Myelography
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myelography
(′mī·ə′läg·rə·fē)
(medicine) Roentgenographic visualization of the subarachnoid space, after the injection of air or an opaque medium.
Yale University Guide to Medical Tests:
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Myelography
General information
Other names
| Where It's Done | Who Does It | How Long It Takes | Discomfort/Pain |
| Hospital imaging suite or radiology laboratory. | Doctor. | 45-60 minutes. | Some discomfort during lumbar puncture and as table is tilted. |
| When Results Ready | Special Equipment | Risks/Complications | Average Cost |
| A few hours to a few days. | Fluoroscope and X-ray equipment with a tilting table, contrast dye, spinal needle, and local anesthetic. | Risks associated with radiation, particularly during pregnancy; seizures; stroke; bleeding; infection and inflammation; headaches; nausea and vomiting; allergic reaction from the contrast dye. | $$ |
Cervical, lumbar, or thoracic myelography.
Purpose- To detect herniated discs, tumors, injuries, enlarged blood vessels, and other abnormalities, especially compression of the spinal cord.
- To evaluate problems in the spinal cord before surgery.
- To detect injuries to the nerve roots branching off the spinal cord.
- To detect tumors in the lower part of the brain.
Contrast dye injected into the cerebrospinal fluid (which surrounds the brain and spinal cord) makes it possible to view internal structures with the help of fluoroscopy, a type of moving X-ray.
Preparation- Avoid eating or drinking for eight hours before the test.
- You remove your clothing and don a hospital gown.
- A lumbar puncture is usually performed before myelography to inject the dye.
- Local anesthesia is administered at the site where the spinal needle will be inserted.
- A long needle is inserted into the spinal canal, with the help of a fluoroscope, and guided to the subarachnoid space, between the layers of membrane that surround the spinal cord.
- Once the needle is in place, a contrast dye is injected and X-ray pictures are taken.
- To move the dye to structures of interest, you may be slowly titled head down during parts of the test. Care will be taken to prevent the contrast dye from entering the brain.
- You are free to leave but you must rest in bed for 12 hours with your head elevated.
- Drink a great deal of fluids.
- Failure to observe dietary restrictions before the test.
- Amount of contrast dye injected.
The doctor examines the X-ray images, called a myelogram, for signs of abnormalities. Abnormalities can also be detected by observing the flow of the contrast dye under a fluoroscope. If the spinal canal is blocked or narrowed, the dye will not spread evenly or will be blocked, and the contour of the spinal cord will also be distorted.
AdvantagesObstruction and abnormalities are easily seen and well defined on X-rays.
Disadvantages- Additional diagnostic information may be obtained from the spinal fluid (see LP testing).
- It's invasive.
- It involves exposure to radiation.
- It cannot be performed in people with severe curvature of the spine or increased intracranial pressure.
Treatment.
PATIENT TIP
Tell the doctor if you have bleeding problems or if you are taking anti-coagulant drugs.
Oxford Dictionary of Sports Science & Medicine:
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myelography
A specialized X-ray technique, involving the injection of a radio-opaque substance, used to examine the spinal canal.
Saunders Veterinary Dictionary:
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myelography
Radiography of the spinal cord after injection of a contrast medium into the subarachnoid space.
- cervical m. — injection of a radiopaque contrast medium into the subarachnoid space before taking an x-ray to outline more clearly the structures in the vertebral canal.
- stress m. — the spine is positioned to place stress on articulations, either hyperextension, ventral flexion or traction. Used most commonly in the diagnosis of wobbler syndrome.
Wikipedia on Answers.com:
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Myelography
| Myelography | |
|---|---|
| Intervention | |
 Myelogram showing arachnoiditis in the lumbar spine. |
|
| MeSH | D009192 |
| OPS-301 code: | 3-130 |
Myelography is a type of radiographic examination that uses a contrast medium to detect pathology of the spinal cord, including the location of a spinal cord injury, cysts, and tumors. The procedure often involves injection of contrast medium into the cervical or lumbar spine, followed by several X-ray projections. A myelogram may help to find the cause of pain not found by an MRI or CT.
Myelography has been largely replaced by the use of CT and MRI scans.
A CT is typically performed after radiographic contrast media (dye) has been placed with fluoroscopic guidance into the sac (dura) surrounding the spinal cord and nerves. The material is typically water-based, which has largely replaced oil based fluids. A CT myelogram is most useful for patients who cannot undergo MRI (e.g., those with pacemakers or cochlear implants), or for those in whom MRI provides limited information (e.g., those with extensive metal in the spine).
The process usually involves lying face down on a table, with the lower extremities secured tightly with straps to the table. After the skin area has been numbed, the dye is injected into the spinal sac, then the table is slowly rotated in a circular motion, first down at the head end for approximately 4–6 minutes, then rotated up at the head end for the same duration. Several more minutes lying flat and the process is complete. This movement insures the contrast has sufficiently worked its way through the spinal cord, followed by x-rays, CT, or MRI scans.
If the fluid introduced in the spinal tap was oil based, the physician conducting the procedure will remove the fluid after the procedure is complete. When water-based fluid is used, it is typically not removed, as the fluid will eventually be absorbed into the body.
Post-procedure case centers around ensuring that infection does not set in and that the "plug" at the site of the spinal tap does not become dislodged. Patients are usually instructed to avoid strenuous activity and heavy lifting, for example. Some patients are given instructions to keep their heads eleveated at least 30 degrees for a specified number of hours. Complications from the surgery can cause a loss of cerebrospinal fluid (CSF), which could cause severe headaches. This can be corrected by returning to the medical facility and having them perform a blood patch. In this procedure a small amount of blood is taken from the arm and injected into the exact spinal tap location to stop the leaking of CSF.
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Myelography punction
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Conventional myelography in oblique projection. You can see the individual nerve root sheaths.
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Computed tomography after conventional myelography. The overlap-free representation often allows a more secure assessment. The high density of contrast material may be troublesome in case of insufficient mixing prior to CT.
References
- Bontranger, Kenneth L. & Lampignano, John P. (2005). Radiographic Positioning and Related Anatomy, St. Louis: Elsevier Mosby. ISBN 0-323-02507-2.
External links
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McGraw-Hill Science & Technology Dictionary
McGraw-Hill Dictionary of Scientific and Technical Terms. Copyright © 2003, 1994, 1989, 1984, 1978, 1976, 1974 by McGraw-Hill Companies, Inc. All rights reserved.
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Yale University Guide to Medical Tests
The Patient's Guide to Medical Tests by Faculty Members at The Yale University of Medicine and G.S. Sharpe Communications, Inc. Copyright © 1997 by Yale University of Medicine and G.S. Sharpe Communications, Inc. Published by Houghton Mifflin Company. All rights reserved.
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Oxford Dictionary of Sports Science & Medicine
The Oxford Dictionary of Sports Science & Medicine. Copyright © Michael Kent 1998, 2006, 2007. All rights reserved.
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Saunders Veterinary Dictionary
Saunders Comprehensive Veterinary Dictionary 3rd Edition. Copyright © 2007 by D.C. Blood, V.P. Studdert and C.C. Gay, Elsevier. All rights reserved.
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