The Laryngoscope Lippincott Williams & Wilkins © 2008 The American Laryngological, Rhinological and Otological Society, Inc. Palatal Flap Modifications Allow Pedicled Reconstruction of the Skull Base Christopher L. Oliver, MD; Trevor G. Hackman, MD; Ricardo L. Carrau, MD; Carl H. Snyderman, MD; Amin B. Kassam, MD; Daniel M. Prevedello, MD; Paul Gardner, MD Objectives: Defects after endoscopic expanded en- Key Words: Reconstructive surgical procedures, donasal approaches (EEA) to the skull base, have exposed skull base complications/surgery, surgical flaps/blood sup- limitations of traditional reconstructive techniques. The ply, palatal flap, nasal cavity reconstruction. ability to adequately reconstruct these defects has lagged Laryngoscope, 118:2102–2106, 2008 behind the ability to approach/resect lesions at the skull base. The posteriorly pedicled nasoseptal flap is our pri- mary reconstructive option; however, prior surgery or INTRODUCTION tumors can preclude its use. We focused on the branches Due to the unparalleled visualization afforded by en- of the internal maxillary artery, to develop novel pedicled doscopes, and the ability to access the skull base via a flaps, to facilitate the reconstruction of defects encoun- transnasal corridor while preserving vital neurovascular tered after skull base expanded endonasal approaches. structures at risk with classic open techniques, endonasal Study Design: Feasibility. skull base surgery has continued to grow as a surgical Methods: We reviewed radiology images with at- tention to the pterygopalatine fossa and the descending discipline. Advances in endoscopic techniques and image palatine vessels (DPV), which supply the palate. Using guidance have allowed major skull base centers to expand cadaver dissections, we investigated the feasibility of the application of endonasal surgery, to larger and more transposing the standard mucoperiosteal palatal flap into complex defects; now approaching the size of those gener- the nasal cavity and mobilizing the DPV for pedicled skull ated through open approaches. The increased defect com- base reconstruction. plexity after endoscopic endonasal skull base surgery has Results: We transposed the palate mucoperiosteum increased the demand for reconstructive options. Free tis- into the nasal cavity through limited enlargement of a sue grafting is a reliable technique to reconstruct small single greater palatine foramen. Our method preserves defects that communicate the arachnoid space and the the integrity of the nasal floor mucosa, and mobilizes the nasal cavity.1 However, their use for the reconstruction of DPV from the greater palatine foramen to their origin in the pterygopalatine fossa. Radiological measurements larger defects resulted in a high incidence of postoperative and cadevaric dissections suggest that the transposed, cerebrospinal fluid (CSF) leaks.2 Reconstruction with vas- pedicled palatal flap (the Oliver pedicled palatal flap) cular pedicle flaps has proven indispensable, for decreas- could be used to reconstruct defects of the planum, sella, ing postoperative CSF leak rates associated with large and clivus. skull base defects after expanded endonasal approaches Conclusions: Our novel modifications to the island (EEA). The introduction of the Hadad-Bassagasteguy flap 2 palatal flap yield a large (12–18 cm ) mucoperiosteal flap (HBF) (vascular pedicle nasoseptal flap) at our institution ϳ based on a 3 cm pedicle. The Oliver pedicled palatal decreased our postoperative CSF leak rates to Ͻ5%.3 flap shows potential for nasal cavity and skull base re- However, the HBF is not always available as the nasosep- construction (see video, available online only). tal area, or its vascular supply can be compromised by tumor or prior surgery. In an attempt to keep pace with the rapidly expanding reconstructive requirements, our From the Department of Otolaryngology (C.L.O., T.G.H.), Head and group has developed alternative reconstructive techniques Neck Surgery, Department of Otolaryngology (R.L.C., C.H.S.) Head and Neck using vascular pedicle flaps, but favoring those mucoperi- Surgery and Neurosurgery, Departments of Neurosurgery and Otolaryn- gology (A.B.K.), Head and Neck Surgery, and Department of Neurosurgery osteal units supplied by branches of the internal maxillary (D.M.P., P.G.), University of Pittsburgh Medical Center, Pittsburgh, Penn- artery.3–5 sylvania, U.S.A. In this report, we present the radiological and cadav- Editor’s Note: This Manuscript was accepted for publication June 27, 2008. eric foundations for novel modifications of the well- Send correspondence to Christopher L. Oliver, MD, Department of described island palatal flap, including the release of the Otolaryngology, Head and Neck Surgery, Mayo Clinic Arizona, 5777 E Mayo descending palatine vessels (DPV) and transposition of Blvd, Phoenix, AZ 85054, U.S.A. E-mail: [email protected] the mucoperiosteal flap into the nasal cavity, to allow for DOI: 10.1097/MLG.0b013e318184e719 pedicled reconstruction of skull base defects after EEAs. Laryngoscope 118: December 2008 Oliver et al.: The Oliver Pedicled Palatal Flap 2102 Fig. 1. Anatomy of the pterygopalatine fossa and palatine canal by illustration and computed tomography (CT). (A) Coronal illustration of the pterygopalatine fossa (star), and the branches of the internal maxillary artery (triangle 1); the sphenopalatine artery (triangle 2); the superior pharyngeal artery (triangle 3); and the descending palatine artery (triangle 4). Note the inferior turbinate (black arrow). (B) Axial CT at the level of the inferior turbinate demonstrating bilateral descending palatine canals (white arrows). (C) Sagital CT demonstrating the palatine canal (white arrow). Note the near sagital plane and the posterior to anterior movement as the bundle approaches the palate. The length of the descending palatine vessels is 27.2 mm from mid pterygopalatine fossa (arrow head) to the greater palatine foramen. MATERIALS AND METHODS the posterior maxillary wall is removed to uncover the junction De-identified preoperative computed tomography (CT) of the sphenopalatine and greater palatine vessels within the scans from patients who have undergone EEAs, were reviewed PPF. The inferior turbinate is then endoscopically divided, and with regard to the pterygopalatine fossa (PPF) and the internal the posterior half freed from the lateral nasal wall to facilitate its maxillary artery anatomy (Fig. 1). The length of the DPV was elevation in concert with the nasal floor mucosa. Elevation of the measured from the midportion of the PPF to the greater palatine nasal floor begins 2.5 to 3 cm posterior to the pyriform aperture, foramen (GPF). The posterior to anterior travel of the DPV was and is carried to the limit of the bony palate posteriorly including measured over the same distance. Finally, we performed mea- the inferior turbinate laterally and extending to the septal junc- surements in the mid-sagittal plane from the level of the PPF to tion medially. Care should be taken to preserve the palatal apo- three skull base landmarks, the anterior cribiform plate, the neurosis at the posterior aspect of the dissection. Using a combi- posterior sellar floor, and the foramen magnum (Fig. 1, Table I). nation of blunt and powered dissection techniques, the Five palatal flaps were raised in four cadavers (two hemi- descending palatine artery is mobilized from the pterygopalatine palatal flaps, three full palatal flaps) using a previously described canal (PPC) into the PPF (the origin of its pedicle). Removal of at technique.6 In brief, full thickness mucosal incisions are made least 200 degrees of the bony canal is necessary for mobilization within 2 to 5 mm of the dentition (when present), extending posteriorly to the limit of the hard palate. The palatal mucosa is of the neurovascular bundle. The palatal mucoperiosteal flap is elevated in a subperiosteal plane, and a unilateral neurovascular then carefully passed into the nasal cavity through the bony bundle carefully preserved. Departing from previous reports, a palatal defect (Fig. 3). The mucosa of the nasal floor and inferior high-speed drill witha2mmcoarse diamond (hybrid) burr is used turbinate are then repositioned over the bony palatal defect, and to enlarge the GPF without injuring the vascular pedicle (Fig. 2). the mucoperiosteal flap is arranged over theoretical EEA defects A wide maxillary antrostomy is created on the pedicle side, and (Figs. 4 and 5). TABLE I. Computed Tomography Measurements from the Pterygopalatine Fossa. Length of Distance to Distance to Distance to Descending Palatine Anterior-Posterior Anterior Cribiform Postsellar Foramen Patient Vessels (mm) Excursion (mm) Plate* (mm) Floor* (mm) Magnum* (mm) Age 1 28.4 12.4 40.4 28.7 40.5 76 2 29.6 9.7 37.8 21.5 46.6 73 3 28.2 14.3 44.9 26.7 44.8 29 4 30.4 12.2 40.6 21.2 45.1 43 5 28.7 12.4 39.5 23.3 52.9 51 Mean (mm) 29.06 12.20 40.64 24.28 45.98 54.4 Standard deviation (mm) 0.92 1.64 2.63 3.30 4.49 19.99 *Indicates measurements made in the mid sagital plane. Laryngoscope 118: December 2008 Oliver et al.: The Oliver Pedicled Palatal Flap 2103 Fig. 2. Harvest and transposition of the palatal flap into the nasal cavity. (A) Outline of the palatal flap. Note ruler. (B and C) Anatomic and illustrated palatal flap harvest with preservation of the greater palatine vasculature. Note the enlarged foramen (arrow). RESULTS posterior sellar floor was 24.3 mm, and to the foramen We noted a consistent length and position of the magnum was 46.0 mm (Table I). descending palatine artery as it passed from the PPF into Consistent with our computed tomography measure- the PPC, which is formed by the posterior wall of the ments, we found that the pedicle length was adequate to maxillary sinus and the anterior extent of the medial allow flap coverage of planum, sellar, and clival defects pterygoid plate (Fig. 1). As the PPC approaches the palate, down to the level of the foramen magnum (Fig. 5). We the bony walls thicken slightly and the DPV exit the GPF found no difficulty in preserving the vascular pedicle in- as the greater palatine neurovascular bundle to supply tegrity during cadaveric PPC dissection.