Extrapolating the Limits of the Nasoseptal Flap With Pedicle Dissection to the Internal Maxillary Artery

Extrapolating the Limits of the Nasoseptal Flap With Pedicle Dissection to the Internal Maxillary... Abstract BACKGROUND The nasoseptal flap is the main pedicled flap used for endoscopic cranial base reconstruction. For large anterior cranial base defects, the anterior edge is a concern for the nasoseptal flap reach. OBJECTIVE To present a surgical technique that completely releases the vascular pedicle of the nasoseptal flap from the sphenopalatine artery (SPA) foramen improving considerably the reach of the flap. METHODS A patient with left anterior cranial base fracture involving the posterior table of the frontal sinus, who presented with cerebrospinal fluid leak and contused brain herniation to the ethmoid and frontal sinuses. Unilateral endoscopic endonasal anterior cranial base reconstruction was performed with left sided nasoseptal flap. The nasoseptal flap pedicle was dissected and completely released from the SPA foramen. The flap was left attached only to the internal maxillary artery (IMAX) vascular bundle. RESULTS The flap covered the entire left anterior cranial base, from the planum sphenoidale to the posterior table of the frontal sinus. There was complete obliteration of the cerebrospinal fluid fistula postoperatively with resolution of the radiographic pneumocephalus and the patient's rhinorrhea. CONCLUSION The complete release of the nasoseptal flap pedicle from the SPA foramen is feasible and remarkably improves the reach of the flap. It also increases the reconstructive area of the flap since the entire septal mucosa can be used for reconstruction and the pedicle length is based exclusively upon the SPA/IMAX. Anterior cranial base, Anterior cranial base defect, Endoscopic cranial base reconstruction, Internal maxillary artery, Nasoseptal flap, Sphenopalatine artery, Pterygopalatine fossa ABBREVIATIONS ABBREVIATIONS CSF cerebrospinal fluid ICP intracranial pressure IMAX internal maxillary artery IRB Institutional Review Board SPA sphenopalatine artery. The nasoseptal flap has revolutionized endoscopic cranial base reconstruction. Based on the posterior septal artery, a branch of the sphenopalatine artery (SPA), it is a robust flap with a great arch of rotation.1,2 Classically, the reconstructive area of the flap corresponds to its most anterior portion, which is the area that covers the quadrangular cartilage. The remaining septal mucosa posteriorly and the mucosa of the sphenoid rostrum usually function as the pedicle, connecting the SPA foramen to the reconstructive area.3 The attachment of the nasoseptal flap to the SPA foramen limits the reach of the flap. During endonasal anterior cranial base reconstruction, for example, the anterior edge of the defect is always a concern.3,4 Similarly, for transclival approaches to the posterior fossa, the coverage of the inferior border of the defect can be challenging.5 The ability to extend the coverage area of the pedicled mucoperichondrial nasoseptal flap would be extremely useful for endoscopic cranial base reconstruction. We postulated that this could be accomplished through a surgical technique that completely releases the vascular pedicle of the nasoseptal flap from the SPA foramen. That would improve considerably the reach of the flap and, also, increase the area of coverage since the entire septal mucosa could be used. Here, we present the first description of the complete release of the nasoseptal flap pedicle from the SPA foramen, leaving the flap attached to the internal maxillary artery (IMAX) for the reconstruction of a wide anterior cranial base osseous and dural defect. METHODS Our Institutional Review Board (IRB) approved the study and the patient signed the informed consent. Clinical Presentation A 21-yr-old male sustained multiple severe craniofacial fractures due to a motor vehicle accident. In addition to extensive facial fractures, cranial CT scan showed bifrontal cerebral contusions and comminuted fractures of the left anterior cranial base (anterior ethmoid, posterior table of the frontal sinus, and orbital roof). With a GCS of 6T on presentation and no evidence of pneumocephalus or clear rhinorrhea, the patient was initially managed with intracranial pressure (ICP) monitoring alone. After 5 d of normal ICPs, the monitor was removed and the patient gradually improved neurologically. Follow-up cranial imaging revealed progressively increasing amounts of pneumocephalus and eventually frontal lobe herniation through the osseous anterior cranial base defect (Figure 1). On hospital admission day 10, the patient developed cerebrospinal fluid (CSF) rhinorrhea, and he was taken that day for operative repair. FIGURE 1. View largeDownload slide Preoperative images. A, CT scan coronal view demonstrating the pneumocephalus. B, CT scan sagittal view. Observe the anterior cranial base defect extending to the posterior table of the frontal sinus. C, MRI axial view showing the extensive frontal lobe contusion and herniation towards the ethmoid sinuses. D, CT scan axial view. Note the defect extending to the posterior table of the frontal sinus. E, Brain tissue herniating to the frontal sinus on the MRI axial view. FIGURE 1. View largeDownload slide Preoperative images. A, CT scan coronal view demonstrating the pneumocephalus. B, CT scan sagittal view. Observe the anterior cranial base defect extending to the posterior table of the frontal sinus. C, MRI axial view showing the extensive frontal lobe contusion and herniation towards the ethmoid sinuses. D, CT scan axial view. Note the defect extending to the posterior table of the frontal sinus. E, Brain tissue herniating to the frontal sinus on the MRI axial view. The facial and orbital fractures were surgically repaired and followed immediately by endoscopic endonasal reconstruction of the anterior cranial base. A left sided pedicled mucoperichondrial nasoseptal flap was used for the reconstruction of the left anterior cranial base, including the posterior table of the frontal sinus. Complete release of the vascular and mucosal pedicle from the SPA foramen was performed and the flap was left attached to the IMAX, permitting its maximal rotation and reach to the very ventral cranial base. Surgical Technique First, a complete ethmoidectomy, sphenoidotomy, and removal of the middle turbinate were performed. A frontal sinusotomy was done with drilling of the frontal beak to expose the posterior table of the frontal sinus and the superior limit of the defect. Contused frontal lobe brain tissue that had herniated into the ethmoids and frontal sinus was removed. The osseous borders of the skull base defect were clearly delineated and found to extend from the location of the anterior ethmoidal artery posteriorly and involve most of the posterior table of the frontal sinus ventrally. The remaining ethmoidal roof posterior to the anterior ethmoidal artery was fractured and unstable but with no evidence of brain tissue herniation or dural disruption. Due to the extent of the osseous and dural defect, reconstruction with a long flap was required to cover the entire ethmoidal roof and the posterior table of the frontal sinus. Due to the anterior reach limitation associated with the standard nasoseptal flap, a complete release of the pedicle off the SPA foramen was performed. Initially, the nasoseptal flap was harvested in the usual manner.6 The anterior edge of the flap was carried up to the caudal border of the septum/columella. Only a unilateral reconstruction was required; therefore, no inclusion of mucosa from the nasal cavity floor was necessary. The flap was placed in the nasopharynx, and a maxillary antrostomy was performed to expose the posterior wall of