Diagnosis of childhood brain and spinal cord tumours

Diagnosis is the process of finding out the cause of a health problem. Diagnosing childhood brain or spinal cord tumours usually begins with a visit to your child’s doctor. The doctor will ask about any symptoms your child has and do a physical exam. Based on this information, your doctor may refer your child to a specialist or order tests to check for brain or spinal cord tumours 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 and 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. If the doctor suspects a brain or spinal cord tumour, your child’s care will be managed by a healthcare team that specializes in caring for children with cancer.

The following tests are usually used to rule out or diagnose brain and spinal cord tumours. Many of the same tests used to diagnose brain or spinal cord tumours are also used to determine if the tumour has spread. Your child’s doctor may also order other tests to check your child’s general health and to help plan their treatment.

A health history is a record of the symptoms, risk factors and all the medical events and problems your child has had in the past. The doctor will ask questions about your child’s personal or family history of certain genetic conditions, including:

• neurofibromatosis
• von Hippel-Lindau (VHL) syndrome
• Li-Fraumeni syndrome
• tuberous sclerosis
• Turcot syndrome
• basal cell nevus syndrome
• Cowden syndrome
• Rubinstein-Taybi syndrome (RSTS)

A physical exam allows the doctor to look for any signs of childhood brain and spinal cord tumours. During a physical exam, the doctor will do a neurological exam to check how the child’s brain, spinal cord and nerves are working. It usually involves a series of questions and tests to measure mental status, cranial nerve function, coordination, movement and how the muscles, senses and reflexes work. A visual field test will be done to measure central vision (how much a person can see when looking straight ahead) and peripheral vision (how far a person can see in all directions when looking straight ahead). Hearing tests may also be done.

Find out more about physical exams.

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 at tumours in the brain and spinal cord areas. An MRI usually provides more detailed images of soft tissue than CT scans. An MRI requires you to lie still for long periods of time. Young children may need a general anesthetic or sedative to help them stay still.

Other special types of MRIs might be done.

A nuclear MRI (NMRI) involves injecting gadolinium (a contrast dye) into a vein to improve the quality of the image and make the blood vessels easier to see.

Magnetic resonance angiography (MRA) is used to look at blood vessels in the brain. It is useful for planning surgery.

Magnetic resonance spectroscopy (MRS) shows some features of brain tumours that are not clearly seen with an MRI. It may help doctors determine the possible tumour type. An MRS is used after treatment to see if an abnormal area is a tumour or only scar tissue.

Magnetic resonance perfusion (perfusion MRI) shows the amount of blood going through different parts of the brain. It can give doctors an idea of how fast a tumour is growing and help them determine the best place to take a biopsy. It is used after treatment to see if an abnormal area is a tumour or only scar tissue. A contrast dye is injected into a vein or IV line for this test.

Functional MRI (fMRI) is a newer type of MRI that looks for tiny changes in blood flow to certain parts of the brain. It can be used to show the part of the brain that functions during a particular activity, such as speaking, thinking, touching or moving. Doctors can use an fMRI to help them plan surgery or radiation therapy. It shows them which areas are important to avoid. It involves asking the child to answer questions or move certain parts of the body while scans are being done.

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 MRI scans to diagnose or stage brain and spinal cord tumours, but are useful in some cases. They may be used to provide better detail of the bones near the tumour or when an MRI is not an option (for example, a child who is very sick, unable to stay still or afraid of enclosed spaces). Sometimes a contrast dye will be injected before the scan to get a better picture of any tumours present.

CT angiography (CTA) shows the blood vessels in the brain and can be used to plan surgery. A contrast dye is injected into a vein or IV line for this test.

Find out more about CT scans.

Tumour markers are substances found in the blood, tissues or fluids removed from the body. An abnormal amount of a tumour marker may mean that a child has a brain or spinal cord tumour. Tumour marker tests can be used to check a child’s response to cancer treatment, but they can also be used to help diagnose certain types of brain and spinal cord tumours. Alpha-fetoprotein (AFP) and human chorionic gonadotropin (HCG) are 2 tumour markers that may be elevated if the child has a certain type of tumour (such as a germ cell or a pineal tumour).

Find out more about tumour marker tests.

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 confirm whether or not cancer cells are found in the sample.

The type of biopsy commonly used for brain and spinal cord tumours is either a surgical (open) biopsy or a stereotactic (closed) biopsy.

Surgical (open) biopsy is used for tumours that appear to be treatable with surgery based on the imaging tests. It involves taking a biopsy sample during surgery to remove the tumour. The type of surgery used to remove a brain tumour is called a craniotomy. During 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 child is still in the operating room. This 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 may be used for tumours that likely can’t be removed with surgery (for example, tumours that are in vital areas or deep within the brain). A local anesthetic is used to freeze the scalp. The skull and brain do not feel pain. Depending on the situation, the child may be awake or under general anesthesia. A special frame is attached to the child’s head to help the surgeon accurately target the tumour. The surgeon makes a small cut (incision) in the scalp and drills a small hole in the skull. An MRI or a CT scan is usually used along with the frame to help the surgeon guide a hollow needle into the tumour and remove tissue samples for biopsy.

Image-guided biopsy may be used for some types of tumours. A hollow needle is guided with the aid of a neuronavigation system through a small hole in the skull into the brain tumour.

Transsphenoidal biopsy may be used for some types of tumours. Instruments are inserted through the nose and sphenoid bone and into the brain.

Find out more about biopsies.

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 is used to see if abnormal areas seen on an MRI or a CT scan are likely to be cancerous. It may also be used after treatment to see if an abnormal area is a tumour or scar tissue.

PET scans may not be available in all cancer treatment centres. Find out more about PET scans.

A lumbar puncture removes a small amount of cerebrospinal fluid (CSF) from the spine to be examined under a microscope. A lumbar puncture may be used in staging brain cancer. A lumbar puncture may be done to see if a brain tumour has spread to the CSF. CSF analysis can also show increased levels of human chorionic gonadotrophic (HCG) and alpha-fetoprotein (AFP) which can occur with pineal tumours.

Find out more about lumbar punctures.

A bone scan uses bone-seeking radioactive materials (called radiopharmaceuticals) and a computer to create a picture of the bones. It is used to see if a certain type of brain cancer, called medulloblastoma, has spread to the bones. A bone scan may be done if a child has bone pain or if blood tests suggest a problem with the bones.

Find out more about bone scans.

During a bone marrow aspiration and biopsy, the doctor removes tissues or cells from the bone marrow so they can be tested in a lab. A bone marrow aspiration and biopsy is done to see if a certain brain tumour, called a medulloblastoma, has spread to the bone or bone marrow.

Find out more about a bone marrow aspiration and biopsy.

A CBC measures the number and quality of white blood cells, red blood cells and platelets. A CBC is done to give the doctors a baseline that they can check against during treatment.

Find out more about a complete blood count (CBC)..

Blood chemistry tests measure certain chemicals in the blood. They show how well certain organs are functioning and can help find abnormalities.

Find out more about blood chemistry tests.

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 cancer may have spread (metastasized) to the space around the spinal cord.

Find out more about x-rays.

During angiography, a contrast 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 and can be helpful in planning surgery. In recent years, angiography has been mostly replaced by other tests, such as magnetic resonance angiography and CT angiography.

Find out more about angiography.

To make the decisions that are right for your child, ask your child's healthcare team questions about a diagnosis.