Radionuclide cisternogram

A Radionuclide cisternogram is medical test which involves injecting a tracer through a needle into a patient's cerebral spinal fluids (CSF) to check to see if it is flowing properly, or determine if there is a leak (also known as a CSF fistula) from the brain into the nasal cavity. A leak is usually confirmed by the presence of Beta-2 transferrin in fluid collected from the nose before this more invasive procedure is performed.

The patient may be instructed to not eat or drink, or take medications such as Ibuprofen or other blood thinners before the procedure. (Nil per os). Pledgets can be inserted into the nasal cavity before the procedure when a CSF leak is suspected.

The patient's spinal fluid is injected with a radiopharmaceutical tracer, such as DTPA tagged with indium 111], through a lumbar puncture. (A intrathecal injection. ) The tracer will diffuse up the spinal column and into the brain as the patient lies flat for six hours. The progress of the tracer's diffusion through the CSF will be recorded by a nuclear medicine gamma camera several times. The patient may be asked to return for a 24 and 48 hour followup scan.

The pledgets will be removed and placed on radiographic film or a gamma counter. If the tracer has leaked onto the pledget through the skull, it will darken the film allowing the diagnostician to determine the location of the leak within the sinus cavity. The site of the CSF leak can be plugged with fat or muscle by endoscopic surgery.

Headaches following the procedure are uncommon, but should fade in 3-5 days. A 'blood patch' can speed the process if headaches persist. Drinking caffeinated liquids, as well as bed rest, is often recommended, though at least one scientific paper disputes the practice.