Meningioma

A meningioma is a tumor that grows from the protective layers covering the brain and spinal cord. While most are slow-growing and not cancerous, they can cause serious problems depending on their size and location.

Table of contents

• What is a meningioma?
• Where meningiomas form
• Types and grades
• Signs and symptoms
• Causes and risk factors
• Who is affected
• How meningiomas are diagnosed
• Treatment options
• Outlook and recovery

What is a meningioma?

A meningioma is a tumor that grows from the meninges, which are the layers of tissue that wrap around your brain and spinal cord to protect them^[1]. These protective layers have three parts: an inner layer called the pia mater, a middle web-like layer called the arachnoid, and a tough outer layer called the dura mater^[1]. Most meningiomas grow from the arachnoid layer^[6].

Although people often call meningiomas brain tumors, they do not actually grow from brain tissue itself^[1][7]. Instead, they grow on the surface of the brain or spinal cord and may press against it^[1].

Meningiomas are the most common type of tumor that forms in the head, accounting for about 37.6% of all primary central nervous system tumors^[4][5]. Most of these tumors grow very slowly, sometimes over many years, and often do not cause symptoms right away^[1][2]. In fact, many are found by accident when brain scans are done for other reasons^[7][13].

• Brain
• Spinal cord
• Meninges (protective tissue layers)

Where meningiomas form

Meningiomas can form in different locations along the meninges. They are most often found near the top and outer surface of the brain^[2][7]. They may also form at the base of the skull^[1][2]. While tumors around the spine are possible, they are much less common^[2].

The location of the tumor matters greatly because it determines what symptoms a person might experience^[3]. Different types based on location include:

• Convexity meningiomas grow on the outer surface of the brain, often toward the front and top. They may not cause symptoms until they become large^[2][3].
• Olfactory groove meningiomas grow at the base of the skull behind the nose, near the nerve that gives you your sense of smell^[2][3].
• Sphenoid wing meningiomas form along a ridge of bone behind the eyes^[2][3].
• Parasagittal and falcine meningiomas grow along the membrane that divides the two sides of the brain. Large tumors in this area may cause leg weakness^[3].
• Posterior fossa meningiomas arise in the back of the head and can cause headaches, unsteadiness, or changes in voice and swallowing^[3].
• Intraventricular meningiomas grow within the chambers of the brain where fluid circulates. They can block fluid flow and cause increased pressure^[2][3].

Types and grades

Meningiomas are grouped into three grades based on how they look under a microscope and how they behave^[4]. The grade tells doctors how fast the tumor grows and how likely it is to come back after treatment^[2].

Grade 1 meningiomas (also called typical or benign meningiomas) are the most common, making up about 80% to 90% of all cases^[3][13]. These are low-grade tumors that grow very slowly^[4]. The word “benign” means not cancerous, but this can be misleading because even benign meningiomas can cause serious problems if they press on important nerves or brain areas^[3].

Grade 2 meningiomas (also called atypical meningiomas) are mid-grade tumors that grow more quickly than grade 1^[2][4]. They have a higher chance of coming back after treatment and may be more resistant to therapy^[2]. Grade 2 types include chordoid and clear cell meningiomas^[4].

Grade 3 meningiomas (also called anaplastic or malignant meningiomas) are rare, making up only about 1% to 3% of cases^[2][5]. These are cancerous tumors that grow and spread quickly^[2][4]. They have irregular cells and are likely to invade the brain or spread to other organs^[4]. Grade 3 types include papillary and rhabdoid meningiomas^[4].

About 1% to 3% of meningiomas can transform from benign to malignant over time^[5].

Signs and symptoms

Because meningiomas usually grow slowly, they may not cause noticeable symptoms until they become large enough to press on important structures around them^[2][9]. The symptoms depend on which part of the brain or spinal cord the tumor affects^[1][2].

Common symptoms may include^[1][2][4]:

• Headaches, often worse in the morning
• Seizures (fits or convulsions)
• Vision changes, such as seeing double, blurring, or bulging eyes
• Hearing loss or ringing in the ears
• Loss of the sense of smell
• Memory problems or confusion
• Weakness in an arm or leg
• Trouble speaking
• Loss of balance or dizziness
• Personality or behavioral changes

Some people may experience very specific symptoms depending on where the tumor is located. For example, tumors between the brain lobes may cause paralysis of one leg, while tumors underneath the brain and behind the nose may cause loss of smell^[6]. Tumors on the spinal cord may cause pain in the spine and weakness^[6].

If you experience new or worsening symptoms like persistent headaches, seizures, or sudden changes in vision or balance, you should see a doctor^[1].

Causes and risk factors

The cause of most meningiomas is not known^[4][9]. For most people, there is nothing they did that caused the tumor to develop^[18].

However, meningiomas often happen because of a chromosomal deletion, which is a change in genes where part of a chromosome is missing^[2]. These changes usually happen randomly, but sometimes they can be inherited as part of certain genetic conditions^[2].

Several factors can increase the risk of developing a meningioma^[2][4][5]:

• Exposure to radiation, especially during childhood or radiation therapy to the head, can increase risk^[4][5]
• Genetic conditions such as Neurofibromatosis type 2, Cowden syndrome, Li-Fraumeni syndrome, and Von Hippel-Lindau disease^[2][4]
• Hormonal factors, including use of hormone replacement therapy or birth control pills^[2][5]
• Having a family history of meningiomas^[2][5]
• Having or having had breast cancer^[2][5]

Meningiomas express hormone receptors on their surface, including receptors for progesterone, estrogen, and androgen^[5]. Progesterone receptors can be found in up to 72% of tumors^[5]. This may help explain why hormonal factors play a role, and why meningiomas can change in size during pregnancy^[5].

