A Meningioma is a common type of brain tumour arising from the tissue lining the brain and spinal cord (meninges). Most meningiomas are benign tumours, but a small proportion can be malignant (cancerous). Although most meningiomas are slow growing, they can still cause symptoms by exerting pressure on the brain and spinal cord.
Meningiomas are classified into 3 groups according to how quickly they grow, and how likely they are to recur after surgery.
Grade I- grow slowly (benign meningiomas)
Grade II- grow more quickly (atypical meningiomas including clear cell and chordoid meningiomas)
Grade III- grow quickly (malignant meningiomas including anaplastic, papillary and rhabdoid meningiomas)
What Are the Causes of A Meningioma?
Meningiomas are more common in older people and in women.
The causes of meningiomas are not well understood but certain risk factors make developing a meningioma more likely, including:
- Previous exposure to ionising radiation (either through atomic bomb exposure, frequent CT scans at a young age, or after therapeutic radiation therapy to the brain or head and neck region). Meningiomas may take more than 20 years to develop after exposure to ionising radiation, so this risk is thought to be highest for patients exposed to radiation at a young age.
- Genetic factors: Patients with genetic disorders such as Neurofibromatosis type 2, Schwannomatosis and Multiple Endocrine Neoplasia type 1 (MEN1) have an increased risk of developing meningiomas.
- Environmental factors: There is some correlation with meningiomas and hormonal factors and obesity.
What Are the Symptoms of A Meningioma?
Small meningiomas do not usually cause symptoms and are found incidentally when a scan of the brain or spine is performed for an unrelated reason. Large meningiomas can exert pressure on normal brain or spinal cord which can result in symptoms.
Meningiomas may cause seizures or focal neurological symptoms such as visual changes, loss of hearing or smell, or limb weakness.
What Are the Treatment Options?
The recommended treatment for a meningioma will depend on the location and grade, whether it is causing symptoms and the age and general health of the patient.
Possible treatments include observation, surgery and/or radiation therapy. Doctors will need to weigh up the potential benefits of treatment versus the potential side effects from treatment.
For small low grade meningiomas that are not causing symptoms close observation with repeat imaging may be recommended. If the meningioma increases in size quickly or starts causing symptoms, treatment would then be recommended.
If a meningioma is large, higher grade, increasing in size quickly and/or causing swelling in the surrounding brain then treatment is recommended. If the tumour is located in a surgically accessible area, surgery to completely remove the tumour is recommended.
The aim of surgery is to remove as much of the meningioma as possible. In some cases it is not possible to remove the entire meningioma due to the location of the tumour, resulting in a high risk of causing damage to the surrounding brain/spinal cord or blood vessels.
If a meningioma is not completely removed with surgery, radiation therapy may be recommended after surgery to stop the residual meningioma from growing.
Radiation Therapy is a localised treatment that uses high energy x-rays. Radiation therapy may be recommended as an alternative to surgery in certain circumstances, especially if the meningioma is in a high-risk area of the brain or spinal cord which makes an operation difficult.
Radiation therapy may also be used after surgery. Whether radiation therapy is recommended after surgery depends on how much of the meningioma remains after surgery and the grade of the meningioma.
There are different techniques used to deliver radiation therapy. The technique used will depend on the size and grade of the meningioma and how close it lies to sensitive structures within the brain or spinal cord.
External Beam Radiation Therapy (EBRT) is the most common type of radiation therapy used. It is usually delivered once a day, five days a week. The total length of treatment can range but is generally 5-6 weeks. Patients will be asked to wear a customised mask during each radiation treatment.
The mask reduces patient movement during treatment and ensures that the radiation treatment is targeting the cancer and avoiding important structures nearby.
In some cases Stereotactic Radiosurgery will be recommended. Stereotactic radiation can be given as one single dose (usually called ‘stereotactic radiosurgery’), or a few treatments (called ‘stereotactic radiation therapy’).
What are the side effects of radiation therapy?
The potential side effects of radiation treatment are divided into acute side effects (can occur during and shortly after radiation treatment) and late effects (can occur months to years after radiation treatment and are permanent).
