An Extended Nasoseptal Flap for Anterior Skull Base Reconstruction: Cadaver Study

Background The adequate reconstruction of a skull base defect is paramount for good patient outcomes. The goals of reconstruction for defects produced by the expanded endoscopic endonasal approach (EEA) are identical to those of reconstructing conventional external approach and include the complete separation of the cranial cavity from the sinonasal tract, the elimination of dead space, and preservation of neurovascular and ocular function. The use of nonvascularized free grafts for the repair of a cerebrospinal fluid (CSF) leak following endoscopic sinus surgery and trauma generally results in successful repair of small CSF leaks. However, endoscopic reconstruction with multilayered free grafts for larger dural defects following skull base tumors resection is associated with a postoperative leak rate of 20 to 30%. However, with the advent of pedicled vascularized flaps, in particular, the nasoseptal flap, CSF leak rates have decreased. Despite this success, specifically, the nasoseptal flap is limited in its ability to reach extremely anterior defects and to cover defects involving more than one anatomical segment, such as those involving the posterior frontal table, and the planum sphenoidale. We present the cadaver study results of an extension of the nasoseptal flap for reconstruction of very large midline defects following endoscopic expanded endonasal approach to allow for vascularized reconstruction of the skull base.

Study design Feasibility, cadaveric study.

Methods Using cadaver dissections, we investigated the feasibility of using an extended nasoseptal flap to reconstruct a large midline skull base defect. The flap was raised, and the technique was investigated using fresh human specimen dissection.

Results Endoscopically an extended nasoseptal flap was used to cover the entire anterior skull base from the sella turcica to the posterior table of the frontal sinus. It was demonstrated that the extended nasoseptal flap could cover the clivus/nasopharynx while simultaneously the standard nasoseptal part covered the posterior wall/sella/planum. No facial incisions were required.

Conclusion The use of an extension of the standard nasoseptal flap could be used to cover larger anterior midline skull base defects, and more than one anatomical area in the midline skull base, if appropriate surgical technique is used. The extended nasoseptal flap has potential as a reconstructive option for anterior skull base defects.