What is a Myelogram?
A Myelogram (Myelography) is an imaging examination performed by a radiologist to detect abnormalities of the spine, spinal cord, or surrounding structures using a real time form of X-ray called fluoroscopy.
Contrast material is injected into the subarachnoid space of the spinal area enabling the radiologist to view and evaluate the status of the spinal cord, nerve roots, and intervertebral discs. Myelography provides a very detailed picture of the spinal cord and spinal column.
How does the procedure work?
X-rays are a form of radiation like radio waves. X-ray machines produce a small burst of radiation that passes through the body, recording an image on photographic film or a special digital image recording plate.
Fluoroscopy uses a continuous X-ray beam to create a sequence of images that are projected onto a fluorescent screen, or television-like monitor. This special X-ray technique makes it possible for the physician to view internal organs in motion.
Diagnostic Use of Myelogram
Myelography is most commonly used to detect abnormalities of the spinal cord, the spinal canal, the spinal nerve roots and the blood vessels that supply the spinal cord.
A myelogram is performed to assess:
- The cause of arm or leg numbness, weakness, or pain
- A tumor or infection causing problems with the spinal cord or nerve roots
- Narrowing of the spinal canal
- Inflammation of the arachnoid membrane that covers the brain and spinal cord.
A myelogram may help to find the cause of pain that cannot be found by other tests, such as an MRI or a CT scan.
How is it Performed?
Myelography is done on an outpatient basis. The patient is asked to lie face down on the examination table. The radiologist then uses the fluoroscope to project a sequence of radiographic images on a monitor. This enables the radiologist to visualize the spine to determine where to inject the contrast material.
The contrast material usually is injected into the lower lumbar spine, because it is considered easier and safer. At the site of the injection, the skin will be cleaned and numbed with a local anesthetic.
Depending on the location of the puncture, the patient will be positioned on their side, on their abdomen, or in a sitting position as the needle is inserted.
The contrast material is then injected and the x-ray table is slowly tilted so that contrast material will run up and down the spine and surround the nerve roots that are next to the spinal cord.
The radiologist will monitor the flow of contrast with fluoroscopy, focusing on the area of the patient’s symptoms.
What are the Risks?
This procedure is very safe, however, as with most procedures; there are possible risks and complications.
Because X-rays are used during this procedure, pregnant women should not have this test as there is a small risk that X-rays may cause an abnormality to the unborn child.
A small percentage of people who have a myelogram may experience headache, nausea, or vomiting after the test.
There is a small risk of infection at the injection site and a possible risk of bleeding into the spinal canal.
The contrast dye used often contains iodine, which can cause allergic reaction in some patients. Also, the contrast dye may cause kidney damage in people who have a history of kidney problems.