What is myelography?The invasive diagnostic procedure may be used in suspected compression of the spinal cord and / or spinal or spinal cord nerves.
Myelography refers to an X-ray contrast agent examination for imaging the spinal canal or subarachnoid space (spinal fluid space), the spinal cord and the outgoing spinal nerves.
The invasive diagnostic procedure is typically used in cases of suspected compression of the spinal cord and / or spinal cord nerves when other imaging techniques such as computed tomography (CT) or magnetic resonance imaging (MRI) are not sufficient for detailed diagnosis,
By injecting a contrast medium into the subarachnoid space followed by X-ray images in different projections or from different perspectives, the space available for myelon and spinal nerves can be graphically displayed.
Function, effect & goals
Different spinal cord impairments associated with nerve damage in the spinal canal may be the reason for myelography if sufficient information can not be provided by CT or MRI.
As a rule, these are due to degenerative spinal diseases, which can cause, for example, a spinal canal stenosis (spinal canal narrowing) with pressure-related damage to the neural structures. These manifest on the basis of pain, sensory disturbances in the legs and arms as well as by powerlessness.
Myelography may also be indicated in cases of suspected neuroforamenal stenosis (local narrowing of one or more nerve root canals). In addition, the diagnostic procedure is often used prior to spinal surgery such as decompression or spinal fusion as a planning aid. The aim of a myelography is the pictorial representation of space conditions in the spinal canal in order to determine and assess the extent and location of potential nerve, vertebral or disc damage.
For this purpose, blood coagulation values are checked in advance of the examination by a blood analysis and blood-thinning medicaments are discontinued to avoid a risk of bleeding. In addition, an x-ray of the spine is often performed prior to myelography to determine optimal access to the spinal canal for the puncture. Following local anesthesia puncture, the water-soluble contrast agent (10 to 20 ml) is injected in the lumbar spine area with a cannula (lumbar puncture) so that it can be distributed in the dura tubing (meningeal tube).
Existing bottlenecks modify the contrast medium flow and are visualized by the subsequent X-ray images. By means of an x-ray image from the front (ap), the distribution of the contrast medium can be used to visualize the space conditions in the spinal cord space and the spinal nerves by contrast medium recesses. Oblique X-rays allow assessment of the spinal nerve nerve branches, while lateral images during the ante- and retroflexion (forward and backward) of the upper body allow conclusions about the space available in the spinal canal.
In addition, a computerized tomography can be performed afterwards (Myelo-CT). The combination of contrast agent injection and slice imaging provides the most detailed information for assessing and detecting spinal cord gene and nerve compression. To avoid or minimize the headache caused by temporary pressure changes in the cerebrospinal fluid (nerve water space) due to the puncture, a 24-hour bed rest should be maintained following myelography.
Furthermore, a sufficiently high fluid intake should be ensured for rapid compensation of nerve water loss. In the context of a rare MR myelography (Rapid Acquisition with Relaxation Enhancement Myelography), it is also possible to obtain very fast water-specific images, which provide information on a transfer of the subarachnoid space, for example by tumors.
Risks, side effects & dangers
As a rule, complications can rarely be observed in myelography. The most common side effect is the temporary headache caused by nerve water loss. In addition, blood vessel injury may cause bleeding into the spinal canal (epidural hematoma), which may result in nerve damage.
If the myelography needle (cannula) is misplaced, the outgoing nerves of the spinal cord can be damaged, which can cause pain, sensory disturbances, and paralysis. Because myelography is an invasive procedure due to puncture skin injury, it can cause infection as a result of germ transmission. This may only be superficial or involve deeper structures of the spine such as the vertebral body, intervertebral disc or spinal cord.
In the worst case, an ascending inflammation of the spinal cord and meninges (meningitis) may manifest. If the dura (spinal cord) is not isolated, CSF may continuously leak out from the puncture site, often resulting in a surgical closure. Myelography may be contraindicated in the presence of hyperthyroidism (hyperthyroidism) due to the iodinated contrast agents used.
Similarly, hypersensitivity to iodine, which can lead to anaphylactic shock (severe circulatory shock), may optionally preclude myelography.