Who is affected

Meningiomas can affect anyone, but certain groups of people are more likely to develop them^[2].

Women are more likely to develop meningiomas than men^[3][7]. Grade 1 meningiomas are especially more common in females, though grades 2 and 3 occur more often in males^[4]. Meningiomas occur most commonly in middle-aged women and people over 40 years old^[3][7]. The risk of developing a meningioma increases with age, with high-grade types most common in people around 60 years old^[4]. They are found in about 3% of people over age 60^[3].

People who are Black are also at higher risk^[2]. High-grade meningiomas are most common in non-Hispanic white people^[4].

People over age 65 have an increased risk of developing meningiomas^[2].

How meningiomas are diagnosed

Diagnosing a meningioma can be challenging because the tumor often grows slowly and symptoms may be subtle or mistaken for normal signs of aging^[8][9].

If your doctor suspects a meningioma, you may be referred to a specialist called a neurologist, who focuses on conditions of the brain and spine^[8]. The neurologist will perform a thorough physical examination and a neurological exam to check your reflexes, balance, coordination, and other brain functions^[2][9].

The main way to diagnose a meningioma is through imaging tests^[2][8]:

MRI scan (magnetic resonance imaging) is the gold standard test for diagnosing meningiomas^[4]. This test uses a magnetic field and radio waves to create detailed pictures of the brain and surrounding structures^[8]. MRI scans provide more detailed images than other tests and can show the size and exact location of the tumor^[8]. Often, a contrast dye is used to make the pictures easier to read^[8].

CT scan (computed tomography) takes X-rays from different angles to create cross-sectional images of the brain^[8][9]. Sometimes an iodine-based dye is used to improve the images^[8].

In some cases, a biopsy may be needed to confirm the diagnosis^[8]. This means taking a small sample of tumor tissue, usually during surgery, and examining it under a microscope^[4]. A specialist called a neuropathologist then reviews the tissue to determine the exact type and grade of meningioma^[4].

Treatment options

Treatment for a meningioma depends on several factors, including the size and location of the tumor, how fast it is growing, its grade, your age and overall health, and your personal goals for treatment^[8][9].

Observation and monitoring

Not everyone with a meningioma needs treatment right away^[1][8]. If the tumor is small, growing very slowly, and not causing symptoms, doctors may recommend a “wait-and-see” approach^[8][20]. This means having regular check-ups and imaging tests (usually every one to two years) to watch for any changes^[9][14]. Many small meningiomas found by accident never need treatment^[7][13].

Surgery

Surgery is often the main treatment for meningiomas that are causing symptoms, growing quickly, or are large^[8][13]. The goal is to remove as much of the tumor as possible^[6]. The surgical procedure to remove a brain tumor is called a craniotomy^[6].

In the best cases, the entire tumor can be removed, which offers the best chance for cure^[6]. However, sometimes complete removal is not possible because the tumor is in a hard-to-reach location or has grown into important blood vessels or nerves^[6][13].

Radiation therapy

Radiation therapy uses high-energy beams to kill tumor cells^[8]. It may be used when surgery cannot remove all of the tumor, when the tumor is in a location that makes surgery too risky, or when the tumor comes back after surgery^[8][20].

Stereotactic radiosurgery is a special type of radiation treatment that delivers a high dose of radiation very precisely to the tumor in one or a few sessions^[13]. Despite its name, it is not actually surgery and does not require any cuts^[13]. This approach is especially useful for small tumors or those in difficult locations^[13].

Medications

Some medications may be used to help manage symptoms. Steroid drugs can help reduce swelling around the tumor and relieve pressure on the brain^[6]. Anti-epileptic medications can help control seizures if they occur^[6].

There is currently no standard chemotherapy for meningiomas, as these tumors generally do not respond well to traditional cancer drugs^[11]. However, researchers are studying new targeted treatments and medications that might work better for higher-grade meningiomas^[11].

Outlook and recovery

The outlook for people with meningiomas depends mainly on the grade of the tumor^[2].

Most people with grade 1 meningiomas have an excellent outlook^[6]. These slow-growing tumors respond well to treatment, with eight out of 10 cases considered cured^[6]. When the entire tumor can be removed by surgery, the chance of it coming back is low^[2].

Grade 2 meningiomas have a higher chance of coming back after treatment, even when completely removed^[2][4]. People with grade 2 tumors usually need more frequent follow-up^[9].

Grade 3 meningiomas are the most challenging to treat and have a five-year survival rate of 32% to 64%^[5]. These tumors are likely to grow back quickly and may be difficult to control^[2].

After treatment, regular follow-up care is very important^[14][21]. Your doctor will create a personalized follow-up plan, which may include check-ups and MRI or CT scans to watch for any signs that the tumor has returned^[21]. People with slow-growing tumors may need check-ups every one to two years, while those with faster-growing tumors may need more frequent visits^[21].

Some people may experience ongoing challenges after treatment, depending on the tumor’s location and the treatments received^[21]. These might include problems with thinking, memory, balance, speech, or movement^[2][21]. Rehabilitation programs including physical therapy, occupational therapy, and speech therapy can help people recover these abilities or learn to adapt^[21].

Support services are available to help with the emotional and practical challenges of living with a meningioma^[21]. These may include support groups, counseling, social work services, and help managing any stress or anxiety^[21]. Fatigue is a common challenge for people living with brain tumors, and learning strategies to manage energy levels can improve quality of life^[16].