How the test is
How to prepare
for the test
How the test
What the risks
Why the test
Myelography uses X-rays and fluoroscopy to provide pictures
of the cavity within the bones of the spine (spinal
canal). Myelography may be done to detect blockage of
the spinal canal caused by a tumour, infection, a herniated
disc, or arthritis.
The spinal canal contains the spinal cord and nerve
roots surrounded by a fluid-filled space called the
subarachnoid space. For myelography, a dye (contrast
material) that contains iodine is injected into the
subarachnoid space. X-ray pictures are taken as the
contrast material moves into different areas of the
Myelography is frequently combined with computed tomography
(CT scan). This technique is called CT myelography.
Full-dose myelography uses a full dose of contrast
material. CT scans are taken about 3 hours after the
contrast material has been injected. Full-dose myelography
is rarely used in the United States. Low-dose myelography
uses a low dose of contrast material. CT scans are usually
done immediately after the contrast material is injected.
For many purposes, magnetic resonance imaging (MRI)
has replaced myelography.
How the test is performed
Myelography is done in an outpatient radiology center
or in the radiology department of a hospital by a radiologist
You will need to remove any jewelry that might interfere
with the X-ray pictures. You will need to take off all
or most of your clothes, depending on which area is
being examined. You may be allowed to keep on your underwear
if it does not interfere with the test. You will be
given a cloth or paper covering to use during the test.
Most commonly, a lumbar puncture is done to enter the
spinal canal. You will lie on your stomach or side on
an X-ray table. The doctor examines your lower back
(lumbar area) and marks the proper insertion site with
a pen. The area is then cleaned with an antiseptic and
draped with sterile towels. A local anesthetic may be
injected under the skin to numb the area where the needle
will be inserted.
After the anesthetic has taken effect, a thin needle
is inserted into the spinal canal and a continuous series
of X-ray pictures (fluoroscopy) helps the doctor see
and place the needle in the desired location. A sample
of the liquid from the spinal canal (cerebrospinal fluid)
may be removed for analysis before the contrast material
is injected. The injection is usually done in your lower
back but may occasionally be done at the base of your
skull or the upper neck (cervical) spine.
After the contrast material is injected, you continue
lying on your stomach or side while the X-ray pictures
are taken. If pictures of your upper back or neck are
needed, the contrast material may be moved into those
areas by tilting the table or you may be asked to move
into different positions. You will be held in position
as the table is tilted, and your chin will be placed
on a small pillow to keep your neck extended. This prevents
the contrast material from entering your head, which
can cause headaches or seizures. You need to lie very
still to avoid blurring the pictures. Your pulse, breathing
rate, and blood pressure may be monitored throughout
After the X-ray pictures have been taken, the injection
site is bandaged. You will be given instructions on
any steps you need to take after having the test.
Frequently, a CT scan of the area (CT myelogram) is
done 3 hours after the myelogram to gain additional
Low-dose myelograms are most common now. They use the
same steps as a standard myelogram, but less contrast
material is used and the standard X-rays are not taken.
Instead, a CT scan of the area of interest is done immediately
after the contrast material is injected.
After the test
A myelogram usually takes between 30 minutes and 1 hour.
If a CT scan is also done, that takes an additional
30 minutes to 1 hour. If a full-dose myelogram is done
followed by a CT scan, you may need to remain in an
observation area for the 3 hours after the X-rays are
taken and before the CT scan is done.
You will be monitored for a short time after the myelogram.
The amount of time you are monitored depends on the
type of myelogram you had. You may be asked to remain
in bed with your head elevated for up to 8 hours after
You will be instructed to drink plenty of water after
the myelogram. You may also need to avoid taking certain
medications for up to 2 days after the test.
How to prepare for the test
Before myelography, tell your health professional if
Have a history of epilepsy or other seizure disorder.
Are or might be pregnant.
Are allergic to the iodine dye used in the contrast
material or any other substance that contains iodine.
Also tell your health professional if you have asthma
or have ever had a serious allergic reaction (anaphylaxis)
from any substance, such as the venom from a bee sting
or from eating shellfish.
Are allergic to any medications.
Have bleeding problems or take blood-thinning medications.
Are taking any medications. Some medications may need
to be stopped temporarily before the test is done.
Have a history of kidney problems or diabetes, especially
if you take metformin (Glucophage) to control your diabetes.
The contrast material used during myelography can cause
kidney damage in people with poor kidney function. If
you have a history of kidney problems, blood tests (creatinine,
blood urea nitrogen) may be done before myelography
to check that your kidneys are functioning properly.
