Brain tumours

Sunday 1 May, 2016

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On this page:  The brain and spinal cord | Nervous tissue | Brain function | What is a brain or spinal cord tumour? | What types are there? | How common are they? | What are the symptoms? | What are the risk factors?


The brain and spinal cord

The brain and spinal cord make up the central nervous system (CNS). The CNS receives messages from cells called nerves, which are spread throughout the body.

The brain interprets information and relays messages through the nerves to muscles and organs. The main sections of the brain are the cerebrum (the largest part of the brain), the cerebellum and the brain stem.

Deep within the brain is the pituitary gland. It controls growth and development by releasing chemical messengers (hormones) into the blood. These chemical messengers signal other hormones to start or stop working.

The spinal cord extends from the brain stem to the lower back.

It consists of nerve cells and nerve bundles that connect the brain to all parts of the body through the peripheral nervous system.

The spinal cord lies in the spinal canal, and is protected by bony vertebrae (spinal column). Both the brain and spinal cord are surrounded by membranes, which is called meninges. Inside the skull and vertebrae, the brain and spinal cord float in liquid. This liquid is called cerebrospinal fluid (CSF).

The brain and spinal cord

Nervous tissue

The brain, spinal cord and nerves consist of billions of nerve cells called neurons or neural cells, which process and send information. Together, this is called nervous tissue.

The three main types of neural cells are:

  • sensory neurons – respond to light, sound and touch
  • motor neurons – cause muscle contractions
  • interneurons – connect neurons in the brain and spinal cord.

Glial cells, or neuroglia, are the other main type of cells in the nervous system. There are several different types of glial cells, including astrocytes and oligodendrocytes. Glial cells surround the neurons and hold them in place. The glial cells also supply nutrients to neurons and clear away dead neurons and germs.

Brain function

The brain plays a unique role in the body’s essential functions. The brain controls all voluntary and involuntary processes, such as moving, learning, sensing, imagining, remembering, breathing, blood circulation and heart rate, body temperature, digestion, and bowel and bladder control (continence).

The cerebrum is the largest part of the brain. The cerebrum is divided into right and left hemispheres. The right hemisphere controls muscles on the left side of the body, and the left hemisphere controls muscles on the right side. The hemispheres are connected by a band of nerve fibres known as the corpus callosum, which transfers information between the two hemispheres.

Each hemisphere is divided into four main areas, called lobes, which control different functions, as shown in the diagram below.

The brain
  • Frontal lobe
    Responsible for cognition, executive thinking and memory, including your ability to concentrate, plan, solve problems and some aspects of personality and character. Also responsible for motor function, or body movement. Your ability to change thoughts into words is also stored here.
  • Parietal lobe
    Responsible for spatial awareness, and integrating senses including speech, visual perception and touch.
  • Occipital lobe
    Responsible for visual processing, including visual memory.
  • Temporal lobe
    Responsible for auditory perception and language, including recognition of words. Contains the hippocampus, where long-term memories are formed.
  • Brain stem
    Controls life-supporting functions including alertness, arousal, breathing, temperature, blood pressure and ability to sleep.
  • Cerebellum
    Responsible for coordination and timing of voluntary movement, as well as balance, standing and walking. Regulates fear, pleasure, attention and language.

What is a brain or spinal cord tumour?

A brain or spinal cord tumour occurs when cells in the central nervous system grow and divide to form a lump. Tumours can be benign or malignant.

Benign (non-cancerous) tumours

Benign tumours usually have slow-growing cells and rarely spread. However, they may press on the brain, spinal cord, or the cranial nerves, and cause symptoms. Benign tumours may be found in areas of the brain that control vital life functions, and require urgent treatment.

Malignant (cancerous) tumours

These life-threatening tumours often grow rapidly, and may spread within the brain and spinal cord, or reoccur even after treatment. Just over 40% of all brain and spinal cord tumours are malignant.

Childhood brain tumours

In Australia, about 130 children under 15 are diagnosed with a brain tumour each year. Around 80% of these are cancerous. Children are more likely to develop tumours in the lower parts of the brain, the area that controls movement and coordination.

Glioma and medulloblastoma are the most common types. About 20 children are diagnosed with a spinal cord tumour each year. If your child has a brain tumour, you may find the section caring for a child with a tumour helpful.

What types are there?

There are more than 100 types of brain and spinal cord tumours (also called central nervous system or CNS tumours). They are usually named after the cell type they started in.

Not all tumours are easily classified as benign or malignant. Some types of tumours, such as gliomas and ependymomas, may be either.

Benign tumours

The most common types are pituitary tumours (which grow from the pituitary gland), meningiomas (which grow from the meninges), neuromas (which grow from the nerves), and pilocytic astrocytomas.

Malignant tumours

The most common type of cancerous brain tumours in adults and children are called gliomas. There are three types of gliomas: astrocytomas, oligodendrogliomas and ependymons. Gliomas can be classified as low or high grade depending on how fast they are growing.A common high grade glioma is glioblastoma (also known as glioblastoma multiforme or GBM), a type of astrocytoma. Medulloblastomas are another type of malignant tumour, which develop in the cerebellum. These are rare in adults but common in children.

Metastatic brain tumours

Secondary brain tumours that begin as a primary cancer in another part of the body before spreading to the brain. Cancers that may spread to the brain include melanoma, bowel, breast, kidney and lung cancer.

How common are they?

