How are brain and spinal cord tumors in adults diagnosed?
Brain and spinal cord tumors are usually found because of signs or symptoms a person is having. If a tumor is suspected, tests will be needed to confirm the diagnosis.
Signs and symptoms of brain and spinal cord tumors
Signs and symptoms of brain or spinal cord tumors may occur gradually and become worse over time, or they can happen suddenly, such as a seizure.
Tumors in any part of the brain may cause the pressure inside the skull (known as intracranial pressure) to rise. This can be caused by growth of the tumor itself, swelling in the brain, or blockage of the flow of cerebrospinal fluid. Increased pressure can lead to general symptoms such as:
- Blurred vision
- Balance problems
- Personality or behavior changes
- Drowsiness or even coma
Headache is a common symptom of a brain tumor, occurring in about half of patients. (Of course, most headaches are not caused by tumors.)
As many as half of people with brain tumors will have seizures at some point. The type of seizure may depend on where the tumor is. Sometimes this is the first sign of a brain tumor, but fewer than 1 in 10 first seizures are caused by brain tumors.
Symptoms of tumors in different parts of the central nervous system
Tumors in different parts of the central nervous system can cause different symptoms. But these symptoms can be caused by any disease in that particular location in the brain — they do not always mean a brain tumor is present.
Brain and spinal cord tumors often cause problems with the specific functions of the region they develop in. For example:
- Tumors in the parts of the cerebrum (the large, outer part of the brain) that control movement or sensation may cause weakness or numbness of part of the body.
- Tumors in or near the parts of the cerebrum responsible for language may cause problems with speech or even understanding words.
- Tumors in the front part of the cerebrum can sometimes affect thinking and personality.
- Tumors in an area of the brain called the basal ganglia typically cause abnormal movements and an abnormal positioning of the body.
- If the tumor is in the cerebellum, which controls coordination, a person might have trouble with walking or other everyday functions, even eating.
- Tumors in the back part of the cerebrum, or around the pituitary gland, the optic nerve, or certain other cranial nerves can cause vision problems.
- Tumors in or near other cranial nerves might lead to loss of hearing, balance problems, weakness of some facial muscles, or trouble swallowing.
- Spinal cord tumors can cause numbness, weakness, or lack of coordination in the arms and/or legs, as well as bladder or bowel problems.
The brain also controls functions of some other organs, including hormone production, so brain tumors can also cause many other symptoms that aren't listed here.
Having one or more of the symptoms above does not mean that you definitely have a brain or spinal cord tumor. All of these symptoms can have other causes. Still, if you have symptoms that suggest you might have a brain or spinal cord tumor, see your doctor so that the cause can be evaluated and treated, if needed.
Medical history and physical exam
If signs or symptoms suggest you might have a brain or spinal cord tumor, your doctor will get a complete medical history, focusing on the symptoms and when they began. The doctor will also do a neurologic exam to evaluate your brain and spinal cord function. It tests reflexes, muscle strength, eye and mouth movement, coordination, alertness, and other functions.
If the results of the exam are abnormal, your doctor may refer you to a neurologist (a doctor who specializes in nervous system diseases) or a neurosurgeon (a surgeon who specializes in nervous system diseases), who may do a more detailed neurologic exam or other tests.
Your doctor may order one or more imaging tests. These tests use x-rays, strong magnets, or radioactive substances to create pictures of internal organs such as the brain and spinal cord. The pictures may be looked at by doctors specializing in this field (neurosurgeons, neurologists, and neuroradiologists) as well as by your primary doctor.
Magnetic resonance imaging (MRI) and computed tomography (CT) scans are used most often for brain diseases. These scans will show a brain tumor, if one is present, in almost all cases, and can often tell the doctors exactly where the tumor is in the brain.
Magnetic resonance imaging (MRI) scan
MRI scans are very helpful in looking at the brain and spinal cord and are considered the best way to look for tumors in these areas. The images they provide are usually more detailed than those from CT scans (described below). But they do not image the bones of the skull as well as CT scans and therefore may not see the effects of tumors on the skull.
MRI scans use radio waves and strong magnets instead of x-rays. The energy from the radio waves is absorbed and then released in a pattern formed by the type of body tissue and by certain diseases. A computer translates the pattern into a very detailed image of parts of the body. A contrast material called gadolinium may be injected into a vein before the scan to better see details.
MRI scans can take a long time — often up to an hour. You have to lie inside a narrow tube, which can be confining and might upset people with a fear of enclosed spaces. Newer, open MRI machines may help with this, but they may provide less detailed images and can't be used in all cases. The machine also makes buzzing and clicking noises that may be disturbing. Some people might need medicine to help them relax for the test.
