What is CT/Myelo?

A CT myelogram is a CT examination of the spine that is performed following a myelogram.

The myelogram is done before the CT examination in order to outline the spinal cord and nerve roots on the CT study so the possibility of mass effect on the cord or nerve roots (from herniated disc, bony osteophyte, etc) can be assessed on the CT study.

How does CT/Myelo work?

The spinal cord is located in a bony canal in the back of the vertebral column. It is surrounded by fluid (cerebrospinal fluid or CSF) that is contained within a long tube-like structure called the dural sac.

A myelogram is performed by inserting a needle into the dural sac in order to inject the x-ray dye that will opacify the cerebrospinal fluid for the CT study.

A radiologist uses Xray (fluoroscopy) to guide needle placement during the myelogram to insure that the dural sac is punctured in a safe fashion below the level of the spinal cord.

After the myelogram is completed, the patient is placed in the CT scanner and a CT examination of the spine is obtained.

How to prepare for your CT/Myelo scan

Discontinue any blood thinner medication (ie. Coumadin, Plavix, etc) as instructed by your physician or Radiology Department staff.

If you are taking any mood altering medications (for example Prozac, Zoloft, etc) you will be asked to discontinue the medication for a few days prior to the study.

These medications slightly increase the chance of having a seizure during the myelogram.

Is CT/Myelo safe?

Myelograms are commonly performed studies and the risks are very low. However, there are a few known risks of this procedure. Major risks including the following:

  • Headache. This is by far the commonest side effect of this diagnostic imaging procedure. The headache can be severe, however, it is usually self-limiting and resolves with a day or two on its own. If it doesn’t resolve spontaneously a blood patch may be required. This is a procedure that is typically performed by an anesthesiologist.
  • Seizure. This is a very rare complication of myelography. It occurs because the Xray dye that is injected into the cerebrospinal fluid is of higher ionicity when compared to normal CSF. The dye is typically injected into the spinal canal in the low back (lumbar region) and usually gets well diluted before it reaches the brain. However, if the dye was allowed to quickly travel up in to the neck region (cervical spine) there is a risk that it could get flow in to the head and the brain may react to the increased ionicity by having a seizure. For this reason we always discontinue any medications that lower the seizure threshold, prior to the myelogram study
  • Bleeding. When placing the needle in the spinal canal there always is the risk that we could injure a small blood vessel and that could lead to bleeding. This is almost always of no concern unless the patient is on “blood thinner” medications such as Coumadin, etc. These medications are typically discontinued before the procedure to prevent this problem.

Common uses of CT/Myelo

  • Preoperative planning
  • Assessment for spinal stenosis, back pain or radiculopathy (pain radiating down leg or arm)

Common exams and preparation

The imaging scheduler will let you know what preparation, if any, is needed for your particular exam when your appointment is scheduled.