Meningioma is the most common intracranial tumor. Technically, it is not a “brain” tumor, but rather a tumor that can grow and press against the brain. Meningiomas arise from the middle layer of cells in a thick membrane located between the skull and brain which is called the meninges. The vast majority of meningiomas are benign and often are slow-growing. They tend to be found more often in females and older adults.
Meningiomas often arise over the outer surface of the brain just underneath the skull, along the inner sheathes that compartmentalize the brain, or along the base of the skull. Occasionally meningiomas can grow into and even through the bone. Most tend to be spherical or have multiple lobules. They can also grow like a carpet of tumor (en plaque). Molecular markers are used to identify some subtypes of meningioma.
Meningiomas are divided into three grades:
- Grade I (benign) These low-grade meningiomas are the most common and tend to grow slowly. They usually have a distinct outer wall or capsule. They may be soft or very firm in consistency. Some may be heavily calcified so that they appear bone-like on imaging studies.
- Grade II (atypical) These tumors are mid-grade and have a higher chance of recurring.
- Grade III (anaplastic) These are malignant meningiomas. They can grow rapidly, invade the brain and spread to other parts of the body.
Meningiomas are usually a benign tumor and well encapsulated, but removal may be complicated by size, firmness and attachment to vital blood vessels or brain tissues.
Often the dura removed during tumor surgery may be replaced with other body tissue (fascia) or a dura substitute.
Signs and Symptoms
Many times a meningioma may be discovered by accident on an imaging study. Sometimes even large meningiomas may produce few or no symptoms since they often grow slowly and the brain accommodates to this gradual distortion. When symptoms do develop, they reflect the area where the tumor is located.
When present in the brain, there may headaches, unsteadiness, limb weakness, sensation disturbance, problems with cognition (thinking, memory, etc.) or seizures. Spinal cord meningiomas may produce weakness or numbness, gait disturbance or trouble with bowel or bladder function.
The exact cause of a meningioma is not fully understood. Risk factors include exposure to radiation, especially during childhood, and having a genetic disorder called type 2 neurofibromatosis.
The presence of symptoms often leads to a physician visit. Many other conditions can produce similar symptoms. Diagnosis begins with the medical history and physical examination, including a neurological exam. Other tests are then used to establish the diagnosis and help guide treatment. These may include computerized tomography CT or magnetic resonance imaging MRI scans of the brain. Often the findings on these brain imaging tests are so characteristic for a meningioma that the test itself may essentially be diagnostic.
A customized treatment plan is put together for you based on:
- Your symptoms and the meningioma’s location, size and growth rate
- Your age and general health
- Your tolerance for treatment
- Your preferences
Treatment for a meningioma may include one or a combination of the following options:
- Observation Many times a neurosurgeon will recommend that your meningioma be followed by periodic neurological examinations and CT or MRI studies, especially if it is small or not producing any symptoms.
- Surgery Tumor removal may be recommended based on its size or symptoms. The risks and benefits of a surgery are always weighed carefully. Depending on factors, especially location, surgery may involve open or minimally invasive craniotomy or an open or minimally invasive skull base surgery. The goal of surgery is complete removal of the menigioma if possible. If not, the tumor is “debulked” to take pressure off the brain or other important structures affected by its presence. After surgery, your neurosurgeon may continue with observation measures to make sure it does not grow back. Surgery requires a hospital stay ranging from overnight to longer, depending on the size and location of your meningioma as well as your general state of health.
- Embolization Some meningiomas are extremely vascular. Embolization treatment may be recommended just before surgery to block off much of the blood supply to the tumor to make surgery safer and prevent significant blood loss. This depends on the size, location and type of meningioma.
- Anti-seizure medicines These medicines may be prescribed to decrease the risk for another seizure or rarely to relieve pain caused by a meningioma pushing on a nerve.
- Radiation This treatment uses high-energy particles or waves to kill or damage tumor cells. It will often be used following surgery for higher-grade meningiomas or if a low-grade meningioma recurs or cannot be completely removed and requires additional treatment. Radiation therapy may also be used initially if treatment is needed and the risk of surgery is too high. External beam radiation therapy or stereotactic radiosurgery may be used, depending on the size and location of your meningioma.
- Corticosteroids These medicines may provide temporary relief of symptoms related to swelling around the tumor.
- Therapies Sometimes a meningioma and its subsequent treatment may affect your motor skills, speech, swallowing or even cognitive abilities, depending on its size and location. If needed, physical, occupational or speech therapies may be used to help regain or compensate for any diminished abilities. These rehabilitative therapies may be performed in an inpatient or outpatient setting.
Follow-up care includes regular monitoring of your clinical condition as well as routine surveillance of your imaging studies (MRI or CT scan). The frequency of your follow-up visits are mostly determined by the grade of your meningioma, its rate of growth and its status following treatment.