Magnetic resonance angiography: This special form of MRI (also known as MR angiography or MRA) may be done to look at the structure of the blood vessels in the brain. This can be very useful before surgery to help the surgeon plan an operation.
Magnetic resonance spectroscopy: This test (also known as MR spectroscopy or MRS) is like an MRI, except that it measures radio wave interactions with different atoms in the brain. MRS highlights some features of brain tumors that are not clearly seen by MRI. It creates graph-like results called spectra (although crude images can also be created). This may help determine the type of tumor, but in most cases a biopsy of the tumor is still needed to be sure. MRS can also be used after treatment to help determine if an area that still looks abnormal on another test is remaining tumor or if it is more likely to be scar tissue.
Magnetic resonance perfusion: For this test, also known as perfusion MRI, a contrast dye is injected quickly into a vein. A special type of MR image is then obtained to look at the amount of blood going through different parts of the brain and tumor. Tumors need a bigger blood supply than normal areas of the brain. The faster a tumor is growing, the more blood it needs.
Perfusion MRI can give doctors an idea of how quickly a tumor is growing or help show them the best place to take a biopsy. It can also be used after treatment to help determine if an area that still looks abnormal is remaining tumor or if it is more likely to be scar tissue.
Functional MRI (fMRI): This newer type of MRI looks for tiny chemical changes in an active part of the brain. It can be used to determine what part of the brain handles a function such as speech, thought, sensation, or movement. Doctors can use this to determine which parts of the brain to avoid when planning surgery or radiation therapy.
This test is similar to a standard MRI, except that you will be asked to perform specific tasks (such as answering simple questions or moving your fingers) while the scans are being done.
Computed tomography (CT) scan
The CT scan is an x-ray test that produces detailed cross-sectional images of your brain and spinal cord (or other parts of the body). Instead of taking one picture, like a regular x-ray, a CT scanner takes many pictures as it rotates around you while you lie on a table. A computer then combines these pictures into images of slices of the body. Unlike a regular x-ray, a CT scan creates detailed images of the soft tissues in the body.
CT scans are not used as often as MRI scans when looking at brain or spinal cord tumors, but they do have features that make them useful in some cases. They may be used if MRI is not an option (such as in people who are very overweight or people who have a fear of enclosed spaces). CT scans also provide greater detail of the bone structures near the tumor.
Before the scan, you may get an injection of a contrast dye through an IV (intravenous) line. This helps better outline any tumors that are present. The contrast may cause some flushing (a feeling of warmth, especially in the face). Some people are allergic and get hives. Rarely, people have more serious reactions like trouble breathing or low blood pressure. Be sure to tell the doctor if you have any allergies or if you ever had a reaction to any contrast material used for x-rays.
CT scans take longer than regular x-rays, but not as long as MRI scans. You need to lie still on a table while they are being done. During the test, the table slides in and out of the scanner, a ring-shaped machine that surrounds the table. Some people feel a bit confined by the ring while the pictures are being taken, although it is not as narrow as an MRI tube. Spiral CT (also known as helical CT) is now used in many medical centers. This type of CT scan uses a faster machine that reduces the dose of radiation and yields more detailed pictures.
CT angiography (CTA): For this test, you are injected with a contrast material through an IV line while you are in the CT scanner. The scan creates detailed images of the blood vessels in the brain, which can help doctors plan surgery. CT angiography can provide better details of the blood vessels in and around a tumor than MR angiography in some cases.
Positron emission tomography (PET) scan
For a PET scan, a radioactive substance (usually a type of sugar known as FDG) is injected into the blood. The amount of radioactivity used is very low. Because cancer cells in the body grow quickly, they absorb larger amounts of the sugar than most other cells. After about an hour, you are moved onto a table in the PET scanner. You lie on the table for about 30 minutes while a special camera creates a picture of areas of radioactivity in the body. The picture is not finely detailed like a CT or MRI scan, but it can provide helpful information about whether abnormal areas seen on other tests (such as MRIs) are likely to be cancerous or not.
This test is also useful after treatment to help determine if an area that still looks abnormal on an MRI scan is remaining tumor or if it is more likely to be scar tissue. Any remaining tumor will show up on the PET scan, while scar tissue will not.
An x-ray may be done to look for tumors in the chest if a tumor is found in the brain, because in adults most tumors in the brain have actually started in another organ (most often the lung) and then spread to the brain. This test can be done in a doctor's office, in an outpatient radiology center, or in a hospital.
For this test, a special dye is injected into blood vessels near the tumor, and the area is then viewed with x-rays. This helps doctors look at the blood supply of a tumor.