the sinus. The mucosa just anterior to the SPA foramen was elevated and the artery was identified. The elevation of the mucosa was carried inferior to the SPA toward the sphenoid rostrum. At that point, the flap was moved from the nasopharynx and placed in the ethmoid region to allow access and view of the superior border of the choana. The standard flap mucosal incision that started at the superior border of the choana was extended laterally along the lateral nasal wall just superior to the inferior turbinate tail towards the maxillary antrostomy. This incision can also be performed from the maxillary antrostomy towards the superior border of the choana with microscissors. The identification of the SPA and the elevation of the mucosa underneath the artery towards the sphenoid rostrum are important to avoid injury to the artery during this lateral mucosal incision between the choana and the maxillary antrostomy (Figure 2). FIGURE 2. View largeDownload slide Picture obtained with a 0° endoscope from the left nasal cavity during an anatomical dissection. A left side nasoseptal flap was harvested and the osseous boundaries of the sphenopalatine foramen were removed. The yellow dashed line represents the mucosal incision just superior to the inferior turbinate tail to connect the maxillary antrostomy to the incision at the superior aspect of the arch of the choana and release the mucosa of the nasoseptal pedicle laterally. The red dashed line illustrates the 360° periosteal incision required to release completely the sphenopalatine artery from the periosteum of the pterygopalatine fossa. Observe in transparency behind the nasoseptal flap pedicle a continuous red line. This line represents the incision to be completed posterior to the pedicle in order to achieve the 360° circumferential incision around the SPA. FIGURE 2. View largeDownload slide Picture obtained with a 0° endoscope from the left nasal cavity during an anatomical dissection. A left side nasoseptal flap was harvested and the osseous boundaries of the sphenopalatine foramen were removed. The yellow dashed line represents the mucosal incision just superior to the inferior turbinate tail to connect the maxillary antrostomy to the incision at the superior aspect of the arch of the choana and release the mucosa of the nasoseptal pedicle laterally. The red dashed line illustrates the 360° periosteal incision required to release completely the sphenopalatine artery from the periosteum of the pterygopalatine fossa. Observe in transparency behind the nasoseptal flap pedicle a continuous red line. This line represents the incision to be completed posterior to the pedicle in order to achieve the 360° circumferential incision around the SPA. The periosteum of the pterygopalatine fossa was then exposed.7 First, a 2-mm kerrison rongeur was carefully used to enter the SPA foramen and remove the orbital process of the palatine bone. The bone of the posterior wall of the maxillary sinus can be drilled and thinned prior to the removal. Once the periosteum that covers the pterygopalatine fossa and the medial aspect of the temporal fossa was well exposed, the periosteal incisions to release the SPA were performed. It is important to make sure that the bone superior to the SPA foramen was removed exposing the periosteum and its connection with the inferior orbital fissure. Then, the superior portion of the vertical plate of the palatine bone just underneath the SPA foramen was drilled and removed to expose the periosteum of the pterygopalatine fossa in that area. The drilling progressed posteriorly with the removal of the sphenoid process of the palatine bone and exposure of the palatovaginal canal contents.8 With those steps, all of the osseous boundaries of the SPA foramen were removed with exposure of the underlining periosteum. A 360° periosteal incision around the SPA was required to completely release the artery (Figure 2). A sickle knife or microscissors can be used to make the first periosteal incision and open the anterior aspect of the pterygopalatine fossa inferior to the SPA. Then, a ball probe (seeker probe) was used to careful dissect the periosteum from the artery. This dissection was carried laterally, as the periosteum is very adherent to the artery at the level of the SPA foramen. The periosteum was elevated superiorly towards the inferior orbital fissure and incised with microscissors. At that point, the IMAX inside the pterygopalatine fossa was dissected from the surrounding soft tissue with a ball probe. That allowed mobilization of the artery anteriorly and permitted the posterior periosteal incision from the inferior orbital fissure towards the vidian and palatovaginal canals. Then, the medial cut was performed just inferior to the SPA towards the palatovaginal canal. The pharyngeal branch of the IMAX that passes through the palatovaginal canal from the pterygopaltine fossa to the nasopharynx was cauterized and transected.8 Once the 360° incision around the SPA was completed, the artery was carefully mobilized with a ball probe anteriorly and completely detached from the foramen. This allowed full freedom of the pedicle of the nasoseptal flap, which remained attached to the IMAX. Finally, the reconstruction was performed with an inlay dural substitute (Duragen™, Integra® Neurosciences, Plainsboro, New Jersey) followed by the nasoseptal flap. The flap with the “released pedicle” was able to be mobilized very anteriorly and easily covered the entire posterior table of the frontal sinus and ethmoidal roof. Surgicel® (Ethicon Inc, Sommerville, New Jersey) was applied at the borders of the flap, followed by Gelfoam® (Pfizer Inc, New York, New York) and Duraseal® (Integra® Neurosciences). Nasopore® (Stryker Corp, Hamilton, Ontario, Canada) was used to keep the flap in position (Figures 3 and 4, and Video, Supplemental Digital Content). FIGURE 3. View largeDownload slide Intraoperative pictures obtained with a 0° endoscope (A-E) and 45° endoscope (F and G). A, The left side nasoseptal flap was harvested and the osseous boundaries of the sphenopalatine foramen were removed. Observe the yellow dashed line that illustrates the mucosal incision to connect the maxillary antrostomy to the standard incision for the nasoseptal flap at the superior aspect of the arch of the choana. This step is important to release the lateral mucosa of the pedicle underneath the SPA and leave the flap attached only to the vascular bundle. B, After the periosteal incision below the SPA, the dissection is progressed laterally and superiorly towards the inferior orbital fissure. C, The flap is placed in the nasopharynx during the posterior periosteal incision from the inferior orbital fissure to the palatovaginal canal (dashed yellow line). D, Incision of the medial aspect of the pterygopalatine fossa periosteum underneath the SPA. Observe that the nasoseptal flap is placed in the ethmoid and sphenoid for this step. E, SPA is completely released and freely mobilized in the nasal cavity. Note the venous drainage system around the IMAX. F, View with a 45° endoscope of the cranial base defect with the inlay dural substitute. Observe the defect is very anterior and involves the posterior table of the frontal sinus. G, After the pedicle was released, the flap reached easily the anterior edge of the defect and covered it completely. FIGURE 3. View largeDownload slide Intraoperative pictures obtained with a 0° endoscope (A-E) and 45° endoscope (F and G). A, The left side nasoseptal flap was harvested and the osseous boundaries of the sphenopalatine foramen were removed. Observe the yellow dashed line that illustrates the mucosal incision to connect the maxillary antrostomy to the standard incision for the nasoseptal flap at the superior aspect of the