What to Expect During a Myelography
This examination is usually done on an outpatient basis.
As you lie 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.
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, you will be positioned on your side or abdomen or in a sitting position as the needle is inserted. In some cases, you will be placed in a sitting position. 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 If requested by the referring physician, a small amount of cerebrospinal fluid may be withdrawn for laboratory studies.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. You are 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. As the table is tilted, the radiologist monitors the flow of contrast material with fluoroscopy, focusing on the area that correlates with the patientís symptoms. At this point, the patient may be repositioned on their side, and additional x-ray images may 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. When these images have been completed, the table is returned to the horizontal position, and the patient is allowed to roll onto their back and assume a position of greater comfort while the images are checked by the radiologist.
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.
At the conclusion of the myelogram, you usually remain in an observation area for 1-2 hours and is discharged. Unless you are to spend the night in hospital, you should arrange to have a relative or friend take you home.
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/or shoulder harness will help 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.
At the end of the myelogram, you will be escorted to a recovery area where vital signs and your general condition is observed for one to two hours. Some facilities have patients stay in the recovery area resting with the head elevated at a 30 degree to 45 degree angle for as long as four hours. You may be 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.
Limitations of a Myelography
The most significant limitation of myelography 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.
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.