Combined Nasoseptal and Inferior Turbinate Flap for Reconstruction of Large Skull Base Defect After Expanded Endonasal Approach: Operative Technique

Combined Nasoseptal and Inferior Turbinate Flap for Reconstruction of Large Skull Base Defect... Abstract BACKROUND Increasing indications for endoscopic endonasal approaches have led neurosurgeons to develop new reconstruction techniques for larger skull base defects. Vascularized grafts have been a great adjunction to reduce the rate of cerebrospinal fluid leak and can also be used to cover exposed critical structures such as the internal carotid artery. The nasoseptal flap and the inferior or middle turbinate flap are thus widely used in endoscopic skull base surgery, but may be insufficient for very large defects. OBJECTIVE To present a new mucosal flap used to cover large skull base defects in which the mucosa of the inferior turbinate, inferior meatus, nasal floor, and nasal septum is harvested in 1 piece keeping both vascular pedicles intact (inferior turbinate and septal arteries). METHODS We describe a surgical technique to harvest a combined inferior turbinate-nasoseptal flap. RESULTS Technical pearls and surgical pitfalls are described through 2 clinical cases in which the nasoseptal mucosa was partially damaged during a previous surgery, rendering the nasoseptal flap insufficient by itself. The flap is harvested thanks to 2 mucosal cuts: a first circular cut around the choanal arch and the junction between the hard and the soft palate, and a second one combining classical cuts of the nasoseptal flap and the inferior turbinate flap. CONCLUSION The inferior turbinate-nasoseptal flap can be a useful alternative in patients whose septal mucosa was partially damaged and/or with very large postoperative skull base defects. Skull base, Surgical flaps ABBREVIATIONS ABBREVIATIONS CSF cerebrospinal fluid CT computed tomography EEA endoscopic endonasal approaches ICA internal carotid artery IT-NSF inferior turbinate-nasoseptal flap ITF inferior turbinate flap MRI magnetic resonance imaging NSA nasoseptal artery NSF nasoseptal flap PLNA posterolateral nasal artery SPA sphenopalatine artery Over the past decade, the increasing use of endoscopic endonasal approaches (EEA) has led surgeons to develop more complex strategies for skull base reconstruction and closure.1 Even if EEA may reduce some aspects of the morbidity compared to traditional transcranial approaches, the risk of postoperative fistula between the intracranial space and the sinonasal tract remains a major concern of this technique, with an increased risk of cerebrospinal fluid (CSF) leak, pneumocephalus or meningitis.2 Vascularized flaps based on the sphenopalatine artery (SPA) have become the main reconstructive options for large skull base defects because of their efficacy, versatility, low complication rate, and rapid healing.3 Current options for vascularized endonasal flaps include the nasoseptal flap (NSF, pedicled on nasoseptal artery [NSA]),4 the posterior pedicled inferior turbinate flap5 (ITF, pedicled on the inferior turbinate artery, a branch of the posterolateral nasal artery [PLNA]), and middle turbinate flap.6,7 Other options based on the vascular supply of the anterior nasal septum and lateral nasal wall have also been described for defects of the anterior skull base.8,9 However, these different flaps may still be insufficient to reconstruct very large defects and to cover a large surface, explaining why surgeons have proposed alternative techniques to increase the overall coverage surface (Janus flap,10 extended NSF,11 or extended ITF12). In multioperated cases in which an endonasal mucosal flap is no longer available, regional vascularized flaps have been developed (pericranial flap,13 palatal flap,14 and temporoparietal fascia flap15) with good results. However, these procedures can also increase surgical morbidity (hematoma, flap necrosis, or infections) and may lead to poor cosmetic results.3 In this report, we describe a new surgical technique for harvesting a one piece combined inferior turbinate-nasoseptal flap (IT-NSF), which includes the mucosa of the inferior turbinate, the inferior meatus, the nasal floor, and the nasal septum providing a large covering surface, even in case of damaged septal mucosa. SURGICAL TECHNIQUE A 30° endoscope was used during the whole procedure (Karl Stortz SE & Co. KG, Tuttlingen, Germany). The nasal cavity is decongested with oxymetazoline 0.05%. To widen the surgical corridor and facilitate bimanual work, the middle turbinate can first be resected. The bulla ethmoidalis and the posterior ethmoid cells are opened and removed. A maxillary antrostomy is performed. The SPA running out from the pterygopalatine fossa is identified using a Doppler probe. The PLNA, inferior turbinate artery, and NSA can also be identified. The subsequent incisions (summarized in Figure 1) of the flap harvest are then performed with scissors and a monopolar electrocautery using an extended Colorado tip (Stryker Corporation, Kalamazoo, MI). FIGURE 1. View largeDownload slide Artistic illustration of the mucosal cuts for harvesting a combined IT-NSF. The mucosal cuts are described in the main text. Abbreviations: Cho, choana; ET, Eustachian tube; FNF, floor of the nasal fossa; IT, inferior turbinate; MS, maxillary sinus; MT, middle turbinate; NS, nasal septum; NSA, nasoseptal artery; OSS, ostium of sphenoid sinus; PLNA, postero-lateral nasal artery; SPA, spheno-palatine artery; ST, superior turbinate. © 2017, Department of Neurosurgery, Lariboisière Hospital, Paris. Printed with permission. All rights reserved. FIGURE 1. View largeDownload slide Artistic illustration of the mucosal cuts for harvesting a combined IT-NSF. The mucosal cuts are described in the main text. Abbreviations: Cho, choana; ET, Eustachian tube; FNF, floor of the nasal fossa; IT, inferior turbinate; MS, maxillary sinus; MT, middle turbinate; NS, nasal septum; NSA, nasoseptal artery; OSS, ostium of sphenoid sinus; PLNA, postero-lateral nasal artery; SPA, spheno-palatine artery; ST, superior turbinate. © 2017, Department of Neurosurgery, Lariboisière Hospital, Paris. Printed with permission. All rights reserved. The first circular cut starts at the base of the sphenoid rostrum along the inferior aspect of the choanal arch as low as possible in order to avoid injury to the posterior septal artery (Figure 1, cut 1). It then continues medially along the free posterior edge of the nasal septum. Once it reaches the nasal cavity floor, the incision continues laterally along the junction between hard and soft palate (Figure 1, cut 2). The cut is then prolonged posteriorly, immediately above the Eustachian tube in order to join the starting point of this first incision. It is easier to perform this posterior circular cut first, before elevation of the mucosa, to avoid being hindered by the bleeding the most anterior cut may cause. The next incision is made similarly to a NSF above the sphenoid sinus ostium and prolonged anteriorly 1 cm below the most superior aspect of the septum in order to preserve the olfactory epithelium (the use of the scissors is preferred for this incision to avoid thermal injury to the olfactory nerves). The incision is then prolonged downward in the direction of the nasal spine toward the floor of the nasal cavity (Figure 1, cut 3). Once the nasal floor is reached, the incision continues laterally, crossing the nasal floor, toward the anterior aspect of the inferior turbinate. A horizontal incision is then made in a posterior direction, above the inferior turbinate, along the lateral nasal wall, toward the maxillary antrostomy (Figure 1, cut 4). Elevation of the flap starts anteriorly with a Cottle dissector. The flap is elevated from the floor of the nasal fossa in a subperiostal plane in an anterior to