for malignant meningiomas, recurrence rates of 33%, 66%, and 100% have been found at 5, 10, and 15 years, respectively Ref.
  
  Atypia and malignancy aside, the most important factor in predicting meningioma recurrence is completeness of resection: 10-year recurrence rates vary from 10% for tumors determined macroscopically to be totally excised (including dural attachment and any abnormal bone) to 100% for tumors that have simply been debulked (Simpson, 1957). The site is considered relevant because the least accessible tumors and those intimately related to vital structures are less likely to be totally resected.
  
  Histology (appearance under the microscope) of benign meningiomas is not related to risk of recurrence Ref. In this retrospective evaluation of 1799 surgical specimens of meningiomas from 1582 patients was made. The classic histopathological type, atypical meningiomas defined by increased cellularity and at least five mitotic figures in 10 high-power fields, anaplastic (malignant) meningiomas, and hemangiopericytic or papillary meningiomas were seen in 87.6%, 7.2%, 2.4%, and 2.8% of operations, respectively. The rates of recurrence in surgically treated patients with classic, atypical, anaplastic, and hemangiopericytic or papillary meningiomas were 6.96%, 34.6%, 72.7%, and 68.2%, respectively. The extent of surgery and the tumor size and site were studied in detail in 252 tumors of all histopathological types. Recurrences were rare in classic meningiomas after complete resection, whereas atypical and anaplastic tumors recurred after complete resection much more frequently. Classic meningiomas, hemangiopericytomas, and papillary meningiomas were smaller at surgery than atypical and malignant meningiomas. Atypical and malignant tumors were operated on more often in falcine and lateral convexity regions than were classic meningiomas.
  
  Gender The meningioma occurs twice as often in women as men and tend to occur later in life (the incidence peaks in the sixth decade of life for men; seventh decade for women). This higher incidence of meningiomas in women, the observation that in women these tumors may enlarge and become symptomatic during hormonal flux, particularly during pregnancy and in the luteal phase of the menstrual cycle, and the observation of a nonrandom association between meningioma and carcinoma of the breast indicate that female hormones play a role in the growth of meningiomas.
  
  
• Predisposition The factors that predispose to meningioma include previous cranial irradiation and neurofibromatosis. Multiple meningiomas occur in 5 to 15 percent of patients, particularly in association with neurofibromatosis.

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Etiology of Meningiomas

• Unknown The cause of the meningioma is unknown, but 40 to 80 percent of meningiomas have loss of genetic material from chromosome 22, at a locus within the gene for neurofibromatosis. The malignant meningioma is associated with deletions of other chromosomes.
  
  
• Hormone receptors are expressed by meningiomas. Estrogen receptors are expressed to a lesser extent but progesterone receptors are expressed to a much greater extent. In one series, approximately 80 percent of meningioma specimens showed progesterone receptors.

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Classification of Meningiomas

• Traditional classification of meningiomas divides tumors according to the appearance under the microscope. This system divides the benign meningiomas into syncytial, fibrous, transitional, psammomatous and angiomatous types. All of these types are benign and have very similar results after surgery, radiotherapy and/or radiosurgery.
  
  
• Atypical meningiomas have higher rates of division (mitosis) as seen under the microscope. The cellular architecture may be abnormal (irregular) but there is no invasion of the surrounding normal brain.
  
  
• Malignant meningiomas have high numbers of mitoses, necrosis (cell death) and loss of normal architecture. The malignant meningiomas invade normal brain, and this invasion is essential for this diagnosis. The primary treatment is surgery and postoperative radiation therapy or radiosurgery.
  
  
• WHO Classification Abstract

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Clinical Presentation of Meningiomas

• Presenting Symptoms for the meningiomas are directly related to the location.
  
  Frontal meningiomas may present with headache, loss of concentration, memory or change in personality. The posterior, dominant frontal meningioma may compress the speech area resulting in aphasia (difficulty forming words).
  
  Olfactory groove meningiomas may present with decreased sense of smell due to compression of the olfactory nerve(s).
  
  Parasagittal meningiomas may present with urinary incontinence or weakness in the contralateral foot or leg.
  
  Medial sphenoid wing or parasellar meningiomas may present with decreased vision due to compression of the optic nerve and/or pituitary insufficiency (decreased thyroid, growth hormone, prolactin, adrenocorticotropic hormone (ACTH) (results in low cortisol for "fight or flight" response).
  
