These grow on the surface of the brain, often toward the front. They may not produce symptoms until they reach a large size. Symptoms of a convexity meningioma are seizures, focal neurological deficits, or headaches.
Falx and Parasagittal meningiomas
The falx is a groove that runs between the two sides of the brain (front to back), and contains a large blood vessel (sagittal sinus). Parasagittal tumors lie near or close to the falx. Because of the danger of puncturing the blood vessels, removing a tumor in the falx or parasagittal region can be difficult. Large parasagittal meningiomas may result in bilateral leg weakness.
Olfactory groove meningiomas
Olfactory groove meningiomas grow along the nerves that run between the brain and the nose. These nerves allow you to smell, and so often tumors growing here cause loss of smell. If they grow large enough, olfactory groove meningiomas can also compress the nerves to the eyes, causing visual symptoms. Similarly, meningiomas growing on the optic nerve can cause visual problems, including loss of patches within your field of vision, or even blindness. They can grow to a large size prior to being diagnosed due to changes in the sense of smell and mental status changes being difficult to recognize.
Sphenoid meningiomas lie behind the eyes. These tumors can cause visual problems, loss of sensation in the face, or facial numbness. Tumors in this location can sometimes involve the blood sources of the brain (e.g. cavernous sinus, or carotid arteries), making them difficult or impossible to remove completely.
Posterior fossa meningiomas
Posterior fossa tumors lie on the underside of the brain. These tumors can compress the cranial nerves causing facial symptoms or loss of hearing. Petroclival tumors can compress the trigeminal nerve, resulting in sharp pain in the face (trigeminal neuralgia) or spasms of the facial muscles. Tentorial meningiomas or those near the area where your spinal cord connects to your brain (foramen magnum) can cause headaches, or other signs of brain stem compression such as difficulty walking.
Intraventricular meningiomas are associated with the connected chambers of fluid that circulate throughout the central nervous system. They can block the flow of this fluid causing pressure to build up, which can produce headaches and dizziness.
Intraorbital meningiomas grow around the eye sockets of your skull and can cause pressure in the eyes to build up, resulting in a bulging appearance. They can also cause an increasing loss of vision.
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Spinal meningiomas account for less than 10 percent of meningiomas. They tend to occur in women (with a female/ male ratio of 5 to 1), usually between the ages of 40 and 70. They are intradural (within or enclosed within the dura mater), extramedullary (outside or unrelated to any medulla) tumors occurring predominantly in the thoracic spine. They can cause back pain, or pain in the limbs from compression of the nerves where they run into the spinal cord.
How common is each location?
Falx or parasagittal 25 percent
Convexity 20 percent
Sphenoid wing 20 percent
Olfactory groove 10 percent
Supresellar 10 percent
Posterior fossa (petrosal) 10 percent
Intraventricular 2 percent
Miscellaneous (e.g., optic nerve, clivius) 3 percent
To learn more about BWH Brain Tumor Services in the Department of Neurosurgery, visit: Brain Tumor Service.