Intrathecal CT Contrast Cisternogram Is Inadequate for Detection of Anterior Skull Base Cerebrospinal Fluid Fistulae

The radiographic and nuclear medicine cistographic work-up are correlated with ultimate surgical and clinical findings in a group of 20 patients treated in a 1-year period with the presumptive diagnosis of cerebrospinal fluid (CSF) rhinorrhea from the anterior skull base. For 10 patients, dual contrasted cisternograms were performed with both CT intrathecal (IT) contrast and radioisotope (RI) dye. The specific protocols for IT CT and RI contrasted cisternography studies are described. All of the patients underwent RI study. CT with IT cisternography detected none of the active leaks in this group, while radioscintigraphy detected 15 of 16 leaks. Four patients were determined to have no leak.

One leak was suspected by noncontrasted CT imaging and was found upon exploration to be present yet had no positive imaging findings.

In conclusion, IT contrasted CT cisternogram is a poorly sensitive study for localizing CSF rhinorrhea sites of origin. Nuclear medicine RI study is the preferred means of detecting occult leaks, yet is not as sensitive as to preclude the presence of small fistula that may be suspected based on clinical presentation and other imaging findings.