A tumor begins when normal cells change and grow uncontrollably, forming a mass. A tumor can be benign (noncancerous) or malignant (cancerous, meaning it can spread to other parts of the body).
The brain and spinal column make up the central nervous system (CNS), where all vital functions of the body are controlled. When a tumor forms in the CNS , it can be especially problematic and challenging to treat because a person's thought processes and movements can be affected.
This guide focuses on meningioma, which is a slow-growing tumor that usually forms on the surface of the brain and may cause significant symptoms if it grows and presses on the brain or spinal cord. Specifically, meningioma is a type of tumor that occurs in the meninges, which are the thin membranes that surround and protect the brain and spinal cord. There are three meningeal layers called the dura mater, arachnoid, and pia mater. The cerebrospinal fluid (CSF) is made near the center of the brain, in the lateral ventricles, and circulates around the brain and spinal cord between the arachnoid and pia layers.
Approximately 80% of meningiomas are benign. The remaining 20% are either atypical (a type of slow-growing tumor that could become cancerous) or, in 1 - 2% of meningiomas, malignant.
Subtypes of meningioma
Meningioma is classified into subtypes based on the location of the tumor.
Falx and parasagittal meningioma (accounts for 25% of meningiomas). The falx is a membrane sitting in a groove that runs between the two sides of the brain. It contains a large blood vessel. Parasagittal meningioma occurs near the falx.
Convexity meningioma (20%). This type of meningioma occurs on the upper surface of the brain.
Sphenoid meningioma (20%). The sphenoidal ridge is located behind the eyes. Sphenoid meningioma occurs mostly in women.
Olfactory groove meningioma (10%). This type of meningioma occurs along the nerves that connect the brain to the nose.
Posterior fossa meningioma (10%). Posterior fossa meningioma develops at the back of the brain, on the underside.
Suprasellar meningioma (10%). Suprasellar meningioma occurs next to the sella turcica, an area at the base of the skull where the pituitary gland sits.
Spinal meningioma (less than 10%). Most common in women between the ages of 40 and 70, a spinal meningioma usually occurs in the spine at chest level and may push against the spinal cord. Spinal meningioma may cause pain radiating around the chest wall, bladder trouble, and/or weakness or numbness in the legs.
Intraorbital meningioma (less than 10%). This type of meningioma develops in or around the eye sockets.
Intraventricular meningioma (2%). Intraventricular meningioma occurs in the chambers that carry fluid throughout the brain.
Find out more about basic terms used in this section .
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