The brain and spinal cord
The brain and spinal cord make up the body’s central nervous system. The central nervous system receives messages from cells called nerves, which are spread throughout the body (the peripheral nervous system). The brain interprets information and relays messages back through the nerves to muscles and organs. The brain is the most important organ in the body, because it controls all voluntary and involuntary processes, such as learning, sensing, imagining, remembering, breathing, blood circulation and heart rate, body temperature, digestion and continence (bladder and bowel control).
There are two main sections of the brain:
- the cerebrum (the largest part)
- the cerebellum.
The spinal cord extends from the base of the brain to the base of the spinal column. It consists of nerve cells and bundles of nerves that connect the brain with all parts of the body through the peripheral nervous system.
The brain and spinal cord are surrounded and protected by membranes called the meninges, the skull and the vertebrae bones. Inside the skull, the brain floats in fluid called cerebrospinal fluid.
Nerve cells
The brain, spinal cord and nerves consist of billions of cells called neurons, which are cells that process and transmit information.
There are three major types of neural cells:
- sensory neurons, which respond to light, sound and touch
- motor neurons, which cause muscle contractions
- interneurons, which connect neurons within the brain and spinal cord.
Glial cells are the other main type of cell in the nervous system.
There are several different types of glial cells, including astrocytes and oligodendrocytes. Glial cells are the glue of the nervous system because they surround and insulate the neurons and hold the neurons in place. The glial cells also supply nutrients and oxygen to neurons and eliminate dead neurons and germs.
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About brain or spinal cord tumours
When cells in the central nervous system grow and divide in an uncontrollable way, they can form a tumour. A tumour can be benign or malignant.
The difference between benign and malignant tumours in the central nervous system is not always clear cut.
Most benign tumours are slow-growing and unlikely to spread throughout the brain. However, some benign brain tumours can become genetically damaged and develop into a rapidly growing malignant tumour. This process is called malignant transformation.
Types of tumours
There are more than 100 types of benign and malignant tumours that originate from the brain, spinal cord and meninges. About 70% of all brain tumours are malignant.
Malignant tumours
- include high-grade astrocytomas, oligodendrogliomas, ependymomas, glioblastomas and mixed gliomas
- usually named after the cell type from which they arise
- in some tumours, the cells are confined to a specific area; in others, malignant cells are also found in tissue surrounding the tumour.
- There are various treatments for tumours, including surgery and radiotherapy
Benign tumours
- most common types: meningiomas, neuromas, pituitary tumours and cranio-pharyngiomas
- can cause problems by pressing on the brain and spinal cord
- surgery or treatments such as radiotherapy may treat the tumour.
Hydrocephalus
A brain tumour can sometimes block the flow of cerebrospinal fluid around the brain and between its cavities. When this happens, fluid can build up, putting pressure on the brain. This is called hydrocephalus, and it is most common in infants and some adults. It is usually treated with a shunt.
Grades of tumours
Brain and spinal cord tumours are usually graded on a scale of one to four based on how quickly they are growing, as well as their ability to invade nearby tissue.
- Grades 1 and 2 are the slowest-growing tumours. They are called low-grade tumours.
- Grade 3 tumours grow at a moderate rate.
- Grade 4 are the fastest-growing tumours. They are called high-grade tumours.
Prognosis
Prognosis means the expected outcome of a disease. You will need to discuss your prognosis with your doctor.
Your prognosis may depend on the type of tumour you have. Both benign and malignant tumours can be life-threatening, but you may have a better prognosis if the tumour is benign, or if a surgeon is able to remove all of the tumour. Some tumours can not be completely removed because surgery would damage parts of the brain or spinal cords essential for normal function.
It is not possible for any doctor to predict the exact course of your illness. Test results, the rate and depth of tumour growth, how well you respond to treatment, and other factors such as age, fitness and your medical history are all important factors in assessing your prognosis.
Some brain or spinal cord tumours can recur, but treatment such as surgery or radiotherapy can often relieve symptoms for several years.
How common are brain and spinal cord tumours?
- About 450 new cases of brain cancer are diagnosed in NSW each year. Brain cancer represents about 1.4% of all cancers in males and 1.2% of all cancers in females.
- Malignant spinal tumours affect about 30 people each year.
Causes of brain tumours
The causes of most brain and spinal cord tumours are unknown. However, there are a few known risk factors for malignant brain tumours:
- People who have had radiation to the head, usually as treatment for another type of cancer, may be at an increased risk of developing a tumour. This is common in people who received radiotherapy for childhood leukaemia.
- It is also possible to have a genetic predisposition to developing a tumour. For example, some people have a condition called neurofibromatosis, which causes nerve tissue to grow tumours.
- Some researchers speculate whether the long-term use of mobile phones increases a person’s risk of brain cancer. At the time of publication, there was insufficient scientific evidence to link mobile phone usage and brain tumours.
