Incidence and Significance of Intraoperative Cerebrospinal Fluid Leak in Endoscopic Pituitary Surgery Using Intrathecal Fluorescein

OBJECTIVE: The true rate of intraoperative cerebrospinal fluid (iCSF) leak during pituitary surgery is not well known because small iCSF leaks are easily missed. Our objective is to determine the rate and significance of iCSF leak in endoscopic pituitary surgery with intrathecal (IT) fluorescein administration and determine factors predictive of iCSF leak. METHODS: IT fluorescein was administered in 203 consecutive endoscopic, endonasal pituitary surgeries. The rate of iCSF leak was noted prospectively and correlated with tumor diameter and volume, gross total resection, and the learning curve. Postoperative CSF leak rate, complications, and nasoseptal flap utility were also investigated. RESULTS: The rate of iCSF leak was 61% overall, 44% for tumors <2 cm compared to 72% for tumors >= 2 cm and 35% for tumors <1.5 cm(3) compared to 68% for those >= 1.5 cm(3) (P < 0.001). Postoperative CSF leak was significantly lower after the first 50 cases (0.7% vs. 10%; P < 0.005) with overall leak of 3%. For tumors >2 cm, the introduction of nasoseptal flap reduced the rate of postoperative CSF leak from 5.6% to 1.4%. We did not find any complications clearly related with the use of IT fluorescein. CONCLUSION: The rate of iCSF leak during endoscopic pituitary surgery using IT fluorescein is higher than previously reported. Tumor diameter and volume are best predictors of the risk of iCSF leak. Based on this knowledge and a closure algorithm that includes a lumbar drain and nasoseptal flap for larger tumors (>2.5 cm), we can conclude that the postoperative CSF leak rate remains exceptionally low, particularly once the learning curve is overcome.