Timothy C. Hain, MD
Page last modified: September 23, 2015
|Sagittal view of an incidental meningioma||Coronal view of an incidental meningioma affecting the temporal lobe (same as left)||Falx meningioma, again incidental.|
Meningiomas are slowly growing tumors that arise from the coverings of the brain (the meninges). Most of them are "incidental", meaning that they are found during the course of an investigation for some other process. Incidental meningiomas are usually checked occasionally to see if they have enlarged, but otherwise are ignored. Meningiomas are not quite as common as pituitary adenoma's. Fortunately, the most common two brain tumors -- meningiomas and pituitary adenomas, are not malignant, and are rarely threats to life.
Most meningiomas are asymptomatic. Dizziness is an occasional symptom, mainly when they occur in the "posterior fossa", which is the lower part of the brain including the cerebellum and brainstem.
Dizziness associated with meningiomas mainly occurs when it impinges on the 8th nerve or the cerebellum. Because these tumors grow very slowly, people with them gradually accommodate to them over years, and often their effects are unnoticed.
When meningiomas are in the same location where acoustic neuromas are commonly found (IAC), they may be mistaken for them. In this situation, surgery may need to be modified. Ordinarily meningiomas do not do as much damage to the 8th nerve as acoustic neuromas as they are tumors of the covering of the nerve rather than of the nerve itself. For this reason, after an IAC meningioma is removed, there may still be considerable vestibular function.
Usually a meningioma is found as an incidental finding on a scan of the brain. They "light up" with contrast on CT scan images, and they are also easily seen on MRI images.
Watchful waiting is the main management of meningiomas. If the tumors grow large enough to impair function, then they are removed surgically.