What are the causes?

A meningioma is a tumor that develops from the meninges—the membranes that surround the brain and spinal cord. The outermost layer is called the dura mater, lined by a thin transparent membrane called the arachnoid, which is the origin of meningiomas. By growing toward the inside of the skull, they gradually compress the brain, spinal cord, or nerves, which can cause neurological disorders. The majority of meningiomas are benign and slow-growing, although some can be more aggressive or located in areas where resection is delicate.

*Anterior clinoid process meningioma — MRI.*

Who's concerned?

Meningiomas represent approximately 36% of all primary brain tumors. They occur most often between the ages of 40 and 70 and are rare in children.

Diagnosis

The lesion is discovered via CT scan or MRI, prescribed in response to symptoms of cerebral or spinal origin. As meningiomas are very characteristic, these exams often allow for near-diagnostic certainty. MRI is the gold standard for specifying the characteristics of the meningioma.

Therapeutic options

Since meningiomas grow slowly, it is not always necessary to treat them. The choice depends on the type of disorders caused, the patient's age and health status, as well as the location and size of the tumor.

MRI monitoring Suitable for elderly patients with few or no symptoms, and for meningiomas linked to certain hormonal treatments (e.g., cyproterone acetate)—upon discontinuation of treatment, the meningioma generally stabilizes or regresses without intervention.
Surgical resection The most common treatment for symptomatic meningiomas. Operative risks vary depending on the location—some interventions are complex, particularly when the meningioma is located at the skull base.
Radiotherapy / Radiosurgery Indicated in cases of incomplete removal, high risk of recurrence (grade II or III), inoperable meningioma, or small size accessible to stereotactic radiosurgery.

Surgery

Technological progress has considerably improved surgical precision, allowing for better tumor delimitation, avoidance of functional areas, and making interventions safer and less invasive.

Among these advances, we notably have neuronavigation, neuro-monitoring, endoscopy, ultrasonic scalpels, and micro-Doppler.

Radiotherapy

The effects of radiotherapy are not immediate: the tumor gradually stops growing and may decrease in size, but exceptionally disappears. There are two main techniques:

Stereotactic radiosurgery

Delivery of a high dose in a single or a few sessions (Gamma Knife, CyberKnife, Novalis). The head is immobilized by a frame or a custom-made face mask. No incision is made.

Fractionated radiotherapy

Daily sessions over 5 to 6 weeks (resting on weekends). The dose is delivered in fractions to allow healthy cells to repair themselves between sessions, thereby reducing side effects.

LEARN MORE ABOUT RADIOTHERAPY →

Post-treatment monitoring

After surgical treatment or radiotherapy, the patient is followed regularly with MRI checks over many years. Although the risk of recurrence decreases over time, a recurrence can occur late—it is therefore essential to maintain this long-term follow-up.

Search

Clinical research

Data from patients treated in our department are analyzed to better understand these tumors and evaluate our results. Our department is particularly interested in the links between meningiomas and exogenous hormonal treatments (contraceptive pills, HRT for menopause, endometriosis treatments).
Fundamental research

Small fragments of operated meningiomas are preserved in the Lariboisière Hospital biobank (CRB — Biological Resource Center), following patient information and written consent. These samples are essential for understanding the origin of meningiomas and developing new treatments.

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 frequent mode of discovery.
Symptoms most often appear gradually and vary depending on where the meningioma is located and which nerve structures they compress.
Meningiomas can cause headaches, convulsions or epileptic seizures, weakness in the arm or leg, speech or vision disorders, 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 very diverse symptoms depending on the exact spot where they are found.
Skull base meningiomas, located under 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.

The precise cause and mechanisms of meningioma development are not known, but a number of risk factors have been clearly identified. Some can be considered the direct cause of the meningioma, even if the mechanisms are not yet fully understood.

Identified risk factors

Exposure to ionizing radiation
People who have undergone cranial radiotherapy, particularly in childhood, have an increased risk of developing one or more meningiomas.
Genetic factors
The presence of certain genes inherited from ancestors, as well as certain genetic diseases such as neurofibromatosis, are associated with an increased risk.
Hormonal factors
Meningiomas are more common in women. Their growth can accelerate during pregnancy and decrease after childbirth. It is now proven that taking progestogens promotes meningiomas.

