What is a meningioma tumor?
Three layers of membranes, called meninges, lying just under the skull, protect the brain and spinal cord. From the outermost layer inward they are: the dura, arachnoid, and pia. A meningioma grows from the arachnoid cells that form the middle layer, and are firmly attached to the dura. Some meningiomas contain cysts or calcified mineral deposits, and others contain hundreds of tiny blood vessels. Because meningiomas tend to grow inward, they commonly cause pressure on the brain (or spinal cord). They can also grow outward, causing the skull to thicken (hyperostosis).
Meningiomas are classified by their cell type and grade by viewing the cells taken during a biopsy under a microscope. Treatment varies, depending on the grade of the meningioma.
- Grade I - benign meningiomas are the slowest growing. If the tumor is not causing symptoms, it may be best to observe its growth over time with periodic MRI scans. If there is a chance the tumor will grow enough in your lifetime to cause symptoms, then surgical removal may be recommended. Patients who undergo complete removal of a grade I meningioma usually do not require additional treatment. Patients who undergo incomplete removal may need radiation after surgery.
- Grade II - atypical meningiomas are slightly more aggressive in growth than grade I and have a slightly higher risk of recurrence. Surgery is the first line of treatment. Some will require radiation after surgery.
- Grade III - malignant meningiomas are the most aggressive and are called anaplastic. Malignant meningiomas account for less than 1% of all meningiomas. Surgery is the first line of treatment, followed by radiation. If the tumor recurs, chemotherapy is used.
What are the symptoms of a meningioma tumor?
Meningiomas grow slowly and may not cause symptoms for years. Some people meningiomas have no symptoms. The tumor may be found incidentally on an MRI or CT scan performed for another reason. Symptoms of a meningioma vary by the location and size of the tumor. They often first appear as headaches and seizures caused by increased pressure of the growing tumor. Weakness in the arms or legs, or loss of sensation, may occur with spinal cord meningiomas.
Meningiomas are named according to their location and cause various symptoms:
- Convexity meningiomas: grow on the surface of the brain. They may not produce symptoms until they reach a large size. Symptoms may include seizures, neurological deficits, or headaches.
- Falx and parasagittal meningiomas: grow from the dura fold that runs between the left and right sides of the brain. Symptoms may include personality changes, headache, vision problems, and arm or leg weakness.
- Olfactory groove meningiomas: grow along the nerves that run between the brain and the nose and often cause a loss of smell. They can compress the frontal lobes, causing personality changes that may be mistaken for depression. They can also compress the optic nerves causing visual problems or even blindness.
- Tuberculum sella meningiomas: grow near the pituitary gland and optic nerves. They often cause visual field problems.
- Sphenoid meningiomas: grow along the bony ridge behind the eyes. These tumors can cause visual problems, loss of sensation in the face, or facial numbness. They often encase major blood vessels (e.g., cavernous sinus, or carotid arteries) as well as the cranial nerves, making them difficult to completely remove.
- Posterior fossa meningiomas: grow along the underside of the brain near the brainstem and cerebellum. These tumors can compress the cranial nerves, causing facial symptoms or loss of hearing. Petroclival tumors can compress the trigeminal nerve, resulting in facial pain or spasms of the facial muscles.
- Foramen magnum meningiomas: grow where the spinal cord connects to the brain; they can cause headaches, brainstem compression, and difficulty walking.
- Intraventricular meningiomas: grow inside the fuild-filled ventricles of the brain. They block the flow of cerebrospinal fluid, causing hydrocephalus, headaches and dizziness.
- Intraorbital meningiomas: grow around the eye sockets of the skull and can cause a buildup of pressure in the eyes, giving a bulging appearance. They can also cause loss of vision.
- Spinal meningiomas: grow mainly in the thoracic spine. They can cause back pain (typically at night) or loss of sensation and paralysis of the legs from compression of the spinal nerves.
What causes a meningioma tumor?
Although the exact cause of brain tumors is not known, studies show that patients who received radiation to the head for other conditions are at higher risk for developing meningiomas later in life. There is a correlation between hormones and meningiomas.
Meningiomas account for 37% of all primary brain tumors and 12% of all spinal cord tumors. They are most often found in adults between the ages of 40 and 60 years and rarely occur in children. Most are benign (not cancer); less than 10% are malignant. While malignant meningiomas occur in both women and men, benign meningiomas are three times more common in women.
How is a meningioma tumor diagnosed?
The doctor will ask you about your personal and family medical history and perform a physical exam, as well as a neurological exam to check mental status and memory, cranial nerve function, muscle strength, coordination, reflexes, and response to pain. They may order imaging scans such as a CT or MRI to help determine the size, location and type of tumor. In some cases, angiograms of the blood vessels are necessary.
What are treatment options for a meningioma tumor?
There are a variety of treatment options for meningiomas. The treatment that is right for you will depend on your age, general health status, and the location, size and grade of the meningioma. Each treatment has benefits, risks and side effects that should be discussed with your doctor.
- Observation – “watch and wait” method that can be used for patients with no or few symptoms. Your doctor will monitor the tumor growth. Patients should immediately report any change in their symptoms.
- Medications – used to relieve side effects.
- Surgery – recommended if symptoms are moderate or severe or if the tumor is growing.
- Radiation – indications for radiation include: (1) incomplete tumor removal, (2) inoperable tumors, (3) malignant meningioma, and (4) patient choice.
- Chemotherapy and biologics – rarely used except in cases of malignant or recurrent meningiomas that don’t respond to surgery or radiation.
- Clinical trials – research studies where new treatments are tested in people to see if they are safe and effective.
What is recovery like after a meningioma?
The location of the tumor is the most important factor in determining the outcome. Convexity, parasagittal, and sphenoid wing meningiomas usually are completely removable, and surgery can yield excellent results. Optic, cavernous sinus, and skull base meningiomas have a higher rate of complication and are more difficult to completely remove. The patient’s age and overall health prior to surgery may also affect the results. Meningiomas may recur after surgery or radiation. Regular follow-up MRI or CT scans (1 to 2 years) are an important part of long-term care for anyone diagnosed with meningioma.