arch of the choana. This step is important to release the lateral mucosa of the pedicle underneath the SPA and leave the flap attached only to the vascular bundle. B, After the periosteal incision below the SPA, the dissection is progressed laterally and superiorly towards the inferior orbital fissure. C, The flap is placed in the nasopharynx during the posterior periosteal incision from the inferior orbital fissure to the palatovaginal canal (dashed yellow line). D, Incision of the medial aspect of the pterygopalatine fossa periosteum underneath the SPA. Observe that the nasoseptal flap is placed in the ethmoid and sphenoid for this step. E, SPA is completely released and freely mobilized in the nasal cavity. Note the venous drainage system around the IMAX. F, View with a 45° endoscope of the cranial base defect with the inlay dural substitute. Observe the defect is very anterior and involves the posterior table of the frontal sinus. G, After the pedicle was released, the flap reached easily the anterior edge of the defect and covered it completely. FIGURE 4. View largeDownload slide Schematic drawing to show the comparison of the anterior reach between the A, standard nasoseptal flap and B, the flap with complete pedicle release from the SPA foramen. After complete liberation, the flap is only attached to the IMAX and its periarterial venous plexus. The sinusoidal course of the IMAX in the infratemporal fossa allows considerable movement of the flap with improvement of its anterior reach. FIGURE 4. View largeDownload slide Schematic drawing to show the comparison of the anterior reach between the A, standard nasoseptal flap and B, the flap with complete pedicle release from the SPA foramen. After complete liberation, the flap is only attached to the IMAX and its periarterial venous plexus. The sinusoidal course of the IMAX in the infratemporal fossa allows considerable movement of the flap with improvement of its anterior reach. RESULTS Postoperative MRI with contrast showed enhancement of the nasoseptal flap in its full extension (Figure 5). The flap covered the entire left anterior cranial base, from the planum sphenoidale to the ethmoidal roof and even the posterior table of the frontal sinus. There was complete obliteration of the CSF fistula postoperatively with resolution of the radiographic pneumocephalus and the patient's rhinorrhea. Nasal endoscopy performed in clinic 1 mo postopeatively showed the flap to be well healed to the cranial base with no evidence of necrosis. FIGURE 5. View largeDownload slide Postoperative MRI T1 sagittal view A, without contrast and B, with contrast. Observe the nasoseptal flap enhanced with contrast and covered completely the anterior cranial base from the planum sphenoidale to the posterior table of the frontal sinus. FIGURE 5. View largeDownload slide Postoperative MRI T1 sagittal view A, without contrast and B, with contrast. Observe the nasoseptal flap enhanced with contrast and covered completely the anterior cranial base from the planum sphenoidale to the posterior table of the frontal sinus. DISCUSSION The nasoseptal flap is a reconstructive option not only for the anterior cranial base reconstruction, but any area of the ventral cranial base, including oropharyngeal and palatal defects.9-11 Classically, the reconstructive area of the nasoseptal flap is the part corresponding to the quadrandular cartilage of the septum. A reasonable area of the septal mucosa is devoted to the pedicle, limiting its use in reconstruction.3 The standard nasoseptal flap is sufficient to cover the majority of cranial base defects. However, often the surgeon faces situations where the reach of the flap is an issue and the flap barely covers a large defect. This is most problematic in the far extremes of the cranial base, such as the posterior table of the frontal sinus and the craniocervical junction.3-5 There are alternatives described in the literature for such situations, like the use of a second flap, grafts or alloderm™ (LifeCell Corp, Branchburg, New Jersey).12-15 We previously described the release of the nasoseptal flap pedicle for ipsilateral transpterygoid approaches. This consists of the removal of the anterior aspect of the pterygopalatine fossa to allow lateral mobilization of the flap pedicle during the drilling of the ipsilateral pterygoid base.16 The initial exposure of the pterygopaltine fossa periosteum is similar; however, no opening of the periosteum was performed for the lateralization of the pedicle. In this present technique, the periosteum was opened in order to completely release the SPA from its foramen. The pedicle was left attached to the IMAX, remarkably increasing its freedom. This increases the reach of the flap to allow it to likely reach any area in the nasal cavity, cranial base, or upper cervical spine. Additionally, more length to the pedicle and subsequently a greater reach of the flap can be added with the IMAX dissection and its mobilization within the infratemporal fossa. The descending palatine artery and the infraorbital artery can be ligated and transected to increase the length of the vascular pedicle. With the increased pedicle length obtained with the release of the SPA from its foramen, the area of the flap that can be used for reconstruction is also increased. Potentially, the entire septal mucosa can be used to cover a skull base defect. In our illustrative case, a middle turbinectomy was performed to expose the entire cranial base defect. In cases where the middle turbinate is preserved, a portion of the tail of the middle turbinate should be transected and included to pedicle of the nasoseptal flap in order to completely free the mucosa around the SPA foramen. There are potential issues with exposing the vascular pedicle to the nasal cavity and risking the viability of the vascularized flap. In our illustrative case, after using the majority of the septal mucosa to cover the skull base from the planum sphenoidale to the posterior table of the frontal sinus, we noticed that the mucosa of the sphenoid rostrum could be used to cover the pterygopalatine fossa and the IMAX. Due to the extensive freedom obtained after the release of the pedicle, it was easy to move that mucosa towards the pterygopalatine fossa. Surgicel® (Ethicon Inc) followed by Duraseal® (Integra® Neurosciences) were used to keep the pedicle in place. In cases where a longer pedicle is required to improve its reach, free mucosal grafts from the nasal cavity floor or middle turbinate, for example, can be used to cover the artery. Another concern with the extended mobilization of the flap's vascular pedicle is the potentially resultant compromise of the venous drainage, the risk of congestion, and subsequent flap necrosis. The venous drainage of the nasoseptal flap is based upon the sphenopalatine vein that passes through the sphenopalatine foramen before draining into the pterygoid plexus.17 The dissection around the IMAX should be meticulous in order to prevent injury to the venous drainage system of the flap. Leaving a cuff of periosteum around the SPA during the 360° periosteal incisional is important to prevent venous injury. The periosteum is very attached to the artery at the level of the SPA foramen. In our illustrative case, it is possible to observe some veins around the IMAX. We have described a technique to improve the reach of the nasoseptal flap used in endonasal cranial base reconstruction. Anatomic knowledge of the palatine bone and the SPA foramen is required to allow for proper release of the pedicle without sacrificing the flap's vascular supply. Additionally, complete understanding of the intricate anatomy of the pterygopalatine fossa and its contents is paramount, particularly the anatomical relations between its