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Diagnosis of brain and spinal cord tumours
Diagnosis is the process of finding out the cause of a health problem. Diagnosing a brain or spinal cord tumour usually begins with a visit to your family doctor. Your doctor will ask you about any symptoms you have and may do a physical exam. Based on this information, your doctor may refer you to a specialist or order tests to check for a brain or spinal cord tumour or other health problems.
The process of diagnosis may seem long and frustrating. It’s normal to worry, but try to remember that other health conditions can cause similar symptoms as brain or spinal cord tumours. It’s important for the healthcare team to rule out other reasons for a health problem before making a diagnosis of a brain or spinal cord tumour.
The following tests are commonly used to rule out or diagnose a brain or spinal cord tumour. Many of the same tests used to diagnose cancer are used to find out the stage (how far the cancer has progressed). Your doctor may also order other tests to check your general health and to help plan your treatment.
Health history and physical exam
Your health history is a record of your symptoms, risk factors and all the medical events and problems you have had in the past. Your doctor will ask questions about your history of:
- symptoms that suggest a brain or spinal cord tumour
- radiation exposure
- inherited conditions
- conditions or medications that weaken the immune system
Your doctor may also ask about a family history of:
- brain or spinal cord tumours
- risk factors for a brain or spinal cord tumour
- other cancers
A physical exam allows your doctor to look for any signs of a brain or spinal cord tumour. During a physical exam, your doctor may also do a neurological examination and vision and hearing exam.
A neurological examination includes checking:
- reflexes, balance and coordination
- fine motor skills, such as picking up an object and handwriting
- muscle strength
- response to pain
- awareness of surroundings
- judgment, reasoning and memory
- the ability to calculate and speak
A vision exam includes checking eye movement and field of vision.
A hearing exam tests how well you hear sounds.
Magnetic resonance imaging (MRI) uses powerful magnetic forces and radiofrequency waves to make cross-sectional images of organs, tissues, bones and blood vessels. A computer turns the images into 3-D pictures. An MRI is considered the best way to look for tumours in the brain and spinal cord. Other special types of MRIs might be done including the following.
- MRA (magnetic resonance angiography) shows the structure of blood vessels in the brain and is useful in planning surgery.
- MRS (magnetic resonance spectroscopy) shows some features of brain tumours that are not clearly seen by MRI. It may help determine the possible tumour type and may be used after treatment to see if an abnormal area is a tumour or scar tissue.
- Perfusion MRI (magnetic resonance perfusion) shows the amount of blood going through different parts of the brain and can give an idea of how fast a tumour is growing. It can help determine the best place to take a biopsy and may be used after treatment to see if an abnormal area is a tumour or scar tissue.
Find out more about MRIs.
A computed tomography (CT) scan uses special x-ray equipment to make 3-D and cross-sectional images of organs, tissues, bones and blood vessels inside the body. A computer turns the images into detailed pictures. CT scans are not used as often as MRIs to diagnose or stage a brain tumour, but they may be used to provide better detail of the bone structures near the tumour or when MRI is not an option (for example, with people who are very overweight or are afraid of enclosed spaces).
CT angiography (CTA) creates detailed images of blood vessels in the brain, which can be useful in planning surgery.
Find out more about CT scans.
A positron emission tomography (PET) scan uses radioactive materials called radiopharmaceuticals to look for changes in the metabolic activity of body tissues. A computer analyzes the radioactive patterns and makes 3-D colour images of the area being scanned.
A PET scan may be used to determine if abnormal areas seen on an MRI or a CT scan are likely to be cancerous. It can also be used after treatment to see if an abnormal area is a tumour or scar tissue.
Find out more about PET scans.
During a biopsy, the doctor removes tissues or cells from the body so they can be tested in a lab. The report from the pathologist will show whether or not cancer cells are found in the sample.
The following biopsies are the main types used for brain or spinal cord tumours.
Surgical (open) biopsy
If the tumour appears to be treatable with surgery based on the imaging tests, a biopsy sample will be taken during surgery to remove the tumour.
During the operation (called a craniotomy), part of the skull is removed so the surgeon can reach the tumour. All or most of the tumour is removed. Small samples of the tumour are examined while the person is still in the operating room. This diagnosis can help guide treatment, including whether further surgery should be done at that time. The bone that was removed from the skull to make an opening is usually replaced after the tumour is taken out.
Stereotactic (closed) biopsy
Stereotactic biopsy may be used for tumours that likely can’t be removed with surgery, such as tumours that are deep within the brain.
A local anesthetic is used to freeze the scalp. Some people may be under general anesthesia. A special frame is fastened to the head to hold it in place to ensure that the surgeon can accurately target the tumour. The surgeon makes a cut (incision) in the scalp and drills a small hole in the skull. An MRI or a CT scan is usually used to help the surgeon guide a hollow needle into the tumour and remove tissue samples for biopsy.
Find out more about biopsies.
A lumbar puncture is a biopsy procedure that removes a small amount of cerebrospinal fluid (CSF) to be examined under a microscope. During the procedure, the doctor inserts a needle into the spine of the lower back and removes CSF from the space where it circulates within the spinal cord. The pathologist looks for any cancer cells in the CSF.
Lumbar punctures are not usually done to diagnose brain and spinal cord tumours, but they may be done after a diagnosis of certain types of brain tumours that are known to spread to the CSF.
Find out more about lumbar punctures.
Blood tests are not used to diagnose brain or spinal cord tumours. However, they are routinely done to provide a baseline before any planned treatment. They can provide helpful information about your general health, how other organs are functioning, other medical conditions and the possible risks of treatment.
Blood tests that may be used are:
- a complete blood count (CBC), which measures the number and quality of white blood cells, red blood cells and platelets
- blood chemistry tests, which measure certain chemicals in the blood and show how well certain organs, such as the liver and kidneys, are working
A urinalysis is a test that measures substances found in urine, such as electrolytes, hormones or other waste products. Urinalysis tests are not used to diagnose brain and spinal cord tumours. However, they may provide helpful information about your general health, how your other organs are functioning and other medical conditions.
Find out more about urinalyses.
An x-ray uses small doses of radiation to make an image of parts of the body on film. A chest x-ray may be done after a brain tumour is found because tumours in the lung often spread to the brain. Spine x-rays may be done if doctors think the tumour may have spread to the space around the spinal cord.
Find out more about x-rays.
During an angiography, dye is injected into the bloodstream and x-rays are taken to map out the size and shape of blood vessels. It is used to look at the blood vessels and the flow of blood in the brain. In recent years, angiography has been mostly replaced by other tests, such as MRA and CTA.
During a myelogram, a dye is injected into the space between the membranes covering the spinal cord (meninges), usually using a lumbar puncture. An x-ray or a CT scan is done to make images of the spinal cord and nerves. It can be used to locate a spinal cord tumour or identify how much the tumour has spread to the spinal cord and nerves. This test has been mostly replaced in recent years by MRI.