Meningioma Facts

A meningioma is a tumour of the meninges:The meningesThe skull protects the brain. Inside the skull, and covering the brain, are 3 thin sheets of body tissue. These are called the meninges and also help to protect the brain. This is the name given to the protective lining of the brain and spinal cord. It can occur in any part of the brain or spinal cord but the commonest sites are at the surface of the brain, either over the top or at the skull base.

About 1 in 4 primary brain tumours in adults (25%) is a meningioma. They are more common in older people and in women. These are tumours growing in the tissues covering the brain. They are most often found in the forebrain or hindbrain. They are usually benign (not cancerous).Some meningiomas are 'atypical'. This means that they behave more aggressively than normally expected for meningiomas. They can grow into surrounding brain tissue and may come back after they have been removed.Meningioma symptoms vary a lot, depending on where in the brain they are growing.Meningiomas are almost always benign and do not spread. Malignant (cancerous) meningiomas are extremely rare. It is also possible, but very rare, to have more than one meningioma. Multiple meningiomas are also extremely rare and present special problems.

How often do meningiomas occur?Because this is a rare condition, meningiomas generally do not occur often, they affect around 1 per 38,000 people. Their incidence increases with age, and they are most commonly found in middle-aged or elderly people, but they also affect younger people & teens.

The majority of meningiomas (over 90%) are benign, but occasionally they recur or re-grow after apparently complete surgical resection. Atypical and malignant meningiomas are more likely to recur.

What causes meningiomas? Like most brain tumours the cause of meningioma is unknown. In some people there may be an underlying genetic abnormality such as a mutation in a specific gene. Recent research has also shown a possible link between meningioma and hormone levels. Meningiomas frequently possess progesterone receptors and, less commonly, oestrogen receptors, which may explain their higher incidence in women.

What are the symptoms?These can vary greatly, dependent on where the tumour is. Symptoms are caused by brain displacement or compression, not by invasion. However, these tumours can be so slow growing that they may go undetected for years. They can grow in and around cranial nerves that control function so that eyesight, taste, smell, sensation (numbness), swallowing or other movement may be affected. They may cause fits or muscle weakness. Sometimes sudden unexplained and/or recurrent severe headaches (which may be accompanied by nausea and/or vomiting) are the first symptom. Occasionally, an eye examination may reveal abnormalities, which lead on to further investigation and diagnosis.

Tests and investigationsIn order to plan the correct treatment doctors need to get as much information as possible about the type, position and size of the tumour. Initially, a neurological examination will take place to assess any effect the tumour has had on the nervous system.
A CT scan or MRI scan will then be done to find the exact position and size of the tumour. MRI scans are the most widely used diagnostic tests since they are very effective in identifying even small meningiomas. The MRI scan usually includes injection of a contrast (a short-acting dye) in order to determine the exact position and size of the tumour. Occasionally, an angiogram will be done, where dye is used to show up the blood vessels in the brain and their relationship with the meningioma.

To confirm the exact type of tumour, a biopsy or sample of cells is taken from the tumour and examined under a microscope, but this is typically done at the time of surgical removal.
The treatment of meningioma depends on a number of factors including your general health, the size and position of the tumour and the rate of progression of the symptoms.
SurgeryWhere possible, surgery is the first form of treatment for meningioma and in many cases the tumour can be removed completely. So far this has been the principal form of treatment for meningioma and it is still so in many circumstances. Surgical resection of meningiomas always has some risk, and growth or size of the meningioma or the progression of the symptoms should justify the risk.

For meningiomas located near the surface of the brain, surgery is often the best option. For meningiomas that are deep (cavernous sinus, medial sphenoid wing, parasellar, skull base and clivus), complete surgical removal may not be possible or it may involve too much risk to the cranial nerves or blood vessels. In addition, meningiomas sometimes recur, especially those that are atypical (on the borderline between benign and malignant). Radiation therapy may then be used to control their regrowth, whereas radiosurgery is increasingly used instead of surgery to control small meningiomas.

Radiation therapy – Conventional radiotherapy may be used after surgery if the meningioma cannot be totally removed, in order to destroy any remaining tumour cells. Radiotherapy and radiosurgery have become a promising alternative to surgery in the treatment of surgically inaccessible meningiomas.

In RT (stereotactic radiotherapy or radiosurgery) a highly focused radiation is given, which precisely targets the tumour with little impact on healthy brain tissue. Radiation is administered in multiple smaller treatments over a number of weeks (often 30 sessions given over six weeks). This allows the overall total dose to be higher than in standard radiation, because it allows normal brain tissue to recover better. It stops tumour growth in the vast majority of cases and in some people it may even cause the tumour to shrink. Each treatment is called a “fraction” therefore this type of therapy is sometimes called “fractionated” therapy. Fractionated stereotactic radiosurgery is often called FSR.

Radiosurgery can be given either with a gamma knife or a modified linear accelerator. Gamma knife radiosurgery is generally a single treatment planned and delivered all in one day, but fractionated radiotherapy using a linear accelerator has overtaken it, as it is safer for most tumours, (though not all). READ RADIOTHERAPY NOTES

Hormonal therapy and chemotherapy – These options have been tried in a small number of patients when meningiomas recurred despite treatment with surgery and/or radiotherapy. Hormonal therapy is based on the fact that many meningiomas contain receptors for hormones such as progesterone. Anti-progesterone drugs have been tried in a few clinical trials, but results thus far have been disappointing. The use of chemotherapy is limited by the fact that meningiomas are typically slow growing and therefore not very susceptible to chemo drugs. These modes of treatment are still not proven and are rarely used, especially when other proven treatment options are available.

Watch and WaitSmall, asymptomatic (few or no symptoms or signs) meningiomas can be carefully observed and followed with regular MRI scans. This can be an option where the tumour is slow growing, and it may be preferable, particularly in elderly patients, when there are no clinical signs (symptoms or impairments). A possible advantage is that better treatments and procedures may be available by the time treatment is needed.