  Petroclival or skull base meningiomas may present with deficits of the lower cranial nerves and compression of the brainstem. Patients may present with diplopia
  
  Cavernous sinus meningiomas may present with double vision (diplopia), facial numbness, decreased pituitary function and headache. The tendency of these tumors to be infiltrative is evident and this seems to occur along connective tissue planes within the cavernous sinus. The trigeminal nerve and ganglion seem to be particularly prone to invasion; this does not correlate with the degree of preoperative impairment of nerve function. Internal carotid artery invasion occurs frequently and can be seen even when there is no narrowing of the artery on arteriography.
  
  Cerebellar meningiomas may present with ataxia (difficulty with balance), facial weakness, decreased hearing, difficulty with swallowing or speaking. These meningiomas may result in hydrocephalus if the pathways for spinal fluid to leave the brain are blocked. This would require placement of a "shunt."
  
  
• Asymptomatic Meningiomas
  
  Meningiomas may be incidentally detected on MRI scan that is done for other reasons. The "asymptomatic" meningioma most often occurs in patients over 70 years of age Ref. In this study of the asymptomatic meningiomas in 196 patients, 87 (44.4%) were surgically removed, whereas 109 (55.6%) were treated conservatively. Of these conservatively treated patients, 63 received follow-up care for more than 1 year. In 20 of these 63 cases, the tumors increased in size over the 27.8-month average follow-up period (range 12–87 months), whereas in the other 43 cases, the tumor size did not increase during a 36.6-month average follow-up period (range 12–96 months).

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Treatments for Meningiomas

• Surgery for Meningiomas

  Small, asymptomatic meningiomas can be carefully observed and followed with serial MRI studies. Surgical resection of meningiomas always has some risk, and the risk should be justified by the growth or size of the meningioma or the progression of the symptoms. Complete resection of meningiomas is often possible with tumors of the convexity, falx, lateral skull base and the cerebellar convexity (laterally and posteriorly). These tumors are near the surface and usually do not encase large blood vessels, involve multiple compartments (fossae) of the skull and do not encase cranial nerves (see skull base surgery below). Complete surgical resection of meningiomas is usually not possible for tumors involving the superior sagittal sinus, clivus, cerebral ventricles, tentorial notch or optic nerve sheath. The complication rate should be less than 10 percent. Even when removed, meningiomas are not always cured. Even after visualized total removal of the tumor, the recurrence rate varies from 10 to 20 percent (measured over 10 years). For patients with obvious residual tumor at the time of resection, this recurrence rate is much higher: 30 to 50 percent.
  
  Skull Base For the surgery of the skull base meningiomas involving the cavernous sinus, medial temporal fossa, clivus and medial petrous temporal regions, the surgery has higher complication rates Ref In this study a large number of preoperative, intraoperative, and follow-up findings were analyzed for correlation with the extent of resection. These included the presence of cranial Nerve III, V, and VI palsies, multiple fossa involvement, and vessel encasement. Analysis revealed that each variable tested was independently and inversely correlated with total tumor resection (P less than 0.002). Thus for the skull base meningiomas alternative therapies such as radiosurgery are often considered.

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• Radiosurgery for Meningiomas

  Radiosurgery is a promising method for treatment of meningiomas. It avoids treatment of normal brain outside the target volume and concentrates dose within the meningioma. Two important variants of radiosurgery are important: the FSR and the single "shot" methods.
  
  FSR The fractionated stereotactic radiosurgery (FSR) offers multiple smaller treatments rather than one big "shot" of radiation. The FSR takes advantage of the difference in response of the normal brain tissues and cranial nerves when compared to the meningioma. The normal tissues can tolerate many smaller treatments but cannot tolerate single large treatments "shots." The FSR provides multiple smaller treatments to spare the normal tissues and to kill the meningioma. There have been no instances of facial pain, facial numbness or decreased vision after FSR for skull base, petroclival, cavernous sinus or other meningiomas.

  FSR offers conformal treatment of the meningioma on an out-patient basis and without drugs, anesthesia, incisions or scars.

  The FSR results in no side effects such as nausea, weight loss, red skin or hair loss.

