A myelogram is a diagnostic imaging test generally done by a radiologist. It uses a contrast dye and X-rays or computed tomography (CT) to look for problems in the spinal canal. Problems can develop in the spinal cord, nerve roots, and other tissues. This test is also called myelography.
The contrast dye is injected into the spinal column before the procedure. The contrast dye appears on an X-ray screen allowing the radiologist to see the spinal cord, subarachnoid space, and other nearby structures more clearly than with standard X-rays of the spine.
The radiologist will also use a CT scan when doing a myelogram. A CT or CAT scan is an imaging test that uses X-rays and a computer to make detailed images of the body. A CT scan shows details images of the spinal canal. CT scans show more details than standard X-rays.
A myelogram may be done to assess the spinal cord, subarachnoid space, or other structures for changes or abnormalities. It may be used when another type of exam, such as a standard X-ray, does not give clear answers about the cause of back or spine problems. Myelograms may be used to evaluate many diseases, including:
- Herniated discs (discs that bulge and press on nerves and/or the spinal cord)
- Spinal cord or brain tumors
- Infection and/or inflammation of tissues around the spinal cord and brain
- Spinal stenosis (degeneration and swelling of the bones and tissues around the spinal cord that make the canal narrow)
- Ankylosing spondylitis (a disease that affects the spine, causing the bones to grow together)
- Bone spurs
- Arthritic discs
- Cysts (benign capsules that may be filled with fluid or solid matter)
- Tearing away or injury of spinal nerve roots
- Arachnoiditis (inflammation of a delicate membrane that covers the brain.)
There may be other reasons for your healthcare provider to recommend a myelogram.
You may want to ask your healthcare provider about the amount of radiation used during the procedure and the risks related to your situation. It is a good idea to keep a record of your radiation exposure, such as previous CT scans and other types of X-rays, so that you can inform your healthcare provider. Risks associated with radiation exposure may be related to the cumulative number of X-ray exams and/or treatments over a long period.
If you are pregnant or think you may be, tell your healthcare provider. Radiation exposure to the fetus may cause birth defects.
There is a risk of an allergic reaction to the contrast dye. Be sure to let your healthcare provider know if you have ever had a reaction to any contrast dye, or have any kidney problems.
Because the contrast is injected into the cerebrospinal fluid (CSF) which also surrounds the brain, there is a small risk of seizure after the injection. Some medications may place you at greater risk for seizure and you may be asked to stop taking these for 48 hours before and after the study. Make sure your healthcare provider has a list of all medicines (prescribed and over-the-counter) and all herbs, vitamins, and supplements that you are taking.
Because this procedure involves a lumbar puncture, these potential complications may happen:
- A small amount of CSF can leak from the needle insertion site. This can cause headaches after the procedure. If there is a persistent leak the headache can be severe.
- There is a slight risk of infection because the needle breaks the skin's surface, providing a possible entry point for bacteria.
- Short-term numbness of the legs or lower back pain may be experienced.
- There is a risk of bleeding in the spinal canal.
There may be other risks depending on your specific medical condition. Be sure to discuss any concerns with your healthcare provider before the procedure.
- Your healthcare provider will explain the procedure to you and ask if you have any questions.
- You will be asked to sign a consent form that gives your permission to do the procedure. Read the form carefully and ask questions if anything is not clear.
- Generally, you will not need to fast (not eat) before this test. Your healthcare provider will tell you if there are any necessary fasting requirements. You may be asked to drink extra fluids the day before the test.
- Be sure to tell your healthcare provider or the radiologist if you have ever had a reaction to any contrast dye or if you are allergic to iodine.
- Tell the radiologist if you are pregnant or think you may be.
- Make sure your healthcare provider has a list of all medicines (prescribed and over-the-counter) and all herbs, vitamins, and supplements that you are taking.
- Sedation (drugs to make you sleepy) may be given before the procedure to help you relax.
- Tell the healthcare provider if you have a history of seizures or if you are taking any medicines for seizures.
