Myelography

As Myelography is a radiological diagnostic method for the representation of the spatial conditions in the spinal canal. Due to non-invasive diagnostic methods such as computer or magnetic resonance tomography, myelography has lost its importance. However, this is often used as an additional diagnostic procedure for specific questions, especially with spinal root compression syndromes.

What is myelography?

As Myelography is an X-ray contrast medium examination to visualize the spinal canal or subarachnoid space (spinal liquor space), the spinal cord and the outgoing spinal nerves.

The invasive diagnostic procedure is usually used if compression of the spinal cord and / or the spinal or spinal cord nerves is suspected, if other imaging procedures such as computed tomography (CT) or magnetic resonance imaging (MRI) are not sufficient for a detailed diagnosis .

By injecting a contrast agent into the subarachnoid space with subsequent X-ray images in different projections or from different perspectives, the spatial conditions for the spinal cord and spinal cord nerves can be represented graphically.

Function, effect & goals

Different impairments of the spine, which are accompanied by nerve damage in the spinal canal, can be the indication for a Myelography justify if sufficient information cannot be provided by a CT or MRI.

As a rule, these can be traced back to degenerative diseases of the spine, which, for example, can cause spinal stenosis (narrowing of the spinal cord) with pressure-related damage to the neural structures. These manifest themselves in the form of pain, sensitivity disorders in the legs and arms, and weakness.

Myelography may also be indicated if neuroforamen stenosis is suspected (local narrowing of one or more nerve root exit openings). In addition, the diagnostic procedure is often used in the run-up to a spinal surgery such as decompression or spinal fusion as a planning aid. The aim of myelography is the pictorial representation of the spatial conditions in the spinal canal in order to be able to determine and assess the extent and location of potential nerve, vertebral body or intervertebral disc damage.

For this purpose, blood clotting values ​​are checked in advance of the examination by means of a blood analysis and blood-thinning medication is discontinued to avoid the risk of bleeding. In addition, an X-ray of the spine is often performed before the myelography in order to determine the optimal access to the spinal canal for the puncture. After the local anesthesia of the puncture site, the water-soluble contrast medium (10 to 20 ml) is injected into the lumbar spine area with a cannula (lumbar puncture) so that it can be distributed in the dural tube (meninges).

Existing bottlenecks modify the contrast medium flow and are made visible by the subsequent X-ray images. By means of an X-ray from the front (a.p.), the spatial conditions in the spinal cord space and the spinal cord nerves can be depicted through the contrast medium recesses based on the distribution of the contrast medium. Angled X-rays allow the assessment of the spinal cord nerve branches, while lateral images during ante- and retroflexion (forward and backward bending) of the upper body allow conclusions to be drawn about the space available in the spinal canal.

Computed tomography (Myelo-CT) can also be performed afterwards. The combination of contrast medium injection and cross-sectional imaging provides the most detailed information for assessing and determining spinal canal genes and nerve compression. In order to avoid or minimize the headaches that can arise from the temporary pressure changes in the CSF (nerve water space) as a result of the puncture, a 24-hour bed rest should be observed after the myelography.

Furthermore, a sufficiently high fluid intake should be ensured to quickly compensate for the loss of nerve water. As part of a rare MR myelography (Rapid Acquisition with Relaxation Enhancement Myelography), water-specific images can also be obtained extremely quickly, which provide information on an obstruction of the subarachnoid space, e.g. due to tumors.

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Risks, side effects & dangers

As a rule, complications can rarely occur in one Myelography to be watched. The most common side effect is the temporary headache caused by the loss of nerve water. In addition, an injury to a blood vessel can cause bleeding into the spinal canal (epidural hematoma), which can 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, impaired sensation and paralysis. Since myelography is an invasive procedure due to the skin damage caused by the puncture, it can lead to an infection as a result of the spread of germs. This can only be superficial or affect deeper structures of the spine such as the vertebral body, intervertebral disc or spinal cord.

In the worst case, a rising inflammation of the spinal cord and meninges (meningitis) can manifest itself. If the dura (skin of the spinal cord) does not close by itself, liquor can continuously seep out of the puncture site, which often results in a surgical closure. Myelography may be contraindicated in the presence of hyperthyroidism (overactive thyroid gland) due to the iodine-containing contrast agent used.

Hypersensitivity to iodine, which can lead to anaphylactic shock (severe circulatory shock), may also rule out myelography.