CT Cisternogram

A clear, watery drip from one side of the nose or ear, especially after a head injury or surgery, can be a sign that spinal fluid is leaking. A CT cisternogram is a test that helps find exactly where the leak is coming from so it can be repaired.

A CT cisternogram combines a spinal tap with contrast dye and a CT scan of the head. Dye is placed in the spinal fluid through a thin needle in the lower back. You are then positioned, often lying face down with your head lower than your feet, so the dye flows up to the base of the skull. A CT scan then looks for dye escaping through a small opening in the bone, usually into the sinuses or ear.

A related test, the radionuclide cisternogram, uses a small amount of radioactive tracer instead of dye and takes pictures over one to three days. It is sometimes used to study spinal fluid flow or to find slow leaks.

A CT cisternogram is used to:

• Find the location of a spinal fluid (CSF) leak from the skull base, which can cause fluid draining from the nose or ear
• Plan the repair of a leak, by showing the exact spot in the bone
• Look for the cause of repeated meningitis, which can happen when there is a hidden leak

It is usually ordered after other tests, such as testing the drained fluid, suggest a leak. Leaks from the spine itself, which can cause intracranial hypotension, are usually found with different tests, such as a dynamic CT myelogram.

• Ask about blood thinners. If you take a blood thinner such as warfarin, apixaban (Eliquis), rivaroxaban (Xarelto), clopidogrel (Plavix) or daily aspirin, you may need to stop it for a few days. Never stop a blood thinner on your own. The doctor who prescribes it and the doctor who ordered the test will tell you if and when to stop.
• Tell the center about any allergy to iodine contrast dye.
• You may be asked not to eat for a few hours before the test.
• If you can, keep track of when the drainage happens and what makes it worse, such as leaning forward. This can help the radiologist.
• Arrange for someone to drive you home.

The dye is placed in your lower back with a thin needle after the skin is numbed, the same way as a spinal tap. You will then lie in specific positions, often face down and tilted head-down, for several minutes. You may be asked to strain gently or lean forward to encourage fluid to leak during the scan. The CT pictures of your head take only a few minutes. Plan on one to two hours in all.

Rest for the rest of the day, drink plenty of fluids, and avoid strenuous activity for 24 hours. Call the doctor who ordered the test if you get a fever, stiff neck, a headache that is much worse when you sit or stand, or more drainage from your nose or ear. The doctor who ordered the test will go over the results with you.

The test is generally safe. Possible side effects include a headache after the spinal tap, a reaction to the dye, and, rarely, infection or bleeding. It uses some radiation from the CT scan.

What is a CT cisternogram used for?

It is used to find where spinal fluid is leaking from the base of the skull, often into the nose or ear, so that the leak can be repaired.

How is a CT cisternogram different from a CT myelogram?

Both place dye in the spinal fluid. A myelogram looks at the spine and nerves, while a cisternogram positions the dye at the base of the skull and scans the head to look for a leak.

What is a radionuclide cisternogram?

It is a related test that uses a small amount of radioactive tracer and pictures taken over one to three days. It can find slow leaks or show how spinal fluid flows.

If you have questions about a CT cisternogram, talk with the doctor who ordered your test. For scheduling or arrival instructions, call the imaging center where it is booked.

Related: All imaging and diagnostic tests · CSF leaks

This information is for educational purposes only and is not medical advice. It does not replace individualized care from a licensed physician. Please talk to your provider about your symptoms and follow the instructions from your imaging center.