• What is Myelography?
• What are some common uses of the procedure?
• How should I prepare?
What does the myelography equipment look like?
• How does the procedure work?
• How is the procedure performed?
What will I experience during and after the procedure?
Who interprets the results and how do I get them?
• What are the benefits vs. risks?
• A Word About Minimizing Radiation Exposure.
What are the limitations of Myelography?
What is Myelography?
Myelography is an imaging examination 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 form of x-ray called fluoroscopy.
What are some common uses of the procedure?
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, which may prevent him or her from undergoing MRI. Sometimes myelography and/or a CT scan are 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. The most common abnormalities are disc extrusions or protrusions that push on nerve roots or the spinal cord. Another condition termed spinal stenosis in which the spinal canal narrows because the surrounding tissues enlarge and encroach upon the central nerve roots. Some processes that may cause this are bony spurs (osteophytes), disc extrusions, and arthritis of the facet joints and ligaments.
Myelography can also be used to assess the following conditions when MR imaging cannot be performed, or in addition to MRI:
You should inform your physician of any medications you are taking and if you have any allergies, especially to barium or iodinated contrast material. Also inform your doctor about recent illnesses or other medical conditions.
Specifically, the physician needs to know if (1) you are taking medications that need to be stopped a few days before the procedure and (2) whether you have a history of reaction to the contrast material used for the myelogram.
Some drugs should be stopped before myelography. These include certain antipsychotic medications, antidepressants, blood thinners, and other drugs-such as Ultram. The most important type of medication that must be stopped is blood thinners (anticoagulants-baby/aspirin, coumadin, plavix). If you are taking blood thinners, you should speak with your physician, and if necessary, about alternative methods of maintaining anticoagulation while you are undergoing a myelogram.
Although reactions to the iodinated contrast material used in the myelogram are extremely uncommon, you should inform your physician if you have previously had a severe allergic reaction to contrast material or other medication.
Usually patients are advised to increase their fluid intake the day before a scheduled myelogram, as it is important to be well hydrated. Solid foods should be avoided for several hours before the exam, but fluids may be continued.
You may be asked to remove some or all of your clothes and to wear a gown during the exam. You may also be asked to remove jewelry, eye glasses and any metal objects or clothing that might interfere with the x-ray images.
Women should always inform their physician or x-ray technologist if there is any possibility that they are pregnant. Many imaging tests are not performed during pregnancy so as not to expose the fetus to radiation.
At the conclusion of the myelogram, the patient is discharged with instructions to be on bed rest for the next 6 hours. You need to arrange to have a relative or friend take you home. Do not plan on driving or working the day of your myelogram. Do eat and drink fluids. You may restart any medications you were asked to discontinue the next day.
What does the myelography equipment look like?
The equipment typically used for this examination consists of a radiographic table, an x-ray tube and a digital monitor that is located in the examining room. When used for viewing images in real time, the image intensifier (which converts x- rays into a video image) is suspended over a table on which the patient lies. When used for taking still pictures, the image is captured electronically.
Fluoroscopy uses a continuous x-ray beam to create a sequence of images that are projected onto a digital monitor. When used with a contrast material, which clearly defines the area being examined, this special x-ray technique makes it possible for the physician to view internal organs in motion. Still images are also captured and stored electronically on a computer.
How is the procedure performed?
This examination is done in our facility on an outpatient basis.
You, the patient, lay face-down on the examination table for a lumbar study, and on your side for a cervical study. The radiologist will use the fluoroscope, which projects radiographic images in a movie-like sequence onto the monitor, to visualize the spine and determine the best place to inject the contrast material. The contrast material is injected into the cervical or lumbar spine.
At the site of the injection, the skin will be cleaned and then numbed with a local anesthetic. Depending on the location of the puncture, the patient will be positioned on their side or abdomen. The needle is advanced, under fluoroscopic guidance, until its tip is positioned within the subarachnoid space within the spinal canal, at which time CSF fluid is obtained. If requested by the referring physician, a small amount of cerebrospinal fluid may be withdrawn for laboratory studies. The contrast material is then injected through the needle, the needle is removed and the skin at the puncture site is again cleaned.
Again using the fluoroscope for guidance, the radiologist then tilts the x-ray table allowing the contrast material to flow up or down within the subarachnoid space and to surround the nerve roots or the spinal cord. At this point, the patient may be repositioned on their and additional x-ray images are be obtained by the radiologist and technologist; while such images are being obtained, it is important for the patient to remain still to reduce the possibility of blurred images. A computed tomography (CT) scan is always performed immediately following the conclusion of the myelography while contrast material is still present within the spinal canal. This combination of imaging studies is known as CT myelography.
A myelography examination is usually completed within 30 to 60 minutes. A CT scan will add another 15 to 30 minutes to the total examination time.
What will I experience during and after the procedure?
You will feel a brief sting when local anesthetic is injected under the skin and you will feel slight pressure on your back as the spinal needle is inserted. Positioning the needle can occasionally cause a sharp pain. During the exam, you will be asked to lay as still as possible. You may find the face-down position uncomfortable; however, you should not have to maintain this position for very long.
Headaches, flushing, or nausea may follow contrast injection, though this is rare. Seizures are also possible, but are very rare with the newer contrast materials that we use.
Following the conclusion of the myelogram, the patient will discharged into the care of their driver. Once home you are to be on bed rest for the next 6 hours. The head can be elevated at a 30° to 45° angle. You are encouraged to take fluids at this time to help eliminate the contrast material from your body and to prevent headache. Following your myelogram, you should refrain from strenuous physical activity and from bending over for one to two days.
You should notify your health professional if you experience fever higher than 100.4°F, excessive nausea or vomiting, severe headache for more than 24 hours, neck stiffness or numbness in your legs. You should also report if you have trouble urinating or moving your bowels.
Who interprets the results and how do I get them?
A radiologist, a physician specifically trained to supervise and interpret radiology examinations, will analyze the images and send a signed report to your primary care or referring physician, who will discuss the results with you.
What are the benefits vs. risks?
Benefits:
Risks:
A Word About Minimizing Radiation Exposure.
Special care is taken during x-ray examinations to use the lowest radiation dose possible while producing the best images for evaluation. National and international radiology protection councils continually review and update the technique standards used by radiology professionals.
Our state-of-the-art x-ray systems have tightly controlled x-ray beams with significant filtration and dose control methods to minimize stray or scatter radiation. This ensures that those parts of a patient's body not being imaged receive minimal radiation exposure.
The most significant limitation of myelography alone is that it only sees inside the spinal canal and the very adjacent spinal nerve roots. Abnormalities outside these areas may be better imaged with MRI or CT. This is why you will always have CT scan to follow the injection of contrast into the spinal canal.
Myelography usually is avoided during pregnancy because of the potential risk to the baby.
The findings may not be accurate if the patient cannot hold still and moves a great deal during the exam.
It may be difficult to inject contrast material in patients with structural defects of the spine or following some forms of spinal injury.
Myelography cannot be performed if the injection site is infected.
Copyright © 2005 Radiological Society of North America, Inc.
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© 2009 Mink Radiologic Imaging, Inc.