Progestogens and meningiomas

Progestogens are used in many indications: gynecological diseases (endometriosis, fibroids, cycle disorders), hormone replacement therapy, oral contraception, intrauterine devices, or in obstetrics. Certain progestogens can be the direct cause of meningiomas:

Progestogens with established risk

Cyproterone acetate (Androcur®)
Nomegestrol acetate (Lutenyl®)
Chlormadinone acetate (Luteran®)

ANSM Recommendations

It is possible that some patients are more susceptible than others to developing meningiomas under the influence of these treatments—which is the subject of much current research.

Department research

Our team was the first to identify the risk of meningioma with cyproterone acetate and nomegestrol acetate. This has been a major research topic since the arrival of Prof. Sébastien Froelich in 2011, in close collaboration with the Epi-Phare agency and the ANSM.

Founding publication — cyproterone acetate Does cyproterone acetate promote meningiomatosis? — 56th Congress of the French National Society of Internal Medicine
Founding publication — nomegestrol acetate Spontaneous regression of meningiomas after interruption of nomegestrol acetate — Acta Neurochir, 2019
France Culture Podcast — Androcur and meningiomas Listen to the podcast on France Culture →

List of publications

Prolonged use of nomegestrol acetate and risk of intracranial meningioma: a population-based cohort study Nguyen P, Roland N, Neumann A, Hoisnard L, Passeri T, Duranteau L, Coste J, Froelich S, Zureik M, Weill A.
Use of progestogens and the risk of intracranial meningioma: national case-control study. Roland N, Neumann A, Hoisnard L, Duranteau L, Froelich S, Zureik M, Weill A. — BMJ, 2024.
Opposed evolution of the osseous and soft parts of progestin-associated osteomeningioma after progestin intake discontinuation. Florea SM, Passeri T, Abbritti R, Bernat AL et al. — J Neurosurg, 2023.
Risk of intracranial meningioma with three potent progestogens: A population-based case-control study. Hoisnard L, Laanani M, Passeri T, Duranteau L et al. — Eur J Neurol, 2022.
The tumours and the three bumps. Bousson V, Guichard JP, Froelich S, Orcel P. — Lancet Oncol, 2022.
Atypical evolution of meningiomatosis after discontinuation of cyproterone acetate. Passeri T, Giammattei L, Le Van T et al. — Acta Neurochir, 2022.
Intracranial Meningiomas Decrease in Volume on MRI After Discontinuing Progestin. Voormolen EHJ, Champagne PO, Roca E et al. — Neurosurgery, 2021.
Use of high dose cyproterone acetate and risk of intracranial meningioma in women: cohort study. Weill A, Nguyen P, Labidi M et al. — BMJ, 2021.
Cyproterone acetate and meningioma: a nationwide population-based study. Champeaux-Depond C, Weller J, Froelich S, Sartor A. — J Neurooncol, 2021.
Spontaneous regression of meningiomas after interruption of nomegestrol acetate: a series of three patients. Passeri T, Champagne PO, Bernat AL et al. — Acta Neurochir, 2019.
Combined hormonal influence of cyproterone acetate and nomegestrol acetate on meningioma: a case report. Champagne PO, Passeri T, Froelich S. — Acta Neurochir, 2019.
Regression of Giant Olfactory Groove Meningioma after Discontinuation of Cyproterone Acetate. Bernat AL, Bonnin S, Labidi M et al. — J Ophthalmic Vis Res, 2018.
Growth stabilization and regression of meningiomas after discontinuation of cyproterone acetate: a case series of 12 patients. Bernat AL, Oyama K, Hamdi S et al. — Acta Neurochir, 2015.
Regression of meningiomas after discontinuation of cyproterone acetate in a transsexual patient. Cebula H, Pham TQ, Boyer P, Froelich S. — Acta Neurochir, 2010.
Does cyproterone acetate promote multiple meningiomas? Froelich S et al. — 10th European Congress of Endocrinology.

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