A myelogram is an imaging test used by doctors to view and diagnose problems related to spinal tissue, according to Johns Hopkins Medicine. Doctors inject a contrast dye into the spine and use X-rays or a computed tomography, or CT, scan to view the tissue.
Use of the contrast dye allows the spinal cord and other tissues to appear more clearly on an X-ray, states Johns Hopkins Medicine. The CT scan uses X-ray images and computer technology to create horizontal images, or slices, that show the spine in great detail. Myelograms help doctors to diagnose conditions such as herniated discs, tumors, spinal infection or inflammation, cysts, degenerative disc disease and injury of the spinal cord roots. They may also be used to diagnose a condition called arachnoiditis, or inflammation of the membrane that covers the brain.
Doctors begin by cleaning the patient's back and numbing the area where the needle is inserted. They then insert a hollow needle into the cerebrospinal fluid and inject the contrast dye, explains Mayfield Clinic. The patient lies on her stomach while the images are taken. Following the procedure, patients are observed for four to eight hours before release. They should rest in bed for 24 hours following the procedure but can return to normal activities the following day. The procedure carries some risk, including exposure to radiation from the X-rays and seizures caused by the injection of the contrast dye into the cerebrospinal fluid, advises Johns Hopkins Medicine.