Local Pedicled Nasal Flaps For Endoscopic Reconstruction Of Skull Base Defects

Abstract

Any surgery to skull base lesion should begin by "planning of the reconstruction", It should be kept in mind that surgery must be safe and oncologically sound, with maximal preservation of critical structures, in order for patients to benefit from such a complex surgical intervention, and the challenging point is to properly reconstruct the resultant defect after handling with the skull base lesion. Open approaches to skull base have a complication rate of 18 to 60%; they often involve significant amounts of brain retraction, neurovascular manipulation, and cosmetic compromise; and need complex plastic surgery closures. In response, collaboration between neurosurgeons and otolaryngologists has recently resulted in the development of the new field of endoscopic endonasal cranial base surgery. Endoscopic approaches are especially appropriate if the lesions are bordering to neurovascular structures since they allow reach such neoplasm with minimal manipulation. Furthermore, they allow the access to deeply seated lesions, a more direct exposition of the midline, rapid decompression of the optical apparatus, and early devascularization of neoplasm, shorter duration of the operations (in some cases), a decreased hospital stay, and improved quality of life of the patients, as wells as the lack of external cuts. Extended endoscopic endonasal approaches includes the transfrontal approach provides access to the floor and posterior wall of the frontal sinus, the trans-cribriform access extends from the crista galli to the planum sphenoidal and across the roof of the ethmoid sinuses (fovea ethmoidalis) to the orbital roof, and the transplanum module provides access to suprasellar lesions. Small defects and CSF fistulas have an excellent rate of closure via an endoscopic technique. A more than 90% closure rate with primary endoscopic surgery and a 97% closure rate with endoscopic revision are possible; while large defects need vascularized flaps especially for patients that will be submitted to post-operative radiotherapy. Nowadays, the incidence of cerebrospinal fluid leaks has diminished from around 20% to 30% to less than 5% with vascularized tissue reconstruction. Vascularized pedicled flaps are the best option for providing a reliable and robust reconstruction after endonasal skull base surgery. Endonasal pedicled flaps are ideal due to their accessibility, but in situations where they are not available or are inadequate, large ventral skull base defects, may be successfully reconstructed with regional pedicled flaps. Currently vascularized pedicled nasal mucosal flaps are used during transnasal transcranial surgery whenever possible. Following the patterns of nasal blood supply “vascular tree” many pedicled vascular flaps can be designed, especially after precise identification of the vascular anatomy of the lateral nasal wall. Blood