Double flap technique for reconstruction of anterior skull base defects after craniofacial tumor resection: technical note

Abstract

Successful reconstruction of large anterior skull base (ASB) defects after craniofacial resection of malignant skull base tumors is paramount for preventing cerebrospinal fluid (CSF) fistulas. The vascularized pedicled pericranial flap (PCF) has been the gold standard for repairing ASB defects after transbasal transcranial approaches. However, flap necrosis and delayed CSF leaks can occur after adjuvant radiation therapy. We describe a "double flap" reconstruction technique in which the PCF is augmented inferiorly by a secondary vascularized pedicled nasoseptal flap (NSF) that is harvested and rotated using an endoscopic endonasal approach. This technique is illustrated in 2 patients who underwent a combined cranionasal (transbasal and endoscopic endonasal) approach for large sinonasal malignancies with significant intracranial extension (1 esthesioneuroblastoma, 1 sinonasal teratocarcinosarcoma). After tumor removal via a combined cranionasal approach, primary repair of the ASB dural defect was performed with a free patch graft. The ASB defect was then repaired using the double flap technique with a vascularized PCF from above and augmented with a vascularized NSF from below. Postoperatively, there were no complications of CSF leakage, meningitis, or tension pneumocephalus in both patients. After subsequent radiation therapy, the double flap repair remained intact at 2 years postoperatively in both patients. The double flap skull base reconstruction technique provides an additional barrier of vascularized tissue to prevent CSF leakage, meningitis, tension pneumocephalus, and postradiation necrosis. This technique is a viable option if a combined transcranial and transnasal endoscopic tumor resection is performed and postoperative radiation is anticipated.