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. The thin and the palate. pliable pedicle allowed for precise placement of a vascu- We found the PPC to be consistently oriented in a larized flap with a large surface area (12–18.5 cm2). Bony near sagittal plane (mean excursion 0.62 mm, standard palate defects for those flaps that included the entire deviation ϭ 0.93, n ϭ 5) (Fig. 1). In contrast, as the palate (bilateral) did not exceed 1.5 cm2 (Fig. 4). neurovascular bundle descends it was found to run diag- onally in a posterior to anterior slant for an average of DISCUSSION 12.2 mm. The mean length of the DPV in our study was Reconstruction of the skull base recreates the sepa- 29.1 mm. We found that the average distance from the origin ration between the cranial cavity and the sinonasal tract of the DPV to the anterior cribiform plate was 40.6 mm, to the preventing postoperative CSF leaks, exposure of neuro-

Fig. 3. Nasal anatomy and pedicle dissection. (A and B) Anatomic and illustrated nasal anatomy after elevation of the nasal floor and the posterior inferior turbinate. (C and D) Anatomic and illustrated view of the descending palatine pedicle (black arrowheads) after dissection and transposition of the palatal flap into the nasal cavity (star) through the bony palatal defect. Note the dis- sected palatine canal (thick black arrow) and the sphenopalatine artery (thin black arrow).

Laryngoscope 118: December 2008 Oliver et al.: The Oliver Pedicled Palatal Flap 2104 Fig. 4. Nasal floor reconstruction. (A and B) Anatomic and illustrated nasal anatomy after replacement of the nasal floor and the posterior inferior turbinate. Note the cut edge of the inferior turbinate (star), the septal remnant (black arrow), the nasopharynx (1), the sphenoid recess (2), the posterior inferior turbinate on the floor of the maxillary sinus (3), the pterygopalatine fossa (4), the nasal floor (5), and the lateral wall of the maxillary sinus (6). The palatal flap has been removed to facilitate visualization. (C) Anatomic view of the bony palatal defect after replacement of the nasal floor mucosa (outline and arrow). vascular structures, and decreasing the risk for ascending flap is based on the posterior lateral nasal artery, has a bacterial meningitis. As technology and experience have somewhat limited arch of rotation and contributes no increased, EEAs have expanded and now commonly result more than 5 cm2 of vascularized tissue.5 The transptery- in defects comparable in size with those produced by tra- goid temporoparietal fascia flap offers a large volume of ditional open approaches. As such, there is intense inter- reconstructive tissue, but may produce significant morbid- est in reliably reconstructing these defects without adding ity during its harvest and transposition.4 significant morbidity. Vascularized flaps have the advan- In 1962, Millard first described the use of the palatal tage of promoting faster and more complete healing, and flap for palate lengthening in conjunction with cleft palate are relatively resistant to radiotherapy. Pedicled vascular repair.7 The indications for the palatal flap were expanded flaps provide the best combination of large surface area, to include the reconstruction of ablative defects by Gullane arc of rotation and reach, and the least retraction during and Arena in 1977.8 Additional reports demonstrated the the healing process. Recently described pedicled flaps for presence of a midline vascular network allowing the entire skull base reconstruction include the HBF, the posterior flap to be based on a single greater palatine artery.9,10 A pedicled inferior turbinate flap, and the transpterygoid recent report by Genden et al.11 describes the use of pal- temporoparietal fascia flap.4,5 The “workhorse” HBF flap atal flaps without donor site morbidity or flap loss in six contributes ϳ 25 cm2 of vascularized tissue, but its use is patients with defects ranging from 4 to 16 cm2. The most precluded in patients with a prior septectomy or wide significant limitation of the palatal flap to date has been sphenoidotomies. The posterior pedicled inferior turbinate the tethering of the neurovascular bundle at the GPF.

Fig. 5. Oliver pedicled palatal flap placement. (A and B) Anatomic and illustrated view of the Oliver pedicled palatal flap in a sellar defect (pedicle denoted by white arrow). (C and D) Anatomic and illustrated view of the Oliver pedicled palatal flap extending to the level of uvula through the posterior nasopharynx. Note the uvula (black arrow) and the flap edge (black arrow heads).

