A meningioma is a tumor that arises from a layer of tissue (the meninges) that covers the brain and spine. Meningiomas grow on the surface of the brain (or spinal cord), and therefore push the brain away rather than growing from within it. Most are considered “benign” because they are slow-growing with low potential to spread.
Meningioma tumors can become quite large. Diameters of 2 inches (5 cm.) are not uncommon. Meningiomas that grow quickly and exhibit cancer-like behavior are called atypical meningiomas or anaplastic meningiomas, and are fortunately rare. Meningiomas represent about 20 percent of all tumors originating in the head and 10 percent of tumors of the spine.
• Visual changes; meningioma can cause partial or complete loss of vision, typically in one eye.
• Hearing loss.
• Changes in thinking; people with large meningioma may have subtle changes in their personality or thinking.
• Arm and/or leg weakness; a meningioma can cause weakness in the arms, legs, or both, depending upon the location of the tumor.
• Headaches, nausea, and vomiting; as a meningioma grows, its increasing size can increase the pressure inside the skull. This can lead to headaches, nausea, and vomiting. In some people, the meningioma can block the flow of spinal fluid around the brain and spinal cord. This can also increase pressure in the skull and cause the same symptoms.
• Grade I or benign meningiomas
Benign (non-cancerous) meningiomas are slow-growing tumors that often do not affect nearby normal brain. Benign meningiomas are the most common type, including more than 90 percent of all meningiomas. Many benign meningiomas do not need any treatment. Most benign meningiomas that are treated do not come back after treatment.
• Grade II or atypical meningiomas
Atypical meningiomas usually grow more rapidly than benign meningiomas and have a higher chance of growing back after treatment.
• Grade III, anaplastic, or malignant meningiomas
Malignant meningiomas are a form of brain cancer, and are most likely to grow back after treatment.
Observation and Waiting
Meningiomas are often slow growing, increasing is size only 1-2 mm per year. Repeating yearly MRI scans may be appropriate in the following situations:
• Patients with small tumors and mild or minimal symptoms, no impact on quality of life, and little or no swelling in adjacent brain areas.
• Older patients with very slowly progressing symptoms. Related seizures can be controlled with medication.
Surgery is the preferred treatment for most meningiomas, especially for tumors that are large, growing quickly, or causing symptoms. The goal of surgery is to remove as much of the tumor as possible. However, this is not always possible, depending upon the size and location of the meningioma. In addition, some tumors cannot be totally removed because the tumor is too close to or involved with important parts of the brain or blood vessels. In such cases, the tumor may be only partially removed.
After surgery, it is possible that the tumor will come back. This risk depends upon how much tumor was removed and whether it was benign, atypical, or malignant. If the tumor is not removed completely with surgery, radiation therapy is often recommended after surgery to reduce the risk of it coming back.
The goals of surgery are to:
• Obtain tissue to confirm the diagnosis
• Remove sufficient tumor in order relieve pressure or distortion of the normal brain tissue
When total removal of the tumor carries significant risk of morbidity (any side effect that can decrease quality of life), it’s better to leave some tumor tissue in place.
If the tumor invades any of the large draining veins, major arteries on the brain surface, or if it is on the underside of the brain, chances of a complete resection decrease and risk of complications increases.
• Preserve and/or improve neurological function
• If possible and safe, remove the entire tumor so that it will not grow back
Meningioma tumors that are near the surface and have not invaded deep structures or major blood vessels are more likely to be totally removed safely.