  For the FSR, after review of the MRI the patient is evaluated for "simulation" (CT scan using the Picker AcQsim scanner). For the simulation the patient is fitted with a plastic, non-invasive relocatable mask that is also localizes and secures the patient during the treatments. The image files are transferred to a workstation for development of the optimal plan. The patient returns on a day subsequent to the simulation and begins treatment. The patient lies on the treatment table and his/her mask is positioned. Prior to initiating treatment, plain film x-rays are taken to ascertain correct positioning. The treatment is given in several smaller segments called "arcs." Between segments the patient's position relative to the treatment machine is precisely changed. The total number of treatments is a function of the size and location of the meningioma. For meningiomas near the optic apparatus (nerve and chiasm) 30 treatments, one per day, may be given. For meningiomas outside of this region, 8 consecutive daily treatments are given. The patient is seen by Dr. Williams every day during treatment.
  
  Single "shot" In comparison, the single "shot" methods may result in higher rates of complication for the cranial nerves. Complications, including cranial neuropathies, occurred in up to 13% of patients in gamma knife radiosurgical series Ref, with the rate increasing with the length of follow up. The reports on linear accelerator-based single "shot" radiosurgery have described similar outcomes. Similarly the effects of gamma knife treatment on the optic nerves has been explored. Leber, et al. Ref retrospectively analyzed optic nerve (and other cranial nerve) toxicity after gamma knife radiosurgery in 50 patients with various types of tumors. They reported the actuarial incidence of optic neuropathy to be 0, 26.7%, and 77.8%, in patient cohorts who received radiation doses of less than 10 Gy, 10 to 15 Gy, and more than 15 Gy, respectively, to the optic pathways. The authors concluded that "the structures of the visual pathways (the optic nerve, chiasm, and tract) exhibit a much higher sensitivity to single-fraction radiation than other cranial nerves."

  Hence, when compared to the FSR for meningioma, the single session or "shot" radiosurgery may have higher risk.

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• RU-486 For Meningiomas

  There is evidence that the growth of meningiomas is influenced by hormones and growth factors. Treatment with anti-estrogens has not been effective. Treatment with anti-progesterone agents has shown promise, but no randomized prospective trial has shown a benefit for patients who receive the RU-486 vs. the placebo.

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Meningioma Registration Page

Patients who have intracranial meningioma may wish to complete and submit this form. It outlines many of the important questions related to meningiomas.

If desired, the form describing the meningioma can be sent to Dr. Williams using the "Send Form" button at the end of the page. Dr. Williams can, if desired, subsequently correspond regarding the issues related to the radiosurgery for meningiomas.

If you wish to convey the MENINGIOMA information below, please enter the responses and click on the "Submit Form" button at the end of this form.

Your email address (if response is desired):

Date of Diagnosis

What is the DATE of the diagnosis of the first meningioma (If a meningioma was diagnosed in the past before the current meningioma)?

How was the first meningioma diagnosed?

Stereotactic Biopsy

Craniotomy

Only radiographically

MENINGIOMA Histology

Please enter the MENINGIOMA histology:

Benign

Malignant

Atypical

Other (not listed above):

MENINGIOMA Location

What was the location of the meningioma? (Please ask your doctor for clarification of the location.)

Skull Base (Middle of skull, deep)

Supratentorial (Above tentorium: e.g. sphenoid wing, convexity)

Posterior Fossa (Cerebellar)

Other

Number of MENINGIOMAS

How many meningiomas were there initially prior to any treatment, right after the first diagnosis?

One (solitary)

Two

Three

Four

Five

More than Five

First MENINGIOMA treatment(s) prior to current treatment (if applicable)

How was the first meningioma (or group of meningioma treated)?
Stereotactic Biopsy only

Craniotomy only

Stereotactic Biopsy and Radiation

Craniotomy and Radiation

No Treatment: Observation only

Date of initial MENINGIOMA treatment after first diagnosis (if applicable)

What was the DATE of the treatment for the FIRST meningioma?

What is the DATE of the DIAGNOSIS of the CURRENT meningioma (or meningiomas if more than one)? (This (these) meningioma(s) are for consideration for the CURRENT radiosurgery or surgical resection).

Number of MENINGIOMAS now

How many meningiomas are there now?
One (solitary)
Two
Three
Four
Five
More than Five

Size of MENINGIOMA now

What is the largest dimension (in centimeters) of the meningioma (or largest meningioma if more than one)? One
Two Centimeters
Three Centimeters
Four Centimeters
Five Centimeters
More than Five Centimeters

Current Treatment other than Radiosurgery

Prior to Radiosurgery (if applicable), how is the CURRENT meningioma (or group of meningiomas) treated?

Stereotactic Biopsy only

Craniotomy and removal of as much tumor as possible

No Surgery

Craniotomy and external beam irradiation (regular radiation)

Stereotactic Biopsy and external beam irradiation (regular radiation)