Cerebrospinal fluid leak repair: utility of intrathecal fluorescein for correct topographic identification of the skull base defects

Background: In the management of cerebrospinal fluid (CSF) leak the identification of the exact discharge spot is paramount. This can represent a challenge for the radiologist and the surgeon. In the present study, we analyzed a series of patients affected by endonasal CSF leak who underwent endoscopic surgical reconstruction aided by the use of intrathecal fluorescein (ITF). The purpose of this work is to assess the efficacy of intraoperative ITF in addition to computed tomography (CT) scan and magnetic resonance imaging (MRI) for correct topographic localization of the CSF leak. Methods: Eighty-three patients were enrolled in the study. The main outcome was the concordance between the supposed radiological defect site and the actual one seen intraoperatively. The recurrence free survival (RFS) was evaluated as secondary outcome. Results: ITF better defined the defect site allowing a change in the treatment in 21 cases (25.3%), in which a non-concordance was observed between the suspected radiological site and the actual surgical one. Good agreement was found between the specific topographic localization (k=0.737, p<0.0001), whereas fair agreement was observed considering the side of the defect (k=0.362, p=0.0009) and correct identification of multiple sites (k=0.044, p=0.666). The 10-year 96% estimate of RFS confirmed the correct repair of the fistula site in most of the cases. Conclusions: Our data demonstrate the utility and safety of intraoperative ITF for management of patients affected by endonasal CSF leak. ITF improved the topographical diagnosis of the leak site, ensuring the best target reconstruction and very low recurrence rate.