The posterior nasoseptal flap: A novel technique for closure after endoscopic transsphenoidal resection of pituitary adenomas
- Department of Neurosurgery, New York University School of Medicine, New York, USA
- Department of Radiology, New York University School of Medicine, New York, USA
- Department of Medicine, New York University School of Medicine, New York, USA
- Department of Pathology, New York University School of Medicine, New York, USA
- Department of Otolaryngology-Head and Neck Surgery, New York University School of Medicine, New York, USA
- Department of Perlmutter Cancer Center, New York University School of Medicine, New York, USA
- Department of Brain Tumor Center, New York University School of Medicine, New York, USA
Richard Lebowitz, Dimitris G. Placantonakis
Department of Neurosurgery, New York University School of Medicine, New York, USA
Department of Perlmutter Cancer Center, New York University School of Medicine, New York, USA
Department of Brain Tumor Center, New York University School of Medicine, New York, USA
DOI:10.4103/sni.sni_192_17Copyright: © 2018 Surgical Neurology International This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as the author is credited and the new creations are licensed under the identical terms.
How to cite this article: James Barger, Matthew Siow, Michael Kader, Katherine Phillips, Girish Fatterpekar, David Kleinberg, David Zagzag, Chandranath Sen, John G. Golfinos, Richard Lebowitz, Dimitris G. Placantonakis. The posterior nasoseptal flap: A novel technique for closure after endoscopic transsphenoidal resection of pituitary adenomas. 14-Feb-2018;9:32
How to cite this URL: James Barger, Matthew Siow, Michael Kader, Katherine Phillips, Girish Fatterpekar, David Kleinberg, David Zagzag, Chandranath Sen, John G. Golfinos, Richard Lebowitz, Dimitris G. Placantonakis. The posterior nasoseptal flap: A novel technique for closure after endoscopic transsphenoidal resection of pituitary adenomas. 14-Feb-2018;9:32. Available from: http://surgicalneurologyint.com/surgicalint-articles/the-posterior-nasoseptal-flap-a-novel-technique-for-closure-after-endoscopic-transsphenoidal-resection-of-pituitary-adenomas/
Background:While effective for the repair of large skull base defects, the Hadad-Bassagasteguy nasoseptal flap increases operative time and can result in a several-week period of postoperative crusting during re-mucosalization of the denuded nasal septum. Endoscopic transsphenoidal surgery for pituitary adenoma resection is generally not associated with large dural defects and high-flow cerebrospinal fluid (CSF) leaks requiring extensive reconstruction. Here, we present the posterior nasoseptal flap as a novel technique for closure of skull defects following endoscopic resection of pituitary adenomas. This flap is raised in all surgeries during the transnasal exposure using septal mucoperiosteum that would otherwise be discarded during the posterior septectomy performed in binostril approaches.
Methods:We present a retrospective, consecutive case series of 43 patients undergoing endoscopic transsphenoidal resection of a pituitary adenoma followed by posterior nasoseptal flap placement and closure. Main outcome measures were extent of resection and postoperative CSF leak.
Results:The mean extent of resection was 97.16 ± 1.03%. Radiographic measurement showed flap length to be adequate. While a defect in the diaphragma sellae and CSF leak were identified in 21 patients during surgery, postoperative CSF leak occurred in only one patient.
Conclusions:The posterior nasoseptal flap provides adequate coverage of the surgical defect and is nearly always successful in preventing postoperative CSF leak following endoscopic transsphenoidal resection of pituitary adenomas. The flap is raised from mucoperiosteum lining the posterior nasal septum, which is otherwise resected during posterior septectomy. Because the anterior septal cartilage is not denuded, raising such flaps avoids the postoperative morbidity associated with the larger Hadad-Bassagasteguy nasoseptal flap.