posterior manner; the septal mucosa is detached sharply from the septum (or from the contralateral septal mucosa in case of septal damage). The mucosa of the inferior turbinate is then carefully elevated and separated from the IT bone. The mucosa of the inferior meatus is elevated, and the nasolacrimal duct is identified at the level of its opening into the inferior meatus. Once isolated, the nasolacrimal duct is sectioned. At the posterior aspect of the inferior turbinate, the mucosa covering the ascending process of the palatine bone is elevated until the sphenopalatine foramen is identified, and the fifth is prolonged posteriorly as far above as possible from the inferior turbinate artery. Care must be taken not to injure (Figure 1, cut 5) the inferior turbinate artery and the SPA, which can be identified again with a Doppler. Elevation of the flap is completed when the circular cut is reached and by finalizing it along the inferior aspect of the choanal arch taking care to preserve both vascular pedicles: the inferior turbinate artery and the NSA (by staying as low as possible on the inferior edge of the choanal arch; Figure 1, cut 6). Depending on the location of the tumor and on the surgical approach, the flap can be stored in the maxillary sinus or in the rhinopharynx during the tumor resection. In order to facilitate the storage of the flap in the maxillary sinus, the posterior wall of the maxillary sinus can be resected and the sphenopalatine foramen and the pterygopalatine fossa opened. If a transpterygoid approach is performed on the same side than the flap harvest, the vidian nerve can be divided in order to facilitate the mobilization of the flap more laterally into the maxillary sinus together with the SPA. CASE ILLUSTRATION AND SURGICAL PICTURES This study was undertaken with patient informed consent and Hospital ethical board approval. Case 1 A 56-yr-old male was referred to our department with a large chordoma (diagnosed with a biopsy) causing nasal obstruction. Preoperative imaging revealed a clivus chordoma with extension to the right petrous apex, right cavernous sinus, sphenoid sinus, and right pterygopalatine fossa, infratemporal fossa and parapharyngeal space (Figure 2A-2C). The patient had been previously operated for an endonasal septoplasty. In this case, a large vascularized flap was necessary to cover the right internal carotid artery (ICA; pharyngeal, petrous, and cavernous sinus portions) and the skull base defect along the clivus and the right cavernous sinus. Considering the facts that the right pterygopalatine fossa was invaded by the tumor, and that the septum was damaged by the previous surgery (reducing the size and the quality of the septal part of the flap), we decided to perform a left IT-NSF. The flap enabled a good coverage of the skull base defect and the postoperative magnetic resonance imaging (MRI) showed good positioning of the flap with a well-vascularized aspect on Gadolinium-enhanced sequences (Figure 2D-2F). In this case, the dura was not invaded by the tumor and was thus preserved, avoiding an intraoperative CSF leak. The postoperative course was uneventful. An endoscopic control done 2 wk after the surgery showed satisfactory healing of the nasal cavity and no sign of flap necrosis. The operative photos show the surgical technique (Figures 3 and 4). FIGURE 2. View largeDownload slide Coronal A, sagittal B, and axial C preoperative T1-weighted MRI with gadolinium enhancement showing a clivus chordoma with extension to the right petrous apex, right cavernous sinus, sphenoid sinus, and right pterygopalatine fossa, infratemporal fossa, and parapharyngeal space. Coronal D, sagittal E, and axial F postoperative (3 mo) T1-weighted MRI showing postoperative aspect of the flap and gross total resection (star: septal part of the flap; white arrow: inferior turbinate part of the flap). © 2017, Department of Neurosurgery, Lariboisière Hospital, Paris. Printed with permission. All rights reserved. FIGURE 2. View largeDownload slide Coronal A, sagittal B, and axial C preoperative T1-weighted MRI with gadolinium enhancement showing a clivus chordoma with extension to the right petrous apex, right cavernous sinus, sphenoid sinus, and right pterygopalatine fossa, infratemporal fossa, and parapharyngeal space. Coronal D, sagittal E, and axial F postoperative (3 mo) T1-weighted MRI showing postoperative aspect of the flap and gross total resection (star: septal part of the flap; white arrow: inferior turbinate part of the flap). © 2017, Department of Neurosurgery, Lariboisière Hospital, Paris. Printed with permission. All rights reserved. FIGURE 3. View largeDownload slide Intraoperative pictures demonstrating the essential steps of the procedure and the anatomic landmarks (part 1). A, intraoperative view of the left nasal fossa before starting the harvest of the flap with the tumor bulging in the cavum behind the suction device. B, The first cut is made along the posterior edge of the nasal septum and the floor of the nasal fossa immediately anterior to the junction between hard and soft palate (cut 1 and 2, white dashed line). C, Maxillary sinus and posterior ethmoid cells have been opened. D, Incisions along the superior and anterior aspect of the septum are made similarly to a classical NSF (cut 3). E and F, The horizontal cut above the inferior turbinate is performed (cut 4); G, the mucosa is detached from the bone of the inferior turbinate. H, At the posterior aspect of the inferior turbinate, the cut is prolonged as posteriorly as possible in the direction of the sphenopalatine foramen (cut 5). I, The SPA running out from the sphenopalatine foramen is identified using a Doppler probe all along the procedure. Abbreviations: ec, ethmoid cell; fl, flap; fnf, floor of the nasal fossa; hp, hard palate; it, inferior turbinate; ns, nasal septum; ms, maxillary sinus; mt, middle turbinate, sp, soft palate; sr, sphenoid rostrum. © 2017, Department of Neurosurgery, Lariboisière Hospital, Paris. Printed with permission. All rights reserved. FIGURE 3. View largeDownload slide Intraoperative pictures demonstrating the essential steps of the procedure and the anatomic landmarks (part 1). A, intraoperative view of the left nasal fossa before starting the harvest of the flap with the tumor bulging in the cavum behind the suction device. B, The first cut is made along the posterior edge of the nasal septum and the floor of the nasal fossa immediately anterior to the junction between hard and soft palate (cut 1 and 2, white dashed line). C, Maxillary sinus and posterior ethmoid cells have been opened. D, Incisions along the superior and anterior aspect of the septum are made similarly to a classical NSF (cut 3). E and F, The horizontal cut above the inferior turbinate is performed (cut 4); G, the mucosa is detached from the bone of the inferior turbinate. H, At the posterior aspect of the inferior turbinate, the cut is prolonged as posteriorly as possible in the direction of the sphenopalatine foramen (cut 5). I, The SPA running out from the sphenopalatine foramen is identified using a Doppler probe all along the procedure. Abbreviations: ec, ethmoid cell; fl, flap; fnf, floor of the nasal fossa; hp, hard palate; it, inferior turbinate; ns, nasal septum; ms, maxillary sinus; mt, middle turbinate, sp, soft palate; sr, sphenoid rostrum. © 2017, Department of Neurosurgery, Lariboisière Hospital, Paris. Printed with permission. All rights reserved. FIGURE 4. View largeDownload slide Intraoperative pictures showing the essential steps of the procedure and the anatomical landmarks (part 2). A, The flap is elevated from the floor of the nasal fossa and dissected from the contralateral septal mucosa, then B, elevated from front to back exposing the initial cut at the junction between soft and hard palate (white dashed