This test is not done much anymore, as it has largely been replaced by other tests that can look at blood vessels, such as computerized tomographic angiography (CTA) or magnetic resonance angiography (MRA).
In very selected cases an angiogram may be used as part of the treatment for certain brain tumors. It is done as a first step of a procedure called embolization, in which the radiologist injects tiny particles into the blood vessels feeding the tumor to block them and make it easier to remove the tumor.
Brain or spinal cord tumor biopsy
Imaging tests such as MRI and CT scans may show an abnormal area that is likely to be a brain or spinal cord tumor. But in most cases these scans can’t tell exactly what type of tumor it is. This can only be done by removing some of the tumor tissue, which is called a biopsy. A biopsy may be done as a procedure on its own, or it may be part of surgery to treat the tumor.
Once the tissue is removed, it is looked at under a microscope by a pathologist (a doctor specializing in diagnosis of diseases by lab tests). Sometimes it might need to be looked at by a neuropathologist, a pathologist who specializes in nervous system diseases. The pathologist determines if the tumor is benign or malignant (cancerous) and exactly what type of tumor it is.
Sometimes, a tumor may look so much like an astrocytoma on an MRI scan that a biopsy is not needed, especially if the tumor is in a part of the brain that would make it hard to biopsy (such as the brain stem). In rare cases a PET scan or MR spectroscopy may give enough information so that a biopsy is not needed.
There are 2 main types of biopsies for brain tumors.
Stereotactic (needle) biopsy
This type of biopsy may be used if, based on imaging tests, the risks of surgery to remove the tumor might be too high (such as with some tumors in vital areas, those deep within the brain, or other tumors that probably can't be treated with surgery) but a sample is still needed to make a diagnosis.
The patient may be asleep (under general anesthesia) or awake during the biopsy. If the patient is awake, the neurosurgeon injects a local anesthetic into areas of skin above the skull to numb them. (The skull and brain do not feel pain.) A rigid frame may then be fixed onto the head. This helps make sure the surgeon is targeting the tumor precisely. An incision (cut) is made in the scalp and a small hole is drilled in the skull. An MRI or CT scan is often used along with the frame to help the neurosurgeon guide a hollow needle into the tumor to remove small pieces of tissue.
Another approach is to attach markers to the scalp, get an MRI or CT, and then use an image-guidance system to direct the needle into the tumor. This still requires making an incision and drilling a small hole into the skull.
The removed tissue is sent to a pathologist, who looks at it under a microscope to determine what type of tumor it is. This is very important in determining the prognosis (outlook) and the best course of treatment.
Surgical or open biopsy (craniotomy)
If the tumor can be treated with surgery based on the imaging tests, the neurosurgeon may not do a needle biopsy. Instead, he or she may do an operation called a craniotomy (described in the “Surgery for adult brain and spinal cord tumors” section) to remove all or most of the tumor. (Removing most of the tumor is known as debulking.)
Small samples of the tumor are looked at right away by the pathologist while the patient is still in the operating room, for a preliminary diagnosis. This can help guide treatment, including whether further surgery should be done at that time. A final diagnosis is made a few days later in most cases.
Lumbar puncture (spinal tap)
This test is used to look for cancer cells in the cerebrospinal fluid (CSF), which is the liquid that surrounds the brain and spinal cord. For this test, you lay on your side on a bed or exam table with your knees up near your chest. The doctor first numbs an area in the lower part of the back near the spine. A small, hollow needle is then placed between the bones of the spine to withdraw some of the fluid.
This fluid is sent to a lab to be looked at under a microscope for cancer cells. Other tests may be done on the fluid as well.
Lumbar punctures are usually very safe, but doctors have to make sure the test does not result in a large drop in pressure in the fluid, which could possibly cause serious problems. For this reason, imaging tests such as CT or MRI scans are done first.
Except for tumors in the pineal region, lumbar punctures usually aren’t done to diagnose brain tumors. But they may be done to help determine the extent of a tumor by looking for cancer cells in the CSF. They are often used if a tumor has already been diagnosed as a type that can commonly spread through the CSF, such as an ependymoma. Lumbar punctures are particularly important in people with suspected brain lymphomas because often the lymphoma cells spread into the spinal fluid.
Blood and urine tests
These lab tests rarely are part of the actual diagnosis of brain and spinal cord tumors, but they may be done to check how well the liver, kidneys, and some other organs are working. This is especially important before any planned surgery. If you are getting chemotherapy, blood tests will be done routinely to check blood counts and to see if the treatment is affecting other parts of the body.
Last Medical Review: 10/09/2012
Last Revised: 02/06/2013