Keywords: Cerebrospinal fluid leak, closure, endoscopy, nasoseptal flap, pituitary adenoma
Pituitary adenomas are a common benign intracranial neoplasm comprising 15.5% of all primary central nervous system (CNS) neoplasms.[
Transsphenoidal pituitary surgery may be performed either microscopically or endoscopically. While both techniques are cost-effective compared to medical therapies alone in patients with a life expectancy greater than ten years,[
Repairing CSF leaks is crucial in preventing serious postoperative infectious complications. The creation of a fistula between the subarachnoid space and nasal cavity carries the risks of bacterial spread from the nasal cavity, potentially leading to ascending meningitis.[
Nasoseptal and middle turbinate rotational flaps have been used since the 1950s, but these early flaps had a random blood supply and unfavorable arcs of rotation. Hadad and Bassagasteguy developed an improved, pedicled vascularized nasoseptal flap in 2006.[
This study represents a retrospective analysis of a prospectively constructed database of 43 serial patients who underwent endoscopic transsphenoidal resection of pituitary adenomas with posterior nasoseptal flap placement at our institution between March, 2014 and June, 2015. Patient charts were reviewed for a number of preoperative, intraoperative, and postoperative parameters, including intra and postoperative CSF leaks. This database does not include patients who were deemed to require an extended transsphenoidal approach for resection of their tumor during preoperative surgical planning. Such patients were reconstructed with Hadad-Bassagasteguy nasoseptal flaps.
After the induction of general endotracheal anesthesia, the patient's nose is decongested with oxymetazoline-soaked cottonoids. The nasal passages are carefully examined, after which the inferior turbinates are first in-fractured and subsequently out-fractured to improve access via the nasal passages. The middle turbinates are injected with 1% lidocaine with epinephrine (1:100,000) for anesthesia and hemostasis, and lateralized using the Freer elevator. The superior turbinates are also visualized and lateralized, allowing for identification of the sphenoid ostium in the sphenoethmoidal recess bilaterally. For larger tumors or cases in which more lateral access is needed, the middle and/or superior turbinates may be partially resected.
The posterior nasoseptal flap is typically raised on the left side unless anatomic or surgical considerations dictate otherwise; however, this is just a matter of surgeon preference. The anterior aspect of the middle turbinate marks the anterior extent of the posterior nasoseptal flap. Directly medial to this point, the mucosa of the midnasal septum is cauterized vertically and incised. From there, the mucoperiosteum is raised posteriorly to the level of the sphenoid rostrum. The sphenoid ostium is identified submucosally as an anatomic landmark, and the septal mucoperiosteum is transected inferiorly along the maxillary crest and dorsally below the expected level of the olfactory epithelium. This creates a posterior septal flap, pedicled on the posterior septal branch of the sphenopalatine artery [
The mucosa of the contralateral septum is then similarly cauterized and incised. The flap is raised from that point posteriorly and the ostium of the sphenoid is identified. The mucosa and bone of the posterior septum on this second side is then resected, thus creating a central surgical corridor between the turbinates with access to both sphenoid sinuses. Because a posterior septectomy is performed to facilitate a binostril approach for tumor resection, the posterior septal flap can be preserved on both sides if it is felt to be necessary for reconstruction.
After elevation of the flap(s) and creation of a central surgical corridor with access to both sphenoid sinuses, the standard tumor resection is performed by the neurosurgeon. If an intraoperative CSF leak occurs, the dural opening is repaired using medium implantable (0.5–1.0 mm) AlloDerm (LifeCell Corporation, New Jersey, USA) placed in an “inlay” fashion in the epidural space just deep to the residual bone of the sella. The graft is then covered with a thin layer of Tisseel (Baxter Inc., Illinois, USA) tissue adhesive to maintain its position.
Whether there has been an intraoperative CSF leak, the posterior septal flap is rotated into position covering the demucosalized bone of the sphenoid rostrum and floor as well as the area of the dural opening. Intersinus septations are removed and the sphenoid rostrum is drilled as needed to allow for direct overlay of the flap along the floor of the sella. The flap is covered with Tisseel tissue adhesive and Gelfoam. A sphenoid pack consisting of 0.5-inch Nu Gauze (Johnson and Johnson, New Jersey, USA) coated in bacitracin ointment is then placed to maintain the position of the flap and underlying grafts. The pack is brought out through the nasal cavity and secured to the membranous septum with a single suture. At the completion of the procedure, the middle turbinates are medialized to their normal anatomic position.
