A myelogram uses a special dye (contrast material) and X-rays (fluoroscopy) to make pictures of the bones and the fluid-filled space (subarachnoid space) between the bones in your spine (spinal canal). A myelogram may be done to find a tumor, an infection, problems with the spine such as a herniated disc, or narrowing of the spinal canal caused by arthritis.
The spinal canal holds the spinal cord, spinal nerve roots, and the subarachnoid space. A dye is put into the subarachnoid space with a thin needle. The dye moves through the subarachnoid space so the nerve roots and spinal cord can be seen more clearly. Pictures may be taken before and after the dye is used. To get more information from the test, a CT scan is often done after the X-rays, while the dye is still present.
Why It Is Done
A myelogram is done to check for:
- The cause of arm or leg numbness, weakness, or pain.
- Narrowing of the spinal canal (spinal stenosis).
- A tumor or infection causing problems with the spinal cord or nerve roots.
- A spinal disc that has ruptured (herniated disc).
- Inflammation of the membrane (arachnoid membrane) that covers the brain and spinal cord.
- Problems with the blood vessels to the spine.
A myelogram may help find the cause of pain that cannot be found by other tests, such as an MRI or a CT scan.
How To Prepare
You may need to stop eating and drinking for 4 to 8 hours before this test. Follow the instructions your doctor gives you about eating and drinking.
Before a myelogram, tell your doctor if you:
- Have epilepsy or a seizure problem.
- Are or might be pregnant.
- Are allergic to any medicines, contrast material, or iodine dye.
- Have bleeding problems or take blood-thinning medicines, such as aspirin, heparin, or warfarin (Coumadin).
- Have asthma.
- Have ever had a severe allergic reaction (anaphylaxis).
- Have had kidney problems.
- Have diabetes, especially if you take metformin (Glucophage).
Arrange to have someone take you home and stay with you after the test.
Talk to your doctor about any concerns you have regarding the need for the test, its risks, or how it will be done. To help you understand the importance of this test, fill out the medical test information form(What is a PDF document?) .
How It Is Done
A myelogram is done in an outpatient radiology center or in the radiology department of a hospital by a radiologist and assistants.
You will need to take off jewelry that might be in the way of the X-ray picture. You may need to take off all or most of your clothes above the waist (you may be allowed to keep on your underwear if it does not get in the way of the test). You will be given a gown to wear during the test.
A lumbar puncture is done to put the dye into the spinal canal. You will lie on your stomach or side on an X-ray table. The doctor cleans an area on your lower back. A numbing medicine (local anesthetic) is put into your skin.
After the area is numb, a thin needle is put into the spinal canal and a continuous stream of X-rays (fluoroscopy) is used to help the doctor place the needle in the right area. A sample of spinal canal fluid (cerebrospinal fluid) may be taken before the dye is put in the canal.
After the dye is put in, you will lie still while the X-ray pictures are taken. If pictures of your upper back or neck are needed, the table may be tilted or you may be asked to move into different positions so the dye will move into that area. Your chin will be placed on a small pillow to keep your head up. This stops the dye from going into your head, which can cause headaches or seizures. Your pulse, breathing rate, and blood pressure may be checked during the test.
After the X-ray pictures are taken, a small bandage is put on your back where the needle was put in. You will be given instructions on what to do after the test.
After the test
A myelogram usually takes 30 minutes to one hour. If a CT scan is also done, that takes more time.
You may need to lie in bed with your head elevated for 4 to 24 hours after the test. To prevent seizures, do not bend over or lie down with your head lower than your body.
Avoid strenuous activity, such as running or heavy lifting, for at least one day after your myelogram.
Drink plenty of water after the myelogram. Your doctor will give you instructions on taking your regular medicines.
How It Feels
You will feel a quick sting from the small needle used to numb the skin on your back. You will feel some pressure as the long, thin spinal needle is put into your spinal canal. You may feel a quick sharp pain down your buttocks or leg when the needle is moved in your spine. You may find it hard to lie on your stomach or side during this test.
The dye may make you feel warm and flushed and have a metallic taste in your mouth. Some people feel sick to their stomachs or have a headache. Tell your doctor how you are feeling.
There is some risk of problems with a myelogram.
- About 20% of people who have a myelogram develop a headache, nausea, or vomiting after the test. The headache may last for 24 hours. In rare cases, a seizure may occur after the dye is put into the spinal canal.
- There is a small risk of a seizure if the dye moves to the brain. This is why if or when you lie down, you need to keep your head raised higher than your body.
- There is a small risk of infection at the needle site or bleeding into the spinal canal.
- In rare cases, the hole made by the needle in the sac around the spine does not close normally. This can allow spinal fluid to leak out. This leak may need to be repaired through a procedure called an epidural blood patch. To do the patch, your doctor injects some of your own blood to cover the hole.
- There is a small risk of having an allergic reaction to the dye. You will be given medicine for a reaction.
- There is a risk of kidney problems if you take metformin (Glucophage) to control your diabetes.
- In rare cases, inflammation of the spinal cord, weakness, numbness, paralysis, or loss of control of your bowel or bladder may develop.
- Also in rare cases, the dye may cause blockage of the spinal canal. If this occurs, surgery is usually needed.
- There is always a slight chance of damage to cells or tissue from radiation, including the low levels of radiation used for this test. But the chance of damage from the X-rays is usually very low compared with the benefits of the test.
After the test
Call 911 or other emergency services immediately if you have a seizure.
Call your doctor immediately if you:
- Have any increase in pain, weakness, or numbness in your legs.
- Have a severe headache, stiff neck, or your eyes become very sensitive to light.
- Have a headache that lasts longer than 24 hours.
- Have problems urinating or having a bowel movement.
- Develop a fever.
A myelogram uses a special dye (contrast material) and X-rays (fluoroscopy) to make pictures of the bones and the fluid-filled space (subarachnoid space) between the bones in your spine (spinal canal).
The dye flows evenly through the spinal canal.
The spinal cord is normal in size, position, and shape. The nerves leaving the spinal cord are normal.
No narrowing or blockage of the spinal canal is seen.
Inflammation of the membrane (arachnoid membrane) that covers the spinal cord is seen.
One or more nerves leaving the spinal cord are pinched.
What Affects the Test
Reasons you may not be able to have the test or why the results may not be helpful include:
- Being pregnant. A myelogram is not usually done during pregnancy because the radiation could damage the developing baby (fetus).
- Not being able to lie still during the test.
- Having had prior surgery on your spine or having a curved spine, severe arthritis, or some types of spinal injuries or defects. These conditions make it hard to place the needle with the dye into the spinal canal.
What To Think About
- Keeping your head higher than your body after a myelogram may help prevent or reduce side effects of the test, such as headache, nausea, or vomiting.
- A CT scan or magnetic resonance imaging (MRI) has replaced the need for a myelogram in many cases. For more information, see the medical tests Computed Tomography (CT) Scan of the Spine and Magnetic Resonance Imaging (MRI) of the Spine.
- A myelogram is often done with a CT scan to make more detailed pictures of the spine.
- If a tumor is seen on the myelogram or if the lumbar puncture causes a total blockage of the spinal canal, surgery may be needed right away.
Other Works Consulted
- Chernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis: Saunders.
- Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.
|Author||Shannon Erstad, MBA/MPH|
|Associate Editor||Tracy Landauer|
|Primary Medical Reviewer||Kathleen Romito, MD - Family Medicine|
|Specialist Medical Reviewer||Howard Schaff, MD - Diagnostic Radiology|
|Last Updated||September 9, 2009|