Meningioma tumors arise from one of the layers of the meninges (the protective tissue covering the brain). They are usually benign, slow growing and do not spread into normal brain tissue. Typically, a meningioma grows inward causing pressure on the brain or spinal cord. It may grow outward toward the skull, causing it to thicken. Some meningiomas contain cysts (pockets of fluid), small deposits of calcium, or tightly packed bunches of blood vessels.

Meningiomas can also occur in the foramen magnum, which is the bony rim at the bottom of the skull that sits on top of the cervical spine. This region is often called the craniocervical junction because it is the transition from the contents of the brain to those of the spinal cord. It contains the bottom of the brain stem and top of the cervical spinal cord, nerves for swallowing, tongue movement and shoulder function, sensation to back of the scalp and arteries that supply the brain stem, spinal cord, and the cerebellum or balance and coordination part of the brain.

Meningiomas are the second most common tumor to arise in the Cerebellopontine Angle (CPA) after acoustic neuromas. While acoustic neuroma and meningioma are both benign and slow-growing, because CPA meningiomas arise from the brain lining rather than nerve cells, they can be removed surgically with less chance of losing hearing or facial nerve function.


Treatments

Standard treatment is surgery to remove the tumor, the lining to which it is attached, and any bone that is involved. When total removal can be done the tumor will not grow back. Radiation therapy or radiosurgery might be of value if the tumor is not entirely resected.

Sometimes surgery may not be recommended. For those with no symptoms, those with minor symptoms and those for whom surgery would be risky, long-term close observation with scans (CT or MRI) may be advised. An alternative includes focused radiation or stereotactic radiosurgery.

Recurrent tumors are treated similarly, with surgery followed by either standard radiation therapy or radiosurgery regardless of the grade of the meningioma. Several drugs may be used to treat symptoms. These include steroids and medications to treat nausea or seizures.

The causes for meningioma formation are not known unless the patient has the genetic syndrome called neurofibromatosis.

Meningiomas are more common in women then men.

A meningioma may grow back if it is not completely removed, either as a slow growing tumor or sometimes as a more rapidly growing, higher grade tumor.

Diagnosis will begin with a neurological exam, followed by an MRI and/or CT scan. An angiography or arteriogram may also be done to look at the blood supply of the tumor. A surgical biopsy may be needed in order to determine an exact diagnosis.

Other tests for tumors in this location include a hearing evaluation (audiogram) and possibly a battery of tests of the balance nerve (vestibular) function called an electromystagmogram (ENG).

Untreated CPA meningiomas can produce irreversible hearing loss, facial weakness or numbness, and in rare cases of very large tumors with brain stem compression there can be weakness of the limbs, difficulty walking, and build-up of brain fluid called hydrocephalus.