Myelography is an imaging exam that involves the introduction of a spinal needle into the spinal canal and the injection of contrast material in the space around the spinal cord (the subarachnoid space) and nerve roots using a real-time type of X-ray called fluoroscopy.
Myelography provides a very detailed picture (myelogram) of the spinal cord and spinal column. The radiologist views the passage of contrast material in real-time within the subarachnoid space as it is flowing using fluoroscopy but also may take X-rays of the contrast material around the spinal cord and nerve roots in order to document abnormalities involving or affecting these structures.
In most cases, the myelogram is followed by a computed tomography (CT) scan to better define the anatomy and any abnormalities.
Common Uses of Myelography
Magnetic resonance imaging (MRI) is often the first imaging exam done to evaluate the spinal cord and nerve roots. However, on occasion, a patient has medical devices, such as a cardiac pacemaker, that may prevent him or her from undergoing MRI. Sometimes, myelography and/or a CT scan is performed in conjunction with MRI to better define abnormalities.
Myelography is most commonly used to detect abnormalities affecting the spinal cord, the spinal canal, the spinal nerve roots and the blood vessels that supply the spinal cord, including:
- Showing whether herniations of the material between the vertebral bodies, termed the intervertebral disks, are pushing on nerve roots or the spinal cord.
- Depicting a condition that often accompanies degeneration of the bones and soft tissues surrounding the spinal canal, termed spinal stenosis. In this condition, the spinal canal narrows as the surrounding tissues enlarge due to the development of bony spurs (osteophytes) and the adjacent ligaments.
Myelography can also be used to assess the following conditions when MR imaging cannot be performed, or in addition to MRI:
- Inflammation of the arachnoid membrane that covers the spinal cord
- Spinal lesions caused by disease or trauma
A myelogram can show whether surgical treatment is promising in a given case and, if it is, can help in planning surgery.