Symptoms
People with a brain or spinal cord tumour have varying symptoms, depending on where the tumour is located. Sometimes, when a tumour grows slowly, symptoms develop gradually and are hardly noticeable. Brain tumours and spinal cord tumours may cause weakness or paralysis in parts of the body. Some people also have trouble balancing or have seizures.
Brain tumours
Other symptoms for brain tumours can include:
- headaches
- nausea and/or vomiting
- difficulty speaking or remembering words
- disturbed vision, hearing, smell or taste
- general irritability or a change in personality – this is sometimes noticed only by family or friends
- drowsiness.
Spinal cord tumours
Symptoms for spinal cord tumours can include:
- back and neck pain
- numbness or tingling in the arms or legs
- clumsiness or difficulty walking
- incontinence (loss of bowel or bladder control).
Common tests used for diagnosis
Physical examination
Most people consult their GP if they have symptoms of a brain tumour. Your doctor may:
- take a detailed history of your symptoms
- test your reflexes (for example, knee jerks)
- test the strength in the muscles of your arms and legs, and ability to feel pinpricks
- ask you to do some simple mental exercises (like arithmetic)
- look into your eyes to see your optic nerve, which transmits visual information from your eyes to your brain.
CT (computerised tomography) scan
An exam that uses x-rays to take pictures of the brain.
You will lie flat on a table while the CT scanner, which is large and round like a doughnut, moves around you and takes pictures.
You may have an injection of dye into your veins before the scan -- this will make pictures clearer.
Painless.
The scan itself takes 5-10 minutes, but the process may take 30-60 minutes.
MRI (magnetic resonance imaging) scan
Scan uses a combination of magnetism and radio waves to build up detailed cross-section pictures of your body.
Involves lying on a table inside a metal cylinder -- a large magnet -- that is open at both ends.
You may have an injection of dye into your veins before the scan -- this will make the pictures clearer.
Painless.
Some people find lying in the cylinder noisy and claustrophobic. If you feel uncomfortable, let your doctor or nurse.
Further tests
Other tests that are sometimes used are:
Magnetic resonance spectroscopy (MRS) scan -- this scan can be conducted at the same time as a standard MRI scan. An MRS scan uses technology to examine the chemical composition and function of neurons.
Single photon emission computerised tomography (SPECT or SPET) scan -- You are injected with a small amount of radioactive fluid. You are then scanned with a machine called a gamma camera, which creates three-dimensional pictures of your body. This scan is often used to assess blood flow in the brain.
Positron emission tomography (PET) scan -- You are injected with radioactive glucose solution, which may be absorbed by active cells, such as cancer cells.
Lumbar puncture (spinal tap) -- A needle is inserted into the spinal column to collect cerebrospinal fluid. This fluid will be sent away for analysis.
Surgical biopsy -- If scans show an abnormality that looks like a tumour in your brain, your doctor may decide to remove some or all of the tissue for examination.
If your doctor recommends any other tests, ask him or her to explain the tests. Understanding what will happen can help you feel less worried before the test.
Staging
Staging describes the size of a tumour and if it has spread from its original location. Staging the cancer helps determine what treatment is required. Brain and spinal cord tumours are usually graded on a scale of one to four based on how quickly they are growing, as well as their ability to invade nearby tissue.
- Grades 1 and 2 are the slowest-growing tumours. They are called low-grade tumours.
- Grade 3 tumours grow at a moderate rate.
- Grade 4 are the fastest-growing tumours. They are called high-grade tumours.
Prognosis
Prognosis means the expected outcome of a disease.
You will need to discuss your prognosis with your doctor, but it is not possible for any doctor to give you a 100% accurate prognosis.
It will be important to complete any tests to assess the stage of the tumour and then to observe how quickly it grows and how well you respond to treatment.
As in most types of cancer, the results of treatment are best when the cancer is found and treated early.
Which health professionals will I see?
Your GP will probably arrange the first tests to assess your symptoms. You will usually be referred to a neurologist, who will arrange further tests and advise you about treatment options. Your health carers may include:
- neurosurgeon and neurologist - diagnose and treat people with illnesses of the brain and nervous system
- nurses - assist and support you through all stages of your treatment
- medical oncologist - prescribes and coordinates chemotherapy treatment
- radiation oncologist - prescribes and coordinates radiotherapy treatment
- dietician - supports and educates patients about nutrition and diet
- social worker, psychologist and pastoral worker - advise you on support services and provide emotional support
- cognitive therapist, physiotherapist, speech therapist and occupational therapist - provide you with rehabilitative services.
Treatment
Tumours of the brain or spinal cord are usually treated with surgery, radiotherapy, chemotherapy or steroid therapy. These treatments may be used alone or in combination. The aim of treatment is to remove the tumour or to slow its growth and/or relieve symptoms by shrinking the tumour and any swelling around it. Your choice of treatment will depend on:
- the type, size and location of your tumour
- your age, medical history and general state of health.
Surgery
Surgical biopsy
- Your doctor may decide to remove some brain or spinal cord tissue for examination (biopsy).
