Risk Factors Associated with Postoperative CSF Leak

Background: The most common complication of endoscopic skull base surgery is the development of postoperative CSF leak. However, minimal data exist in the literature clearly identifying risk factors associated with this complication.

Aim: To determine whether BMI, gender, tumor pathology, lumbar drain, and type of reconstruction are independent risk factors for the development of postoperative CSF leak after endoscopic endonasal approach (EEA) for resection of intradural skull base tumors.

Methods: A retrospective review of patients from January 1997-June 2012, who underwent EEA for the resection of intradural pathology was performed. Pituitary tumors were included if an intraoperative CSF leak requiring dural repair was noted. Basic demographic data were collected, along with patient BMI, tumor pathology, reconstructive technique, perioperative lumbar drain, and presence of postoperative CSF leak. Rates of postoperative CSF leak were analyzed using a chi-square analysis.

Results: Of the 615 patients who met inclusion criteria, 103 developed postoperative CSF leak (16.75%). There was no difference in the leak rate between male and female patients (18.5% vs. 15.7%; P = 0.315).

There was a higher leak rate in overweight and obese patients (BMI > 25) when compared with those of normal BMI (18.78% vs. 11.56%; P = 0.04). Female patients with postoperative CSF leak had a higher average BMI than those who did not develop a CSF leak (31.5 mg/kg² vs. 29.38 mg/kg²; P = 0.02); in males there was no difference in BMI between these two groups (29.3 mg/kg² vs. 29.2 mg/kg²; P = 0.91).

Patients in whom a pedicled vascularized flap was used for skull base reconstruction had a lower leak rate compared with those in whom a free graft was used (13.54% vs. 27.89%; P = 0.0005). In patients with a BMI >25, use of a pedicled flap reduced the rate of CSF leak from 29.56% to 15.0% (P = 0.000); in patients of normal weight, this reduction did not reach statistical significance (21.8% vs. 9.2%; P = 0.09).

Rates of CSF leak varied based on tumor pathology, with the highest leak rates occurring in patients with chondroid tumors (30.77%) and meningiomas (24.12%) and the lowest rate in those with esthesioneuroblastoma (5.88%). There was no difference in leak rate between patients treated with a perioperative lumbar drain and those who were not (21.77% vs. 15.17%; P = 0.08).

Prior to 2006, the rate of postoperative CSF leak was 36.5%, which dropped to 15.7% after 2006 (P < 0.0000). During 2011-2012, the postoperative CSF leak rate was 9.6%.

Discussion: Patient gender and use of perioperative lumbar drain were not associated with varying rates of CSF leak. A preoperative BMI > 25 is associated with increased rates of postoperative CSF leak. As with open approaches, tumor pathologies more commonly found in the posterior fossa are associated with higher rates of postoperative CSF leak. Use of a vascularized flap is associated with lower rates of CSF leak and may provide additional benefit to overweight and obese patients. Analysis of postoperative CSF leak rate over time shows reduced rates in more recent years.