Who gets a discogram:
Lumbar discography is considered for patients who, despite extensive conservative treatment, have disabling low back pain, groin pain, hip pain, buttock, and thigh pain that may be caused by a painful disc.
Why is the test done:
There is strong evidence that a tear in the outer covering of a lumbar disc is often the cause of back pain. These tears are common, as are bulges in discs, and they are not always painful. Discograms are done to find out if there is a painful tear in a disc.
Why discography is unique and must sometimes be done in addition to MRI and CT scans.
Discography is less about the anatomy of the disc (what the disc looks like) and more about finding out whether or not the disc is causing pain. Discography is more like the examination a doctor does when he/she examines a knee by bending it this way and that to put stress on different ligaments one by one; asking you to say when your pain occurs. The ligament that hurts when it is stressed is the one causing the pain, even if it looks normal on x-rays. In discography, the disc or discs that cause your typical pain when they are injected are likely to be the ones causing your back pain, no matter what they look like on x-rays. It is well known to discographers that a disc that looks really abnormal on the MRI scan may not be painful and a normal looking disc may cause severe pain. MRI scans do not always show tears in discs. It is impossible to diagnose a painful disc without performing a discogram in addition to other test. This is the most common point of misunderstanding among patients and physicians alike: X-rays alone cannot tell us where pain is coming from. We believe that discography increases the success rate of treatments for painful discs because only painful discs will be treated. If we have to guess whether or not an abnormal looking disc is painful, we will guess wrong sometimes and provide treatment that is not necessary and not helpful in eliminating back pain.
While different discographers may vary the procedure slightly, the following provides an overview of modern technique for a lumbar discogram.
Usually, sedation and anesthesia are avoided so as not to interfere with your ability to tell the doctor what he/she needs to know during the test. We give a mild painkiller (Toradol,“ [ketorolac tromethamine]) just before the procedure so that it is working by the time the procedure is done. Narcotic painkillers (vicodin, percoset) are often given just after the procedure, as well. You cannot be pregnant when you receive X-rays, so tell the doctor if there is any chance you may be pregnant. You are placed on a specialized table around which a fluoroscopic (X-ray) unit is positioned. Your back is then marked with an ink pen over the disc spaces that will ultimately be examined. Then your back is thoroughly cleansed and sterile drapes are applied. The fluoroscope will also be sterilely draped and the discographer will be in a sterile surgical gown.
Administration of local anesthesia
The goal is to anesthetize a core of tissue that extends from your skin to the disc surface. When these tissues are numbed a guide needle is directed towards the disc and will just touch the outer surface of the annulus (the outer margin of the disc).
Through this guide needle a much smaller (25 gauge) disc needle is advanced towards and eventually into the center of the disc. This process should not be painful, but sometimes may be.
Pressurizing the discs – the diagnostic portion of the procedure
After all of the needles are placed, the discs are “pressurized” one at a time. Pressurization consists of injecting small amounts of a sterile liquid (usually contrast material [x-ray dye]) using a syringe that reads out the injection pressure, into the center of the disc. Injection pressures are increased to the point of pain or until the normal maximum pressure is exerted on the disc (between 60 and 80 psi). You will not be told which disc is being pressurized, to avoid bias.
This is the most important part of the test and you must concentrate on the doctor’s questions. This is why heavy sedation cannot be used. There are essentially three choices:
A.) You feel nothing
B.) You feel pressure
C.) You feel pain
If you feel pain from the injection, the pain is either:
Familiar pain, which translates into “ouch, that ís my pain!”
Unfamiliar pain, which belongs to someone else or translates into “ouch, Iíve never felt pain there before.”
You will also be asked to rate how much the pain increased during pressurization on a 0-10 scale (0 is no increase, 10 is the maximum possible)
After each level is pressurized, pictures are taken with the fluoroscopic x-ray machine and the needles are removed. Usually, a post-discogram CT is obtained to document the internal architecture of the disc. This is especially important if you are being evaluated for thermal annuloplasty
How long is the procedure and what happens after it?
The procedure usually takes less than an hour to perform. Youíll have soreness from the needle punctures that lasts several days, and your back pain may increase for up to a week. You may use acetaminophen, ibuprofen, and your usual pain medications, and apply an ice pack for a 15 minutes every 2 hours to ease the soreness. Some physicians prescribe short-term narcotic pain medications for use after the procedure. It is wise to take the day after the procedure off from work to see how your body feels. you would not damage yourself by working right away despite the pain, but you would be more likely to make mistakes and you might prolong the post-procedure soreness a few days if you push it.
Possible risks and complications
As with any other invasive test, there are risks and possible complications. The most feared complication is a disc space infection called discitis, which can be very difficult to treat. Fortunately, by using very strict sterile techniques this is a very uncommon complication (less than 1 in 2,000 chance). Discitis would show up as increasing, severe new back pain that starts 5 to 10 days after the procedure. It is treated with antibiotics, and sometimes requires surgery to remove the infected disc. There are extremely remote possibilities of nerve root injury. Nerve root injury would be obvious right after the procedure as new numbness in a leg. Tell the doctor if this happens, before you leave to go home, so he/she may examine you. Spinal headache is also a remote risk. Spinal headache is a headache that gets better when you lie down, it is not dangerous, and it can be treated successfully. It can begin anytime in the 24 hours after the discogram. Numbness in the legs is possible as a side effect of the local anesthetic used. It wears off in an hour or two, and it must be gone before you can go home. With a skilled and experienced discographer who uses modern discography techniques, all of these risks are very, very rare. Notify your doctor if any of the symptoms mentioned here appear.
In summary, a discogram is a test designed to determine if an intervertebral disc is causing pain, and there is no other test that can do this well. If pressurization of a disc causes your familiar pain, and at least one other disc isn’t painful when pressurized, then surgery (fusion or thermal annuloplasty) may be an option to relive your pain.