Evolution of the Graded Repair of Cerebrospinal Fluid Leaks and Skull Base Defects in Endonasal Endoscopic Tumor Surgery: Trends in Repair Failure and Meningitis Rates in 509 Patients

Objective We previously described a graded approach to skull base repair following endonasal microscopic or endoscope-assisted surgery for parasellar tumors. Herein, we review our experience with skull base reconstruction in the endoscopic era.

Methods A retrospective review of our prospective database (April 2010 to April 2017) of patients undergoing endonasal endoscopic tumor removal was undertaken. Intraoperative CSF leaks were graded based on size (Grades 0, I, II, III) and repair technique was documented across grades. The series was divided into two epochs based on implementation of a strict perioperative antibiotic protocol and more liberal use of rigid (permanent) and/or soft (temporary) buttresses starting in September 2013; repair failure rates and postoperative meningitis rates were assessed before and during protocol.

Results A total of 551 operations were performed in 509 patients (median age: 50 years). Lesions included pituitary adenoma (66%), Rathke's cleft cyst (7%), meningioma (6%), craniopharyngioma (4%), and other (17%). There were nine postoperative CSF leaks (1.6%) and six cases of meningitis (1.1%). Postoperative leak rates for Grades 0, I, II, III were 0, 1.9, 3.1, and 4.8%, respectively. Fat grafts were used in 33, 84, 97, and 100% of Grades 0, I, II, and III leaks, respectively. Pedicled mucosal flaps (78 in total) were used in 2.6% of Grades 0, I, II leaks (combined) and in 79.5% of Grade III leaks (60 nasoseptal and 6 middle turbinate flaps). Nasoseptal flap usage was highest in patients with craniopharyngiomas (80%) and lowest in those with pituitary adenomas (2%). Two (3%) nasoseptal flaps failed. Contributing factors for the nine repair failures were BMI ≥ 30 (7/9), lack of buttress (4/9), Grade III leak (4/9), and postoperative vomiting (4/9). In comparing first and second epochs of the series, repair failures decreased from 6/261 (2.3%) to 3/290 (1%); meningitis rates decreased from 5 (1.9%) to 1 (0.3%), (p = 0.079). Prophylactic lumbar CSF drainage was used in only four patients (<1%) and discontinued in 2012. In comparing pre- and postprotocol epochs, increased buttress use was documented: permanent buttress in Grade I and III leaks (13–55% and 32–76%, respectively, p < 0.001); and autologous septal/keel bone as permanent buttress in Grades I, II, III leaks (15–51%, p < 0.001).

Conclusion A graded approach to skull base repair after endonasal surgery remains valid in the endoscopic era. However, the technique has evolved significantly, with further reduction in postoperative CSF leak rates. These data suggest that rigid or soft buttresses are beneficial for repair of most Grade I and II leaks, and all Grade III leaks. Pedicled flaps appear advantageous in repair of all Grade III leaks. CSF diversion was rarely used and offers no apparent value. High BMI is a likely risk factor for repair failure and should prompt an aggressive multilayered repair strategy. Achieving repair failure and meningitis rates of less than 1% is a reasonable goal in endoscopic skull-base tumor surgery.