I would like to continue to inform potential patients of the various imaging procedures that are performed by radiologists and this week I will discuss myelograms.
A myelogram provides detailed information about the spinal cord and the nerve roots. This information is valuable in helping your doctor make a diagnosis or plan the appropriate treatment to help relieve back or leg symptoms. A myelogram is a procedure that involves multiple images obtained after an iodine containing contrast agent was injected into the spinal canal and the sac that contains the spinal cord and nerve roots.
A myelogram is performed by placing a needle in the lower back or occasionally in the neck. The needle placement is localized using imaging guidance. Although local anesthesia is used, the needle tip is in a location near the nerve roots, so pain or an electric shock sensation may be felt down the leg; if this happens, the needle position can be adjusted. A small amount of cerebrospinal fluid is removed and contrast is injected, and the needle is removed. A series of x-ray images are obtained. A CT scan is routinely performed after the myelogram in order to provide cross sectional information. Much of the procedure is performed with the patient lying face down. The entire procedure from start to finish lasts approximately one hour and the patient is awake during the procedure.
In order to prepare for a myelogram certain medications should be withheld because they lower the seizure threshold; e.g. anti-depressant medications, Zyban (for smoking cessation), anti-psychotic medications, CNS stimulants, muscle relaxants or any other medication that lowers the seizure threshold. The physician and the radiologist should be informed in advance so that these medications can be stopped at least 48 hours before the procedure. Patients should not have any caffeine or alcohol on the day of the procedure. A nurse will take vital signs, start intravenous line and answer any questions just prior to the procedure. Routine radiographs are usually performed prior to a myelogram.
Are there alternatives to a myelogram? Yes. An MRI can provide much of the same information as a myelogram without an injection of contrast. In those individuals who cannot tolerate MRI scanning because of claustrophobia or contraindications, such as a pacemaker, a myelogram is an extremely useful examination. In certain instances the physician may recommend that both tests (a myelogram and an MR examination) be performed.
After the procedure the patient will be placed on bed rest with their head elevated (about 30 degrees) to decrease the risk of headache and encouraged to drink plenty of fluids throughout the day of the procedure. Mild soreness at the site of the lumbar puncture is expected. Headache is not an uncommon complication and may occur immediately after the procedure or within hours, lasting from hours (usually) to days. Non-steroidal anti-inflammatory drugs are usually used for treatment.