line). C and D, This cut is then prolonged laterally above the Eustachian tube (cut 6). E and F, The initial circular cut is then finalized by prolonging the initial cut at the posterior edge of the nasal septum to the inferior aspect of the choanal arch, in order to join laterally the cut above the Eustachian tube. G, The flap is then mobilized. H, In this case, the middle turbinate was conserved but the posterior wall of the maxillary sinus was resected and the sphenopalatine foramen opened to facilitate the mobilisation and the storage of the flap in the maxillary sinus. I, After tumor resection, the flap is positioned to cover the skull base defect. Abbreviations: ec, ethmoid cell; et, Eustachian tube; fl, flap; fnf, floor of the nasal fossa; it, inferior turbinate; ms, maxillary sinus; mt, middle turbinate; ns, nasal septum; Pa, ascending process of the palatine bone; sp, soft palate; hp, hard palate. © 2017, Department of Neurosurgery, Lariboisière Hospital, Paris. Printed with permission. All rights reserved. FIGURE 4. View largeDownload slide Intraoperative pictures showing the essential steps of the procedure and the anatomical landmarks (part 2). A, The flap is elevated from the floor of the nasal fossa and dissected from the contralateral septal mucosa, then B, elevated from front to back exposing the initial cut at the junction between soft and hard palate (white dashed line). C and D, This cut is then prolonged laterally above the Eustachian tube (cut 6). E and F, The initial circular cut is then finalized by prolonging the initial cut at the posterior edge of the nasal septum to the inferior aspect of the choanal arch, in order to join laterally the cut above the Eustachian tube. G, The flap is then mobilized. H, In this case, the middle turbinate was conserved but the posterior wall of the maxillary sinus was resected and the sphenopalatine foramen opened to facilitate the mobilisation and the storage of the flap in the maxillary sinus. I, After tumor resection, the flap is positioned to cover the skull base defect. Abbreviations: ec, ethmoid cell; et, Eustachian tube; fl, flap; fnf, floor of the nasal fossa; it, inferior turbinate; ms, maxillary sinus; mt, middle turbinate; ns, nasal septum; Pa, ascending process of the palatine bone; sp, soft palate; hp, hard palate. © 2017, Department of Neurosurgery, Lariboisière Hospital, Paris. Printed with permission. All rights reserved. Case 2 A 60-yr-old patient was referred to our department for a large skull base chordoma with right oculomotor nerve and left abducens nerve palsy. He had been previously operated through endonasal approaches 3 times. A significant volume of residual tumor was still present following the third surgery and the patient underwent radiotherapy. He was referred to our center 12 mo after radiotherapy with a symptomatic large growing lesion. Preoperative imaging showed a skull base chordoma, with extension to the sphenoid sinus, sellae turcica, both cavernous sinus, left infratemporal fossa and pterygopalatine fossa, and prepontine cistern (Figure 5A-5C). Considering that the patient was previously irradiated and that the ICA was expected to be exposed on a large segment after resection of the tumor, a vascularized flap was deemed necessary. Available options for vascularized coverage were thus reviewed, based on information obtained from the preoperative computed tomography (CT)-angiogram and MRI. Due to a central septal perforation resulting from previous EEAs (Figure 5B), a right NSF extended to the floor of the nasal fossa was expected to be insufficient in comparison to the size of the defect (however, the mucosa below and above the perforation was still available). The extended ITF on the left side was not available due to tumor invasion. On the preoperative CT-angiogram, the right SPA and PLNA were well delineated. We decided to perform a combined right IT-NSF, which was the only intranasal flap large enough to reach the left infratemporal fossa. We performed a right middle turbinectomy to facilitate bimanual work and flap mobilization. As we can see on Figure 5B and 5C, the retroclival dura in front of the pons was invaded by the tumor. However, the arachnoidal layer was kept intact, avoiding an intraoperative high-flow CSF leak. The dural defect was rebuilt with Tachosil and fibrin glue. The flap afterwards enabled a good coverage of the skull base defect. Positioning of the flap is figured on the postoperative MRI (Figure 5D-5F). The postoperative course was uneventful. FIGURE 5. View largeDownload slide Coronal A, sagittal B, and axial C preoperative T1-weighted MRI with gadolinium enhancement showing a large skull base chordoma, with extension to the sphenoid sinus, sellae turcica, both cavernous sinus, left sphenopalatine fossa, infratemporal fossa, and prepontine cistern. Note the septal perforation due to a previous surgery. Coronal D, sagittal E, and axial F immediate postoperative T1-weighted MRI with gadolinium enhancement showing total gross resection of the lesion and good positioning and vascularization of the flap (star: septal part of the flap; white arrow: inferior turbinate part of the flap). © 2017, Department of Neurosurgery, Lariboisière Hospital, Paris. Printed with permission. All rights reserved. FIGURE 5. View largeDownload slide Coronal A, sagittal B, and axial C preoperative T1-weighted MRI with gadolinium enhancement showing a large skull base chordoma, with extension to the sphenoid sinus, sellae turcica, both cavernous sinus, left sphenopalatine fossa, infratemporal fossa, and prepontine cistern. Note the septal perforation due to a previous surgery. Coronal D, sagittal E, and axial F immediate postoperative T1-weighted MRI with gadolinium enhancement showing total gross resection of the lesion and good positioning and vascularization of the flap (star: septal part of the flap; white arrow: inferior turbinate part of the flap). © 2017, Department of Neurosurgery, Lariboisière Hospital, Paris. Printed with permission. All rights reserved. DISCUSSION This report documents the surgical technique to harvest a 1-piece combined IT-NSF flap, with conservation of both vascular pedicles coming from the posterior septal and lateral nasal artery of the inferior turbinate. We used this technique in 2 cases of large skull base chordoma and this flap allowed for adequate mucosal coverage of the whole resection cavity in both cases despite very large postoperative defects. We speculated that the NSF alone would be insufficient to reconstruct the whole postoperative defect because of tumor extension toward the nasal floor and damage to the nasal septum during previous procedures (endoscopic septoplasty in the case presented in this article and septal perforation due to previous surgery in the other case). Another option for reconstruction would have been a temporoparietal fascia flap, although this technique would have increased the length and the morbidity of the procedure. Our technique consists of a combination of an extended NSF and an extended ITF flap. The major difference from previous description of extended nasoseptal or ITFs is the circular cut that enables the mobilization of the whole flap in 1 piece while preserving the 2 vascular pedicles (nasoseptal and inferior turbinate arteries). In a recent anatomic study, Wu et al16 described a combined posterior pedicled IT-NSF on cadaveric dissection. Their incisions were quite similar to what is presented in this report, but Wu et al16 kept only the posterolatero nasal artery, assuming that the anastomosis between the PLNA and the NSA allowed the PLNA to also supply the nasoseptal mucoperichondrium and mucoperiosteum. However, this technique was an anatomic report, not applied to a surgical case. Choby et al12 used an ITF extended to the nasoseptum, pedicled on the