A meningioma is a tumor that develops from the meninges. The brain and spinal cord are surrounded by an envelope called the meninges. The outermost, thickest layer is called the dura mater. A second, thin, transparent membrane called the arachnoid doubles the dura mater. It is the origin of meningiomas. Between the arachnoid and the brain lies the cerebrospinal fluid (CSF).
Because meningiomas tend to grow towards the inside of the skull, they progressively compress the brain or spinal cord and nerves, and can cause neurological disorders.
The majority of meningiomas are non-cancerous, benign and slow-growing. However, some may be more aggressive and located in areas where resection is perilous.
Some people with meningiomas have no symptoms at all. The tumor may be discovered during a radiological examination (CT scan or MRI) carried out for another reason or for screening. This is called serendipity. This is an increasingly common method of discovery.
Symptoms usually appear gradually, and vary according to the location of the meningioma and the nerve structures it compresses.
Meningiomas can cause headaches, convulsions or epileptic seizures, weakness in the arm or leg, speech disorders, visual problems, abnormal sensations, personality changes, balance problems, dizziness, hearing loss, loss of smell…..
Meningiomas are classified into several grades. Treatment varies according to this grade, defined by analysis of a sample obtained at the time of surgery.
- Grade I: Benign meningiomas. They are slow-growing. If the meningioma doesn’t cause symptoms, it’s often more sensible to monitor it with a regular MRI or CT scan before treating it. Some meningiomas do not grow. They can also sometimes regress spontaneously when a hormonal treatment (progestogen therapy) that favored their growth is stopped.
- Grade II: Atypical meningiomas. They are more aggressive, with a higher risk of recurrence once the meningioma has been removed. Some grade II meningiomas require radiotherapy after surgery.
- Grade III: Malignant meningiomas. They are the most aggressive, but account for less than 1% of all meningiomas. It’s a rare, serious pathology, and surgery is always followed by radiotherapy. The risk of recurrence is high.
- Meningiomas are named according to their location (frontal meningioma, temporal meningioma, cavernous sinus meningioma ….) and can cause a wide variety of symptoms depending on their exact location.
Meningiomas of the skull base, located beneath the brain, are among the most complicated to treat, due to their deep location and the difficulty of accessing them. These meningiomas require specific advanced surgical techniques to access them, and are one of our department’s specialties.
Who’s concerned?
Meningiomas account for around 36% of all primary brain tumors. They most often occur between the ages of 40 and 70. They are rare in children.
How is the diagnosis made?
The lesion is discovered on CT scan or MRI , prescribed in the presence of symptoms suggesting a cerebral or spinal cord origin. As meningiomas are very characteristic, these examinations often provide a virtually certain diagnosis. MRI is the most important examination for determining the characteristics of the meningioma.
What treatments are available?
Because they grow slowly, they don’t necessarily need to be treated, and monitoring can be a temporary and sometimes permanent solution. This is the case for meningiomas caused by certain hormone treatments such as cyproterone acetate. When treatment is discontinued, the meningioma usually stabilizes or regresses, and no further treatment is required. Simple monitoring is enough.
If they need to be treated, the options are surgery and radiotherapy. The proposed treatment will depend on the type of disorder caused by the meningioma, the patient’s age and state of health, and the location and size of the meningioma.
Because meningiomas develop slowly, elderly patients with few or no symptoms can simply be monitored by regular MRI scans.
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Surgery
Surgical removal is the most common treatment for meningiomas that cause symptoms.
The risks of surgery vary according to the location of the tumor. When deciding whether to operate, the risks of surgery should be considered lower than those associated with the natural evolution of the meningioma; it is therefore sometimes preferable to simply monitor the disease and let it evolve. Some operations are very complex, when the meningioma is located in more threatening, deeper areas such as the base of the skull.
Technological advances have improved the surgeon’s ability to locate the tumour precisely, define its boundaries and avoid touching vital, functional areas of the brain. They enable safer, less invasive interventions.
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Radiotherapy
Radiotherapy is indicated when removal of the meningioma is incomplete and the tumor grows back, when there is a significant risk of regrowth after surgery (Grade II or III meningioma), when the meningioma is inoperable due to its location or the frailty of the patient’s state of health or age, or when the meningioma is small and lends itself well to radiosurgical treatment (single-dose stereotactic radiotherapy).
The effects of radiotherapy are not immediate, but occur over time. The tumor will stop growing and, in some cases, shrink in size. Exceptionally, it disappears.
There are two techniques for delivering radiation: a single high dose (stereotactic radiosurgery) or several low doses (fractionated radiotherapy).
Radiosurgery (Gamma Knife, Cyberknife, Novalis) delivers a high dose of radiation in one or more sessions. Although the word surgery is used in radiosurgery, no incisions are made. It’s because the precision of irradiation is similar to surgery that it’s been given this name.
For this treatment, the head must be completely immobilized either by a frame fixed to the head or by a custom-made face mask.
Fractional radiotherapy takes place over 5 to 6 weeks, with a session every day of the week, with a rest at the weekend. A mask is used to precisely locate the tumor. By delivering only a fraction of the total radiation dose each day, normal cells can repair themselves between treatments. This reduces side effects.
Find out more about radiotherapy
Monitoring
After treatment, whether by surgery or radiotherapy, the patient is monitored regularly, and must have regular MRI checks for many years. Although the risk of recurrence diminishes over time, it can still occur long after treatment, and it’s important not to miss out.
Search
- Clinical research: Data on patients treated in our department are studied to better understand these tumors and evaluate the results of the treatments we offer. Our department is particularly interested in the links between meningiomas and exogenous sex hormone treatments (contraceptive pills, hormone replacement therapy for menopause, hormone treatments for gynecological pathologies such as endometriosis).
- Basic research: Small fragments of all meningiomas operated on in our department are stored for research purposes. Preserving these small pieces of tumor is essential to understanding the origin of these tumors and developing new treatments. This storage of part of the meningioma removed at the time of the operation is only done after the patient has been informed and agreed. Consent is given to patients before each procedure. These samples are stored in the biobank at the Lariboisière Hospital’s CRB (Biological Resource Centre).