Patients are monitored postoperatively for signs of CSF leak, diabetes insipidus, and pituitary dysfunction, and given stool softeners to reduce straining. For patients who did not have intraoperative CSF leaks, the nasal packing is removed before discharge (typically postoperative day 2 or 3). If an intraoperative CSF leak did occur, the packing is left in place until the 1-week postoperative visit.
Calculation of tumor volume
Tumor volumes were calculated based on the (A × B × C)/2 formula, where A, B, and C represent the largest tumor dimension in the anterior-posterior, superior-inferior, and medio-lateral dimensions.
All statistical analyses were performed with Prism (Graphpad). Population means were compared with Student's t-test. Population statistics are presented as mean ± standard error. Linear correlations were analyzed with Spearman correlation coefficient. Significance was set at P < 0.05.
Patient demographic information and data related to tumors and surgical parameters are shown in
Intraoperative CSF leaks were noted in 21 (48.8%) of the patients [
Postoperatively, 2 patients were treated for presumed CSF rhinorrhea, but a CSF leak was confirmed in only one of them. This patient had no documented intraoperative leak, and the skull base defect had been repaired with the posterior septal flap. However, postoperatively, the patient experienced difficulty in breathing and oxygen desaturation, which led us to remove the nasal packing. The leak occurred subsequent to the packing removal while the patient was straining during a bowel movement. She was treated with secondary surgical repair and lumbar drain placement. The second patient had a small intraoperative leak repaired with the multilayered closure. Clear rhinorrhea, suspicious for a CSF leak, was noted on postoperative day 1. A lumbar drain was placed before β2-transferrin results returned negative, indicating that there was, in fact, no CSF leak. Overall, the posterior nasoseptal flap has a 97.7% success rate in preventing postoperative CSF leaks despite a 48.8% rate of observable intraoperative leaks. Furthermore, barring extenuating circumstances, such as Valsalva maneuvers, the success rate is expected to be even closer to 100%.
Planning the posterior nasoseptal flap
A review of the preoperative MRI showed the distance between the sphenoid rostrum and the middle turbinate (the length of the flap) to be longer than the distance between the sphenoid rostrum and the posterior sphenoid (the length of the defect) in all but 4 cases; on average, it was 5.61 ± 0.69 mm longer [
(a) Representative preoperative sagittal gadolinium-enhanced T1-weighted image demonstrates the lengths of the flap and skull defect. (b) Intraoperative photograph through the endoscope demonstrates the posterior nasoseptal flap covering the skull defect. (c) In the postoperative MRI, the vascularized flap (arrows) can be visualized lining the patent sphenoid sinus. (d) Endoscopic photograph of the flap 2 years after the initial surgery
Cerebrospinal fluid leak repair
The pituitary gland, seated in the sella turcica, is considered an intradural, extra-arachnoidal part of the brain by virtue of the diaphragma sellae, a reflection of the arachnoid, that separates it from the suprasellar cistern. Because the pituitary is extra-arachnoidal, CSF leaks do not occur as a matter of course during pituitary surgery but rather as a consequence of violation of the diaphragma sellae during tumor resection. The attempt to achieve gross total tumor resection often results in violation of the diaphragma sellae. Our intraoperative CSF leak rate of approximately 49% matches previously published reports,[
Persistent CSF leaks after pituitary adenoma surgery are a concern because they can lead to ascending meningitis. Multiple repair techniques have been described over the years. In 2006, Hadad and Bassagasteguy described a pedicled nasoseptal flap with excellent vascular supply and a wide arc of rotation, and reported success rates in excess of 90%.[
The Hadad-Bassagestaguy flap, though extremely effective, was conceived for use in the setting of intraoperative CSF leaks in extended transsphenoidal approaches for resection of skull base tumors other than pituitary adenomas.[
The posterior nasoseptal flap represents a modification of the Hadad-Bassagestaguy flap, but is smaller and consists primarily of mucosal tissue that is otherwise discarded during the posterior septectomy for the binostril transsphenoidal approach. As such, the crusting associated with denuded septal cartilage after raising Hadad-Bassagestaguy flaps is minimized with posterior flaps. Another fundamental difference between the two approaches is that we raise the posterior flap in all surgeries, regardless of anticipated or observed intraoperative CSF leak, without much added operative time.