sole PLNA (called extended ITF in their study) with good result in 2 patients. Our technique of combined IT-NSF enables the harvest of a very large flap with a strong vascular supply since the 2 main pedicles are preserved. However, similarly to a standalone IT flap, the inferior turbinate pedicle can limit the arc of rotation of the flap and preclude optimal positioning of the flap. The circular cut around the choanal arch enables improved mobilization of the whole flap around the sphenopalatine pedicle and reduce overall tensions. Moreover, our technique requires a maxillary antrostomy to be able to individualize and dissect the mucosa around the SPA at its exit from the pterygopalatine fossa, which also increases the overall mobility of the flap. On the other hand, in large tumor with very large defect expected after resection, a maxillary antrostomy is most often required for the approach. In the presented case, the IT-NSF allowed for an extensive surface of mucosal coverage despite a damaged septum due to previous surgery. We believe that the IT-NSF can be an alternate option for endoscopic reconstruction of large skull base defects. After every expended endonasal surgery, care must be taken to diagnose and treat nasal crusting. We therefore systematically perform endoscopic controls and resection of the crusts at least twice after the surgery (at week 1 and 2), and monthly afterwards. Besides, the patient performs nasal cavity washes with saline 6-times a day during several weeks in order to prevent the formation of crusts. Nasal morbidity can thereby be significantly reduced. CONCLUSION The inferior turbinate-nasoseptal flap can be a useful alternative to traditional flaps in patients whose septal mucosa was partially damaged and/or with very large postoperative skull base defects. Disclosure Dr Froelich would like to acknowledge the material support of KARL STORZ SE & Co. KG to the Laboratoire d'anatomie neurochirurgicale de l'Hopital Lariboisière. REFERENCES 1. Patel MR, Taylor RJ, Hackman TG et al.   Beyond the nasoseptal flap: outcomes and pearls with secondary flaps in endoscopic endonasal skull base reconstruction. Laryngoscope . 2014; 124( 4): 846- 852. Google Scholar CrossRef Search ADS PubMed  2. Gardner PA, Kassam AB, Thomas A et al.   Endoscopic endonasal resection of anterior cranial base meningiomas. Neurosurgery . 2008; 63( 1): 36- 54. Google Scholar CrossRef Search ADS PubMed  3. Harvey RJ, Parmar P, Sacks R, Zanation AM. Endoscopic skull base reconstruction of large dural defects: a systematic review of published evidence. Laryngoscope . 2012; 122( 2): 452- 459. Google Scholar CrossRef Search ADS PubMed  4. 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  5. Fortes FSG, Carrau RL, Snyderman CH et al.   The posterior pedicle inferior turbinate flap: a new vascularized flap for skull base reconstruction. Laryngoscope . 2007; 117( 8): 1329- 1332. Google Scholar CrossRef Search ADS PubMed  6. Pinheiro-Neto CD, Snyderman CH. Nasoseptal flap. Adv Otorhinolaryngol . 2013; 74: 42- 55. doi:10.1159/000342271. Google Scholar PubMed  7. Suh JD, Chiu AG. Sphenopalatine-derived pedicled flaps. Adv Otorhinolaryngol . 2013; 74: 56- 63. doi:10.1159/000342275. Google Scholar PubMed  8. Meier JC, Bleier BS. Anteriorly based pedicled flaps for skull base reconstruction. Adv Otorhinolaryngol . 2013; 74: 64- 70. doi:10.1159/000342281. Google Scholar PubMed  9. Hadad G, Rivera-Serrano CM, Bassagaisteguy LH et al.   Anterior pedicle lateral nasal wall flap: a novel technique for the reconstruction of anterior skull base defects. Laryngoscope . 2011; 121( 8): 1606- 1610. Google Scholar CrossRef Search ADS PubMed  10. Nyquist GG, Anand VK, Singh A, Schwartz TH. Janus flap: bilateral nasoseptal flaps for anterior skull base reconstruction. Otolaryngol Head Neck Surg . 2010; 142( 3): 327- 331. Google Scholar CrossRef Search ADS PubMed  11. 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 Part B Skull Base . 2013; 74( 06): 369- 385. Google Scholar CrossRef Search ADS   12. Choby GW, Pinheiro-Neto CD, de Almeida JR et al.   Extended inferior turbinate flap for endoscopic reconstruction of skull base defects. J Neurol Surg Part B Skull Base . 2014; 75( 04): 225- 230. Google Scholar CrossRef Search ADS   13. Zanation AM, Snyderman CH, Carrau RL, Kassam AB, Gardner PA, Prevedello DM. Minimally invasive endoscopic pericranial flap: a new method for endonasal skull base reconstruction. Laryngoscope . 2009; 119( 1): 13- 18. Google Scholar CrossRef Search ADS PubMed  14. Oliver CL, Hackman TG, Carrau RL et al.   Palatal flap modifications allow pedicled reconstruction of the skull base. Laryngoscope . 2008; 118( 12): 2102- 2106. Google Scholar CrossRef Search ADS PubMed  15. Fortes FSG, Carrau RL, Snyderman CH et al.   Transpterygoid transposition of a temporoparietal fascia flap: a new method for skull base reconstruction after endoscopic expanded endonasal approaches. Laryngoscope . 2007; 117( 6): 970- 976. Google Scholar CrossRef Search ADS PubMed  16. Wu P, Li Z, Liu C, Ouyang J, Zhong S. The posterior pedicled inferior turbinate-nasoseptal flap: a potential combined flap for skull base reconstruction. Surg Radiol Anat . 2016; 38( 2): 187- 194. Google Scholar CrossRef Search ADS PubMed  COMMENTS This paper presents a combined vascularized flap for endonasal reconstruction combining the nasoseptal flap and inferior turbinate flap, connected with a circular incision around the choana. This is an interesting and innovative concept, presented by a very experienced skull base group. This flap does have some challenges and it is difficult to judge the efficacy of this flap given the lack of clinical cases to date, especially considering that only one involved an intraoperative CSF leak. Nevertheless, it is clear that there are applications for this technique and the efficacy will be defined as experience is gained. Difficulties with this flap include the natural curling of the proximal inferior turbinate pedicle and the limited arc of rotation of the IT flap which it would seem to do for this flap as well. The authors' experience with this aspect is valuable, and attention should be paid to the steps they outline for mobilizing the flap pedicle; this is especially difficult given the addition of a rounded central aspect of the flap surrounding the choana. Overall, these challenges render the flap with some significant limitations and therefore it may not be used regularly. However, having this option is important for advanced revision cases and, perhaps even more importantly, the knowledge and ability to understand the vascular supply, pedicle anatomy, and techniques for raising and rotating this flap are critical for any team performing complex endoscopic endonasal reconstruction. Paul A. Gardner Pittsburgh, Pennsylvania The authors describe a novel mucosal flap combining a nasal septal flap and an inferior turbinate flap based on 2 arterial pedicles that arise as branches from the sphenopalantine artery, namely 1) the nasospetal artery, and 2) the inferior turbinate artery branch of the posterolateral nasal artery. A detailed description of the technique is provided including the unique circular mucosal cut around the choana. Two case examples are described of large chordomas that were resected using endoscopic endonasal approaches using this novel flap for reconstruction of large skull base defects. I think that this technique is a useful potential option for closure of complex defects during endoscopic endonasal skull base surgery. Michael Robert 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

Combined Nasoseptal and Inferior Turbinate Flap for Reconstruction of Large Skull Base Defect After Expanded Endonasal Approach: Operative Technique

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Congress of Neurological Surgeons
