Assessment of frontal lobe sagging after endoscopic endonasal transcribriform resection of anterior skull base tumors: is rigid structural reconstruction of the cranial base defect necessary?

ABSTRACT

OBJECTIVES/HYPOTHESIS: The endoscopic endonasal transcribriform approach (EETA) is a viable alternative option for resection of selected anterior skull base (ASB) tumors. However, this technique results in the creation of large cribriform defects. Some have reported the use of a rigid substitute for ASB reconstruction to prevent postoperative frontal lobe sagging. We evaluate the degree of frontal lobe sagging using our triple-layer technique [fascia lata, acellular dermal allograft, and pedicled nasoseptal flap (PNSF)] without the use of rigid structural reconstruction for large cribriform defects. STUDY DESIGN: Retrospective analysis. METHODS: Nine patients underwent an EETA for resection of large ASB tumors from August 2010 to November 2011. The degree of frontal lobe displacement after EETA, defined as the ASB position, was calculated based on the most inferior position of the frontal lobe relative to the nasion-sellar line defined on preoperative and postoperative imaging. A positive value signified upward displacement, and a negative value represented inferior displacement of the frontal lobe. RESULTS: The average cribriform defect size was 9.3 cm(2) (range, 5.0-13.8 cm(2) ). The average distance of postoperative frontal lobe displacement was 0.2 mm (range, -3.9 to 2.9 mm) without any cases of significant brain sagging. The mean follow-up period was 10.1 months (range, 4-19 months). There were no postoperative CSF leaks. CONCLUSIONS: Rigid structural repair may not be necessary for ASB defect repair after endoscopic endonasal resection of the cribriform plate. Our technique for multilayer cranial base reconstruction appears to be satisfactory in preventing delayed frontal lobe sagging.