Meningiomas

What is a meningioma?

A meningioma is a benign (non-cancerous) tumour that arises from the protective lining of the brain or spine called the dura, a membrane that sits between the brain and the skull and spinal cord/nerves and spine. They do not come from, nor spread to, the rest of the body. Most meningiomas are slow growing with an average growth rate of 1-2mm per year. Some, once detected, do not grow further having ‘burnt out’.

They can occur in any location and sometimes there can be more than one. Your surgeon will give you more information about the location of your specific tumour and if there is evidence of others. When they grow they tend to do so by growing inward from the dura, sometimes causing pressure on the brain or spinal cord giving rise to symptoms. Sometimes they can cause an overgrowth of the surrounding bone, giving an appearance of thickening of the surrounding bone on scans.

At least a quarter of primary brain tumours are thought to be meningiomas. Their overall prevalence is approximately 1 in 40,000 in the general population. They are more frequently found in women and those over 40.

The most common locations for meningiomas in the brain are as follows:

Convexity – These tumours grow on the surface of the brain.
Falx and parasagittal – The falx is a sheet of dura that runs between the two sides of the brain, front to back. Running along the top of this sheet is a large blood vessel, called the superior sagittal sinus which helps to drain blood from the brain. Falx tumours arise from dura folded into the groove between the two hemispheres. Parasagittal tumours arise from the dura close to the superior sagittal sinus at the top.
Sphenoid wing – These tumours lie along the sphenoid bone, which makes up part of the skull base, behind the eyes.
Olfactory groove – Olfactory groove meningiomas grow from the area at the front of the skull base where the nerves for smell run between the brain and the nose, and therefore very commonly affect smell and taste.
Suprasellar – These meningiomas grow above a bony depression that houses the pituitary gland and are very close to where the optic nerve from each eye intersects with the other. As a consequence they can affect vision if they grow.
Posterior fossa – Posterior fossa tumours arise at the underside of the brain. They commonly affect balance and co-ordination.
Intraventricular – Intraventricular meningiomas are associated with the connected chambers of fluid, known as cerebro-spinal fluid (CSF), that circulate throughout the brain and spine.
Spine – They can occur at any point in the spine and grow in from the lining (dura) which surrounds the spinal cord and cauda equina. Symptoms depend on their size, and where in the spine they occur.

When tested in the laboratory they are graded as 1-3 and this relates to their growth potential/ability. Grade 1 meningiomas are the most common and slowest growing kind.

What are the causes of meningiomas?

For the majority of people the cause is unknown. A small number of people develop meningiomas after radiotherapy to the head and spine. This tends to be after whole brain or spine radiotherapy, is rare, and occurs years after the primary treatment. A very small proportion of patients with meningiomas, usually multiple, have a genetic condition that pre-disposes them to meningiomas. This again is uncommon. Your surgeon will discuss this with you if this is applicable.

What are the symptoms?

Symptoms are very variable according to the location of the meningioma. Many patients do not have any symptoms related to their meningiomas and they have been found incidentally while performing brain or spine imaging for a different problem. You doctor will talk through your symptoms, if you have any, when they see you as to whether they relate to your meningioma.

How will the diagnosis be made?

Usually diagnosis is made from imaging, a computerized tomography scan (CT) or a magnetic resonance imaging scan (MRI). Often if you have only had a CT scan and can safely have an MRI scan you will be asked to attend for an MRI scan as it gives greater detail than a CT for meningiomas.
You may be sent for other tests such as blood tests, scans of the rest of your body, visual tests, hearing tests. Each test will be explained fully if it is required.

What treatments are available?

Need for treatment, and what type is required varies from person to person. It varies according to tumour size, location, growth rates, symptoms, your general health and preferences.

There are three treatment options available for any meningioma:

Active surveillance with imaging +/- visual testing depending on the location of the meningioma
Surgery (to remove or reduce the size of the meningioma)
Radiotherapy/radiosurgery (aimed at stopping further growth of the meningioma)

Active surveillance with imaging

If you do not have symptoms from your meningioma it may be appropriate to simply observe the meningioma with periodic scans to assess if it is growing, or has ‘burnt out’. If it has ‘burnt out’ i.e. has stopped growing observation may be all that is required. Typically once detected, meningiomas are monitored with scans for up to 15 years from their diagnosis, yearly for the first 5 years then often every other year for the remaining years. This is due to the slow growing nature of most meningiomas.

Surgery

Surgery is generally considered for meningiomas that are causing symptoms, or those that are growing and there is concern that without intervention they could cause symptoms in the future. Surgery is very different, as well as the recovery period, depending on the location and size of your meningioma. Sometimes other surgeons than just your Neurosurgeon may be involved, for example a Craniofacial or ENT surgeon depending on the location of your tumour. You will meet all involved surgeons in advance of your operation and be given the opportunity to ask any questions you may have.

The risks of the surgery vary greatly depending on these two factors too. Your surgeon will discuss the specifics of your surgery with you in great detail if that is required, including the recovery period, potential driving restrictions and so on. For general advice please see the section on 'What is it like to have a Neurosurgery Operation?' as well as consulting the Diet, Exercise and Psychology sections.

Radiosurgery & Radiotherapy

This is an effective technique that uses highly targeted doses of radiation with the aim of stopping the tumour from growing any more. Sometimes people hear of this in relation to the name 'gamma knife' - this is the name of one type of machine that can be used to deliver radio-surgery. When just one dose of radiation is required this is usually called radiosurgery, and where a course of treatments (up to 6 weeks of daily treatment) is required this is called radiotherapy. The principle behind the treatment is the same. The decision as to which course is appropriate is based on the location and size of the area to be treated.

Radiosurgery/therapy is usually offered to patients with small but growing tumours, as an alternative or adjunct to surgery. This can be delivered in one dose (single fraction) or several doses (fractionated, which can be a course delivered over a period of up to six weeks on a daily basis). What type is offered, and whether this is a safe and appropriate option, depends on the size and shape of your tumour. This will be discussed with you in more detail if required/appropriate by your Doctor.

FAQ & Resources

Is there anything I can do to reduce my risk of meningioma growth?

There is research that has shown that taking some medications containing an excess of progesterone (typically given for contraceptive reasons) can increase the risk of meningioma growth - specifically medrogestone, medroxyprogesterone acetate, and promegestone for a year or more increases the risk of intracranial meningioma. Levonorgestrel intrauterine systems do not increase people's risk (https://www.bmj.com/content/384/bmj-2023-078078). There is not evidence that HRT increases the risk of meningioma growth at present. There is some evidence that pregnancy can. If you are concerned about this please discuss with the team who is looking after your meningioma.

Other than these unfortunately at the moment there is no clear evidence that patient modifiable factors (for example dietary or exercise changes) that reduces the risk of meningioma growth.

Should I not have a biopsy?

Biopsies are offered where there is uncertainty about a diagnosis. Meningiomas are usually quite distinguishable from other tumours on imaging studies and therefore if there is clarity on imaging that you have a meningioma undergoing the risks of a biopsy is not recommended.

The following pages contain additional information on meningiomas which you may find helpful:

https://www.braintumourresearch.org/info-support/types-of-brain-tumour/meningioma

https://www.macmillan.org.uk/cancer-information-and-support/brain-tumour/meningioma

https://www.nhs.uk/conditions/benign-brain-tumour/