Some brain tumors not a cause for concern
DEAR DOCTOR: I’ve recently been diagnosed with meningioma, but my doctor tells me not to worry about it. What should I know?
DEAR READER: Meningiomas are the most common brain tumors within the central nervous system, and most are considered benign. As the name implies, meningiomas arise from the meninges, the layer of membranes that surrounds the brain and the spinal cord. Approximately 26,000 new cases are diagnosed each year, often found incidentally — meaning they’re detected via brain imaging for symptoms not related to the tumor.
Ionizing radiation, a history of breast cancer, obesity and a family history of meningiomas are all risk factors for this type of tumor.
Of meningiomas, 80 to 90 percent are classified as grade 1, meaning they’re slow-growing because the cells within them don’t replicate rapidly. This is most likely the type of meningioma that you have. An additional 10 percent to 15 percent of meningiomas are classified as grade 2, meaning the cells within them replicate more rapidly and are more likely to invade local structures, making them more dangerous. A final 1 percent to 3 percent of meningiomas are considered grade 3, because the cells within them replicate very rapidly. These types of cancerous meningiomas are more difficult to treat and can spread to distant sites.
A CT scan or an MRI of the brain should be able to detect signs that indicate whether a meningioma is atypical or malignant, such as by assessing whether the tumor has swelling around it or whether it’s invading the bone.
If your doctor says you have no reason to be concerned, that’s probably because the meningioma is in an area where it isn’t compressing any portion of the brain. Some meningiomas, even though they are grade 1, are located in an area of the brain where they compress nerves. This can lead to alterations in vision, loss of hearing or smell, even weakness of the arms and legs and, rarely, if the tumor blocks the movement of fluid within the brain, confusion. Lastly, meningiomas increase the risk of having seizures.
Robert Ashley, M.D., is an internist and assistant professor of medicine at the University of California, Los Angeles.
Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA 90095.