Meningiomas are tumors that grow from the covering of the brain (meninges) or the spinal cord. Most meningiomas (90%) are categorized as benign tumors, with the remaining 10% being atypical or malignant. However, the word “benign” can be misleading in this case, because when benign tumors grow, constricting and affecting the brain, they can result in disability and even a life threatening condition.
A primary brain tumor originates in the central nervous system, while metastatic brain tumors spread to the brain from other parts of the body. Meningiomas account for about 27% of primary brain tumors, making them the most common of that type.
Meningiomas are most common in people between the ages of 40 and 70. Among middle-aged patients, there is a marked female bias, with a female: male ratio of almost 3:1 in the brain and up to 6:1 in the spinal cord. Meningiomas are very rare in children, with pediatric cases accounting for only 1.5% of the total.
In many cases, benign meningiomas grow slowly meaning that depending upon its location, a meningioma may reach a relatively large size before it causes symptoms. Other meningiomas grow more rapidly, or have sudden growth spurts. There is no way to predict the rate of growth for a meningioma, or to know for certain how long a specific tumor was growing before diagnosis.
Meningiomas vary in their symptoms and appropriate treatment options depending on where they are located. These tumors may cause seizures, headaches, and focal neurological defects, such as arm or leg weakness, or vision loss. Patients often have subtle symptoms for a long period before the meningioma is diagnosed. Sometimes memory loss, carelessness, and unsteadiness are the only symptoms.
Meningiomas can occur in people with certain inherited diseases, such as neurofibromatosis, however, most commonly they arise spontaneously. These tumors, although not malignant, are usually treated surgically; however, when they are very large, or have a large blood supply, surgical removal is riskier. When this is the case, they may be treated through endovascular methods by placing a catheter into the blood vessels supplying the tumor and injecting materials to block off the blood supply to the tumor. This procedure, called embolization, is usually performed within a few days prior to the surgery.