1. Myelography

2. What is Myelography
An x-ray exam of the spinal cord and the fluid-filled space surrounding it.
X-ray film is taken after injecting a contrast medium through a needle into the subarachnoid space surrounding the cord.
A myelogram may be used to find a variety of different problems.

3. A Myelogram may find...
Blockages in the spinal canal that may be caused by a tumor or by a ruptured spinal disc
Inflammation of a membrane covering the brain and spinal cord
Difficulties in blood supply to the spinal cord
Abnormalities of the spinal cord and the nerves that branch off from it

4. Myelography
By defining the level and extent of abnormalities, myelography is an important method of diagnosis for physicians, particularly neurosurgeons who need to locate pathologies for surgical treatment.
Most often a myelogram will be performed in conjunction with a computed tomography scan or a magnetic resonance imaging scan to provide the most adequate information possible.

5. Indications
A patient experiencing pain or numbness-may be an indicator of a lesion within the spinal canal or protruding into the spinal canal.
These lesions could be both benign and malignant tumors, cysts, herniated nucleus pulposus, and extradural masses or bone fragments caused by trauma.

6. Commonly...
Most myelograms are performed in the cervical and lumbar regions because the greatest amount of pathology and trauma occur here.
A herniated nucleus pulposus is the most common pathologic finding of myelography.
Symptoms include numbness, pain , or a burning sensation in particular areas of the body, especially in the extremities.

8. Contraindications
Sensitivity to iodine or contrast media
Arachnoiditis
The presence of blood in the cerebral spinal fluid
Abnormal intracranial pressure
A spinal puncture performed within two weeks of the myelogram
Furthermore, bleeding abnormalities, such as elevated prothrombin and partial thromboplastin times, decreased platelet count, or patients on anticoagulation therapies should also abstain from a myelogram.

9. Preprocedural Care
Thorough explanation of the procedure by the performing physician.
Signed informed consent by the patient.
The patient will then be asked to do several things before the exam…

10. Patient is asked to…
Stop smoking the day before the exam and on the day of the exam.
Drink 4-8 ounces of fluid every hours while awake starting at noon the day before the exam.
Have a clear liquid breakfast two hours before the procedure (tea, apple juice, broth, etc.).
Empty bladder just prior to procedure.

11. DRUGS
Since most patients exhibit apprehension, fear and anxiety of the exam, a sedative or muscle relaxant is prescribed 1 hour prior to starting the procedure.
A common drug and dosage used is 10 mg of diazepam (Valium) given intramuscularly.

12. Equipment
Sterile tray includes: contrast medium, anti-septic solution, sterile gloves, basins, three prep-sponges, band-aid, towels, gauze sponges, fenestrated drape, 5 and 20 ml syringe, 18, 22, and 25 g needles, 18 g spinal needle, extension tubing, local anesthetic, and test tubing.
Radiographic-fluoroscopic room
90-degree two-way tilt table with footrest, ankle boots, and shoulder supports
Prep razor
Lab requisitions
Positioning sponges

13. Injection Procedure
Most common puncture sites are the lumbar and basal cistern regions. Lumbar is safest.
Radiologist uses fluoro to locate the best placement for the needle.
Puncture site is shaved and cleaned with Betadine and the fenestrated drape is centered on the puncture site.
The skin and underlying tissue are injected with a local anesthetic.

14. Injection Procedure
Patient is positioned lying on one side with knees drawn up and chin tucked into the chest while the spinal needle is inserted.
This position allows the spaces between the vertebrae to open up.
The spinal cord ends at the interspace between L-1 and L-2, so commonly the needle is inserted well above, at L-3, L-4.
Radiologist uses fluoro to guide the needle into the subarachnoid space.
An indication that the needle is in the correct place is a backflow of CSF through the needle.

15. Injection Procedure
Once the needle is in place, CSF will be collected and sent to the lab for analysis.
The physician will then slowly injected the iodinated contrast agent, watching with fluoro for abnormalities within the spinal canal.
After contrast is administered, the needle is removed and the radiographer is ready to position the patient to take images of the contrast filled subarachnoid space.

16. Contrast Media An ideal contrast medium: Mixes well with CSF
Is readily absorbed by the body
Is nonreactive with body substances or to the patient
Provides good radiopacity.
The 3 most common types used in myelography are:
Air or gas
Oil-based
Water-soluble

17. Air or gas contrast Rare
Sometimes employed when the patient has a sensitivity to iodine
Causes no known patient reactions
Inadequate radiopacity under fluoroscopy
Difficult to move in the spinal canal

18. Oil-based contrast Used in mid1940s till early 1980s
Good radiopacity but poor visualization of nerve roots
Major drawback: the contrast had to be removed from the spinal canal after the exam because it was not readily absorbed or excreted by the body
Frequently associated with arachnoiditis

19. Water-soluble contrast
Widely preferred today because: low viscosity, excellent visualization of nerve roots, and it is rapidly absorbed and excreted by the body within 48 hours
Only drawback is that the filming procedures must be performed immediately because the contrast is absorbed so quickly.

20. Filming and Positioning
Under fluoro, the table and patient are tilted from upright to trendelenburg to facilitate flow of contrast to area of interest
In trendelenburg, patient’s chin must remain hyperextended to prevent contrast from entering the head.
Once spot filming is completed, routine radiographs are taken by the radiographer
Positioning is dictated by the area of interest
Radiologist tilts the table to pool the contrast at the appropriate level for routing filming

21. AP and Lateral view of the lumbar spine

22. Post Procedural Care
Once the spinal needle is removed, the puncture site should be bandaged
Patient should maintain a semi-erect position of degrees for the first 8 hours following the procedure
Fluids and foods are encouraged to help eliminate contrast from the body and prevent headaches
Patient is asked not to engage in strenuous physical activity or bend over for one or two days

23. Complications
Other rare complications may include: nausea, obscured visualization due to the contrast injected into the wrong space, and irritated nerve tissue.
Rare contrast media reactions include: headache, nausea, vomiting, chest pains, abnormal heart rates, changes in blood pressure, seizures, aseptic meningitis, allergic symptoms, and central nervous system abnormalities.
Headaches are the most common complication. They are caused by the passage of air through the subarachnoid space into the ventricles of the brain.
A totally erect position should be avoided during and after the procedure.
Rest and increased fluid intake will usually relieve a mild headache.

24. Conclusion
Myelography may be done in either a hospital x-ray department or an outpatient radiology unit.
For patients who cannot have an MRI, myelography will usually be performed.
A CT scan is almost always performed immediately after the exam while the contrast is still present in the spinal canal. This combination of imaging studies is known as CT myelography.

25. Conclusion
Myelography usually takes about 30 to 60 minutes to complete and a CT scan can add another 30 to 60 minutes to the total examination time.
Myelography is more expensive than CT and MRI done alone because of the likelihood of the extra expense of the hospital stay for patient observation.
In some cases, myelography will show the cause of pain and other spinal symptoms even when a CT scan and MRI is negative.