Myelography is a diagnostic imaging procedure that uses a special dye injected into the fluid-filled space around your spinal cord to produce detailed pictures of your spine. The dye, called contrast agent, makes structures like nerves, discs, and the spinal cord itself visible on X-ray and CT images in a way that standard imaging sometimes cannot. While MRI has replaced myelography for many spinal conditions, it remains an important tool when MRI isn’t an option or doesn’t provide enough detail.
How Myelography Works
The basic idea is straightforward: your spinal cord and nerves sit inside a sac filled with cerebrospinal fluid. Normally, these soft tissues don’t show up well on X-rays. By injecting a water-soluble contrast dye into that fluid, the outline of the spinal cord, nerve roots, and surrounding structures becomes clearly visible. Anything pressing on those structures, whether it’s a herniated disc, a tumor, bone spur, or narrowing of the spinal canal, shows up as an irregularity in the dye pattern.
For decades, myelography was the only way to see soft-tissue problems inside the spinal canal. Disc herniations, nerve root compression, tumors expanding the spinal cord, and narrowing caused by hemorrhage were all invisible on conventional X-rays. Myelography made them diagnosable for the first time.
Why It’s Still Used in the MRI Era
MRI is now the first-choice imaging test for most spinal problems, but myelography fills gaps that MRI cannot. The most common reason is simple: some patients can’t have an MRI. If you have certain metallic implants, a pacemaker, or severe claustrophobia that prevents you from lying still in the scanner, CT myelography is a reliable alternative. Studies have confirmed that CT myelography can be used dependably in place of MRI for evaluating spinal conditions, with some researchers recommending it as a complement to MRI for assessing disease around the spinal cord.
Myelography also has a practical advantage: it can be performed with the patient in different positions, including standing or bending. This matters for conditions like spinal stenosis, where narrowing of the spinal canal may only become significant when you’re upright and bearing weight. An MRI, taken while you’re lying flat, might miss that dynamic compression entirely.
Conditions That May Require a Myelogram
- Herniated discs pressing on the spinal cord or nerve roots
- Spinal stenosis, or narrowing of the spinal canal
- Spinal tumors, both inside and outside the spinal cord
- Nerve root compression causing pain, numbness, or weakness
- Spinal cord injuries or suspected leaks of spinal fluid
Your doctor may also order a myelogram before spinal surgery to give the surgeon a precise roadmap of which structures are affected and where.
What Happens During the Procedure
Myelography typically takes 30 to 60 minutes. You’ll lie on an X-ray table, usually on your stomach. After cleaning and numbing a small area of your lower back (or occasionally your upper neck), the radiologist inserts a thin needle between two vertebrae into the fluid space surrounding your spinal cord. This is similar to a lumbar puncture, or spinal tap.
The needle placement is guided by real-time X-ray imaging called fluoroscopy, which lets the radiologist watch the needle’s position on a screen and make adjustments. Once the needle is confirmed to be in the right spot, a small test injection of about half a milliliter of contrast dye verifies proper placement. Then the full dose, typically around 10 milliliters, is injected.
After the injection, you may be tilted on the table into different positions so the dye flows to the area being examined. For a lower back study, the dye needs to travel high enough to include the bottom of the spinal cord. You’ll then be moved to a CT scanner for a detailed cross-sectional scan, usually within a few minutes. This combination of contrast dye and CT scanning, called CT myelography, produces the clearest images.
Preparing for a Myelogram
Preparation requires attention to your medications. Certain drugs need to be stopped days or even weeks in advance because they raise the risk of bleeding or seizures during and after the exam. Blood-thinning medications may need to be paused up to 14 days beforehand, depending on the specific drug. Aspirin alone is generally acceptable if you’re not taking other blood thinners.
Several categories of psychiatric and neurological medications also need to be stopped 48 hours before the procedure and held until 24 hours afterward. These include most antidepressants (SSRIs, tricyclics, and MAO inhibitors) and some anti-anxiety medications. The concern is that these drugs can lower the seizure threshold when combined with contrast dye in the spinal fluid. If you cannot safely stop these medications, your procedure will likely need to be rescheduled rather than performed with the drugs in your system.
You should also tell your medical team about any history of allergies (particularly to iodine or shellfish), bleeding disorders, seizures, kidney disease, heart disease, asthma, thyroid problems, or diabetes. Pregnancy is a contraindication because of radiation exposure to the fetus.
Side Effects and Risks
The most common side effects are headache, nausea, and vomiting. Nausea and vomiting occur in roughly 10 to 20 percent of cases, though modern contrast agents have made these reactions milder than they used to be.
Post-procedure headaches are the complaint patients worry about most. These happen because the needle puncture creates a tiny hole in the membrane surrounding the spinal fluid, which can leak afterward. Staying well hydrated and sitting at a slight incline (around 45 degrees) or walking around after the procedure tends to reduce nausea, though it doesn’t reliably prevent headaches. Most headaches resolve on their own within a day or two.
Seizures are rare with today’s contrast agents. The current estimated risk falls somewhere between 0.09 and 0.85 percent. Older dye formulations caused seizures in up to 0.6 percent of patients, but only three case reports of seizures with the modern standard agent have appeared in the past 15 years. This is a major reason why certain medications are paused before the procedure: they can lower the seizure threshold enough to tip the odds in a dangerous direction.
Allergic reactions to the contrast dye are uncommon. In one large survey, 78 percent of radiologists reported zero contrast reactions over a five-year period, and 19 percent reported only one or two. Of the reactions that did occur, 88 percent were minor, and most happened in patients with no prior history of contrast allergy. Other rare complications include infection, bleeding at the puncture site, and nerve injury.
Recovery After the Procedure
You’ll typically stay in a recovery area for one to two hours for monitoring. Research on post-myelography positioning found that patients who sat at a 45-degree angle or walked around shortly after the procedure experienced less nausea and vomiting than those who stayed flat in bed. Drinking plenty of fluids helps your body replenish the spinal fluid and flush out the contrast dye.
Most people can return to normal activities the next day, though you’ll generally be advised to avoid strenuous exercise and heavy lifting for 24 to 48 hours. If you develop a severe headache that worsens when you sit or stand, persistent vomiting, fever, or new numbness or weakness, those warrant prompt medical attention as they could signal a complication like a persistent spinal fluid leak or infection.