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Meningiomas are tumors of the meninges, with most being benign. Atypical meningiomas may be malignant and grow back after treatment, while grade III meningiomas grow aggressively. Diagnosis is made through MRI and symptoms include headaches, seizures, and sensitivity to light. Treatment involves surgical removal and radiation therapy.
Meningiomas are tumors of the meninges, the membrane that covers the brain and spinal cord. Most commonly, these are benign meningiomas, or grade I meningiomas, which stay small and don’t grow indefinitely like cancerous tumors. An atypical meningioma, also called grade II meningioma, is a meningeal tumor that may be malignant and grow back after treatment or removal. A grade III meningioma grows aggressively, threatening to compress adjacent brain tissue and invade bone. Even a benign meningioma can be dangerous due to its proximity to the brain.
One of the most common forms of brain tumors, meningiomas account for approximately 30% of all such tumors. Diagnosis of meningiomas is most often made through magnetic resonance imaging (MRI). Patients who have symptoms will first have had a neurological exam and then brain imaging to determine if they have a brain tumor. In asymptomatic patients, diagnosis sometimes occurs during brain imaging required for another medical complaint.
Symptomatic patients often have the atypical or malignant varieties. They report neurological symptoms such as headaches, seizures, loss of sensation, nausea, blurred vision and sensitivity to light. They can develop almost anywhere in the nervous system, but most meningiomas occur in the head, often near the brainstem, base of the skull, sinus venosus, or optic nerve sheath.
An atypical meningioma is more common in middle-aged or older women and is rare in children; Spinal meningiomas are rarely found in men. They have a faster growth rate than grade I tumors, but grow less rapidly than those that are clearly malignant. Grade II meningiomas comprise less than 10% of the total incidence. Malignant cases of II degree are about 2%.
Scientists have linked the onset of maningiomas to a mutation in a gene encoding a tumor suppressor protein. Severe, congenital mutations of this gene cause a syndrome in which patients develop multiple benign tumors. Other mutations carry a higher risk of benign or atypical meningioma. A small percentage of cases have been linked to an inherited form of the disease; most children who develop grade II meningiomas fall into this category. Grade II and III meningiomas in children are often quite severe and rapidly progressing.
An atypical meningioma may require treatment to prevent further growth. Any tumor that causes symptoms in the patient is usually treated as if it were malignant. Treatment involves surgical removal and follow-up with radiation therapy to kill remaining cancer cells.
The decision to treat the tumor is made based on its growth, present and future risks to the brain tissue, age and health of the patient, and possible consequences of the surgery such as infection or brain edema. Sometimes the shock of radiation and surgery might be more of a problem than the risk imposed by a slow-growing tumor. For example, in elderly patients who do not have fast-growing tumors, regular observation is often preferred as a treatment, because surgery may present more life-threatening complications than the tumors themselves. A grade I tumor rarely comes back if it was surgically removed, but an atypical meningioma has a higher risk of coming back.