Every year about 1700 malignant brain tumours are diagnosed in Australia. The most common type in adults is a type of glioma called glioblastoma multiforme or GBM. These tumours are generally found in the cerebral hemispheres.

Malignant spinal cord tumours are rare. About 80 people are diagnosed with malignant spinal cord or central nervous system tumours each year.

Data about benign brain and spinal cord tumours is not collected, but they are more common than malignant tumours. In Australia, an estimated 2350 people – including children – are diagnosed with a benign tumour each year.

Electromagnetic radiation and brain cancer

Many people are concerned that mobile phones or microwave ovens may cause brain cancer.

Evidence to date does not show that mobile phone use causes cancer. However, if you are concerned about potential harm from mobile phones,you may choose to use a headset, limit the time you spend on your mobile phone or consider texting rather than calling. Additionally, you could consider limiting your child’s mobile phone use.

Microwave ovens have been in widespread use since the 1980s. There is no evidence that ovens in working order emit electromagnetic radiation at levels harmful to humans.

What are the symptoms?

Brain tumour symptoms depend on where it is located and whether it is causing pressure in the skull or on the brain

or spinal cord. Sometimes, when a tumour grows slowly, symptoms develop gradually, so you may not be aware of its presence at first.

General symptoms of brain or spinal cord tumours include headaches, seizures, changes in personality, or changes in balance. Increased pressure in the skull can result in nausea, vomiting and confusion. Tumours may also cause weakness or paralysis in parts of the body. Other symptoms might include memory loss, vision loss, hearing difficulties or speech changes. Symptoms may differ depending on where in the brain or spinal cord the tumour is located - see the table below.

Many symptoms of brain tumours, such as a headache, are more likely to be caused by other factors. However, new or worsening symptoms should be reported to your doctor.

"My doctor thought I had depression but I insisted on a CT scan as I had persistent headaches, felt disorientated and couldn’t think clearly. The scan showed that I had a brain tumour." - Richard
Part of the brain
Symptom
Frontal lobe
  • changes in personality, including loss of inhibition
  • mood swings
  • difficulty with planning and organising
  • weakness in part of the face, or on one side of the body
  • difficulty walking
  • loss of sense of smell
  • problems with your sight or speech
Parietal lobe
  • difficulty speaking or understanding what is said to you
  • problems with reading or writing
  • loss of feeling in part of the body
Temporal lobe
  • forgetting words
  • difficulty finding the correct word
  • short term memory loss
  • fits associated with strange feelings, smells< or déjà vu
  • hearing voices in your head
Occiptal lobe
  • partial or complete loss of vision
Cerebellum
  • coordination problems
  • uncontrolled eye movement
  • stiff neck
  • dizziness
Spinal cord
  • back and neck pain
  • numbness or tingling in the arms or legs
  • clumsiness or difficulty walking
  • loss of bowel or bladder control (incontinence)
Pituitary gland
  • headaches
  • loss of vision, particularly peripheral vision
  • nausea or vomiting
  • sexual problems
Brain stem
  • coordination problems
  • difficulty swallowing or speaking
  • double vision
  • drooping eyelid or mouth on one side
Meninges
  • headaches
  • vomiting
  • weakness in an arm or a leg
  • personality changes or confusion
  • seizures (fits)
Optic nerve
  • vision problems
Hearing nerve
  • hearing problems

What are the risk factors?

The causes of most brain and spinal cord tumours are unknown. However, there are a few known risk factors for malignant brain tumours:

Family history

It is possible to have a genetic predisposition to developing a tumour.This means that you may have a fault in your genes, usually passed down from one of your parents, that increases your risk. For example, some people have a genetic condition called neurofibromatosis, which causes nerve tissue tumours.

Radiotherapy

People who have had radiation to the head, usually to treat another type of cancer, may be at an increased risk of developing a tumour. This may affect people who had radiotherapy for childhood leukaemia.

Hydrocephalus

A brain tumour can sometimes block the flow of cerebrospinal fluid around the brain and its spaces (cavities). When this happens, fluid can build up and put pressure on the brain. This is called hydrocephalus. The condition is most common in infants, but it can occur in some adults. It is usually treated with a shunt.


Reviewed by: A/Prof Matthew Foote, Associate Professor, University of Queensland and Staff Specialist, Radiation Oncology, Princess Alexandra Hospital, QLD; Dr Jason Papacostas, Neurosurgeon, Mater Private Hospital, QLD; Dr Dianne Clifton, Psychiatrist and Coordinator of Education, Psychosocial Cancer Care and Palliative Care, St Vincent’s Hospital, VIC; A/Prof Georgia Halkett, Assocaite Professor, Senior Research Fellow, School of Nursing and Midwifery, Faculty of Health Sciences, Curtin University, WA; Lawrence Cher, Neurologist and Neuro-oncologist, Olivia Newton John Cancer & Wellness Centre, Austin Hospital, VIC; Kate Brennan, Occupational Therapist, Princess Alexandra Hospital, QLD; Vivien Biggs, Neuro-oncology nurse practitioner, Briz Brain & Spine, QLD; Lindy Cohn, 13 11 20 advisor, Cancer Council NSW, NSW; Ms Dianne Legge, Brain Tumour Support Officer, Cancer Services, Olivia Newton-John Cancer & Wellness Centre, Austin Hospital, VIC; Russ Talbot, consumer, SA.

Updated: 01 May, 2016