A myelography is a type of diagnostic medical imaging examination in which x-rays are taken of the interior of the spinal canal. This procedure is used to examine the spine for abnormalities that may indicate the presence of disease. The overall purpose of myelography is to diagnose disease and contribute to an assessment of the type of spinal treatment a patient requires.
Myelography is used to examine the structures of the spine, including the spinal canal, spinal cord, spinal nerves, and spinal cord blood vessels. In addition to infection, inflammation, tumors, and lesions, this type of medical imaging test can detect disc herniation and a degenerative soft tissue disease called spinal stenosis. This diagnostic test may be carried out in cases where an MRI is not appropriate. If, for example, a patient uses a medical device such as a pacemaker, he or she cannot undergo an MRI, as the magnetic energy emitted by the machine may interfere with the pacemaker. In such cases he or she may undergo a myelogram.
In preparing for a myelogram, a patient should be aware that certain medications may interfere with the procedure or may add to the risk of the procedure. These include seizure medications, antidepressants and antipsychotic medications, blood thinners, and certain diabetes medications. A patient who is taking one of these medications, or who has any allergies, should speak to his or her doctor before the procedure to discuss preparation. A woman who is pregnant, or thinks she may be pregnant, should also ensure her physician, and the x-ray technicians and radiologist involved in the procedure, are aware of the pregnancy.
At the start of a myelography procedure, a contrast dye is injected into a location in the spine called the subarachnoid space. This space is located between two membranes which enclose the spinal cord. After the dye has been injected, the patient’s spine is viewed using an x-ray technique called fluoroscopy, in which a continuous beam of x-ray energy is directed at the area of interest. This technique allows the radiologist to view the contrast dye as it flows through the subarachnoid space, which means he or she can evaluate function as well as structure.
The procedure usually takes between thirty and sixty minutes to complete. In some cases a patient may undergo a CT scan following the myelogram, which takes another thirty minutes. Following the procedure, a patient will remain in the hospital or clinic for a short time for observation.
Myelography is painless and generally safe, with few risks. Some patients may experience headaches following the procedure, which may require medication. People who are allergic to the contrast dye may experience rashes, sneezing, itching, or nausea. Very rarely, the dye injection may cause nerve damage, inflammation, or infection.