Meningiomas are generally considered benign brain tumors. These tumors are a common variety of brain tumors accounting for 15-25% of neoplasms that arise in the brain with an incidence of approximately 6 per 100,000 population. They occur commonly in the middle age or elderly with a peak incidence during the 6th and 7th decades of life. There is a female predominance. They may occur in association with hereditary syndromes such as neurofibromatosis.
Meningiomas are overwhelmingly located attached to the dura, a covering of the brain. About 3% are located in the ventricles. The tumors may occur over the cerebral convexities or surface of the brain; along the base of the brain in regions such as the orbits, olfactory groove, sphenoid ridge, falx, tentorium, petro-cliva or in the suprasellar region; or in the spine. The presenting symptoms and signs are therefore associated with the area of the brain involved with the tumor. Tumors over the surface of the brain may present with seizures and headaches while those along the base of the brain may present with loss of vision, double vision, balance difficulties, or headaches. The tumors are diagnosed with CT or MR imaging.
Small or moderated sized tumors located in area that are not well-suited for surgery may be good candidates for Gamma Knife radiosurgery. Gamma Knife radiosurgery may also be a good treatment option for patients with small or focal recurrent meningiomas after surgery.
Treatment options depend on the specifics of the individual patient. These include observation with serial CT or MR imaging, surgical resection, or radiation treatment. For example, older patients with small or moderate sized meningiomas may be best treated with observation and serial CT or MR imaging. Younger patients the meningiomas located in a surgically respectable location may be treated primarily with surgery.
Complications and Outcomes
Meningiomas generally grow at a slow rate that may take years to increase in size to a point that they become symptomatic. The rate of growth varies with individual tumors. Progression is also associated with the histological grade. Tumors are generally classified in WHO grades I/IV (82%), II/IV(12%), or III/IV(3%). Gamma Knife radiosurgery controls the growth of meningiomas in greater than 80% of tumors. Radiosurgery does not necessary decrease the size of the tumor. The incidence of significant radiation induced injury is low, often less than 5%, but is dependent upon a number of factors. These include location of tumor near critical brain structures, size of the tumor, or dose of radiation delivered.