This technique is used for detailed imaging of the spine, nerve roots and spinal cord. It is used less these days since the advent of MRI scanning, but still has a role to play, when patients are unable to undergo scanning (e.g. if they have a pacemaker in-situ) or when further information about the flow of the cerebro-spinal fluid is needed.
The procedure is performed by inserting a needle, under local anaesthetic, into the spinal canal, to allow the injection of contrast material. At the same time the spinal fluid may be sampled, which may help in the diagnosis of certain conditions such as infections and inflammatory states.
Once injected the contrast material can be seen on an x-ray, and the doctor performing the test can, by tilting the patient on a special table, follow the flow of the fluid throughout the spine. This is usually followed by a CT scan, which adds further to the information obtained.
Myelogram + CT showing narrowing at L4/5 associated with a Spondylolysthesis (a slip of one bone on another)
There were problems with myelography some years ago, because many people suffered a reaction to the contrast material then used, leading to a condition known as arachnoiditis. This material has since been replaced and such reactions are now very rare.
Patients undergoing this investigation are usually kept in hospital for several hours, or overnight, after the procedure, to ensure that they recover adequately. A number will develop a headache due to the fluid being withdrawn and may require to stay in longer until this settles down.