Early Investigation Assessing the Feasibility of Electrospinning of Cyanoacrylate Glue for Endonasal Skull Base Repair

Background: The expanded endonasal approach (EEA) helps to minimize neurologic morbidity by eliminating brain retraction and the need to work through corridors bordered by cranial nerves. However, despite numerous technologic and surgical innovations, post-operative CSF fistula following EEA continues to be associated with considerable morbidity. Cyanoacrylate glues offer enhanced strength and durability for skull base repair compared with fibrin and polyethylene glycol alternatives. However, problems with unwieldy deposition and inhomogeneity have limited options for clinical application. Electrospinning is a novel method that uses electric force to draw together charged threads of polymer solutions. Such a method facilitates precise deposition of ultrathin continuous nanofibers, which may make skull base repair with cyanoacrylate glue a promising alternative. In this study, we investigate the application of electrospinning cyanoacrylate glue as a promising future method for endonasal skull base repair.

Methods: A piece of calvarial bone measuring approximately 5 cm² in size was removed from a fresh frozen cadaver. A central defect, measuring approximately 1 cm, was created in the calvarial bone to simulate a skull base defect. Temporalis fascia obtained from a fresh frozen cadaver was placed as an inlay graft. An endoscope-like extended electrospinning device was then utilized to apply a thin film of ethyl cyanoacrylate (ECA) glue fibers on bone and fascia surfaces. A rhodamine red dye was added to glue solution for better visualization. High voltage of 7 to 10kV was applied to the needle and the distance between the needle and the target was adjusted between 10 and 15 cm to control the glue deposition area. Cyanoacrylate glue was fed at the constant rate of 1 mL/h using the syringe pump. Scanning electronic microscopy (SEM), EVEX miniSEM SX-30, was used to evaluate the ECA fibers. Samples were coated with gold using Denton Desk II bench-top sputter coater for SEM observation.

Results: ECA fibers were deposited successfully on the fresh cadaver bone and fascia model. Deposition areas of 250 and 78 cm² were conveniently controlled by adjusting the electrospinning distance from 15 to 10 cm, respectively. Deposition on 78 cm² area only required 50 uL of glue for approximately 3 minutes of electrospinning. Based on SEM observation, electrospun glue fiber forms a film structure embedding ECA nanofibers which congealed satisfactory with the temporalis fascia over the bone defect.

Conclusion: The method of electrospinning investigated facilitated precise and meticulous deposition of ECA glue on fresh cadaveric tissue. Developed endoscope-like electrospinning device have demonstrated the potential for the surgical use in EEA. Excellent film homogeneity and adhesive characteristics have obtained for dural repair purpose. Data from this investigation will pave the wave for additional research into endonasal application of glue and skull base repair using the electrospinning glue nanofibers.