Historically the procedure involved the injection of a radiocontrast agent into the cervical or lumbar spine, followed by several X-ray projections.

Today, myelography has largely been replaced by the use of MRI scans, although the technique is still sometimes used under certain circumstances – though now usually in conjunction with CT rather than X-ray projections.

[3] For those who had recently done lumbar puncture in one week time, there may be some cerebrospinal fluid (CSF) accumulates in the subdural space.

[3] Water-soluble non-ionic iodinated contrast agent is used nowadays and cause very little complication, unlike oil-based dye that was used previously which can cause arachnoiditis.

In this procedure, a small amount of blood is taken from the arm and injected into the exact spinal tap location to stop the leaking of CSF.

Prior to the late 1970s, iofendylate (trade names: Pantopaque, Myodil) was the radiocontrast agent typically employed in the procedure.

It was an iodinated oil-based substance that the physician performing the spinal tap usually attempted to remove at the end of the procedure.

The process of removing the contrast agent necessitated removing some of the patient's CSF along with it and the resulting deficiency of CSF gave rise to severe headache if the patient was raised from the prone position, requiring bed rest in the laying position.

Moreover, iofendylate's persistence in the body might sometimes lead to arachnoiditis, a potentially painful and debilitating lifelong disorder of the spine.

If there is doubt that the needle is in the subdural space, AP and lateral views of the radiograph should be taken and the subject is to be rebook for another date for the same procedure.