Meningiomas are often described by their location within the brain. The most common are:
Convexity meningioma grow on the surface of the brain directly under the skull. Accounting for approximately 20% of meningiomas, convexity meningiomas may not present symptoms until the tumor has become quite large. If large enough, however, convexity meningiomas will present symptoms based on its location and where it is pushing on the brain.
Falcine and Parasagittal Meningioma
Falcine and parasagittal meningioma, which forms in the falx – a very thin layer of tissue between the two sides of the brain (falcine meningioma), or near the falx (parasagittal meningioma)
Intraventricular meningioma, which forms within the ventricular system in the brain, which is where cerebrospinal fluid (CSF) is made and distributed. An intraventricular meningioma may cause an obstruction of CSF, leading to hydrocephalus.
Some meningiomas form in the bones that form the bottom of the skull and the bony ridge in the back of the eyes. Skull base meningiomas are more difficult to remove surgically than convexity meningiomas.
Skull base meningiomas also include:
Sphenoid Wing Meningioma
Sphenoid wing meningioma, which forms on the skull base behind the eyes. Approximately 20% of meningiomas are sphenoid wing.
Olfactory Groove Meningioma
Olfactory groove meningioma, which forms along the nerves connecting the brain to the nose. Olfactory groove meningiomas account for around 10% of meningiomas. This type of tumor can cause a loss of smell, and if overgrown, can cause problems with vision.
Posterior Fossa / Petrous Meningioma
Posterior fossa / petrous meningioma, which forms on the underside of the brain. Accounting for approximately 10% of meningiomas, posterior fossa meningiomas can press on the cranial nerves, causing facial and hearing problems. Petrous meningiomas often press on the trigeminal nerve, causing a condition called trigeminal neuralgia.
Suprasellar meningioma, which forms in the center of the base of the skull. Tumors in this area can cause visual problems and dysfunction of the pituitary gland.
Any meningioma may come back. When a meningioma does recur, it may be the same grade as the previous tumor or it may progress to a more aggressive or malignant form.