What is a discography?
A discography, or discogram, is an imaging test of the spine to determine which particular disc is causing a patient’s back pain. The doctor injects a dye into a specific disc to reveal damage on an X-ray image.
A doctor may choose discography for patients with persistent pain when other imaging methods have failed to precisely locate the source of pain. A discogram is most commonly done prior to a lumbar fusion surgery.
A spinal disc is a sponge-like cushion in between the vertebrae of the spine. It has a tough layer surrounding a jelly-like material inside. It has three functions:
- Shock absorption
- To maintain the position of adjacent bones of the spine (vertebrae)
- Spinal flexibility and mobility
A radiologist (a doctor specialized in performing and interpreting imaging tests) performs the procedure. The radiologist injects a dye into a few selected discs, depending on the region of pain, to determine if it produces pain in the patient. They also observe an X-ray and CT monitor to see if there are tears or herniation in the discs that cause the pain.
How is a lumbar discography performed?
The lumbar discography is usually an outpatient procedure. It is likely to take about three hours total, while the procedure itself takes about 30 to 60 minutes, depending on the number of discs planned for testing.
Before the discogram a patient needs to,
- refrain from eating or drinking in the morning before the test
- stop taking blood thinners (such as anticoagulants and aspirin)
The radiologist does not use general anesthesia as the patient needs to be awake and responsive during the procedure. Some may administer a mild sedative to relax the patient. They may also give an antibiotic to prevent infection. They attach an IV line for administering fluids and medications if required.
- The patient lies down on their side or abdomen for the discogram.
- The radiologist injects a local anesthetic to numb the area.
- They insert the needle in the abnormal disc guiding the insertion with the help of a live X-ray image on a monitor.
- The doctor injects the dye in the disc and observes the patient’s pain response.
- The material injected increases the pressure in the disc and may cause pain or pressure.
- The patient must describe the kind of pain, its location and intensity.
- The doctor also studies the imaging results on a live X-ray known as fluoroscopy, and sometimes also on a CT monitor.
- The doctor repeats this process on each of the discs that need to be examined.
The patient remains under observation for 30 to 60 minutes after the procedure.
The patient may feel nothing if the disc is normal or feel some pressure or pain. If the discogram causes a pain that is similar to the pain that the patient has been experiencing, it may indicate that the disc is the source of pain.
Why is a lumbar discography performed?
A lumbar discography is performed to precisely locate the source of back pain. Typically, the doctor does not rely solely on a discogram, but uses it in combination with CT, MRI and physical examination. The doctor performs a lumbar discography in the following situations:
- To devise alternate treatment plans for persistent back pain conservative treatments like medication, physical therapy and activity modification cannot relieve.
- When less invasive tests have failed to locate the precise location or cause of the pain.
- To decide if a spinal surgery will be effective.
- To assess the disc before a surgery such as lumbar fusion.
How painful is a discogram?
The needle insertions for IV and local anesthetic may cause a mild stinging pain from the pricking.
The discogram is designed to provoke existing pain to find out the source, so certain amount of pain is to be expected. If the disc is normal there will most likely be no pain, there might be a sense of pressure.
If the disc is abnormal, the discogram duplicates the patient’s original pain. The sedation helps reduce the patient’s pain and discomfort, and painkillers can be used to relieve the pain.
How useful is a discogram?
The use of discography as a diagnostic tool has its pros and cons, and doctors only use it when more conservative treatments have failed or surgery is being considered.
The most important advantage is the capacity to pinpoint the problem disc for treatment, which greatly improves the success rate in relieving a patient’s pain. The diagnosis from this procedure also helps in avoiding an unnecessary surgical operation.
What are the risks and side effects of a discogram?
A discogram performed with due precautions is generally safe. There usually are a few side effects like headache and some amount of back pain that is relieved with analgesics. Following are a few risks and complications:
- Allergic reaction to the dye material
- Exposure to excessive radiation
- Meningitis or discitis caused by infection
- Nerve or blood vessel damage leading to pain or bleeding
- Spinal headache
- Aggravation of the chronic back pain
- Disc herniation
All above are preventable and highly unlikely in a procedure done in a qualified medical facility by a competent radiologist. Disc herniation and paralysis are rare. The procedure’s potential to aggravate chronic back pain still needs further study.