What is myelography?
Myelography, also called a myelogram, is an imaging test that checks for problems in your spinal canal. The spinal canal contains your spinal cord, nerve roots, and the subarachnoid space. The subarachnoid space is a fluid-filled space between the spinal cord and the membrane that covers it. During the test, contrast dye is injected into the spinal canal. Contrast dye is a substance that makes specific organs, blood vessels, and tissue show up more clearly on an x-ray.
Myelography involves using one of these two imaging procedures:
- Fluoroscopy, a type of x-ray that shows internal tissues, structures, and organs moving in real time.
- CT scan (computerized tomography), a procedure that combines a series of x-ray images taken from different angles around the body.
Other names: myelogram
What is it used for?
Myelography is used to look for conditions and diseases that affect the nerves, blood vessels, and structures in the spinal canal. These include:
- Herniated disk. Spinal disks are rubbery cushions (disks) that sit between the bones of your spine. A herniated disk is a condition in which the disk bulges out and presses on spinal nerves or the spinal cord.
- Spinal stenosis, a condition that causes swelling and damage to the bones and tissues around the spinal cord. This leads to narrowing of the spinal canal.
- Infections, such as meningitis, that affect the membranes and tissues of the spinal cord
- Arachnoiditis, a condition that causes inflammation of a membrane that covers the spinal cord
What happens during myelography?
A myelography may be done at a radiology center or in the radiology department of a hospital. The procedure usually includes the following steps:
- You may need to remove your clothing. If so, you will be given a hospital gown.
- You will lie on your stomach on a padded x-ray table.
- Your provider will clean your back with an antiseptic solution.
- You will be injected with numbing medicine, so you won't feel any pain during the procedure.
- Once the area is numb, your provider will use a thin needle to inject contrast dye into your spinal canal. You may feel some pressure when the needle goes in, but it should not hurt.
- Your provider may remove a sample of spinal fluid (cerebrospinal fluid) for testing.
- Your x-ray table will be tilted in different directions to allow the contrast dye to move to different areas of the spinal cord.
- Your provider will remove the needle.
- Your provider will capture and record images using fluoroscopy or a CT scan.
After the test, you may be monitored for one to two hours. You may also be advised to lie down at home for a few hours and to avoid strenuous activity for one to two days after the test.
Will I need to do anything to prepare for the test?
Your provider may ask you to drink extra fluids on the day before the test. On the day of the test, you will probably be asked to not eat or drink anything, except for clear fluids. These include water, clear broth, tea, and black coffee.
Talk to your provider about any medicines you are taking. Certain medicines, especially aspirin and blood thinners, should not be taken before your test. Your provider will let you know how long you need to avoid these medicines. It may be as long as 72 hours before the test.
Are there any risks to the test?
You should not take this test if you are pregnant or think you may be pregnant. Radiation can be harmful to an unborn baby.
For others, there is little risk to having this test. The dose of radiation is very low and is not considered harmful for most people. But talk to your provider about all the x-rays you've had in the past. The risks from radiation exposure may be linked to the number of x-ray treatments you've had over time.
There is a small risk of an allergic reaction to the contrast dye. Tell your provider if you have any allergies, especially to shellfish or iodine, or if you've ever had a reaction to contrast material.
What do the results mean?
If your results were not normal, it may mean you have one of the following conditions:
- Herniated disk
- Spinal stenosis
- Nerve injury
- Bone spurs
- Arachnoiditis (inflammation of the membrane surrounding the spinal cord)
A normal result means your spinal canal and structures were normal in size, position, and shape. Your provider may want to do more tests to find out what is causing your symptoms.
If you have questions about your results, talk to your health care provider.
Is there anything else I need to know about myelography?
MRI (magnetic resonance imaging) has replaced the need for myelography in many cases. MRIs use a magnetic field and radio waves to create images of organs and structures inside the body. But myelography can be more useful in diagnosing some conditions, such as certain spinal tumors and spinal disk problems. It's also used for people who are unable to have an MRI because they have metal or electronic devices in their bodies. These include a pacemaker, surgical screws, and cochlear implants.
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