For more information, see the medical tests Creatinine
and Creatinine Clearance and Blood Urea Nitrogen.
You may be instructed not to eat or drink, or to limit
your intake to clear liquids, for 8 hours before the
test. You may need to take a laxative or have an enema
before the test to empty your bowels. Ask your health
professional what instructions you need to follow before
the myelography test.
If you are not spending the night in the hospital after
having this test, you should arrange to have someone
take you home. Check with your health professional ahead
of time to find out when you will be able to go home.
Talk to your health professional about any concerns
you have regarding the need for the test, its risks,
or how it will be done. Complete the medical test information
form to help you understand the importance of this test.
How the test will feel
The X-rays are painless. You will feel a brief sting
from the small needle used for numbing your skin around
the myelogram injection site. You will feel slight pressure
as the longer spinal needle is inserted into your spinal
canal. You may feel an occasional sharp pain while the
needle is being positioned in your spine.
You may find it uncomfortable to lie on your stomach
or side during the procedure. Some people find it difficult
to swallow or to breathe deeply while in this position.
However, this position does not usually need to be held
for long. You may also find some of the other positions
uncomfortable, especially when your head is lower than
You may feel pressure or warmth as the contrast material
is injected. The contrast material may also cause a
headache, flushing, nausea, or vomiting. Rarely, contrast
injections into the fluid-filled space (subarachnoid
space) can cause seizures. After the test, you will
be instructed to keep your head elevated and to avoid
bending over or lying flat. This will help keep the
contrast material out of your head and prevent seizures.
After the test, contact your health professional immediately
- Have a seizure.
- Notice any increase in pain, weakness, or numbness
in your legs.
- Have a severe headache.
- Have a headache that lasts longer than 24 hours.
- Feel extremely irritable.
- Have problems urinating or having a bowel movement.
- Develop a fever higher than 100.4°F (38°C).
What the risks are
There is some risk of developing a problem after a
myelogram. The risk is greater with a full-dose myelogram
than it is with a low-dose myelogram.
There is slight risk of developing an allergic reaction
to the iodine contrast material. The reaction can be
mild (itching, rash) or severe (difficulty breathing
or sudden shock). Death resulting from an allergic reaction
is rare. Most reactions can be controlled using medication.
Tell your health professional if you have allergies
of any kind, such as hay fever, iodine allergy, eczema,
hives, or food allergies.
About 20% of people who have a myelogram develop a headache,
nausea, or vomiting after the test. Rarely, seizures
may occur after an injection of contrast material into
the fluid-filled space (subarachnoid space). After the
test, you will be instructed to keep your head elevated
and to avoid bending over or lying flat. This will help
keep the contrast material out of your head and prevent
There is a slight risk of infection at the injection
site or bleeding into the space around the spinal cord.
There is a risk of kidney problems if you take metformin
(Glucophage) to control your diabetes. You will need
to stop taking your medication for a few days before
the test and resume taking it a few days after the test.
The contrast material can cause water loss or damage
to the kidneys that may lead to kidney failure. This
is a concern if you are dehydrated or have poor kidney
function. If you have a history of kidney problems,
blood tests (creatinine, blood urea nitrogen) may be
done before the myelogram to check that your kidneys
are functioning properly. For more information, see
the medical tests Creatinine and Creatinine Clearance
and Blood Urea Nitrogen.
Very rarely, inflammation of the covering of the spinal
cord (arachnoiditis), weakness, numbness, paralysis,
or inability to control bowel or bladder function may
develop. Any paralysis is usually temporary, but may
There is also a very slight risk that the contrast material
will cause blockage of the spinal canal. If this occurs,
surgery is usually needed.
There is always a slight risk of damage from being exposed
to any radiation, including the low levels of X-rays
used for this test. However, if this test is really
needed, the risk of damage from the X-rays is usually
very low compared with the potential benefits of the
Why the test is performed
Myelography is done to detect narrowing of the spinal
canal or abnormalities of the nerves branching off the
canal. This may be caused by:
- Spinal stenosis.
- A tumour or infection.
- A spinal disc that has ruptured (herniated disc).
- Inflammation of the membrane (arachnoid membrane)
that covers the brain and spinal cord.
- Abnormalities of the blood supply to the spinal
Myelography may help determine or verify the cause
of pain that could not be found by other imaging methods,
such as magnetic resonance imaging (MRI) or CT scanning.
Text courtesy of WebMD Health web site.
Back to Top