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Copyright © 2018 by the Congress of Neurological Surgeons
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2332-4252
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10.1093/ons/opy046
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Abstract

Abstract BACKROUND Increasing indications for endoscopic endonasal approaches have led neurosurgeons to develop new reconstruction techniques for larger skull base defects. Vascularized grafts have been a great adjunction to reduce the rate of cerebrospinal fluid leak and can also be used to cover exposed critical structures such as the internal carotid artery. The nasoseptal flap and the inferior or middle turbinate flap are thus widely used in endoscopic skull base surgery, but may be insufficient for very large defects. OBJECTIVE To present a new mucosal flap used to cover large skull base defects in which the mucosa of the inferior turbinate, inferior meatus, nasal floor, and nasal septum is harvested in 1 piece keeping both vascular pedicles intact (inferior turbinate and septal arteries). METHODS We describe a surgical technique to harvest a combined inferior turbinate-nasoseptal flap. RESULTS Technical pearls and surgical pitfalls are described through 2 clinical cases in which the nasoseptal mucosa was partially damaged during a previous surgery, rendering the nasoseptal flap insufficient by itself. The flap is harvested thanks to 2 mucosal cuts: a first circular cut around the choanal arch and the junction between the hard and the soft palate, and a second one combining classical cuts of the nasoseptal flap and the inferior turbinate flap. CONCLUSION The inferior turbinate-nasoseptal flap can be a useful alternative in patients whose septal mucosa was partially damaged and/or with very large postoperative skull base defects. Skull base, Surgical flaps ABBREVIATIONS ABBREVIATIONS CSF cerebrospinal fluid CT computed tomography EEA endoscopic endonasal approaches ICA internal carotid artery IT-NSF inferior turbinate-nasoseptal flap ITF inferior turbinate flap MRI magnetic resonance imaging NSA nasoseptal artery NSF nasoseptal flap PLNA posterolateral nasal artery SPA sphenopalatine artery Over the past decade, the increasing use of endoscopic endonasal approaches (EEA) has led surgeons to develop more complex strategies for skull base reconstruction and closure.1 Even if EEA may reduce some aspects of the morbidity compared to traditional transcranial approaches, the risk of postoperative fistula between the intracranial space and the sinonasal tract remains a major concern of this technique, with an increased risk of cerebrospinal fluid (CSF) leak, pneumocephalus or meningitis.2 Vascularized flaps based on the sphenopalatine artery (SPA) have become the main reconstructive options for large skull base defects because of their efficacy, versatility, low complication rate, and rapid healing.3 Current options for vascularized endonasal flaps include the nasoseptal flap (NSF, pedicled on nasoseptal artery [NSA]),4 the posterior pedicled inferior turbinate flap5 (ITF, pedicled on the inferior turbinate artery, a branch of the posterolateral nasal artery [PLNA]), and middle turbinate flap.6,7 Other options based on the vascular supply of the anterior nasal septum and lateral nasal wall have also been described for defects of the anterior skull base.8,9 However, these different flaps may still be insufficient to reconstruct very large defects and to cover a large surface, explaining why surgeons have proposed alternative techniques to increase the overall coverage surface (Janus flap,10 extended NSF,11 or extended ITF12). In multioperated cases in which an endonasal mucosal flap is no longer available, regional vascularized flaps have been developed (pericranial flap,13 palatal flap,14 and temporoparietal fascia flap15) with good results. However, these procedures can also increase surgical morbidity (hematoma, flap necrosis, or infections) and may lead to poor cosmetic results.3 In this report, we describe a new surgical technique for harvesting a one piece combined inferior turbinate-nasoseptal flap (IT-NSF), which includes the mucosa of the inferior turbinate, the inferior meatus, the nasal floor, and the nasal septum providing a large covering surface, even in case of damaged septal mucosa. SURGICAL TECHNIQUE A 30° endoscope was used during the whole procedure (Karl Stortz SE & Co. KG, Tuttlingen, Germany). The nasal cavity is decongested with oxymetazoline 0.05%. To widen the surgical corridor and facilitate bimanual work, the middle turbinate can first be resected. The bulla ethmoidalis and the posterior ethmoid cells are opened and removed. A maxillary antrostomy is performed. The SPA running out from the pterygopalatine fossa is identified using a Doppler probe. The PLNA, inferior turbinate artery, and NSA can also be identified. The subsequent incisions (summarized in Figure 1) of the flap harvest are then performed with scissors and a monopolar electrocautery using an extended Colorado tip (Stryker Corporation, Kalamazoo, MI). FIGURE 1. View largeDownload slide Artistic illustration of the mucosal cuts for harvesting a combined IT-NSF. The mucosal cuts are described in the main text. Abbreviations: Cho, choana; ET, Eustachian tube; FNF, floor of the nasal fossa; IT, inferior turbinate; MS, maxillary sinus; MT, middle turbinate; NS, nasal septum; NSA, nasoseptal artery; OSS, ostium of sphenoid sinus; PLNA, postero-lateral nasal artery; SPA, spheno-palatine artery; ST, superior turbinate. © 2017, Department of Neurosurgery, Lariboisière Hospital, Paris. Printed with permission. All rights reserved. FIGURE 1. View largeDownload slide Artistic illustration of the mucosal cuts for harvesting a combined IT-NSF. The mucosal cuts are described in the main text. Abbreviations: Cho, choana; ET, Eustachian tube; FNF, floor of the nasal fossa; IT, inferior turbinate; MS, maxillary sinus; MT, middle turbinate; NS, nasal septum; NSA, nasoseptal artery; OSS, ostium of sphenoid sinus; PLNA, postero-lateral nasal artery; SPA, spheno-palatine artery; ST, superior turbinate. © 2017, Department of Neurosurgery, Lariboisière Hospital, Paris. Printed with permission. All rights reserved. The first circular cut starts at the base of the sphenoid rostrum along the inferior aspect of the choanal arch as low as possible in order to avoid injury to the posterior septal artery (Figure 1, cut 1). It then continues medially along the free posterior edge of the nasal septum. Once it reaches the nasal cavity floor, the incision continues laterally along the junction between hard and soft palate (Figure 1, cut 2). The cut is then prolonged posteriorly, immediately above the Eustachian tube in order to join the starting point of this first incision. It is easier to perform this posterior circular cut first, before elevation of the mucosa, to avoid being hindered by the bleeding the most anterior cut may cause. The next incision is made similarly to a NSF above the sphenoid sinus ostium and prolonged anteriorly 1 cm below the most superior aspect of the septum in order to preserve the olfactory epithelium (the use of the scissors is preferred for this incision to avoid thermal injury to the olfactory nerves). The incision is then prolonged downward in the direction of the nasal spine toward the floor of the nasal cavity (Figure 1, cut 3). Once the nasal floor is reached, the incision continues laterally, crossing the nasal floor, toward the anterior aspect of the inferior turbinate. A horizontal incision is then made in a posterior direction, above the inferior turbinate, along the lateral nasal wall, toward the maxillary antrostomy (Figure 1, cut 4). Elevation of the flap starts anteriorly with a Cottle dissector. The flap is elevated from the