Meningioma: Symptoms, Treatment, and Specialists

Most brain tumors develop from the brain tissue itself. 

A meningioma, on the other hand, arises from the cells of the meninges. The meninges consist of three layers. In a meningioma, the arachnoid membrane—the middle layer—is affected. The tumor often grows adjacent to the dura mater, which can be significant during surgery. The cells of this meningeal layer then grow uncontrollably.

Why the growth of these cells gets out of control has not yet been fully clarified. In addition to known risk factors, genetic changes may also play a role in the development of meningiomas.

However, researchers have identified risk factors that increase the likelihood of developing a meningioma. These include

• radiation therapy for a previous cancer,
• dental X-ray diagnostics (depending on the X-ray technique used and the time at which the diagnostic procedure was performed),
• the hereditary condition neurofibromatosis type 2. People with this condition are significantly more likely to develop meningiomas. Often, multiple meningiomas form, whereas people without this hereditary condition typically develop only one tumor.

Meningiomas form in the arachnoid membrane, the middle layer of the meninges © olgadanilina | AdobeStock

A meningeal tumor grows very slowly, so the first signs often do not appear until years after the tumor has begun to develop. The clinical symptoms depend heavily on the tumor’s location. Symptoms do not appear until the tumor mass begins to displace neighboring brain regions or nerve structures. However, these symptoms are extremely nonspecific and can also occur in other conditions.

If the tumor is located near the motor center, patients experience paralysis of the arms and legs.

Meningiomas located in the olfactory groove of the brain, on the other hand, result in a reduction or loss of the sense of smell. However, since these olfactory disturbances tend to develop gradually, they often go unnoticed.

A meningioma can also irritate the three meninges and trigger epileptic seizures. During these episodes, patients briefly lose control of their bodies and experience twitching and convulsions. In some cases, they may also lose consciousness.

The tumor increases the pressure inside the skull. Elevated intracranial pressure manifests through various symptoms. These include:

• Headaches
• Vomiting
• Dizziness
• Paralysis of the eye muscles with visual disturbances
• Respiratory and consciousness disturbances
• edema around the optic disc (papilledema)
• Rise in blood pressure accompanied by a drop in heart rate

In most cases, these symptoms develop gradually. If meningiomas occur on the meninges in the area of the spinal cord, this leads to what is known as local compression syndrome. Patients complain of sensory disturbances and pain in the corresponding distribution area. A significant mass within the spinal canal leads to myelopathy. Depending on its location, this manifests as

• gait disturbances,
• sensory disturbances, and
• difficulty with bowel and bladder function.

In some cases, the meningioma grows so slowly that the brain is able to adapt to the structural changes. These asymptomatic brain tumors are discovered incidentally during a CT or MRI scan.

Various imaging techniques can be used to diagnose a meningioma. Modern imaging plays a central role in diagnosis. The most commonly used method is magnetic resonance imaging (MRI). MRI is the standard for intracranial tumors in particular, as it clearly distinguishes between different soft tissue types and does not involve radiation exposure. During an MRI, the administration of a contrast agent can also help to more clearly delineate the meningioma.

This imaging method is also almost exclusively used for examining the spinal canal.

A more detailed characterization of the space-occupying lesion in the brain can be achieved using

• magnetic resonance spectroscopy (MRS),
• diffusion-weighted MRI, and
• measuring cerebral blood flow using computed tomography.

Despite the findings from the imaging techniques mentioned, only the examination of tissue samples can confirm the diagnosis. This is particularly important when a brain tumor is detected for the first time. To do this, tissue is removed from the tumor during surgery and then examined in the laboratory.

Not every meningeal tumor requires treatment. Watchful waiting is considered the primary form of therapy for smaller meningiomas when no symptoms are present. This requires patients to visit a radiologist at regular intervals. The radiologist uses CT or MRI to monitor whether the tumor is growing or remaining stable.

If, on the other hand, the tumor causes symptoms, treatment is usually surgical, often involving open surgery. For tumors with a particularly rich blood supply, preoperative embolization may be advisable. In this procedure, the blood vessels are blocked to reduce the risk of significant blood loss during surgery.

If meningiomas cannot be completely removed, radiation therapy follows. This involves the use of high-dose ionizing radiation, which is intended to damage the tumor’s genetic material and thus prevent its growth.

Another treatment option is the Gamma Knife: This radiosurgical device focuses radiation beams at a single point to destroy the tumor.

The prognosis for this brain tumor depends primarily on the severity of the disease. It is classified according to the WHO grade as I, II, or III.

Most meningiomas are classified as WHO Grade I. They typically grow slowly and can usually be completely removed during surgery, resulting in a very good prognosis.

About ten percent of all meningiomas are classified as WHO Grade II. They can grow faster than Grade I tumors and are more likely to recur after successful surgery.

WHO Grade III meningiomas are classified as malignant. Unlike Grade I and II tumors, they can also metastasize to other organs. The chances of a cure are low in these cases, and the prognosis is correspondingly poor.

Overall, the 5-year survival rate for meningiomas is more than 90 percent. This means that 90 percent of patients are still alive five years after diagnosis.