neurovascular structures (Figure 6). No complications such as dry eye or numbness in the V2 distribution were noticed in our patient. However, these potential complications should be discussed with the patient prior to the surgery. Working so close to the SPA and IMAX requires training and experience, as the described technique does add additional risk of injury to the pedicle during the dissection. Experience with arterial ligation of the SPA/IMAX to control severe posterior epistaxis may be beneficial to aid with proper pedicle dissection. FIGURE 6. View largeDownload slide A, Anatomic dissection of specimen injected with blue silicone for the venous system and red silicone for the arterial system. Observe the venous plexus around the internal maxillary artery within the infratemporal fossa. B, Picture obtained with a 0° endoscope from the left nasal cavity during an anatomical dissection of specimen injected only with red silicone into the arterial system. Observe the complex anatomy of the neurovascular structures within the pterygopalatine fossa. FIGURE 6. View largeDownload slide A, Anatomic dissection of specimen injected with blue silicone for the venous system and red silicone for the arterial system. Observe the venous plexus around the internal maxillary artery within the infratemporal fossa. B, Picture obtained with a 0° endoscope from the left nasal cavity during an anatomical dissection of specimen injected only with red silicone into the arterial system. Observe the complex anatomy of the neurovascular structures within the pterygopalatine fossa. At the moment, this modified technique could be considered an option in exceptional and challenging cases of reconstruction. For instance, cases where the pericranial flap is not available and the traditional nasoseptal flap cannot reach and cover the anterior edge of the defect. Currently, the alternative for such situations would be multilayer closure with avascular tissue and/or association with other local smaller flaps. CONCLUSION The complete release of the nasoseptal flap pedicle from the SPA foramen is feasible and remarkably improves the reach of the flap. It also increases the reconstructive area of the flap since the entire septal mucosa can be used for reconstruction and the pedicle length is based exclusively upon the SPA/IMAX. With careful dissection and adherence to the principles of pedicled flap dissection and positioning, we were able to avoid issues with venous congestion or flap necrosis. Further studies are necessary to demonstrate the efficiency of our technique and other potential complications related to this aggressive dissection of the flap pedicle. Disclosure The authors have no personal, financial, or institutional interest in any of the drugs, materials, or devices described in this article. REFERENCES 1. Hadad G , Bassagasteguy L , Carrau RL et al. A novel reconstructive technique after endoscopic expanded endonasal approaches: vascular pedicle nasoseptal flap . Laryngoscope . 2006 ; 116 ( 10 ): 1882 – 1886 . Google Scholar CrossRef Search ADS PubMed 2. Pinheiro-Neto CD , Prevedello DM , Carrau RL et al. Improving the design of the pedicled nasoseptal flap for skull base reconstruction: a radioanatomic study . Laryngoscope . 2007 ; 117 ( 9 ): 1560 – 1569 . Google Scholar CrossRef Search ADS PubMed 3. Pinheiro-Neto CD , Ramos HF , Peris-Celda M et al. Study of the nasoseptal flap for endoscopic anterior cranial base reconstruction . Laryngoscope . 2011 ; 121 ( 12 ): 2514 – 2520 . Google Scholar CrossRef Search ADS PubMed 4. MacArthur FJD , McGarry GW . The radioanatomy of endonasal flap coverage of skull base defects: a tool for preoperative planning . Laryngoscope . 2017 doi: 10.1002/lary.26925 . 5. Peris-Celda M , Pinheiro-Neto CD , Funaki T et al. The extended nasoseptal flap for skull base reconstruction of the clival region: an anatomical and radiological study . J Neurol Surg B . 2013 ; 74 ( 06 ): 369 – 385 . Google Scholar CrossRef Search ADS 6. Pinheiro-Neto CD , Snyderman CH . Nasoseptal flap . Adv Otorhinolaryngol . 2013 ; 74 ( 1 ): 42 – 55 . Google Scholar PubMed 7. Pinheiro-Neto CD , Fernandez-Miranda JC , Prevedello DM , Carrau RL , Gardner PA , Snyderman CH . Transposition of the pterygopalatine fossa during endoscopic endonasal transpterygoid approaches . J Neurol Surg B . 2013 ; 74 ( 05 ): 266 – 270 . Google Scholar CrossRef Search ADS 8. Pinheiro-Neto CD , Fernandez-Miranda JC , Rivera-Serrano CM et al. Endoscopic anatomy of the palatovaginal canal (palatosphenoidal canal) . Laryngoscope . 2012 ; 122 ( 1 ): 6 – 12 . Google Scholar CrossRef Search ADS PubMed 9. Rivera-Serrano CM , Lentz AK , Pinheiro-Neto C , Snyderman CH . Cadaveric study of the posterior pedicle nasoseptal flap . Plast Reconstr Surg . 2013 ; 132 ( 5 ): 1269 – 1275 . Google Scholar CrossRef Search ADS PubMed 10. Pinheiro-Neto CD , Galati LT . Nasoseptal flap for reconstruction after robotic radical tonsillectomy . Head Neck . 2016 ; 38 ( 9 ): E2495 – E2498 . Google Scholar CrossRef Search ADS PubMed 11. Lee DH , Yoon TM , Lee JK , Lim SC . Nasoseptal flap reconstruction after oropharyngeal cancer resection . Medicine . 2017 ; 96 ( 44 ): 8527 [Epub ahead of print]. Google Scholar CrossRef Search ADS 12. Patel MR , Stadler ME , Snyderman CH et al. How to choose? Endoscopic skull base reconstructive options and limitations . Skull Base . 2010 ; 20 ( 06 ): 397 – 404 . Google Scholar CrossRef Search ADS PubMed 13. Biroli F , Esposito F , Fusco M et al. Novel equine collagen-only dural substitute . Neurosurgery . 2008 ; 62 ( 3 Suppl 1 ): 273 – 274 . Google Scholar PubMed 14. Dadgostar A , Okpaleke C , Al-Asousi F , Javer A . The application of a free nasal floor mucoperiosteal graft in endoscopic sinus surgery . Am J Rhinol Allergy . 2017 ; 31 ( 3 ): 196 – 199 . Google Scholar CrossRef Search ADS PubMed 15. Ting JY , Metson R . Free graft techniques in skull base reconstruction . Adv Otorhinolaryngol . 2013 ; 74 ( 1 ): 33 – 41 . Google Scholar PubMed 16. Pinheiro-Neto CD , Paluzzi A , Fernandez-Miranda JC et al. Extended dissection of the septal flap pedicle for ipsilateral endoscopic transpterygoid approaches . Laryngoscope . 2014 ; 124 ( 2 ): 391 – 396 . Google Scholar CrossRef Search ADS PubMed 17. Beale TJ . Nose, nasal cavity and paranasal sinuses . In: Standring S , ed. Gray's Anatomy: The Anatomical Basis of Clinical Practice . London : Elsevier ; 2008 : 547 – 559 . Supplemental digital content is available for this article at www.operativeneurosurgery-online.com. Supplemental Digital Content. Video Supplemental Digital Content. Video Close Acknowledgments The authors deeply acknowledge Professor A. L. Rhoton. The dissection of figure 6A was performed by the second author at the Microsurgical and Endoscopic Neuroanatomy Laboratory under his direction in Gainesville, Florida. COMMENTS Skull base reconstruction remains a challenging operative procedure, and the variation in anatomy and defects constantly requires adaptation on every case. Techniques such as described in this paper help surgeons with added options. John Schneider St. Louis, Missouri The authors summarize the limits of the nasoseptal flap with pedicle dissection to the internal maxillary artery. The report is a video case report of how to perform this technique, and as such nicely presents some modifications of the nasoseptal with extended dissection of its internal maxillary pedicle to close a post-traumatic anterior skull base defect. This is a potentially useful variation to enable greater nasoseptal flap mobilization for more complex repairs. Michael Chicoine St. Louis, Missouri Copyright © 2018 by the Congress of Neurological Surgeons http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Operative Neurosurgery Oxford University Press