In our experience, the posterior septal flap provides excellent coverage for surgical defects associated with endoscopic transsphenoidal surgery for pituitary adenomas, obviating the need for a full-length nasoseptal flap. The posterior nasoseptal flap has the additional advantage of being placed in all cases, thus preventing postoperative leaks from arachnoidal defects and small CSF leaks that may not have been noted during the procedure, as occurred in one of the patients in the study. Importantly, using this flap in all surgical cases for endoscopic pituitary adenectomy virtually eliminates the risk of postoperative CSF leak. This allows us to pursue aggressive resection of pituitary adenomas, as evidenced by the 97% extent of resection in our series. It should be emphasized that this flap is not conceived for use in cases involving larger skull base defects, as in extended transsphenoidal or transnasal approaches, which require the use of full Hadad-Bassagestaguy flaps.
Multilayered closure in cases with documented intraoperative cerebrospinal fluid leak
In cases where we identify a CSF leak intraoperatively, we employ a multilayered approach for closure of the skull defect. A layer of Alloderm is placed in the epidural space tucked under the edges of the remaining sellar bone and covering the dural opening at the floor of the sella. After a thin layer of Tisseel, we place the posterior nasoseptal flap over the Alloderm. This strategy provides two barriers preventing postoperative leaks. We only rarely have to consider use of abdominal fat graft or lumbar drain using this approach. In fact, none of our patients with documented intraoperative CSF leaks had postoperative CSF rhinorrhea. The only patient in our cohort with postoperative rhinorrhea developed it as a result of straining despite no evidence of an intraoperative leak.
Alloderm has been previously used by itself for closure of skull base defects in endoscopic surgery.[
The Hadad-Bassagasteguy nasoseptal flap causes donor site morbidity because of exposure of the anterior septal cartilage. This denuded cartilage takes months to fully re-mucosalize and requires repeated office debridement, as well as the use of topical ointments and saline rinses during the healing period.[
In a study of 200 patients who underwent microscopic transsphenoidal hypophysectomy between 1998 and 2001, the incidence of isolated sphenoid sinusitis in the year following surgery was 7.5%.[
The posterior nasoseptal flap is a novel technique that uses septal mucoperiosteum, which would otherwise be resected during the posterior septectomy, to prevent postoperative CSF leaks following endoscopic transsphenoidal resection of pituitary adenomas. The flap is raised in all cases, regardless of anticipated or observed intraoperative CSF leak. In addition, the flap provides early vascularized coverage of the demucosalized bone of the sphenoid sinus. It is raised at the beginning of the case and provides adequate coverage of the sellar defect without the need for further extension of the flap in the event of an intraoperative CSF leak. In our experience, the flap heals well, maintains a patent sphenoidotomy, and can be elevated and reused if revision surgery is necessary. This approach is uncomplicated, safe, and has advantages relative to alternative flap techniques, such as the rescue flap and the Hadad-Bassagasteguy nasoseptal flap. While not appropriate for closure of larger approaches, the use of the posterior nasoseptal flap virtually eliminates the risk of postoperative CSF leak after pituitary adenectomy, thereby allowing surgeons to pursue complete resection of these benign tumors despite the elevated rate of intraoperative CSF leak associated with aggressive surgery. For these reasons, we propose that the posterior nasoseptal flap is an excellent option for skull defect closure following endoscopic transsphenoidal pituitary adenectomy.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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