A radionuclide cisternogram is a nuclear scan test used to diagnose spinal fluid circulation problems.

A lumbar puncture (spinal tap) is done first. Small amounts of radioactive material, called a radioisotope, are injected into the fluid in the lower spine.

You will be scanned 4 - 6 hours after receiving this injection. A special camera creates images that show how the radioactive materials travel with the cerebrospinal fluid through the spine and if the fluid leaks outside the spine.

You will be scanned again 24 hours after injection, and possibly at 48 and 72 hours after injection.

No preparation is usually necessary. However, if you are very anxious or agitated, sedation may be necessary. You must sign a consent form. You will wear a hospital gown to make the spine more accessible. Remove jewelry or metallic objects before the scan.

During lumbar puncture, the lower back over the spine is numbed with an anesthetic. However, many people find lumbar puncture somewhat uncomfortable, usually because of the pressure on the spine during insertion of the needle.

The scan is painless, although the table may be cold or hard. No discomfort is produced by the radioisotope or the scanner.

The test is performed to detect problems with spinal fluid circulation and spinal fluid leaks.

A normal value indicates normal circulation of CSF through all parts of the brain and spinal cord.

An abnormal study indicates disorders of CSF circulation, including:

• Hydrocephalus
• CSF leak
• Normal pressure hydrocephalus (NPH)
• Whether or not a CSF shunt is open or blocked

Risks associated with a lumbar puncture include pain at the injection site, bleeding, and infection. There is also a very rare chance of nerve damage.

The amount of radiation used during the nuclear scan is very small, and virtually all of the radiation is gone within a few days. There have been no documented cases of injury or damage caused by the radioisotope used with this scan. However, as with any radiation exposure, caution is advised if you are pregnant or breastfeeding.

In extremely rare cases, a person will develop an allergic reaction to the radioisotope used during the scan. This may include a serious anaphylactic reaction.

You should lie flat after the lumbar puncture (to help prevent headache from the lumbar puncture). No other special care is usually necessary.

Silberstein S, Young W. Headache and Facial Pain. In: Goetz, CG, eds. Textbook of Clinical Neurology. 3rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 53.