A meningioma is a central nervous system tumor, or brain tumor, originating from the meninges, the covering of the brain and spinal cord called dura. The dura covers and protects the brain and spinal cord. A meningioma does not spread from other locations in the body; it begins and grows from the dura over the brain and spinal cord. Cranial meningiomas do not grow from the brain tissue and can occur in many different places in the brain space. Spinal meningiomas are uncommon and do not grow from the spinal cord.

Meningiomas make up 41% of newly diagnosed brain tumors, and of those, the majority are benign.

“Meningiomas are generally considered benign, but a small group of more uncommon tumors could be cancerous,” says neurosurgeon Michele Aizenberg, MD. “Meningiomas stay in the nervous system, so they don’t spread to other body parts. If you have some other cancer in your body, it does not predispose you to have a meningioma.”

There are three categories, or grades, of meningiomas (not including subtypes):

• Grade I is a benign, slow-growing meningioma that is most common.
• Grade II, or atypical, is a quicker-growing meningioma that may be more resistant to treatment. As a mid-grade tumor, it may have a higher chance of returning after removal or becoming malignant.
• Grade III, or anaplastic, is a rarer cancerous meningioma that grows and spreads quickly. Rarely, these can spread outside of the nervous system.

Meningioma tumors can vary in location and tissue type. They can grow near the brain's surface, within the brain ventricles that carry cerebrospinal fluid (less common), in the bone of the skull, or in other areas such as the base of the skull or behind the eyes.

A meningioma can cause problems or harm if it grows large enough to cause pressure on the nerves, brain structures or the spinal cord. A person can develop a single meningioma or, less commonly, develop multiple tumors that grow simultaneously or over time in various locations of the brain or spinal cord.

Meningioma symptoms

Because meningiomas are typically slow-growing, people may not notice any symptoms for many years – or ever. Location matters: A person may begin to notice symptoms when the tumor grows large enough to create pressure on other structures around it. When brain tissue is compressed, it can also affect cranial nerves and blood vessels or grow into the bones of the head or face.

If the tumor is pressing on other structures in the brain, symptoms may include seizures, headaches, nausea, vision, smell or hearing loss, behavior changes, confusion or other neurological symptoms.

Sometimes, meningiomas are discovered accidentally because of an MRI or CT scan performed for other reasons. “But even if someone had a CT scan, we would request an MRI because we’re going to get better visualization of the character of the lesion and how it's affecting the surrounding structures,” adds Dr. Aizenberg. “If a person finds they have a meningioma, I recommend seeing a neurosurgeon for evaluation.”

Is there treatment for meningiomas?

The first step is to talk to your doctor about your symptoms. You may be referred to a neurosurgeon for evaluation. Once a likely diagnosis is determined, your physician will discuss your best treatment options, risks and benefits.

Oftentimes, meningiomas are found when they’re small and can be monitored. Predicting a meningioma’s growth rate is difficult, which is why doctors often take a “wait and watch” approach with small tumors that are not causing symptoms. Monitoring with an MRI scan at regular intervals gives doctors a better idea of how fast or slow they are growing.

Treatment highly depends on the individual. Depending on the location and size of the meningioma and the severity of your symptoms, your doctor may recommend observation over time, surgical removal, radiation therapy or other medicines depending on your situation.

Surgical removal is the definitive treatment, offering a potential cure. In contrast, other treatment methods are not a cure because they don’t make the tumor disappear.

“I would consider surgically removing a meningioma if it is symptomatic, meaning the patient is having symptoms or troubles from it, “adds Dr. Aizenberg. “Surgery can potentially be curative, but a decision for surgery would depend on the tumor’s size and growth threshold, and if there’s swelling in the brain or other symptoms.”

Are there risk factors?

The vast majority of meningiomas that develop are sporadic. Although researchers don’t know precisely what causes meningiomas, there are possible connections, including that they:

• Are more prevalent in women than men.
• May arise after previous ionizing radiation treatment or other radiation exposure.
• Seem to correlate with hormones due to estrogen, progesterone and androgen receptors found in the tumors. There may be a link between breast cancer and meningioma and also between the tumor’s growth and hormone levels.
• Can occur at any age, but increased risk is observed after age 65.
• Can occur at higher rates in black people than other ethnic groups in the United States.
• May pose a higher risk factor for people with the genetic disorder Neurofibromatosis type 2 (NF2).