When the spinal cord is damaged, doctors use an imaging test called myelography to identify problems. A radiologist injects a contrast dye into the space around the spinal cord so they can take videos and pictures of your spine with fluoroscopy [floo-ROS-kuh-pee] and x-ray images. This test is often used to identify problems such as herniated disks, damaged spinal nerve roots, and tumors.
The spinal cord is a nerve in a long tube, protected by the spine bones and ligaments. When the nerve is hurt, your doctor may order tests, including myelography [mahy-uh-LOG-ruh-fee], to see what the problem is.
In a myelography, your doctor puts a needle into the spinal canal and injects a contrast dye into the space around the spinal cord and nerve roots.
The contrast material allows the doctor to see things better than in a standard x-ray. The doctor can examine the spinal column, subarachnoid [suhb-uh-RAK-noid] or surrounding space, and nerve roots.
A detailed image, or myelogram [MAHY-uh-luh-gram], is taken as the contrast material flows in the subarachnoid space. Along with observing the flow of the contrast dye in real-time, the radiologist will take permanent x-ray images to document any issues.
A myelography test is used to diagnose problems like:
- Herniated [HUR-nee-eyt-uhd], or bulging disks between vertebra that put pressure on the nerve roots or spinal cord
- Weak bones and tissues around the spinal canal (spinal stenosis)
- Spinal lesions caused by disease or trauma
- Infection or inflammation
After a myelogram, your doctor may also recommend other imaging tests:
- A CT scan can take pictures of your body that are more detailed than x-rays. It is preferred for those who have a medical device, such as a cardiac pacemaker, or spinal instrumentation, such as plates, rods, or screws, that prevent them from undergoing MRI.
- An MRI is a noninvasive medical test that allows the doctor to see the entire cervical canal and spinal cord. MRI visualizes the spinal cord and nerve roots from multiple angles and is better in detecting unsuspected issues in certain segments of the spine.
Being exposed to radiation like x-rays can increase your chance of cancer. X-rays can increase your risk of cancer. However, this risk is small, and most doctors think getting an accurate diagnosis outweighs this small risk. Women should always tell their doctor if there is any chance that they are pregnant, as the developing baby is more sensitive to radiation.
Less common risks include:
- Headache associated with needle puncture
- Adverse/allergic reactions to the contrast material, causing itching, rash, sneezing, or nausea
Rare side effects include:
- Severe reactions involving the lungs and heart
- Hives or wheezing
- Nerve injury from the spinal needle
- Bleeding around nerve roots in the spinal canal
- Inflamed or infected meninges [men-IN-jeez], meaning the membranes covering the spinal cord
- The need for surgery if fluid around the spinal canal becomes blocked
Myelography is a relatively safe and painless procedure. It is an important test since it helps your doctor to make the best diagnosis and treatment plan.
You should tell your doctor about all medicines, recent illnesses, medical conditions, and allergies (especially to iodine or contrast materials) before the myelography.
Your doctor will give you instructions on how to prepare for this test. You may need to stop using certain medicines, such as certain antipsychotic medicines, antidepressants, and blood thinners, one or two days before myelography.
Your doctor may tell you to drink more fluids the day before and the day of your myelogram. You will also likely be asked to not eat solid foods for several hours before the test.
At the hospital, you will be given a gown to wear and asked to remove some of your clothes. You will also need to take off any metal objects that could interfere with an x-ray, such as glasses and jewelry.
After the exam, you will stay in an observation area for about two hours before the doctor lets you go home. If your doctor does not need you to stay overnight, you should arrange for a ride home.
For a myelogram, you will lie down on an x-ray table on your side or stomach. The skin at the injection site is cleaned, and a local anesthetic is injected so that the test won’t hurt. The radiologist will use the fluoroscope [FLOOR-ah-SKOHP] to take a video of the inside of your body so that they can decide the best spot to inject the contrast dye. A longer needle is then used to inject the contrast dye into the spinal canal.
Using the fluoroscope for guidance again, the doctor will slowly tilt the x-ray table so the dye will flow through your subarachnoid space. This will help your doctor see any problems and take x-ray images for further study. The doctor will use this myelogram to look for damage to the spinal cord so your doctor can determine the best treatment.
Your doctor may also want an MRI or CT scan to be performed directly after the myelography, while the contrast dye is still in the spinal canal. A myelography exam takes less than an hour, and a CT scan will add another 15 to 30 minutes to the exam time.
Myelography is usually done by a radiologist, who is trained to review and interpret the results. The radiologist will look at the images and send a report to your doctor, who will follow up with you on results and treatment.
Follow-up exams may be needed to see if treatment is working. Sometimes, your doctor will also want to look more closely at a problem with different imaging techniques. If your doctor is monitoring a problem over time, you may need regular follow-up exams.