Extrapolating the Limits of the Nasoseptal Flap With Pedicle Dissection to the Internal Maxillary Artery

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Abstract

Abstract BACKGROUND The nasoseptal flap is the main pedicled flap used for endoscopic cranial base reconstruction. For large anterior cranial base defects, the anterior edge is a concern for the nasoseptal flap reach. OBJECTIVE To present a surgical technique that completely releases the vascular pedicle of the nasoseptal flap from the sphenopalatine artery (SPA) foramen improving considerably the reach of the flap. METHODS A patient with left anterior cranial base fracture involving the posterior table of the frontal sinus, who presented with cerebrospinal fluid leak and contused brain herniation to the ethmoid and frontal sinuses. Unilateral endoscopic endonasal anterior cranial base reconstruction was performed with left sided nasoseptal flap. The nasoseptal flap pedicle was dissected and completely released from the SPA foramen. The flap was left attached only to the internal maxillary artery (IMAX) vascular bundle. RESULTS The flap covered the entire left anterior cranial base, from the planum sphenoidale to the posterior table of the frontal sinus. There was complete obliteration of the cerebrospinal fluid fistula postoperatively with resolution of the radiographic pneumocephalus and the patient's rhinorrhea. CONCLUSION The complete release of the nasoseptal flap pedicle from the SPA foramen is feasible and remarkably improves the reach of the flap. It also increases the reconstructive area of the flap since the entire septal mucosa can be used for reconstruction and the pedicle length is based exclusively upon the SPA/IMAX. Anterior cranial base, Anterior cranial base defect, Endoscopic cranial base reconstruction, Internal maxillary artery, Nasoseptal flap, Sphenopalatine artery, Pterygopalatine fossa ABBREVIATIONS ABBREVIATIONS CSF cerebrospinal fluid ICP intracranial pressure IMAX internal maxillary artery IRB Institutional Review Board SPA sphenopalatine artery. The nasoseptal flap has revolutionized endoscopic cranial base reconstruction. Based on the posterior septal artery, a branch of the sphenopalatine artery (SPA), it is a robust flap with a great arch of rotation.1,2 Classically, the reconstructive area of the flap corresponds to its most anterior portion, which is the area that covers the quadrangular cartilage. The remaining septal mucosa posteriorly and the mucosa of the sphenoid rostrum usually function as the pedicle, connecting the SPA foramen to the reconstructive area.3 The attachment of the nasoseptal flap to the SPA foramen limits the reach of the flap. During endonasal anterior cranial base reconstruction, for example, the anterior edge of the defect is always a concern.3,4 Similarly, for transclival approaches to the posterior fossa, the coverage of the inferior border of the defect can be challenging.5 The ability to extend the coverage area of the pedicled mucoperichondrial nasoseptal flap would be extremely useful for endoscopic cranial base reconstruction. We postulated that this could be accomplished through a surgical technique that completely releases the vascular pedicle of the nasoseptal flap from the SPA foramen. That would improve considerably the reach of the flap and, also, increase the area of coverage since the entire septal mucosa could be used. Here, we present the first description of the complete release of the nasoseptal flap pedicle from the SPA foramen, leaving the flap attached to the internal maxillary artery (IMAX) for the reconstruction of a wide anterior cranial base osseous and dural defect. METHODS Our Institutional Review Board (IRB) approved the study and the patient signed the informed consent. Clinical Presentation A 21-yr-old male sustained multiple severe craniofacial fractures due to a motor vehicle accident. In addition to extensive facial fractures, cranial CT scan showed bifrontal cerebral contusions and comminuted fractures of the left anterior cranial base (anterior ethmoid, posterior table of the frontal sinus, and orbital roof). With a GCS of 6T on presentation and no evidence of pneumocephalus or clear rhinorrhea, the patient was initially managed with intracranial pressure (ICP) monitoring alone. After 5 d of normal ICPs, the monitor was removed and the patient gradually improved neurologically. Follow-up cranial imaging revealed progressively increasing amounts of pneumocephalus and eventually frontal lobe herniation through the osseous anterior cranial base defect (Figure 1). On hospital admission day 10, the patient developed cerebrospinal fluid (CSF) rhinorrhea, and he was taken that day for operative repair. FIGURE 1. View largeDownload slide Preoperative images. A, CT scan coronal view demonstrating the pneumocephalus. B, CT scan sagittal view. Observe the anterior cranial base defect extending to the posterior table of the frontal sinus. C, MRI axial view showing the extensive frontal lobe contusion and herniation towards the ethmoid sinuses. D, CT scan axial view. Note the defect extending to the posterior table of the frontal sinus. E, Brain tissue herniating to the frontal sinus on the MRI axial view. FIGURE 1. View largeDownload slide Preoperative images. A, CT scan coronal view demonstrating the pneumocephalus. B, CT scan sagittal view. Observe the anterior cranial base defect extending to the posterior table of the frontal sinus. C, MRI axial view showing the extensive frontal lobe contusion and herniation towards the ethmoid sinuses. D, CT scan axial view. Note the defect extending to the posterior table of the frontal sinus. E, Brain tissue herniating to the frontal sinus on the MRI axial view. The facial and orbital fractures were surgically repaired and followed immediately by endoscopic endonasal reconstruction of the anterior cranial base. A left sided pedicled mucoperichondrial nasoseptal flap was used for the reconstruction of the left anterior cranial base, including the posterior table of the frontal sinus. Complete release of the vascular and mucosal pedicle from the SPA foramen was performed and the flap was left attached to the IMAX, permitting its maximal rotation and reach to the very ventral cranial base. Surgical Technique First, a complete ethmoidectomy, sphenoidotomy, and removal of the middle turbinate were performed. A frontal sinusotomy was done with drilling of the frontal beak to expose the posterior table of the frontal sinus and the superior limit of the defect. Contused frontal lobe brain tissue that had herniated into the ethmoids and frontal sinus was removed. The osseous borders of the skull base defect were clearly delineated and found to extend from the location of the anterior ethmoidal artery posteriorly and involve most of the posterior table of the frontal sinus ventrally. The remaining ethmoidal roof posterior to the anterior ethmoidal artery was fractured and unstable but with no evidence of brain tissue herniation or dural disruption. Due to the extent of the osseous and dural defect, reconstruction with a long flap was required to cover the entire ethmoidal roof and the posterior table of the frontal sinus. Due to the anterior reach limitation associated with the standard nasoseptal flap, a complete release of the pedicle off the SPA foramen was performed. Initially, the nasoseptal flap was harvested in the usual manner.6 The anterior edge of the flap was carried up to the caudal border of the septum/columella. Only a unilateral reconstruction was required; therefore, no inclusion of mucosa from the nasal cavity floor was necessary. The flap was placed in the nasopharynx, and a maxillary antrostomy was performed to expose the posterior wall of the sinus. The mucosa just anterior