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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.
When the contrast material is injected into the subarachnoid space, the radiologist is able to view and evaluate the status of the spinal cord, nerve roots, and meninges, which are the membranes which surround and cover the spinal cord and nerve roots. Myelography provides a very detailed picture 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 permanent images, called x-rays or radiographs, 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.
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, 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:
Myelography can also be used to assess the following conditions when MR imaging cannot be performed, or in addition to MRI:
A myelogram can show whether surgical treatment is promising in a given case and, if it is, can help in planning surgery.
How should I prepare?
You should inform your physician of any medications you are taking and if you have any allergies, especially to barium or iodinated contrast materials. Also inform your doctor about recent illnesses or other medical conditions.
Some drugs should be stopped one or two days before myelography. These include certain antipsychotic medications, antidepressants, blood thinners, and drugs-especially metformin-that are used to treat diabetes. The most important type of medication that must be stopped is blood thinners (anticoagulants).
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.
Women should always inform their physician or x-ray technologist if there is any possibility that they are pregnant.
At the conclusion of the myelogram, the patient usually remains in an observation area for 1-2 hours and is discharged.
How is the procedure performed?
As the patient lies face-down on the examination table, 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 usually is injected into the lower lumbar spine, because it is considered easier and safer. Occasionally, if it is deemed safer or more useful, the contrast material will be injected into the upper cervical 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 or in a sitting position as the needle is inserted. The needle is advanced, usually under fluoroscopic guidance, until its tip is positioned within the subarachnoid space within the spinal canal, at which time a free slow flow of 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. The patient is then positioned on the table, usually lying on their abdomen.
Again using the fluoroscope for guidance, the radiologist then slowly 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. A computed tomography (CT) scan is frequently 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 while the table is tilted at different angles. A foot rest and straps or supports for your feet and ankles will keep you from sliding out of position. You may find the face-down position uncomfortable; however, you should not have to maintain this position for very long. Rarely, a patient may experience difficulty breathing deeply or swallowing when the table is tilted face down. If this should occur, please tell the radiologist or technologists and the table will be raised to a more comfortable position.
Headaches, flushing, or nausea may follow contrast injection, though this is rare. Seizures are also possible, but are very rare when the newer contrast materials are used.
Following the conclusion of the myelogram, the patient will be escorted to a recovery area where vital signs and general patient conditions are observed for one to two hours. 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.
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