Extrusion of Non-porous Polyethylene Implants after Endoscopic Reconstruction of Large Skull Base Defects

Background: Reconstruction of skull base defects after endonasal endoscopic approaches is often technically challenging, and many different methods and materials have been employed with the goal of preventing postoperative cerebrospinal fluid (CSF) leaks. Multi-layered reconstruction techniques include gasket seal and modified gasket seal, as well as acellular dermal allografts or fascial grafts followed by a vascularized septal flap. Our recent experience has demonstrated an unexpectedly high incidence of extrusion of large non-porous polyethylene plate implants for skull base reconstruction when used in patients receiving adjuvant radiotherapy.

Methods: We retrospectively reviewed cases from 2011 to 2015 to identify patients in whom non-porous polyethylene implants were used. The primary outcome of interest was subsequent implant extrusion requiring operative revision. Patient baseline demographics were collected, as were tumor pathologies, type of closure used, use of postoperative radiotherapy, incidence of sinusitis, and extrusion-related complications.

Results: Among 74 patients who received porous or nonporous polyethylene implants from 2011 to 2015, six patients experienced extrusion of the non-porous polyethylene implant during the postoperative period. Underlying pathology included both benign and malignant neoplasms, however, all tumors were locally aggressive and were treated with adjuvant radiotherapy. All patients were noted to have high flow CSF leaks intraoperatively. Skull base defects were closed with multilayered reconstruction (gasket seal or modified gasket seal). Mean time to implant extrusion was found to be 9.2 months postoperatively, with a range of 1.5 to 18 months. Four patients had instances of acute on chronic sinusitis postoperatively requiring antibiotics. Two patients experienced intracranial infections and brain abscesses. Three patients underwent operative revision surgery with implant removal, and one patient is currently scheduled to undergo operative revision.

Conclusion: Due to the unexpectedly high incidence of implant extrusion and related morbidity, our experience argues against the use of non-porous polyethylene plates to buttress skull base reconstruction, especially in patients who will receive adjuvant radiation. For these patients, we recommend multilayered reconstruction without a rigid buttress, utilizing either acellular dermal allograft or autologous fascial grafts followed by a vascularized septal flap.