floor of the nasal fossa in a subperiostal plane in an anterior to posterior manner; the septal mucosa is detached sharply from the septum (or from the contralateral septal mucosa in case of septal damage). The mucosa of the inferior turbinate is then carefully elevated and separated from the IT bone. The mucosa of the inferior meatus is elevated, and the nasolacrimal duct is identified at the level of its opening into the inferior meatus. Once isolated, the nasolacrimal duct is sectioned. At the posterior aspect of the inferior turbinate, the mucosa covering the ascending process of the palatine bone is elevated until the sphenopalatine foramen is identified, and the fifth is prolonged posteriorly as far above as possible from the inferior turbinate artery. Care must be taken not to injure (Figure 1, cut 5) the inferior turbinate artery and the SPA, which can be identified again with a Doppler. Elevation of the flap is completed when the circular cut is reached and by finalizing it along the inferior aspect of the choanal arch taking care to preserve both vascular pedicles: the inferior turbinate artery and the NSA (by staying as low as possible on the inferior edge of the choanal arch; Figure 1, cut 6). Depending on the location of the tumor and on the surgical approach, the flap can be stored in the maxillary sinus or in the rhinopharynx during the tumor resection. In order to facilitate the storage of the flap in the maxillary sinus, the posterior wall of the maxillary sinus can be resected and the sphenopalatine foramen and the pterygopalatine fossa opened. If a transpterygoid approach is performed on the same side than the flap harvest, the vidian nerve can be divided in order to facilitate the mobilization of the flap more laterally into the maxillary sinus together with the SPA. CASE ILLUSTRATION AND SURGICAL PICTURES This study was undertaken with patient informed consent and Hospital ethical board approval. Case 1 A 56-yr-old male was referred to our department with a large chordoma (diagnosed with a biopsy) causing nasal obstruction. Preoperative imaging revealed a clivus chordoma with extension to the right petrous apex, right cavernous sinus, sphenoid sinus, and right pterygopalatine fossa, infratemporal fossa and parapharyngeal space (Figure 2A-2C). The patient had been previously operated for an endonasal septoplasty. In this case, a large vascularized flap was necessary to cover the right internal carotid artery (ICA; pharyngeal, petrous, and cavernous sinus portions) and the skull base defect along the clivus and the right cavernous sinus. Considering the facts that the right pterygopalatine fossa was invaded by the tumor, and that the septum was damaged by the previous surgery (reducing the size and the quality of the septal part of the flap), we decided to perform a left IT-NSF. The flap enabled a good coverage of the skull base defect and the postoperative magnetic resonance imaging (MRI) showed good positioning of the flap with a well-vascularized aspect on Gadolinium-enhanced sequences (Figure 2D-2F). In this case, the dura was not invaded by the tumor and was thus preserved, avoiding an intraoperative CSF leak. The postoperative course was uneventful. An endoscopic control done 2 wk after the surgery showed satisfactory healing of the nasal cavity and no sign of flap necrosis. The operative photos show the surgical technique (Figures 3 and 4). FIGURE 2. View largeDownload slide Coronal A, sagittal B, and axial C preoperative T1-weighted MRI with gadolinium enhancement showing a clivus chordoma with extension to the right petrous apex, right cavernous sinus, sphenoid sinus, and right pterygopalatine fossa, infratemporal fossa, and parapharyngeal space. Coronal D, sagittal E, and axial F postoperative (3 mo) T1-weighted MRI showing postoperative aspect of the flap and gross total resection (star: septal part of the flap; white arrow: inferior turbinate part of the flap). © 2017, Department of Neurosurgery, Lariboisière Hospital, Paris. Printed with permission. All rights reserved. FIGURE 2. View largeDownload slide Coronal A, sagittal B, and axial C preoperative T1-weighted MRI with gadolinium enhancement showing a clivus chordoma with extension to the right petrous apex, right cavernous sinus, sphenoid sinus, and right pterygopalatine fossa, infratemporal fossa, and parapharyngeal space. Coronal D, sagittal E, and axial F postoperative (3 mo) T1-weighted MRI showing postoperative aspect of the flap and gross total resection (star: septal part of the flap; white arrow: inferior turbinate part of the flap). © 2017, Department of Neurosurgery, Lariboisière Hospital, Paris. Printed with permission. All rights reserved. FIGURE 3. View largeDownload slide Intraoperative pictures demonstrating the essential steps of the procedure and the anatomic landmarks (part 1). A, intraoperative view of the left nasal fossa before starting the harvest of the flap with the tumor bulging in the cavum behind the suction device. B, The first cut is made along the posterior edge of the nasal septum and the floor of the nasal fossa immediately anterior to the junction between hard and soft palate (cut 1 and 2, white dashed line). C, Maxillary sinus and posterior ethmoid cells have been opened. D, Incisions along the superior and anterior aspect of the septum are made similarly to a classical NSF (cut 3). E and F, The horizontal cut above the inferior turbinate is performed (cut 4); G, the mucosa is detached from the bone of the inferior turbinate. H, At the posterior aspect of the inferior turbinate, the cut is prolonged as posteriorly as possible in the direction of the sphenopalatine foramen (cut 5). I, The SPA running out from the sphenopalatine foramen is identified using a Doppler probe all along the procedure. Abbreviations: ec, ethmoid cell; fl, flap; fnf, floor of the nasal fossa; hp, hard palate; it, inferior turbinate; ns, nasal septum; ms, maxillary sinus; mt, middle turbinate, sp, soft palate; sr, sphenoid rostrum. © 2017, Department of Neurosurgery, Lariboisière Hospital, Paris. Printed with permission. All rights reserved. FIGURE 3. View largeDownload slide Intraoperative pictures demonstrating the essential steps of the procedure and the anatomic landmarks (part 1). A, intraoperative view of the left nasal fossa before starting the harvest of the flap with the tumor bulging in the cavum behind the suction device. B, The first cut is made along the posterior edge of the nasal septum and the floor of the nasal fossa immediately anterior to the junction between hard and soft palate (cut 1 and 2, white dashed line). C, Maxillary sinus and posterior ethmoid cells have been opened. D, Incisions along the superior and anterior aspect of the septum are made similarly to a classical NSF (cut 3). E and F, The horizontal cut above the inferior turbinate is performed (cut 4); G, the mucosa is detached from the bone of the inferior turbinate. H, At the posterior aspect of the inferior turbinate, the cut is prolonged as posteriorly as possible in the direction of the sphenopalatine foramen (cut 5). I, The SPA running out from the sphenopalatine foramen is identified using a Doppler probe all along the procedure. Abbreviations: ec, ethmoid cell; fl, flap; fnf, floor of the nasal fossa; hp, hard palate; it, inferior turbinate; ns, nasal septum; ms, maxillary sinus; mt, middle turbinate, sp, soft palate; sr, sphenoid rostrum. © 2017, Department of Neurosurgery, Lariboisière Hospital, Paris. Printed with permission. All rights reserved. FIGURE 4. View largeDownload slide Intraoperative pictures showing the essential steps of the procedure and the anatomical landmarks (part 2). A, The flap is elevated from the floor of the nasal fossa and dissected from the contralateral septal mucosa, then B, elevated from front to back exposing the