In another study, clinical outcomes were compared for 213 patients undergoing surgery vs. 351 patients under watchful observation. Only 6% of the conservatively treated patients developed symptoms later, while among the surgically treated patients, 5.6% developed persistent morbid condition, and 9.4% developed surgery-related morbid condition.Observation is not recommended in tumors already causing symptoms. Furthermore, close follow-up with imaging is required with an observation strategy to rule out an enlarging tumor. Surgery
Meningiomata usually can be surgically resected (removed) and result in a permanent cure if the tumor is superficial on the dural surface and easily accessible. Transarterial embolization has become a standard preoperative procedure in the preoperative management. If invasion of the adjacent bone occurs, total removal is nearly impossible. It is rare for benign meningiomata to become malignant.The probability of a tumor recurring or growing after surgery may be estimated by comparing the tumors WHO (World Health Organization) grade and by the extent of surgery by the Simpson Criteria. Radiation therapy
Radiation therapy may include photon-beam or proton-beam treatment, or fractionated external beam radiation. Radiosurgery may be used in lieu of surgery in small tumors located away from critical structures. Fractionated external-beam radiation also can be used as primary treatment for tumors that are surgically unresectable or, for patients who are inoperable for medical reasons.Radiation therapy often is considered for WHO grade I meningiomata after subtotal (incomplete) tumor resections. The clinical decision to irradiate after a subtotal resection is somewhat controversial, as no class I randomized, controlled trials exist on the subject.
Genetics
The most frequent genetic mutations (~50%) involved in meningiomata are inactivation mutations in the neurofibromatosis 2 gene (merlin) on chromosome 22q.TRAF7 mutations are present in about one-fourth of meningiomata. Mutations in the TRAF7, KLF4, AKT1, and SMO genes are commonly expressed in benign skull-base meningiomata. Mutations in NF2 are commonly expressed in meningiomata located in the cerebral and cerebellar hemispheres. Pathophysiology
Meningiomata arise from arachnoidal cap cells, most of which are near the vicinity of the venous sinuses, and this is the site of greatest prevalence for meningioma formation. Some subtypes may arise from the pial cap cells that migrate during the development together with blood vessels into the brain parenchyma. They most frequently are attached to the dura over the superior parasagittal surface of frontal and parietal lobes, along the sphenoid ridge, in the olfactory grooves, the sylvian region, superior cerebellum along the falx cerebri, cerebellopontine angle, and the spinal cord. The tumor is usually gray, well-circumscribed, and takes on the form of the space it occupies. They usually are dome-shaped, with the base lying on the dura. Locations
Parasagittal/falcine (25%)
Convexity (surface of the brain) (19%)
Sphenoid ridge (17%)
Suprasellar (9%)
Posterior fossa (8%)
Olfactory groove (8%)
Middle fossa/Meckels cave (4%)
Tentorial (3%)
Peri-torcular (3%)
Intraparenchymal (rare)Other uncommon locations are the lateral ventricle, foramen magnum, and the orbit/optic nerve sheath. Meningiomata also may occur as a spinal tumor, more often in women than in men. This occurs more often in Western countries than Asian.Histologically, meningioma cells are relatively uniform, with a tendency to encircle one another, forming whorls and psammoma bodies (laminated calcific concretions).