to the SPA foramen was elevated and the artery was identified. The elevation of the mucosa was carried inferior to the SPA toward the sphenoid rostrum. At that point, the flap was moved from the nasopharynx and placed in the ethmoid region to allow access and view of the superior border of the choana. The standard flap mucosal incision that started at the superior border of the choana was extended laterally along the lateral nasal wall just superior to the inferior turbinate tail towards the maxillary antrostomy. This incision can also be performed from the maxillary antrostomy towards the superior border of the choana with microscissors. The identification of the SPA and the elevation of the mucosa underneath the artery towards the sphenoid rostrum are important to avoid injury to the artery during this lateral mucosal incision between the choana and the maxillary antrostomy (Figure 2). FIGURE 2. View largeDownload slide Picture obtained with a 0° endoscope from the left nasal cavity during an anatomical dissection. A left side nasoseptal flap was harvested and the osseous boundaries of the sphenopalatine foramen were removed. The yellow dashed line represents the mucosal incision just superior to the inferior turbinate tail to connect the maxillary antrostomy to the incision at the superior aspect of the arch of the choana and release the mucosa of the nasoseptal pedicle laterally. The red dashed line illustrates the 360° periosteal incision required to release completely the sphenopalatine artery from the periosteum of the pterygopalatine fossa. Observe in transparency behind the nasoseptal flap pedicle a continuous red line. This line represents the incision to be completed posterior to the pedicle in order to achieve the 360° circumferential incision around the SPA. FIGURE 2. View largeDownload slide Picture obtained with a 0° endoscope from the left nasal cavity during an anatomical dissection. A left side nasoseptal flap was harvested and the osseous boundaries of the sphenopalatine foramen were removed. The yellow dashed line represents the mucosal incision just superior to the inferior turbinate tail to connect the maxillary antrostomy to the incision at the superior aspect of the arch of the choana and release the mucosa of the nasoseptal pedicle laterally. The red dashed line illustrates the 360° periosteal incision required to release completely the sphenopalatine artery from the periosteum of the pterygopalatine fossa. Observe in transparency behind the nasoseptal flap pedicle a continuous red line. This line represents the incision to be completed posterior to the pedicle in order to achieve the 360° circumferential incision around the SPA. The periosteum of the pterygopalatine fossa was then exposed.7 First, a 2-mm kerrison rongeur was carefully used to enter the SPA foramen and remove the orbital process of the palatine bone. The bone of the posterior wall of the maxillary sinus can be drilled and thinned prior to the removal. Once the periosteum that covers the pterygopalatine fossa and the medial aspect of the temporal fossa was well exposed, the periosteal incisions to release the SPA were performed. It is important to make sure that the bone superior to the SPA foramen was removed exposing the periosteum and its connection with the inferior orbital fissure. Then, the superior portion of the vertical plate of the palatine bone just underneath the SPA foramen was drilled and removed to expose the periosteum of the pterygopalatine fossa in that area. The drilling progressed posteriorly with the removal of the sphenoid process of the palatine bone and exposure of the palatovaginal canal contents.8 With those steps, all of the osseous boundaries of the SPA foramen were removed with exposure of the underlining periosteum. A 360° periosteal incision around the SPA was required to completely release the artery (Figure 2). A sickle knife or microscissors can be used to make the first periosteal incision and open the anterior aspect of the pterygopalatine fossa inferior to the SPA. Then, a ball probe (seeker probe) was used to careful dissect the periosteum from the artery. This dissection was carried laterally, as the periosteum is very adherent to the artery at the level of the SPA foramen. The periosteum was elevated superiorly towards the inferior orbital fissure and incised with microscissors. At that point, the IMAX inside the pterygopalatine fossa was dissected from the surrounding soft tissue with a ball probe. That allowed mobilization of the artery anteriorly and permitted the posterior periosteal incision from the inferior orbital fissure towards the vidian and palatovaginal canals. Then, the medial cut was performed just inferior to the SPA towards the palatovaginal canal. The pharyngeal branch of the IMAX that passes through the palatovaginal canal from the pterygopaltine fossa to the nasopharynx was cauterized and transected.8 Once the 360° incision around the SPA was completed, the artery was carefully mobilized with a ball probe anteriorly and completely detached from the foramen. This allowed full freedom of the pedicle of the nasoseptal flap, which remained attached to the IMAX. Finally, the reconstruction was performed with an inlay dural substitute (Duragen™, Integra® Neurosciences, Plainsboro, New Jersey) followed by the nasoseptal flap. The flap with the “released pedicle” was able to be mobilized very anteriorly and easily covered the entire posterior table of the frontal sinus and ethmoidal roof. Surgicel® (Ethicon Inc, Sommerville, New Jersey) was applied at the borders of the flap, followed by Gelfoam® (Pfizer Inc, New York, New York) and Duraseal® (Integra® Neurosciences). Nasopore® (Stryker Corp, Hamilton, Ontario, Canada) was used to keep the flap in position (Figures 3 and 4, and Video, Supplemental Digital Content). FIGURE 3. View largeDownload slide Intraoperative pictures obtained with a 0° endoscope (A-E) and 45° endoscope (F and G). A, The left side nasoseptal flap was harvested and the osseous boundaries of the sphenopalatine foramen were removed. Observe the yellow dashed line that illustrates the mucosal incision to connect the maxillary antrostomy to the standard incision for the nasoseptal flap at the superior aspect of the arch of the choana. This step is important to release the lateral mucosa of the pedicle underneath the SPA and leave the flap attached only to the vascular bundle. B, After the periosteal incision below the SPA, the dissection is progressed laterally and superiorly towards the inferior orbital fissure. C, The flap is placed in the nasopharynx during the posterior periosteal incision from the inferior orbital fissure to the palatovaginal canal (dashed yellow line). D, Incision of the medial aspect of the pterygopalatine fossa periosteum underneath the SPA. Observe that the nasoseptal flap is placed in the ethmoid and sphenoid for this step. E, SPA is completely released and freely mobilized in the nasal cavity. Note the venous drainage system around the IMAX. F, View with a 45° endoscope of the cranial base defect with the inlay dural substitute. Observe the defect is very anterior and involves the posterior table of the frontal sinus. G, After the pedicle was released, the flap reached easily the anterior edge of the defect and covered it completely. FIGURE 3. View largeDownload slide Intraoperative pictures obtained with a 0° endoscope (A-E) and 45° endoscope (F and G). A, The left side nasoseptal flap was harvested and the osseous boundaries of the sphenopalatine foramen were removed. Observe the yellow dashed line that illustrates the mucosal incision to connect the maxillary antrostomy to the standard incision for the nasoseptal flap at the superior aspect of the arch of the choana. This step is