The length of the nasal septum comprises sufficient mucoperichondrium and mucoperiosteum to allow the harvesting of a nasoseptal flap that could cover any defect resulting from an anterior skull base, a transsellar/transplanar, or a transclival EEA. Similarly, the height of the nasal septum has the potential to yield a nasoseptal flap with a width that is adequate to cover the laterolateral aspect of any defect of the anterior skull base and clivus. Skull base defects resulting from combined EEAs, such as those that would create a defect that comprises the skull base from sella turcica to frontal sinus, are beyond the potential dimensions of a single nasoseptal flap. This and other defects resulting from a combination of EEAs require other strategies, such as the use of bilateral nasoseptal flaps, or the use of other reconstructive options.

The nasoseptal flap had an important role in the development of endoscopic endonasal surgery of the cranial base. The flap is pedicled upon the posterior septal artery, which is a terminal branch of the sphenopalatine artery. The reliable vascular supply promotes rapid healing and the flap is an effective barrier for the prevention of CSF leaks. For large skull base defects, it has dramatically decreased the risk of a postoperative CSF leak to less than 5%. The nasoseptal flap is a versatile flap with a wide arc of rotation that allows the flap to reach defects from the frontal sinus to the lower clivus. This chapter provides a comprehensive review of the nasoseptal flap. The harvesting and reconstruction techniques, modifications of the flap and complications are described.

The vidian nerve transposition for EEAs to the skull base is an alternative technique that is feasible and conservative. It seems to be a good option that could prove beneficial to the quality of life of patients after surgery.

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The dimensions of NS flap are sufficient to cover completely the ASB defect. The anterior edge of the defect presents increased risk for failure in coverage. Additional width adding the nasal floor mucosa to the flap is important to decrease the risk of gap in the anterior orbit-orbit defect. It is more common to find two branches of the SA in the pedicle.