Side effects during/soon after treatment (Early or ‘acute’ side effects)
General – Fatigue is quite common in the second half of treatment and is very variable between patients. Fatigue may persist for several weeks after treatment.
Local – The other side effects of radiation therapy come from the structures/organs in and just next to where the radiation is being targeted. These side effects appear half way through treatment and increase in severity toward the end of treatment.
Due to the cumulative nature of these side effects they can peak in severity 7-10 days following treatment.
Skin reddening and irritation – The skin on the scalp may become red, dry and/or itchy. Usually the skin reaction is mild to moderate.
Loss of hair (alopecia) – The hair loss can be temporary or permanent depending on the amount of radiation.
Cerebral oedema (swelling in the brain) – Radiation therapy can cause temporary inflammation around the meningioma. This may cause headaches, nausea, vomiting and/or drowsiness. If these symptoms occur during treatment, corticosteroid medication may be used to treat these symptoms.
Inflammation may also worsen pre-existing neurological symptoms temporarily.
Tinnitus (ringing in the ears) and hearing loss – These symptoms are uncommon during radiation treatment.
What can help reduce acute side effects?
Resting as needed can help with fatigue. Creams can be used on the scalp for skin reddening and irritation. Wigs can be used for temporary or permanent hair loss.
If headaches, nausea and/or vomiting occur during treatment, corticosteroid medication may be used to reduce the swelling around the tumour, which usually improves symptoms.
Pain medications and anti-nausea medications are prescribed if needed.
Early-delayed side effects (side effects occurring 1-6 months after treatment)
Somnolence syndrome- this is uncommon but can occur 1-6 months following radiation treatment. Symptoms can include sleepiness, irritability, headaches, nausea, vomiting and loss of appetite.
The symptoms usually resolve after a few weeks and corticosteroid medication may be used to treat symptoms.
Side effects well after treatment (Late or long-term side effects)
Late side effects may occur a few months to years after treatment. They are more rare than early side effects. Depending on the problem it may occur once and then go or may be more persistent over the long term or may come and go over time.
The likelihood of developing late side effects from radiation treatment depends on the amount of radiation and the relationship of the brain tumour to important structures located nearby.
Your Radiation Oncologist will explain the potential late side effects of your treatment and how to manage potential side effects in more detail.
General – Neurocognitive effects include changes that can affect thinking, learning, processing or remembering information. Neurocognitive effects may also occur following surgery.
Local – If the meningioma is located close to the following structures, uncommon side effects may occur.
Eye and optic nerves – Radiation can cause the lens of the eye to become cloudy (cataract). This can cause painless visual impairment years after treatment. Radiation changes to the retina may be asymptomatic or cause painless loss of vision, which can be partial or total. Radiation to the optic nerves can very rarely cause permanent visual loss.
Ear – Hearing loss and ringing in the ear (tinnitus) can develop progressively over a few years following treatment and is usually permanent if it occurs.
Pituitary gland – Radiation may cause the pituitary gland to become underactive. Your doctor may recommend blood tests following treatment to monitor for this.
Brain necrosis (tissue death) – This is an uncommon event occurring after high doses of radiation. It tends to occur 1-3 years post treatment. Symptoms depend on the location of the necrosis. It can be a very serious complication that may require surgical treatment.
Radiation induced cancers – Second cancers occurring as a result of radiation therapy are an extremely rare side effect of radiation therapy.
What can be done to treat late side effects?
Changes in vision following radiation treatment should be assessed to determine the cause. If radiation results in a cataract, the lens can be replaced with a minor operation. Radiation effects to the retina or optic nerve are generally irreversible. It is important to prevent and treat other medical conditions that can contribute to eye problems (diabetes).
Hearing aids may be beneficial for hearing loss. If the pituitary gland becomes underactive, hormone replacement is prescribed.
Medications may be useful for some neurocognitive changes that occur after radiation treatment. There are medications under investigation that may be helpful in preventing neurocognitive effects from radiation.
The best person to discuss radiation therapy with is a Radiation Oncologist. You can ask your surgeon or General Practitioner for a referral to a Radiation Oncologist for a discussion whether radiation therapy is a suitable treatment option for you.
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