important to release the lateral mucosa of the pedicle underneath the SPA and leave the flap attached only to the vascular bundle. B, After the periosteal incision below the SPA, the dissection is progressed laterally and superiorly towards the inferior orbital fissure. C, The flap is placed in the nasopharynx during the posterior periosteal incision from the inferior orbital fissure to the palatovaginal canal (dashed yellow line). D, Incision of the medial aspect of the pterygopalatine fossa periosteum underneath the SPA. Observe that the nasoseptal flap is placed in the ethmoid and sphenoid for this step. E, SPA is completely released and freely mobilized in the nasal cavity. Note the venous drainage system around the IMAX. F, View with a 45° endoscope of the cranial base defect with the inlay dural substitute. Observe the defect is very anterior and involves the posterior table of the frontal sinus. G, After the pedicle was released, the flap reached easily the anterior edge of the defect and covered it completely. FIGURE 4. View largeDownload slide Schematic drawing to show the comparison of the anterior reach between the A, standard nasoseptal flap and B, the flap with complete pedicle release from the SPA foramen. After complete liberation, the flap is only attached to the IMAX and its periarterial venous plexus. The sinusoidal course of the IMAX in the infratemporal fossa allows considerable movement of the flap with improvement of its anterior reach. FIGURE 4. View largeDownload slide Schematic drawing to show the comparison of the anterior reach between the A, standard nasoseptal flap and B, the flap with complete pedicle release from the SPA foramen. After complete liberation, the flap is only attached to the IMAX and its periarterial venous plexus. The sinusoidal course of the IMAX in the infratemporal fossa allows considerable movement of the flap with improvement of its anterior reach. RESULTS Postoperative MRI with contrast showed enhancement of the nasoseptal flap in its full extension (Figure 5). The flap covered the entire left anterior cranial base, from the planum sphenoidale to the ethmoidal roof and even the posterior table of the frontal sinus. There was complete obliteration of the CSF fistula postoperatively with resolution of the radiographic pneumocephalus and the patient's rhinorrhea. Nasal endoscopy performed in clinic 1 mo postopeatively showed the flap to be well healed to the cranial base with no evidence of necrosis. FIGURE 5. View largeDownload slide Postoperative MRI T1 sagittal view A, without contrast and B, with contrast. Observe the nasoseptal flap enhanced with contrast and covered completely the anterior cranial base from the planum sphenoidale to the posterior table of the frontal sinus. FIGURE 5. View largeDownload slide Postoperative MRI T1 sagittal view A, without contrast and B, with contrast. Observe the nasoseptal flap enhanced with contrast and covered completely the anterior cranial base from the planum sphenoidale to the posterior table of the frontal sinus. DISCUSSION The nasoseptal flap is a reconstructive option not only for the anterior cranial base reconstruction, but any area of the ventral cranial base, including oropharyngeal and palatal defects.9-11 Classically, the reconstructive area of the nasoseptal flap is the part corresponding to the quadrandular cartilage of the septum. A reasonable area of the septal mucosa is devoted to the pedicle, limiting its use in reconstruction.3 The standard nasoseptal flap is sufficient to cover the majority of cranial base defects. However, often the surgeon faces situations where the reach of the flap is an issue and the flap barely covers a large defect. This is most problematic in the far extremes of the cranial base, such as the posterior table of the frontal sinus and the craniocervical junction.3-5 There are alternatives described in the literature for such situations, like the use of a second flap, grafts or alloderm™ (LifeCell Corp, Branchburg, New Jersey).12-15 We previously described the release of the nasoseptal flap pedicle for ipsilateral transpterygoid approaches. This consists of the removal of the anterior aspect of the pterygopalatine fossa to allow lateral mobilization of the flap pedicle during the drilling of the ipsilateral pterygoid base.16 The initial exposure of the pterygopaltine fossa periosteum is similar; however, no opening of the periosteum was performed for the lateralization of the pedicle. In this present technique, the periosteum was opened in order to completely release the SPA from its foramen. The pedicle was left attached to the IMAX, remarkably increasing its freedom. This increases the reach of the flap to allow it to likely reach any area in the nasal cavity, cranial base, or upper cervical spine. Additionally, more length to the pedicle and subsequently a greater reach of the flap can be added with the IMAX dissection and its mobilization within the infratemporal fossa. The descending palatine artery and the infraorbital artery can be ligated and transected to increase the length of the vascular pedicle. With the increased pedicle length obtained with the release of the SPA from its foramen, the area of the flap that can be used for reconstruction is also increased. Potentially, the entire septal mucosa can be used to cover a skull base defect. In our illustrative case, a middle turbinectomy was performed to expose the entire cranial base defect. In cases where the middle turbinate is preserved, a portion of the tail of the middle turbinate should be transected and included to pedicle of the nasoseptal flap in order to completely free the mucosa around the SPA foramen. There are potential issues with exposing the vascular pedicle to the nasal cavity and risking the viability of the vascularized flap. In our illustrative case, after using the majority of the septal mucosa to cover the skull base from the planum sphenoidale to the posterior table of the frontal sinus, we noticed that the mucosa of the sphenoid rostrum could be used to cover the pterygopalatine fossa and the IMAX. Due to the extensive freedom obtained after the release of the pedicle, it was easy to move that mucosa towards the pterygopalatine fossa. Surgicel® (Ethicon Inc) followed by Duraseal® (Integra® Neurosciences) were used to keep the pedicle in place. In cases where a longer pedicle is required to improve its reach, free mucosal grafts from the nasal cavity floor or middle turbinate, for example, can be used to cover the artery. Another concern with the extended mobilization of the flap's vascular pedicle is the potentially resultant compromise of the venous drainage, the risk of congestion, and subsequent flap necrosis. The venous drainage of the nasoseptal flap is based upon the sphenopalatine vein that passes through the sphenopalatine foramen before draining into the pterygoid plexus.17 The dissection around the IMAX should be meticulous in order to prevent injury to the venous drainage system of the flap. Leaving a cuff of periosteum around the SPA during the 360° periosteal incisional is important to prevent venous injury. The periosteum is very attached to the artery at the level of the SPA foramen. In our illustrative case, it is possible to observe some veins around the IMAX. We have described a technique to improve the reach of the nasoseptal flap used in endonasal cranial base reconstruction. Anatomic knowledge of the palatine bone and the SPA foramen is required to allow for proper release of the pedicle without sacrificing the flap's vascular supply. Additionally, complete understanding of the intricate anatomy of the pterygopalatine fossa and its contents is paramount, particularly the anatomical relations between its neurovascular structures (Figure 