- Tell your healthcare provider if you have a history of bleeding disorders or if you are taking any anticoagulant (blood-thinning) medicine, aspirin, or other medicines that affect blood clotting. You may need to stop these medicines before the procedure.
- If the procedure is done on an outpatient basis, you may be asked to stay in the hospital for several hours afterwards. You should plan to have another person drive you home.
- Based on your medical condition, your healthcare provider may give you other instructions on what to do before the procedure.
A myelogram may be done on an outpatient basis or as part of your stay in a hospital. The procedure takes about an hour, but may vary depending on your condition and the clinic's practices.
Generally, a myelogram follows this process:
- You will be asked to remove any clothing, jewelry or other objects that may get in the way of the procedure.
- If you are asked to remove your clothing, you will be given a gown to wear.
- You will be reminded to empty your bladder before the start of the procedure.
- During the procedure, you will lie on your stomach on a padded table.
- Your back will be cleaned with an antiseptic solution and draped with sterile towels.
- The radiologist will numb the skin of your lower spine by injecting a local anesthetic (numbing) drug using a thin needle. This injection may sting for a few seconds, but it makes the procedure less painful.
- A needle will be inserted through the numbed skin, between two vertebrae (the spinal bones), and into the subarachnoid space where the spinal fluid is located. You will feel some pressure while the needle goes in, but you must stay still.
- The radiologist will remove some of the spinal fluid from the spinal canal. Next, a small amount of contrast dye will be injected into the spinal canal through the needle. You may feel a warming sensation when the contrast dye is injected.
- The X-ray table will be tilted in various directions to allow gravity to help move the contrast dye to different areas of your spinal cord. You will be held in place by a special brace or harness. More contrast dye may be given during this process through the secured lumbar puncture needle.
- The needle is then removed and the X-rays and/or CT scan pictures are taken.
- You should tell the radiologist right away if you feel any numbness, tingling, headache, or lightheadedness during the procedure.
You may experience discomfort during the myelogram. The radiologist will use all possible comfort measures and complete the procedure as quickly as possible to minimize any discomfort or pain.
You need to sit or lay down for several hours after the procedure to reduce your risk of developing a CSF (cerebral spinal fluid) leak.
You will be asked to drink extra fluids to rehydrate after the procedure. This helps to wash out the contrast dye and it helps your body replace the spinal fluid that was removed. It also reduces the chance of developing a headache.
A nurse will monitor your vital signs (blood pressure, temperature, pulse, and respirations) frequently after the test. You will be given pain medicine if you develop a headache.
When you have completed the recovery period, you will be taken to your hospital room or discharged to your home.
Once you are at home, tell your doctor of any changes including:
- Numbness and tingling of the legs
- Blood or other drainage from the injection site
- Pain at or near the injection site
- Nausea or vomiting
- Inability to urinate
- Stiff neck
- Leg numbness
If the headaches persist for more than 24 hours after the procedure, or are worse when you change positions, you should contact your doctor.
You may be instructed to limit your activity for 24 hours after the procedure. Generally, if you don’t have any problems, you may return to your normal diet and activities.
Your doctor may give you additional or alternative instructions after the procedure, depending on your particular situation.
Before you agree to the test or the procedure make sure you know:
- The name of the test or procedure
- The reason you are having the test or procedure
- What results to expect and what they mean
- The risks and benefits of the test or procedure
- What the possible side effects or complications are
- When and where you are to have the test or procedure
- Who will do the test or procedure and what that person’s qualifications are
- What would happen if you did not have the test or procedure
- Any alternative tests or procedures to think about
- When and how will you get the results
- Who to call after the test or procedure if you have questions or problems
- How much will you have to pay for the test or procedure
January 16, 2018
Fischbach, Frances Talaska. A Manual of Laboratory and Diagnostic Tests. 2009;8:783–85.
Shelat, Amit, MD,Ziegler, Olivia, MS, PA