- There are many types of biopsy -- the neurosurgeon might make a small opening in your skull and scalp and insert a needle to obtain an adequate sample. In other cases, the neurosurgeon will remove part of your skull to access the tumour. This is called a craniotomy.
- Not everyone with a brain or spinal cord tumour has a biopsy.
Surgery for a brain tumour
- A craniotomy is the main type of operation to treat a brain tumour.
- Some of your hair will be shaved off and you will be given a general anaesthetic. The neurosurgeon will cut through your scalp and move it aside, then remove a piece of skull above the brain tumour.
- The neurosurgeon will remove as much of the tumour as possible without damaging other parts of the brain.
- If the tumour is near the part of the brain that controls speech or movement, this part of the brain will be avoided.
- Awake craniotomy -- the patient is awakened during the craniotomy, when their brain is exposed. The operating team will ask the patient to speak or move a limb, and if the patient cannot respond when certain areas of their brain are stimulated, the neurosurgeon can identify and avoid the speech centres of the brain.
If the tumour is near the base of your brain, you may have endoscopic transnasal brain surgery.
- This is a rarer type of surgery.
- The surgeon puts a long tube (endoscope) into your nose and through a small hole created in the back of your nose. The surgeon uses small tools to remove part or all of the tumour through the nostrils.
- Faster recovery time and fewer long term side effects.
- Gross total resection -- surgical removal of the entire tumour.
- Partial resection -- surgical removal of part of the tumour. This may be an option if a tumour is more spread out, is near major blood vessels, or cannot be removed without damaging other important parts of the brain or spinal cord.
- Removing all or part of the tumour often improves your condition, which may allow you to lead an active life for some time.
- Sometimes tumours can't be removed because it would be too dangerous, so you may have another type of treatment to ease your symptoms.
Shunts
Some people experience fluid build-up in their brain (hydrocephalus), either as a result of surgery or as a symptom of a tumour.
If this is a problem, the surgeon may insert a small permanent tube, called a shunt, just beneath the skin in your head. The shunt will drain the extra fluid from the brain into the abdomen, where it is safely absorbed into your bloodstream.
Sometimes a shunt may be inserted to relieve symptoms of hydrocephalus before surgery.
Radiotherapy
Radiotherapy is a type of treatment that uses high-energy x-ray beams to kill or damage cancer cells. The radiation is specifically targeted at the treatment site to minimise damage to healthy cells. A personalised plastic face mask is often worn during treatment to assist the targeting of the radiotherapy. You will be able to see and breathe through the mask, but it will immobilise you so that the radiation beams always treat the same areas of your brain. You will only wear the mask for about 10 minutes at a time. Let your doctor know if you are claustrophobic. Radiotherapy treatment is usually given once daily, Monday to Friday, for several weeks. However, the course of your treatment will depend on the size and type of tumour.
Stereotactic radiotherapy is a type of radiation therapy that may be used for some tumours. A rigid head frame is attached to the skull to aim high-dose radiation beams directly at the tumour. This causes less damage to nearby healthy tissue
Chemotherapy
Chemotherapy is the use of cytotoxic drugs to treat cancer. Cytotoxic drugs damage or destroy rapidly dividing cells such as cancer cells while causing the least possible damage to healthy cells. Your doctor will determine your treatment schedule and dose. You may have chemotherapy two ways:
- Commonly, chemotherapy is delivered through an oral capsule or intravenous drip. It can be difficult to treat brain tumours this way because the body has a natural defence mechanism called the blood-brain barrier that only allows certain substances from the blood into the brain. Only certain drugs can penetrate this barrier.
- Some craniotomy patients have small, dissolvable chemotherapy wafers inserted into their brain during surgery. The wafer slowly releases chemotherapy drugs into the brain to treat any remaining cancer cells.
Chemotherapy is often combined with radiotherapy for treatment of some types of brain tumours, such as gliomas. The combination of treatments enhances the effects of radiotherapy treatment.
Other therapies
Some types of treatment are used to make you more comfortable or reduce your symptoms or side effects. Steroids
- drugs that can reduce swelling around a brain tumour
- they do not treat the tumour itself, but may decrease symptoms
- can cause an increased appetite and weight gain, diabetes or muscle weakness
- talk to your doctor about ways to monitor and manage side effects.
Anti-convulsants
- drugs that are used to prevent seizures
- blood and liver-function tests are common before this medication is prescribed
- side effects vary and may include tiredness, weight changes, tremors, nausea and vomiting
- your doctor will monitor you and adjust your dose to reduce side effects
- limit your alcohol intake
- grapefruit, Seville oranges and some herbal medicines may negatively interact with some anti-convulsants - ask your doctor or pharmacist.
Palliative treatment
Palliative treatment helps to improve quality of life by alleviating symptoms of cancer without trying to cure the disease.
Often treatment is concerned with pain relief and stopping the spread of cancer, but it can also involve the management of other physical and emotional symptoms.
Treatment may include surgery, radiotherapy, chemotherapy and other medication.