initial cut at the junction between soft and hard palate (white dashed line). C and D, This cut is then prolonged laterally above the Eustachian tube (cut 6). E and F, The initial circular cut is then finalized by prolonging the initial cut at the posterior edge of the nasal septum to the inferior aspect of the choanal arch, in order to join laterally the cut above the Eustachian tube. G, The flap is then mobilized. H, In this case, the middle turbinate was conserved but the posterior wall of the maxillary sinus was resected and the sphenopalatine foramen opened to facilitate the mobilisation and the storage of the flap in the maxillary sinus. I, After tumor resection, the flap is positioned to cover the skull base defect. Abbreviations: ec, ethmoid cell; et, Eustachian tube; fl, flap; fnf, floor of the nasal fossa; it, inferior turbinate; ms, maxillary sinus; mt, middle turbinate; ns, nasal septum; Pa, ascending process of the palatine bone; sp, soft palate; hp, hard palate. © 2017, Department of Neurosurgery, Lariboisière Hospital, Paris. Printed with permission. All rights reserved. FIGURE 4. View largeDownload slide Intraoperative pictures showing the essential steps of the procedure and the anatomical landmarks (part 2). A, The flap is elevated from the floor of the nasal fossa and dissected from the contralateral septal mucosa, then B, elevated from front to back exposing the initial cut at the junction between soft and hard palate (white dashed line). C and D, This cut is then prolonged laterally above the Eustachian tube (cut 6). E and F, The initial circular cut is then finalized by prolonging the initial cut at the posterior edge of the nasal septum to the inferior aspect of the choanal arch, in order to join laterally the cut above the Eustachian tube. G, The flap is then mobilized. H, In this case, the middle turbinate was conserved but the posterior wall of the maxillary sinus was resected and the sphenopalatine foramen opened to facilitate the mobilisation and the storage of the flap in the maxillary sinus. I, After tumor resection, the flap is positioned to cover the skull base defect. Abbreviations: ec, ethmoid cell; et, Eustachian tube; fl, flap; fnf, floor of the nasal fossa; it, inferior turbinate; ms, maxillary sinus; mt, middle turbinate; ns, nasal septum; Pa, ascending process of the palatine bone; sp, soft palate; hp, hard palate. © 2017, Department of Neurosurgery, Lariboisière Hospital, Paris. Printed with permission. All rights reserved. Case 2 A 60-yr-old patient was referred to our department for a large skull base chordoma with right oculomotor nerve and left abducens nerve palsy. He had been previously operated through endonasal approaches 3 times. A significant volume of residual tumor was still present following the third surgery and the patient underwent radiotherapy. He was referred to our center 12 mo after radiotherapy with a symptomatic large growing lesion. Preoperative imaging showed a skull base chordoma, with extension to the sphenoid sinus, sellae turcica, both cavernous sinus, left infratemporal fossa and pterygopalatine fossa, and prepontine cistern (Figure 5A-5C). Considering that the patient was previously irradiated and that the ICA was expected to be exposed on a large segment after resection of the tumor, a vascularized flap was deemed necessary. Available options for vascularized coverage were thus reviewed, based on information obtained from the preoperative computed tomography (CT)-angiogram and MRI. Due to a central septal perforation resulting from previous EEAs (Figure 5B), a right NSF extended to the floor of the nasal fossa was expected to be insufficient in comparison to the size of the defect (however, the mucosa below and above the perforation was still available). The extended ITF on the left side was not available due to tumor invasion. On the preoperative CT-angiogram, the right SPA and PLNA were well delineated. We decided to perform a combined right IT-NSF, which was the only intranasal flap large enough to reach the left infratemporal fossa. We performed a right middle turbinectomy to facilitate bimanual work and flap mobilization. As we can see on Figure 5B and 5C, the retroclival dura in front of the pons was invaded by the tumor. However, the arachnoidal layer was kept intact, avoiding an intraoperative high-flow CSF leak. The dural defect was rebuilt with Tachosil and fibrin glue. The flap afterwards enabled a good coverage of the skull base defect. Positioning of the flap is figured on the postoperative MRI (Figure 5D-5F). The postoperative course was uneventful. FIGURE 5. View largeDownload slide Coronal A, sagittal B, and axial C preoperative T1-weighted MRI with gadolinium enhancement showing a large skull base chordoma, with extension to the sphenoid sinus, sellae turcica, both cavernous sinus, left sphenopalatine fossa, infratemporal fossa, and prepontine cistern. Note the septal perforation due to a previous surgery. Coronal D, sagittal E, and axial F immediate postoperative T1-weighted MRI with gadolinium enhancement showing total gross resection of the lesion and good positioning and vascularization of the flap (star: septal part of the flap; white arrow: inferior turbinate part of the flap). © 2017, Department of Neurosurgery, Lariboisière Hospital, Paris. Printed with permission. All rights reserved. FIGURE 5. View largeDownload slide Coronal A, sagittal B, and axial C preoperative T1-weighted MRI with gadolinium enhancement showing a large skull base chordoma, with extension to the sphenoid sinus, sellae turcica, both cavernous sinus, left sphenopalatine fossa, infratemporal fossa, and prepontine cistern. Note the septal perforation due to a previous surgery. Coronal D, sagittal E, and axial F immediate postoperative T1-weighted MRI with gadolinium enhancement showing total gross resection of the lesion and good positioning and vascularization of the flap (star: septal part of the flap; white arrow: inferior turbinate part of the flap). © 2017, Department of Neurosurgery, Lariboisière Hospital, Paris. Printed with permission. All rights reserved. DISCUSSION This report documents the surgical technique to harvest a 1-piece combined IT-NSF flap, with conservation of both vascular pedicles coming from the posterior septal and lateral nasal artery of the inferior turbinate. We used this technique in 2 cases of large skull base chordoma and this flap allowed for adequate mucosal coverage of the whole resection cavity in both cases despite very large postoperative defects. We speculated that the NSF alone would be insufficient to reconstruct the whole postoperative defect because of tumor extension toward the nasal floor and damage to the nasal septum during previous procedures (endoscopic septoplasty in the case presented in this article and septal perforation due to previous surgery in the other case). Another option for reconstruction would have been a temporoparietal fascia flap, although this technique would have increased the length and the morbidity of the procedure. Our technique consists of a combination of an extended NSF and an extended ITF flap. The major difference from previous description of extended nasoseptal or ITFs is the circular cut that enables the mobilization of the whole flap in 1 piece while preserving the 2 vascular pedicles (nasoseptal and inferior turbinate arteries). In a recent anatomic study, Wu et al16 described a combined posterior pedicled IT-NSF on cadaveric dissection. Their incisions were quite similar to what is presented in this report, but Wu et al16 kept only the posterolatero nasal artery, assuming that the anastomosis between the PLNA and the NSA allowed the PLNA to also supply the nasoseptal mucoperichondrium and mucoperiosteum. However, this technique was an anatomic report, not applied to a surgical case. Choby