Radiological and clinical interpretation of the patients with CSF leaks developed during or after endoscopic sinus surgery

Cerebrospinal fluid (CSF) leaks associated with endoscopic sinus surgery (ESS) are a rare complication related to anatomical and technical factors. The anatomical variations at skull base level are imperative to be detected preoperatively by CT scan to avoid this complication. Identifying the factors playing a role in the incidence of the CSF leaks during and after ESS and the common leak sites. A retrospective review of 24 patients presented with incidental CSF leaks, gathered from 1999 to 2016 was performed. Images interpretation of the skull base area was done using four parameters includes Keros classification, skull base slope, fovea plane and maxillary ethmoid height ratio (MER). Each parameter is classified into three types according to the anatomical configuration, then these parameters scores categorized according to the level of the safety into a level I, II and III, all levels were correlated with each other and with the site of leakage. It was found that the major group presented with the level I and the least group with level III safety, with an evidence of the most unsafe anatomical variation was the least relevant. Parameters measurements revealed that the larger group of the anatomical variation type III was in the MER and the commonest leak site was in the posterior ethmoidal roof. CT scan study of the skull base is crucial in delineating the variations and be a roadmap to proceed safely through the dissection remembering that incidental CSF leaks are multifactorial in etiology.