6). No complications such as dry eye or numbness in the V2 distribution were noticed in our patient. However, these potential complications should be discussed with the patient prior to the surgery. Working so close to the SPA and IMAX requires training and experience, as the described technique does add additional risk of injury to the pedicle during the dissection. Experience with arterial ligation of the SPA/IMAX to control severe posterior epistaxis may be beneficial to aid with proper pedicle dissection. FIGURE 6. View largeDownload slide A, Anatomic dissection of specimen injected with blue silicone for the venous system and red silicone for the arterial system. Observe the venous plexus around the internal maxillary artery within the infratemporal fossa. B, Picture obtained with a 0° endoscope from the left nasal cavity during an anatomical dissection of specimen injected only with red silicone into the arterial system. Observe the complex anatomy of the neurovascular structures within the pterygopalatine fossa. FIGURE 6. View largeDownload slide A, Anatomic dissection of specimen injected with blue silicone for the venous system and red silicone for the arterial system. Observe the venous plexus around the internal maxillary artery within the infratemporal fossa. B, Picture obtained with a 0° endoscope from the left nasal cavity during an anatomical dissection of specimen injected only with red silicone into the arterial system. Observe the complex anatomy of the neurovascular structures within the pterygopalatine fossa. At the moment, this modified technique could be considered an option in exceptional and challenging cases of reconstruction. For instance, cases where the pericranial flap is not available and the traditional nasoseptal flap cannot reach and cover the anterior edge of the defect. Currently, the alternative for such situations would be multilayer closure with avascular tissue and/or association with other local smaller flaps. CONCLUSION The complete release of the nasoseptal flap pedicle from the SPA foramen is feasible and remarkably improves the reach of the flap. It also increases the reconstructive area of the flap since the entire septal mucosa can be used for reconstruction and the pedicle length is based exclusively upon the SPA/IMAX. With careful dissection and adherence to the principles of pedicled flap dissection and positioning, we were able to avoid issues with venous congestion or flap necrosis. Further studies are necessary to demonstrate the efficiency of our technique and other potential complications related to this aggressive dissection of the flap pedicle. Disclosure The authors have no personal, financial, or institutional interest in any of the drugs, materials, or devices described in this article. REFERENCES 1. Hadad G , Bassagasteguy L , Carrau RL et al. A novel reconstructive technique after endoscopic expanded endonasal approaches: vascular pedicle nasoseptal flap . Laryngoscope . 2006 ; 116 ( 10 ): 1882 – 1886 . Google Scholar CrossRef Search ADS PubMed 2. Pinheiro-Neto CD , Prevedello DM , Carrau RL et al. Improving the design of the pedicled nasoseptal flap for skull base reconstruction: a radioanatomic study . Laryngoscope . 2007 ; 117 ( 9 ): 1560 – 1569 . Google Scholar CrossRef Search ADS PubMed 3. Pinheiro-Neto CD , Ramos HF , Peris-Celda M et al. Study of the nasoseptal flap for endoscopic anterior cranial base reconstruction . Laryngoscope . 2011 ; 121 ( 12 ): 2514 – 2520 . Google Scholar CrossRef Search ADS PubMed 4. MacArthur FJD , McGarry GW . The radioanatomy of endonasal flap coverage of skull base defects: a tool for preoperative planning . Laryngoscope . 2017 doi: 10.1002/lary.26925 . 5. Peris-Celda M , Pinheiro-Neto CD , Funaki T et al. The extended nasoseptal flap for skull base reconstruction of the clival region: an anatomical and radiological study . J Neurol Surg B . 2013 ; 74 ( 06 ): 369 – 385 . Google Scholar CrossRef Search ADS 6. Pinheiro-Neto CD , Snyderman CH . Nasoseptal flap . Adv Otorhinolaryngol . 2013 ; 74 ( 1 ): 42 – 55 . Google Scholar PubMed 7. Pinheiro-Neto CD , Fernandez-Miranda JC , Prevedello DM , Carrau RL , Gardner PA , Snyderman CH . Transposition of the pterygopalatine fossa during endoscopic endonasal transpterygoid approaches . J Neurol Surg B . 2013 ; 74 ( 05 ): 266 – 270 . Google Scholar CrossRef Search ADS 8. Pinheiro-Neto CD , Fernandez-Miranda JC , Rivera-Serrano CM et al. Endoscopic anatomy of the palatovaginal canal (palatosphenoidal canal) . Laryngoscope . 2012 ; 122 ( 1 ): 6 – 12 . Google Scholar CrossRef Search ADS PubMed 9. Rivera-Serrano CM , Lentz AK , Pinheiro-Neto C , Snyderman CH . Cadaveric study of the posterior pedicle nasoseptal flap . Plast Reconstr Surg . 2013 ; 132 ( 5 ): 1269 – 1275 . Google Scholar CrossRef Search ADS PubMed 10. Pinheiro-Neto CD , Galati LT . Nasoseptal flap for reconstruction after robotic radical tonsillectomy . Head Neck . 2016 ; 38 ( 9 ): E2495 – E2498 . Google Scholar CrossRef Search ADS PubMed 11. Lee DH , Yoon TM , Lee JK , Lim SC . Nasoseptal flap reconstruction after oropharyngeal cancer resection . Medicine . 2017 ; 96 ( 44 ): 8527 [Epub ahead of print]. Google Scholar CrossRef Search ADS 12. Patel MR , Stadler ME , Snyderman CH et al. How to choose? Endoscopic skull base reconstructive options and limitations . Skull Base . 2010 ; 20 ( 06 ): 397 – 404 . Google Scholar CrossRef Search ADS PubMed 13. Biroli F , Esposito F , Fusco M et al. Novel equine collagen-only dural substitute . Neurosurgery . 2008 ; 62 ( 3 Suppl 1 ): 273 – 274 . Google Scholar PubMed 14. Dadgostar A , Okpaleke C , Al-Asousi F , Javer A . The application of a free nasal floor mucoperiosteal graft in endoscopic sinus surgery . Am J Rhinol Allergy . 2017 ; 31 ( 3 ): 196 – 199 . Google Scholar CrossRef Search ADS PubMed 15. Ting JY , Metson R . Free graft techniques in skull base reconstruction . Adv Otorhinolaryngol . 2013 ; 74 ( 1 ): 33 – 41 . Google Scholar PubMed 16. Pinheiro-Neto CD , Paluzzi A , Fernandez-Miranda JC et al. Extended dissection of the septal flap pedicle for ipsilateral endoscopic transpterygoid approaches . Laryngoscope . 2014 ; 124 ( 2 ): 391 – 396 . Google Scholar CrossRef Search ADS PubMed 17. Beale TJ . Nose, nasal cavity and paranasal sinuses . In: Standring S , ed. Gray's Anatomy: The Anatomical Basis of Clinical Practice . London : Elsevier ; 2008 : 547 – 559 . Supplemental digital content is available for this article at www.operativeneurosurgery-online.com. Supplemental Digital Content. Video Supplemental Digital Content. Video Close Acknowledgments The authors deeply acknowledge Professor A. L. Rhoton. The dissection of figure 6A was performed by the second author at the Microsurgical and Endoscopic Neuroanatomy Laboratory under his direction in Gainesville, Florida. COMMENTS Skull base reconstruction remains a challenging operative procedure, and the variation in anatomy and defects constantly requires adaptation on every case. Techniques such as described in this paper help surgeons with added options. John Schneider St. Louis, Missouri The authors summarize the limits of the nasoseptal flap with pedicle dissection to the internal maxillary artery. The report is a video case report of how to perform this technique, and as such nicely presents some modifications of the nasoseptal with extended dissection of its internal maxillary pedicle to close a post-traumatic anterior skull base defect. This is a potentially useful variation to enable greater nasoseptal flap mobilization for more complex repairs. Michael Chicoine St. Louis, Missouri Copyright © 2018 by the Congress of Neurological Surgeons

Journal

Operative NeurosurgeryOxford University Press

Published: Apr 24, 2018

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