Myelography is an imaging examination procedure in which doctors inject contrast medium into the spinal canal to take X-ray images. The examination is used to diagnose pathological changes in the spinal canal and the spinal cord within it.
Below you will find further information on this diagnostic procedure and specialists for carrying out a myelography.
Myelography is an X-ray examination with a contrast medium that detects pathological changes in the spinal canal and the spinal cord within it.
Conventional X-rays can also be combined with myelo-computed tomography. Currently, doctors mainly diagnose changes in the spine and spinal cord using magnetic resonance imaging. In contrast to myelography, this is possible without puncturing the spinal canal. However, myelography is still required in some areas.
RARE MR myelography (Rapid Acquisition with Enhanced Relaxation Myelography) is an MRI sequence that rapidly acquires water-specific images.
Like conventional myelography, it can also clearly show constrictions of the subarachnoid space (e.g. caused by tumors) without the use of a contrast agent.
Myelography is used when MRI and CT provide no information about the spatial and dynamic conditions of the spinal column.
In order to analyze the interaction between the bones of the spine, intervertebral discs, spinal cord and nerves, doctors look at the spine dynamically.
When bending, for example, the intervertebral disc can bulge out of the disc space into the spinal canal and pinch a nerve there. At the same time, it can behave completely unnoticed in an upright position.
Furthermore, not every slipped disc requires treatment. It always depends on how much space is left to the adjacent nerves.
The interconnected vertebrae form the bony membrane of the spinal canal. It contains a dural sac in which the spinal cord and the outgoing nerve roots are located.
The spinal cord is surrounded by cerebrospinal fluid. Without a contrast agent, the contents of the spinal canal cannot be seen on an X-ray.
If there is a narrowing of the spinal cord, nerve roots or spinal canal, this can lead to pain and paralysis. The exact extent of the narrowing or displacement of the spinal cord can be determined using myelography.
With the advent of modern non-invasive transverse imaging techniques such as MRI and CT, the importance of myelography has decreased.
Nevertheless, myelography is still used for special problems in neurosurgery. Even when CT or MRI are not feasible.
In principle, myelography is mainly usedto diagnose neoplasms in the spinal canal. During the assessment, doctors should look for gaps in the contrast medium.
In the case of spinal root compression syndromes, the advantage of dynamic imaging in myelography can be useful. Especially to detect filling defects in root pockets.
Myelography is therefore used to clarify unanswered questions before an operation. Especially when MRI or CT are not feasible, such as in the case of scoliosis.
After contrast medium injection and myelography, computer tomography is also possible in order to obtain images of additional layers.
Scoliosis is a three-dimensional deformation of the spine that leads to a more or less clearly visible incorrect posture @ filins /AdobeStock
The examination is carried out in a sitting or lateral position. After administering a local anesthetic at the puncture site, the doctor inserts a thin hollow needle into the spinal canal between the lumbar vertebrae.
There is no spinal cord at this level, only nerve roots. The doctor first takes several milliliters of cerebrospinal fluid (CSF) with a syringe, which he has examined in the laboratory.
This ensures the correct position of the needle. He then injects a contrast agent into the spinal canal through the hollow needle.
The patient then lies head down so that the contrast agent spreads to the thoracic and cervical spine. This is followed by X-ray and cross-sectional images.
After the examination, the patient must lie down for several hours and remain in bed until the end of the day. Otherwise, the change in pressure in the spinal canal leads to severe headaches, nausea and vomiting. The body excretes the contrast medium in the urine within a few hours.
In order to assess spatial relationships between nerve roots, myelography in combination with post-myelo-CT is superior to other imaging procedures.
Thanks to the strong contrast, doctors can distinguish the nerves from the surrounding structures with millimeter precision.
The contrast agent is injected into the spinal canal @ Aldona /AdobeStock
The examination is usually carried out in a hospital. One day before the examination, the doctor will discuss the procedure and possible risks with you. You must report any intolerances (allergies) to disinfectants, iodine-containing contrast agents and patches in advance.
The following blood parameters must be known for the examination:
Laboratory values should not be older than four weeks. You can have them determined in advance on an outpatient basis. You may have to stop taking anticoagulants a few days beforehand.
After the myelography, you should rest in bed for 6 hours and drink plenty of fluids. You must not be pregnant.
Myelography is a low-risk diagnostic procedure. Despite care, complications can occur in some cases, which are usually easy to control.
Possible adverse effects are
The first contrast agents available for the first myelographs around 1922 were oil-based. The body was unable to absorb them and the removal of the oily liquid via a puncture cannula was much more stressful than the injection of the contrast medium itself. In many cases this did not help. Some drops remained at the bottom of the dural sac and caused scars. Today, absorbable contrast media are used, which no longer cause this problem.
Any procedure that penetrates intact skin can lead to infection. The pathogens that cause pus in the spinal canal are a serious problem, as purulent meningitis can be fatal.
Today, however, this complication is extremely rare. A puncture of the dural sac is often followed by a loss of cerebrospinal fluid. The cerebrospinal fluid flows out through the opening like water and creates negative pressure inside the skull. This results in severe headaches (postdural puncture headache).
The advantages of this examination method compared to MRI and computer tomography also have disadvantages. Myelography is an X-ray examination and an invasive examination procedure.
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