[Surgical occlusion of cerebrospinal fistulas of the anterior skull base using intrathecal sodium fluorescein].

BACKGROUND: For more than 25 years, intrathecal 5% sodium fluorescein has been routinely used at the University ENT Hospital at Graz during surgical closures of CSF leaks of the anterior skull base. Especially with endoscopic approaches, this technique has been of significant help in identifying and localizing dural defects. No fluorescein-related complications occurred in the series reported.

MATERIAL AND METHODS: In a retrospective study, indications, techniques, and results of surgical closures of CSF leaks of the anterior skull base are reviewed. During 5 1/2 years from 1990-1995, 72 patients with CSF-rhinorrhea were operated on at our department, 69 of whom had sodium fluorescein applied intrathecally. In 41 patients strictly endoscopic techniques were applied, in 22 patients an external approach was chosen and in 9 cases combined approaches were used. Defects in the roof of the ethmoid, the lamina cribrosa, and in the sphenoid sinus almost exclusively were approached endoscopically. Defects in the posterior table of the frontal sinus, especially when located laterally, were approached from externally or via combined endonasal and external routes. The causes of the CSF leaks, their localization, and the surgical approaches chosen are analysed and the surgical techniques described in detail.

RESULTS: The direct coronal CT of the paranasal sinuses/anterior skull base proved to be significantly better in detecting lesions compared to axial CT images (82% vs. 53%). In all cases intrathecal fluorescein allowed for a precise localization of the defect(s). There were no fluorescein related complications in this series. In one patient with massive frontobasal chip fractures and substantial dural defect, a rhinosurgical closure was not successful. Two patients developed recurrent fistulae after several months and years respectively. One of these patients had to be operated 3 times until permanent closure was achieved. Two patients had to be revised because of mucoceles of the frontal sinuses, in both cases the initial closure of the dural defect proved to be tight.

CONCLUSION: Our results demonstrate that with exception of defects of the posterior lateral table of the frontal sinus, CSF leaks of the rhinobasis can be closed safely endoscopically. After a follow-up from 19-65 months, the overall success rate for 72 CSF leaks was at 94.5%. When applied correctly, the fluorescein technique proves to be an extremely helpful technique for diagnosis and surgery of CSF leaks.