A Review of the Current Closure Techniques of Anterior Skull Base Defects in Expanded Endoscopic Endonasal Surgery

Introduction: The Incidence of CSF leaks in extended endonasal endoscopic skull base surgery has significantly decreased over the past 15 years. The use of neuronavigation allows for minimally invasive and more precise approach to a variety of anterior skull base lesions compared with the original and more invasive open transcranial approaches. Offering an expanded 3D panoramic viewing field and extended cranial access from the frontal sinus to the craniocervical junction, patients undergoing procedures with extended endoscopic approaches have had a decrease in morbidity and hospital length of stay. Historically, studies had reported CSF leak rates between 20 and 50% along with risk of intracranial extension of infections. However, newer techniques such as gasket seal closures, button grafts, pericranial flap, Hadad-Bassagasteguy, neuromuscular, pedicle and bilateral nasoseptal flaps have proved to be effective closure techniques of the anterior skull base This review paper examines the newer EEAs, reconstructive closure techniques and highlights the intraoperative and post op results from more recent studies involving the efficacy and use potential of EEAs.

Results: Over the past 10 years studies have shown the current CSF leak has improved to < 10%, along with a decreased incidence of meningitis and need for post -op reconstructive repair procedures. Primary reconstructive closure of EEA in patients at high risk for CSF leak was attained with a 94% success rate through vascularized nasoseptal flap in a prospective study involving 70 cases. Evaluating the efficacy of reconstructive closure for post -op CSF leak, 127 cases were assessed in an algorithmic approach with excellent efficacy revealing an initial 91.3% successful reconstruction rate. An extradurally placed button graft is another technique that is useful as a standalone or adjuvant to a nasoseptal flap proving to have a 4.5x decrease in CSF leak rate in a retrospective study involving 40 patients OR: 0.22 (95% CI 0.04–0.92, p = 0.037). CSF leak rates at UPMC decreased 4× with the introduction of a vascular pedicle nasoseptal flap called the Hadad-Bassagasteguy flap offering significant potential as a reconstructive alternative, especially for large dural defects. Similarly the pericranial flap, neuromuscular pedicle bilateral nasoseptal flaps showed a sharp decrease in CSF leak rates as well as proved to be a viable option for larger dural defects. Yet another study evaluating the efficacy of newer closure techniques is a gasket seal had a 0% CSF leak for ASB yielding it as an effective water seal method for EEA’s. However, one observational study examined 30 cases of CSF leaks with large (>5.5 cm) dural defects and found the rate to be comparable to open approaches. Anterior skull base surgery through EEA’s and newer closure techniques may provide an effective alternative if not replace traditional open approaches as a primary technique for many ASB lesions

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