The Nasoseptal Flap: Variations on a Theme

Based on the posterior septal artery, the pedicled NSF provides vascularized tissue to reconstruct a variety of ventral skull base defects. As our experience utilizing the NSF has matured, we have begun to adapt modifications to tailor reconstructions to the clinical scenario and defect location to minimize patient morbidity. In this presentation we will discuss three of these modifications.

Lateral sphenoid encephalocele: A NSF and a posterior septectomy provide hearty vascularized tissue for these reconstructions. This provides a more robust repair with lower recurrence rate and provides improved visualization and dexterity of instruments with bilateral access. Given the distance from the encephalocele to the contralateral NSF, the flap needs considerable length but does not require substantial width. To increase the length of the NSF while preserving septal mucosa, a curvilinear superior cut is utilized that arcs to the nasal floor near the posterior edge of the hard palate. The inferior cut is then performed along the choana and posterior septal edge and includes a releasing notch to provide additional length once the flap is rotated about this notch. This allows preservation of the anterior septal mucosa and decreases sinonasal morbidity.

Cribriform/Ethmoid encephaloceles: The ipsilateral middle turbinate is removed and the sinonasal cavity is widely opened with preservation of the posterior septal artery pedicle. Although this may increase healing time as compared with a free mucosal graft, a lower recurrent leak rate and a more durable reconstruction are of greater importance. To reduce the risk of potential hyposmia, we raise a long thin NSF inferior to the olfactory filaments within the septum incorporating the posterior septal artery. We then transpose this tissue onto the defect. There is an area of mucosa on mucosa at the posterior aspect of the septum, and thus a theoretical chance of a mucocele; however, we have not encountered this and have excellent visualization in the postoperative cavity for surveillance.

Frontal encephalocele: While the aforementioned variations on the NSF were based on the posterior septal artery, anterior ethmoid or frontal encephaloceles are frequently encountered that are not amenable to a traditional NSF. Once the ipsilateral cavity is widely opened and the encephalocele and anterior ethmoid artery are identified we raise a flap centered around the anterior ethmoid artery in a vertical orientation. A mucoperiosteal bridge to the artery must be maintained for venous outflow. This flap requires considerable rotation and makes an alarming tortuous course to rotate from the floor of the nose to the posterior table of the frontal; however, we have not experienced difficulty with flap viability.

Sellar reconstructions serve as the learning ground for raising and utilizing NSFs. While our experience has increased, we have started to develop variations to better serve the wide reconstructive needs of the anterior skull base while decreasing morbidity in our patients.

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