A myelogram is an imaging test that checks for problems inside your spinal canal. It combines a special dye (contrast material) injected into the fluid surrounding your spinal cord with X-ray or CT imaging, giving doctors a detailed view of whether something is pressing on your nerves or spinal cord. While MRI has become the default for most spinal imaging, myelograms remain uniquely valuable in specific situations and are still considered a gold standard diagnostic tool.
What a Myelogram Can Detect
The test is designed to reveal anything that’s compressing, displacing, or irritating the structures inside your spinal canal. That includes herniated discs (where the rubbery cushion between vertebrae bulges out and presses on nerves), spinal stenosis (narrowing of the spaces in the spine), tumors, infections of the spinal membranes like meningitis, and inflammatory conditions like arachnoiditis.
What makes a myelogram different from a standard X-ray or even an MRI is the contrast dye. Once injected into the fluid surrounding your spinal cord, it highlights the outlines of nerve roots, the spinal cord itself, and the membranes that protect them. Any compression or blockage shows up clearly because the dye can’t flow past it normally.
How the Procedure Works
You’ll lie face down on an exam table while a radiologist uses a live X-ray feed (called fluoroscopy) to guide the process. First, they’ll identify the best injection site, which is usually in the lower back because it’s considered easier and safer. Occasionally, if the problem area is in the neck, the injection goes into the upper cervical spine instead.
The skin at the injection site is cleaned and numbed with a local anesthetic. A needle is then advanced under fluoroscopic guidance into the subarachnoid space, the fluid-filled area surrounding the spinal cord. Once the needle tip is correctly positioned and spinal fluid flows freely, the contrast material is injected, and the needle is removed.
Here’s where the test gets distinctive. The radiologist slowly tilts the exam table, using gravity to guide the contrast material up or down through the spinal canal. They watch the dye’s movement in real time on the fluoroscopy monitor, focusing on the area that matches your symptoms. This dynamic view is something a static MRI scan simply can’t replicate. The entire procedure typically takes 30 to 60 minutes.
CT Myelogram: The Combined Approach
In most cases today, a myelogram doesn’t end with the fluoroscopy portion. After the contrast dye is in place, you’ll be moved to a CT scanner for a series of thin-slice images. This combination, called a CT myelogram, gives radiologists two complementary views: the real-time flow information from fluoroscopy and the highly detailed cross-sectional anatomy from CT.
CT myelography is particularly strong at visualizing bone. Surgeons widely recognize its superiority for identifying bony abnormalities in both the cervical and lumbar spine. The fluoroscopic portion, meanwhile, shows whether structural changes seen on other imaging are actually compressing nerve roots or blocking the flow of spinal fluid. Sometimes it’s the live fluoroscopic impression that proves most diagnostic.
Why Doctors Order a Myelogram Instead of MRI
MRI is noninvasive and excellent at imaging soft tissue, so it’s the first choice for most spinal problems. A myelogram comes into play when MRI isn’t an option or doesn’t tell the full story.
If you have a pacemaker, certain metal implants, or other contraindications to MRI, a CT myelogram is the alternative. It’s also more resistant to image distortion from patient movement and acquires images quickly, which matters if you have trouble staying still in a scanner. Beyond these practical advantages, research comparing the two techniques has found that CT myelography provides greater reliability for assessing foraminal stenosis (narrowing of the openings where nerves exit the spine) and bony lesions. Studies focused on the lumbar spine have found that MRI can actually underestimate the degree of nerve root compression, while CT myelography offers more reproducible measurements of how severe lumbar stenosis really is.
MRI does have the edge in some areas. It’s generally considered more reliable for assessing the degree of nerve root compression in the cervical spine and for evaluating soft tissue conditions like disc degeneration. In practice, many complex spinal cases benefit from both tests, with each filling in gaps the other leaves behind.
What Recovery Looks Like
After the procedure, you’ll need to lie down for about two hours. This rest period is important because it reduces your risk of developing a spinal fluid leak at the puncture site. During this time, keep your head elevated above the rest of your body.
Hydration is the other key part of recovery. You’ll be asked to drink plenty of extra fluids, which serves a triple purpose: it helps your body replace the small amount of spinal fluid removed during the test, it flushes out the contrast dye, and it reduces your chances of getting a headache afterward. Avoid alcohol during this period. Most people go home the same day with instructions to rest for the remainder of the day and avoid heavy lifting or strenuous activity for 24 hours.
Headaches and Other Risks
The most talked-about side effect is a post-procedure headache caused by spinal fluid leaking through the tiny hole left by the needle. This type of headache, called a postdural puncture headache, is distinctive: it worsens when you sit or stand up and improves when you lie flat. Estimates of how often it happens vary widely, from roughly 2% to 40% depending on the type and size of needle used. With modern small-gauge, noncutting needles, the rate drops to the lower end of that range.
Several factors raise your risk. Being female, being between 20 and 40 years old, having a low body mass index, being dehydrated, and having a history of headaches all increase the likelihood. If you’ve had a postdural puncture headache before, you’re more likely to get one again. For most people, these headaches resolve on their own within a few days with rest and fluids. In stubborn cases, a targeted treatment can seal the leak.
Other possible complications include soreness at the injection site, brief nausea, and, rarely, infection or an allergic reaction to the contrast material. Serious complications are uncommon.
What Sets It Apart From Other Spine Tests
A standard X-ray shows bones but tells you almost nothing about nerves or soft tissue. An MRI excels at soft tissue but can miss or underestimate bony compression. A myelogram bridges that gap by showing real-time fluid dynamics around the spinal cord while also producing excellent bone detail on the CT portion. It’s the only spinal imaging test that lets a radiologist watch, in real time, how contrast flows around your nerve roots and identify exactly where an obstruction occurs. For surgical planning in complex cases, that information can be the deciding factor.