A new technique for the use of intrathecal fluorescein in the repair of cerebrospinal fluid rhinorrhea using a hypodense diluent.

The intrathecal injection of fluorescein is used in the diagnosis and treatment of skull base liquoric fistulas since it allows precise localization of the site of drainage. The fluorescein is always diluted in cerebrospinal fluid (CSF) resulting in a hyperdense solution in relation to the CSF. For this reason it is necessary to put the patient in the Trendelenburg position for 30 to 40 minutes so that the fluorescein reaches the cerebral cisterns and is visualized at the level of the fistulae. From October 1997 to May 1999 intrathecal fluorescein in a hypodense solution was used in the repair of 23 skull base defects associated with CSF rhinorrhea. This hypodense solution was obtained by diluting 0.5 cm3 of 5% fluorescein in 10 cm3 of distilled water. This solution density is 1001, which is hypodense when compared to CSF (density range 1004-1006) and therefore allows fluorescein to reach rapidly the cerebral cisterns when the patient is recumbent. The author discusses the advantages and the lack of complications with the use of fluorescein in a hypodense solution.