Laryngoscope 118: December 2008 Oliver et al.: The Oliver Pedicled Palatal Flap 2105 Dissection of the PPC and transposition of the palatal atic septal perforations, velopalatal insufficiency, great flap into the nasal cavity through a limited enlargement of vessel coverage, and osteoradionecrosis of the skull base. the GPF creates a large (Ͼ10 cm2) mucoperiosteal flap based on a 2.5 to 3.0 cm pedicle (the Oliver pedicled BIBLIOGRAPHY palatal flap, OPPF). In contrast to the HBF and the pos- 1. Hegazy HM, Carrau RL, Snyderman CH, Kassam A, Zweig J. terior pedicled inferior turbinate flap, the OPPF can be Transnasal endoscopic repair of cerebrospinal fluid rhi- harvested and transposed after the surgical resection; and norrhea: a meta-analysis. Laryngoscope 2000;110: thus, can be tailored to the specific reconstructive sce- 1166–1172. 2. Kassam AB, Carrau RL, Snyderman CH, Gardner P, Mintz A. nario. Additionally, the OPPF could be combined with Evolution of reconstructive techniques following endo- other pedicled flaps (i.e., the HBF) for extensive skull base scopic expanded endonasal approach. Neurosurg Focus reconstruction. 2005;19:E8. An obvious potential complication of the OPPF is a 3. Hadad G, Bassagasteguy L, Carrau R, et al. A novel recon- persistent oronasal fistula. Preserving the nasal floor mu- structive technique after endoscopic expanded endonasal approaches: vascular pedicle nasoseptal flap. Laryngoscope cosa overlying the palatal defect minimizes this risk. In 2006;116:1882–1886. addition, the literature supports the use of acellular der- 4. Fortes FS, Carrau RL, Snyderman CH, et al. Transpterygoid mis for palatal reconstruction.12 Based on prior experi- transposition of a temporoparietal fascia flap: a new ences, our initial strategy will involve the use of the intact method for skull base reconstruction after endoscopic expanded endonasal approaches. Laryngoscope 2007;117: nasal floor mucosa, acellular dermis grafting, and fibrin 970–976. glue. Reports regarding the palatal flap support that a 5. Fortes F, Carrau R, Snyderman C, et al. The posterior pedicle complete palatal remucosalization occurs 3 to 4 weeks inferior turbinate flap: a new vascularized flap for skull postoperatively.11 base reconstruction. Laryngoscope 2007;117:1329–1332. Other possible complications of the OPPF include 6. Ward B. The palatal flap. Oral Maxillofac Surg Clin North Am 2003;15:467–473. flap loss, injury to the vascular pedicle, and introduction 7. Millard D. Wide and or short cleft palate. Plast Reconstr Surg of new bacterial subtypes (oral flora) into the operative 1962;29:40–57. field. Balbuena et al.13 reported an 85% decrease in total 8. Gullane PJ, Arena S. Palatal island flap for reconstruction of oral cavity bacterial counts 4 hours after chlorohexedine oral defects. Arch Otolaryngol Head Neck Surg 1977;103: 598–589. mouthwash and gargle, we plan to add a similar protocol 9. Maher WP. Distribution of palatal and other arteries in cleft to our existing parenteral antibiotic prophylaxis in EEA and non-cleft human palates. Cleft Palate J 1977;14:1–2. patients likely to undergo OPPF reconstruction. 10. Gullane PJ, Arena S. Extended palatal island mucoperiosteal flap. Arch Otolaryngol Head Neck Surg 1985;1:330–332. CONCLUSIONS 11. Genden E, Lee B, Urken M. The palatal island flap for reconstruction of palatal and retromolar trigone defects revis- Based on previous reports and our findings, we be- ited. Arch Otolaryngol Head Neck Surg 2001;127:837–841. lieve that the OPPF shows significant potential as a re- 12. Kirschner R, Cabiling D, Slemp A, Siddiqi F, Larossa D, constructive alternative for skull base defects of the pla- Losee J. Repair of oronasal fistulae with acellular dermal num, sella, or clivus alone or in combination with existing matrices. Plast Reconstr Surg 2006;118:1431–1440. 13. Balbuena L, Stambaugh KI, Ramirez SG, Yeager C. Effects of reconstructive options. Furthermore, it is intriguing to topical oral antiseptic rinses on bacterial counts of saliva in speculate that the use of the OPPF may be extended to healthy human subjects. Otolaryngol Head Neck Surg include treatment of nasopharyngeal stenosis, symptom- 1998;118:625–629.

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