et al12 used an ITF extended to the nasoseptum, pedicled on the sole PLNA (called extended ITF in their study) with good result in 2 patients. Our technique of combined IT-NSF enables the harvest of a very large flap with a strong vascular supply since the 2 main pedicles are preserved. However, similarly to a standalone IT flap, the inferior turbinate pedicle can limit the arc of rotation of the flap and preclude optimal positioning of the flap. The circular cut around the choanal arch enables improved mobilization of the whole flap around the sphenopalatine pedicle and reduce overall tensions. Moreover, our technique requires a maxillary antrostomy to be able to individualize and dissect the mucosa around the SPA at its exit from the pterygopalatine fossa, which also increases the overall mobility of the flap. On the other hand, in large tumor with very large defect expected after resection, a maxillary antrostomy is most often required for the approach. In the presented case, the IT-NSF allowed for an extensive surface of mucosal coverage despite a damaged septum due to previous surgery. We believe that the IT-NSF can be an alternate option for endoscopic reconstruction of large skull base defects. After every expended endonasal surgery, care must be taken to diagnose and treat nasal crusting. We therefore systematically perform endoscopic controls and resection of the crusts at least twice after the surgery (at week 1 and 2), and monthly afterwards. Besides, the patient performs nasal cavity washes with saline 6-times a day during several weeks in order to prevent the formation of crusts. Nasal morbidity can thereby be significantly reduced. CONCLUSION The inferior turbinate-nasoseptal flap can be a useful alternative to traditional flaps in patients whose septal mucosa was partially damaged and/or with very large postoperative skull base defects. Disclosure Dr Froelich would like to acknowledge the material support of KARL STORZ SE & Co. KG to the Laboratoire d'anatomie neurochirurgicale de l'Hopital Lariboisière. REFERENCES 1. Patel MR, Taylor RJ, Hackman TG et al.   Beyond the nasoseptal flap: outcomes and pearls with secondary flaps in endoscopic endonasal skull base reconstruction. Laryngoscope . 2014; 124( 4): 846- 852. Google Scholar CrossRef Search ADS PubMed  2. Gardner PA, Kassam AB, Thomas A et al.   Endoscopic endonasal resection of anterior cranial base meningiomas. Neurosurgery . 2008; 63( 1): 36- 54. Google Scholar CrossRef Search ADS PubMed  3. Harvey RJ, Parmar P, Sacks R, Zanation AM. Endoscopic skull base reconstruction of large dural defects: a systematic review of published evidence. Laryngoscope . 2012; 122( 2): 452- 459. Google Scholar CrossRef Search ADS PubMed  4. 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  5. Fortes FSG, Carrau RL, Snyderman CH et al.   The posterior pedicle inferior turbinate flap: a new vascularized flap for skull base reconstruction. Laryngoscope . 2007; 117( 8): 1329- 1332. Google Scholar CrossRef Search ADS PubMed  6. Pinheiro-Neto CD, Snyderman CH. Nasoseptal flap. Adv Otorhinolaryngol . 2013; 74: 42- 55. doi:10.1159/000342271. Google Scholar PubMed  7. Suh JD, Chiu AG. Sphenopalatine-derived pedicled flaps. Adv Otorhinolaryngol . 2013; 74: 56- 63. doi:10.1159/000342275. Google Scholar PubMed  8. Meier JC, Bleier BS. Anteriorly based pedicled flaps for skull base reconstruction. Adv Otorhinolaryngol . 2013; 74: 64- 70. doi:10.1159/000342281. Google Scholar PubMed  9. Hadad G, Rivera-Serrano CM, Bassagaisteguy LH et al.   Anterior pedicle lateral nasal wall flap: a novel technique for the reconstruction of anterior skull base defects. Laryngoscope . 2011; 121( 8): 1606- 1610. Google Scholar CrossRef Search ADS PubMed  10. Nyquist GG, Anand VK, Singh A, Schwartz TH. Janus flap: bilateral nasoseptal flaps for anterior skull base reconstruction. Otolaryngol Head Neck Surg . 2010; 142( 3): 327- 331. Google Scholar CrossRef Search ADS PubMed  11. 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 Part B Skull Base . 2013; 74( 06): 369- 385. Google Scholar CrossRef Search ADS   12. Choby GW, Pinheiro-Neto CD, de Almeida JR et al.   Extended inferior turbinate flap for endoscopic reconstruction of skull base defects. J Neurol Surg Part B Skull Base . 2014; 75( 04): 225- 230. Google Scholar CrossRef Search ADS   13. Zanation AM, Snyderman CH, Carrau RL, Kassam AB, Gardner PA, Prevedello DM. Minimally invasive endoscopic pericranial flap: a new method for endonasal skull base reconstruction. Laryngoscope . 2009; 119( 1): 13- 18. Google Scholar CrossRef Search ADS PubMed  14. Oliver CL, Hackman TG, Carrau RL et al.   Palatal flap modifications allow pedicled reconstruction of the skull base. Laryngoscope . 2008; 118( 12): 2102- 2106. Google Scholar CrossRef Search ADS PubMed  15. Fortes FSG, Carrau RL, Snyderman CH et al.   Transpterygoid transposition of a temporoparietal fascia flap: a new method for skull base reconstruction after endoscopic expanded endonasal approaches. Laryngoscope . 2007; 117( 6): 970- 976. Google Scholar CrossRef Search ADS PubMed  16. Wu P, Li Z, Liu C, Ouyang J, Zhong S. The posterior pedicled inferior turbinate-nasoseptal flap: a potential combined flap for skull base reconstruction. Surg Radiol Anat . 2016; 38( 2): 187- 194. Google Scholar CrossRef Search ADS PubMed  COMMENTS This paper presents a combined vascularized flap for endonasal reconstruction combining the nasoseptal flap and inferior turbinate flap, connected with a circular incision around the choana. This is an interesting and innovative concept, presented by a very experienced skull base group. This flap does have some challenges and it is difficult to judge the efficacy of this flap given the lack of clinical cases to date, especially considering that only one involved an intraoperative CSF leak. Nevertheless, it is clear that there are applications for this technique and the efficacy will be defined as experience is gained. Difficulties with this flap include the natural curling of the proximal inferior turbinate pedicle and the limited arc of rotation of the IT flap which it would seem to do for this flap as well. The authors' experience with this aspect is valuable, and attention should be paid to the steps they outline for mobilizing the flap pedicle; this is especially difficult given the addition of a rounded central aspect of the flap surrounding the choana. Overall, these challenges render the flap with some significant limitations and therefore it may not be used regularly. However, having this option is important for advanced revision cases and, perhaps even more importantly, the knowledge and ability to understand the vascular supply, pedicle anatomy, and techniques for raising and rotating this flap are critical for any team performing complex endoscopic endonasal reconstruction. Paul A. Gardner Pittsburgh, Pennsylvania The authors describe a novel mucosal flap combining a nasal septal flap and an inferior turbinate flap based on 2 arterial pedicles that arise as branches from the sphenopalantine artery, namely 1) the nasospetal artery, and 2) the inferior turbinate artery branch of the posterolateral nasal artery. A detailed description of the technique is provided including the unique circular mucosal cut around the choana. Two case examples are described of large chordomas that were resected using endoscopic endonasal approaches using this novel flap for reconstruction of large skull base defects. I think that this technique is a useful potential option for closure of complex defects during endoscopic endonasal skull base surgery. Michael Robert Chicoine St. Louis, Missouri Copyright © 2018 by the Congress of Neurological Surgeons

Journal

Operative NeurosurgeryOxford University Press

Published: Mar 29, 2018

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